WO2011138743A1

WO2011138743A1 - Use of pyromellitic diimides in organic electronics and organic photovoltaics

Info

Publication number: WO2011138743A1
Application number: PCT/IB2011/051965
Authority: WO
Inventors: Jianqiang Qu; Ralf Kopecek; Anette SAUERHÖFER; Martin KÖNEMANN; Jochen Brill; Sorin Ivanovici; Ulrich Schalkowsky; Thomas Musiol; Hagen Klauk; Ute Zschieschang
Original assignee: Basf Se; Basf (China) Company Limited
Priority date: 2010-05-06
Filing date: 2011-05-04
Publication date: 2011-11-10

Abstract

Disclosed are pyromellitic diimides of the general formula (I), wherein X¹, X², R¹ and R² are defined as in the description. Uses of said pyromellitic diimides in organic electronics and organic photovoltaics are also disclosed.

Description

Use of pyromellitic diimides in organic electronics and organic photovoltaics

Description The present invention relates to the use of pyromellitic diimides in organic electronics and organic photovoltaics.

It is expected that, in the future, not only the classical inorganic semiconductors but increasingly also organic semiconductors based on low molecular weight or polymeric materials will be used in many sectors of the electronics industry. In many cases, these organic semiconductors have advantages over the classical inorganic semiconductors, for example better substrate compatibility and better processibility of the semiconductor components based on them. They allow processing on flexible substrates and enable their interface orbital energies to be adjusted precisely to the particular application range by the methods of molecular modeling. The significantly reduced costs of such components have brought a renaissance to the field of research of organic electronics.

Organic electronics is concerned principally with the development of new materials and manufacturing processes for the production of electronic components based on organic semiconductor layers. These include in particular organic field-effect transistors (OFETs) and organic electroluminescent devices (hereinafter abbreviated as "EL" devices). Great potential for development is ascribed to organic field-effect transistors, for example in storage elements and integrated optoelectronic devices. An organic electroluminescent device is a self-emission device utilizing the principle that a fluorescent material emits light by the recombination energy of holes injected from an anode and electrons injected from a cathode when an electric field is applied. EL devices in form of organic light-emitting diodes (OLEDs) are especially of interest as an alternative to cathode ray tubes and liquid-crystal displays for producing flat visual display units. Owing to the very compact design and the intrinsically low power consumption, devices which comprise OLEDs are suitable especially for mobile applications, for example for applications in cell phones, laptops, etc.

Organic photovoltaics is concerned principally with the development of new materials for organic solar cells. A great potential for development is ascribed to materials which have maximum transport widths and high mobilities for light-induced excited states (high exciton diffusion lengths) and are thus advantageously suitable for use as an active material in so-called excitonic solar cells. It is generally possible with solar cells based on such materials to achieve very good quantum yields. There is therefore a great need for organic compounds which are suitable as charge transport materials or exciton transport materials. Q. Zheng, J. Huang, A. Sarjeant and H. Katz describe in J. Am . Chem. Soc. 2008, 130, 14410 - 1441 1 the use of pyromellitic diimides for high mobility n-channel transistor semiconductors. The benzene rings of the pyromellitic diimides do not bear additional substituents.

US 2007/0160905 describes imide derivatives of the formula (A)

wherein R^a and R^b are each a hydrogen atom, a halogen atom, a cyano group, an alkyl group, a fluoroalkyl group or an aryl group; at least one of R^a and R^b is a fluoroalkyl group; and R^c and R^d are each a substituted or unsubstituted benzyl group, an aryl group, a heterocycle, a fluoroalkyl group or an imide group. The only concrete disclosure of the fluoroalkyl group is trifluoromethyl and pentafluoroethyl.

Also disclosed in this document is a material for an organic electroluminescent device of the formula (B)

wherein R¹¹ to R²⁰ are each a hydrogen atom, a halogen atom, a fluoroalkyl group or a cyano group, provided that a material, wherein all of R¹¹ to R²⁰ are a hydrogen atom is excluded. It has now been found that, surprisingly, substituted pyromellitic diimides with certain (especially electron withdrawing) groups bound to the benzene ring are particularly advantageous as semiconductor materials in organic electronics and organic photovoltaics. The invention therefore provides for the use of compounds of the general formula (I)

(I)

wherein R¹ and R² are each independently selected from branched C3-C3o-alkyl,

linear or branched perfluoro-Ci-C3o-alkyl,

linear or branched 1 H,1 H-perfluoro-C2-C3o-alkyl,

linear or branched 1 H,1 H,2H,2H-perfluoro-C3-C3o-alkyl,

or a phenyl-(Ci-C3o)-alkyl group, wherein the benzene ring of the phenylalkyl group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI, Br,

CN and perfluoro-Ci-C3o-alkyl,

X¹ and X² are each independently selected from F, CI, Br, CN, COOR^a, CONR^bR^c, branched C3-C3o-alkyl,

linear or branched perfluoro-C3-C3o-alkyl,

linear or branched 1 H,1 H-perfluoro-C2-C3o-alkyl,

linear or branched 1 H,1 H,2H,2H-perfluoro-C3-C3o-alkyl,

branched NH(C₃-C₃₀-alkyl),

linear or branched NH(perfluoro-Ci-C3o-alkyl),

linear or branched NH(1 H,1 H-perfluoro-C2-C3o-alkyl) or

linear or branched NH(1 H,1 H,2H,2H-perfluoro-C₃-C₃o-alkyl),

R^a, R^b and R^c are each independently hydrogen or Ci-C3o-alkyl, as a semiconductor material in organic electronics or in organic photovoltaics.

In the compounds of the formula (I), the R¹ and R² radicals may have identical or different definitions. In a preferred embodiment, the R¹ and R² radicals have identical definitions.

In the compounds of the formula (I), the X¹ and X² radicals may have identical or different definitions.

Preferably, in the compounds of the formula (I) X¹ and X² are both F. Additionally preferably, in the compounds of the formula (I) X¹ and X² are both CI. Additionally preferably, in the compounds of the formula (I) X¹ and X² are both Br.

Additionally preferably, in the compounds of the formula (I) X¹ and X² are both CN. Additionally preferably, in the compounds of the formula (I) X¹ and X² are both perfluoro-C3-C3o-alkyl. In particular, the perfluoro-C3-C3o-alkyl groups X¹ and X² have the same meaning.

Additionally preferably, in the compounds of the formula (I) one of the radicals X¹ and X² is selected from halogen and the other is selected from

branched NH(C₃-C₃₀-alkyl), NH(perfluoro-Ci-C₃o-alkyl),

NH(1 H,1 H-perfluoro-C₂-C₃o-alkyl) and NH(1 H,1 H,2H,2H-perfluoro-C₃-C₃o-alkyl).

Preferably, in the compounds of the formula (I) R¹ and R² are each independently selected from branched C3-C3o-alkyl.

Additionally preferably, in the compounds of the formula (I) R¹ and R² are each independently selected from perfluoro-Ci-C3o-alkyl. More preferably, R¹ and R² have the same meaning and are perfluoro-Ci-C3o-alkyl.

Additionally preferably, in the compounds of the formula (I) R¹ and R² are each independently selected from 1 H,1 H-perfluoro-C2-C3o-alkyl. More preferably, R¹ and R² have the same meaning and are 1 H,1 H-perfluoro-C2-C3o-alkyl. Additionally preferably, in the compounds of the formula (I) R¹ and R² are each independently selected from 1 H,1 H,2H,2H-perfluoro-C3-C3o-alkyl. More preferably, R¹ and R² have the same meaning and are 1 Η,Ι H,2H,2H-perfluoro-C3-C3o-alkyl.

Additionally preferably, in the compounds of the formula (I) R¹ and R² are each independently selected from phenyl-(Ci-C3o)-alkyl groups, wherein the benzene ring of the phenylalkyl group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI, Br, CN and perfluoro-Ci-C3o-alkyl and the phenylalkyl group is attached to imide nitrogen atom via the alkyl moiety of the phenylalkyl group. More preferably, R¹ and R² have the same meaning and are selected from phenylalkyl groups, wherein the benzene ring of the phenylalkyl group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI, Br, CN and perfluoro-Ci-C3o-alkyl.

Additionally preferably, in the compounds of the formula (I), at least one of the radicals R¹ and R² is a group of the formula COOR^a, wherein R^a is preferably hydrogen or Ci-C2o-alkyl. More preferably R^a is hydrogen or Ci-Cio-alkyl. If R^a is Ci-Cio-alkyl it is preferably selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec. -butyl, tert. -butyl, n-pentyl and n-hexyl. In a special embodiment, in the compounds of the formula (I), R¹ and R² have the same meaning and are both a group of the formula COOR^a.

Additionally preferably, in the compounds of the formula (I), at least one of the radicals R¹ and R² is a group of the formula CONR^bR^c, wherein R^b and R^c are preferably each independently hydrogen or Ci-C2o-alkyl. More preferably R^b and R^c are each independently hydrogen or Ci-Cio-alkyl. If R^b and/or R^c is Ci-Cio-alkyl it is preferably selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert. -butyl, n-pentyl or n-hexyl. In a special embodiment, in the compounds of the formula (I), R¹ and R² have the same meaning and are both a group of the formula CONR^bR^c.

Preferably, at least one of the radicals R¹, R², X¹ and/or X² is a branched C3-C3o-alkyl group or at least one of the radicals X¹ and/or X² is a branched NH(C3-C3o-alkyl) group. Then, the branched C3-C3o-alkyl groups are preferably selected from groups of the formula (II)

wherein

# represents the bonding site to an imide nitrogen atom or the benzene ring, and q is an integer of 0, 1 , 2, 3, 4, 5 or 6,

R^d and R^e are each independently selected from Ci-C28-alkyl, with the proviso that the total number of carbon atoms of group (II) is 3 to 30.

In the groups of the formula (I I), q is preferably 0 or 1 , more preferably 0.

Radicals of the formula (I I) comprise those in which q is 0, for example

1-ethylpropyl, 1-methylpropyl, 1-propylbutyl, 1-ethylbutyl, 1-methylbutyl, 1-butylpentyl, 1-propylpentyl, 1-ethylpentyl, 1-methylpentyl, 1-pentylhexyl, 1-butylhexyl,

1-propylhexyl, 1-ethylhexyl, 1-methylhexyl, 1-hexylheptyl, 1-pentylheptyl, 1-butylheptyl, 1-propylheptyl, 1-ethylheptyl, 1-methylheptyl, 1-heptyloctyl, 1-hexyloctyl, 1-pentyloctyl, 1-butyloctyl, 1-propyloctyl, 1-ethyloctyl, 1-methyloctyl, 1-octylnonyl, 1-heptylnonyl, 1-hexylnonyl, 1-pentylnonyl, 1-butylnonyl, 1-propylnonyl, 1-ethylnonyl, 1-methylnonyl, 1-nonyldecyl, 1-octyldecyl, 1-heptyldecyl, 1-hexyldecyl, 1-pentyldecyl, 1-butyldecyl, 1-propyldecyl, 1-ethyldecyl, 1-methyldecyl, 1-decylundecyl, 1-nonylundecyl,

1-octylundecyl, 1-heptylundecyl, 1-hexylundecyl, 1-pentylundecyl, 1-butylundecyl, 1 -propylundecyl, 1-ethylundecyl, 1-methylundecyl, 1-undecyldodecyl, 1-decyldodecyl, 1-nonyldodecyl, 1-octyldodecyl, 1-heptyldodecyl, 1-hexyldodecyl, 1-pentyldodecyl, 1 -butyldodecyl, 1-propyldodecyl, 1-ethyldodecyl, 1-methyldodecyl, 1-dodecyltridecyl, 1-undecyltridecyl, 1-decyltridecyl, 1-nonyltridecyl, 1-octyltridecyl, 1-heptyltridecyl, 1-hexyltridecyl, 1-pentyltridecyl, 1-butyltridecyl, 1-propyltridecyl, 1-ethyltridecyl, 1-methyltridecyl, 1-tridecyltetradecyl, 1-undecyltetradecyl, 1-decyltetradecyl,

1-nonyltetradecyl, 1-octyltetradecyl, 1-hetyltetradecyl, 1-hexyltetradecyl,

1-pentyltetradecyl, 1-butyltetradecyl, 1-propyltetradecyl, 1-ethyltetradecyl,

1 -methyltetradecyl, 1-pentadecylhexadecyl, 1-tetradecylhexadecyl, 1-tridecylhexadecyl, 1-dodecylhexadecyl, 1-undecylhexadecyl, 1-decylhexadecyl, 1-nonylhexadecyl, 1-octylhexadecyl, 1-heptylhexadecyl, 1-hexylhexadecyl, 1-pentylhexadecyl,

1-butylhexadecyl, 1-propylhexadecyl, 1-ethylhexadecyl, 1-methylhexadecyl,

1 -hexadecyloctadecyl, 1 -pentadecyloctadecyl, 1 -tetradecyloctadecyl,

1-tridecyloctadecyl, 1-dodecyloctadecyl, 1-undecyloctadecyl, 1-decyloctadecyl, 1-nonyloctadecyl, 1-octyloctadecyl, 1-heptyloctadecyl, 1-hexyloctadecyl,

1-pentyloctadecyl, 1-butyloctadecyl, 1-propyloctadecyl, 1-ethyloctadecyl,

1-methyloctadecyl, 1-nonadecyleicosanyl, 1-octadecyleicosanyl,

1 -heptadecyleicosanyl, 1 -hexadecyleicosanyl, 1 -pentadecyleicosanyl,

1-tetradecyleicosanyl, 1-tridecyleicosanyl, 1-dodecyleicosanyl, 1-undecyleicosanyl, 1-decyleicosanyl, 1-nonyleicosanyl, 1-octyleicosanyl, 1-heptyleicosanyl,

1-hexyleicosanyl, 1-pentyleicosanyl, 1-butyleicosanyl, 1-propyleicosanyl,

1-ethyleicosanyl, 1-methyleicosanyl, 1-eicosanyldocosanyl, 1-nonadecyldocosanyl, 1 -octadecyldocosanyl, 1 -heptadecyldocosanyl, 1 -hexadecyldocosanyl,

1 -pentadecyldocosanyl, 1 -tetradecyldocosanyl, 1 -tridecyldocosanyl,

1-undecyldocosanyl, 1-decyldocosanyl, 1-nonyldocosanyl, 1-octyldocosanyl,

1-heptyldocosanyl, 1-hexyldocosanyl, 1-pentyldocosanyl, 1-butyldocosanyl,

1-propyldocosanyl, 1-ethyldocosanyl, 1-methyldocosanyl, 1-tricosanyltetracosanyl, 1 -docosanyltetracosanyl, 1 -nonadecyltetracosanyl, 1 -octadecyltetracosanyl,

1 -heptadecyltetracosanyl, 1 -hexadecyltetracosanyl, 1 -pentadecyltetracosanyl,

1 -pentadecyltetracosanyl, 1-tetradecyltetracosanyl, 1-tridecyltetracosanyl,

1 -dodecyltetracosanyl, 1 -undecyltetracosanyl, 1 -decyltetracosanyl,

1-nonyltetracosanyl, 1-octyltetracosanyl, 1-heptyltetracosanyl, 1-hexyltetracosanyl, 1-pentyltetracosanyl, 1-butyltetracosanyl, 1-propyltetracosanyl, 1-ethyltetracosanyl, 1 -methyltetracosanyl, 1 -heptacosanyloctacosanyl, 1 -hexacosanyloctacosanyl,

1-pentacosanyloctacosanyl, 1-tetracosanyloctacosanyl, 1-tricosanyloctacosanyl, 1 -docosanyloctacosanyl, 1 -nonadecyloctacosanyl, 1 -octadecyloctacosanyl,

1 -heptadecyloctacosanyl, 1 -hexadecyloctacosanyl, 1 -hexadecyloctacosanyl,

1 -pentadecyloctacosanyl, 1 -tetradecyloctacosanyl, 1 -tridecyloctacosanyl,

1 -dodecyloctacosanyl, 1-undecyloctacosanyl, 1-decyloctacosanyl, 1-nonyloctacosanyl, 1-octyloctacosanyl, 1-heptyloctacosanyl, 1-hexyloctacosanyl, 1-pentyloctacosanyl, 1-butyloctacosanyl, 1-propyloctacosanyl, 1-ethyloctacosanyl, 1-methyloctacosanyl; in which q is 1 , for example

2-methylpropyl, 2-ethylbutyl, 2-methylbutyl, 2-butylpentyl, 2-propylpentyl, 2-ethylpentyl, 2-methylpentyl, 2-butylhexyl, 2-propylhexyl, 2-ethylhexyl, 2-methylhexyl, 2-pentylheptyl, 2-butylheptyl, 2-propylheptyl, 2-ethylheptyl, 2-methylheptyl, 2-heptyloctyl, 2-hexyloctyl, 2-pentyloctyl, 2-butyloctyl, 2-propyloctyl, 2-ethyloctyl, 2-methyloctyl, 2-heptylnonyl, 2-hexylnonyl, 2-pentylnonyl, 2-butylnonyl, 2-propylnonyl, 2-ethylnonyl, 2-methylnonyl, 2-octyldecyl, 2-heptyldecyl, 2-hexyldecyl, 2-pentyldecyl, 2-butyldecyl, 2-propyldecyl, 2-ethyldecyl, 2-methyldecyl, 2-nonylundecyl, 2-octylundecyl, 2-heptylundecyl,

2-hexylundecyl, 2-pentylundecyl, 2-butylundecyl, 2-propylundecyl, 2-ethylundecyl, 2_methylundecyl, 2-decyldodecyl, 2-nonyldodecyl, 2-octyldodecyl, 2-heptyldodecyl, 2-hexyldodecyl, 2-pentyldodecyl, 2-butyldodecyl, 2-propyldodecyl, 2-ethyldodecyl, 2-methyldodecyl, 2-undecyltridecyl, 2-decyltridecyl, 2-nonyltridecyl, 2-octyltridecyl, 2-heptyltridecyl, 2-hexyltridecyl, 2-pentyltridecyl, 2-butyltridecyl, 2-propyltridecyl, 2-ethyltridecyl, 2-methyltridecyl, 2-tridecyltetradecyl, 2-undecyltetradecyl,

2-decyltetradecyl, 2-nonyltetradecyl, 2-octyltetradecyl, 2-hetyltetradecyl,

2-hexyltetradecyl, 2-pentyltetradecyl, 2-butyltetradecyl, 2-propyltetradecyl,

2-ethyltetradecyl, 2-methyltetradecyl, 2-dodecylpentadecyl, 2-tetradecylhexadecyl, 2-tridecylhexadecyl, 2-dodecylhexadecyl, 2-undecylhexadecyl, 2-decylhexadecyl, 2-nonylhexadecyl, 2-octylhexadecyl, 2-heptylhexadecyl, 2-hexylhexadecyl,

2-pentylhexadecyl, 2-butylhexadecyl, 2-propylhexadecyl, 2-ethylhexadecyl,

2-methylhexadecyl, 2-tetradecylheptadecyl, 2-pentadecyloctadecyl,

2-tetradecyloctadecyl, 2-tridecyloctadecyl, 2-dodecyloctadecyl, 2-undecyloctadecyl, 2-decyloctadecyl, 2-nonyloctadecyl, 2-octyloctadecyl, 2-heptyloctadecyl,

2-hexyloctadecyl, 2-pentyloctadecyl, 2-butyloctadecyl, 2-propyloctadecyl,

2-ethyloctadecyl, 2-methyloctadecyl, 2-pentadecylnonadecyl, 2-heptadecyleicosyl, 2-octadecyleicosanyl, 2-heptadecyleicosanyl, 2-hexadecyleicosanyl,

2-pentadecyleicosanyl, 2-tetradecyleicosanyl, 2-tridecyleicosanyl, 2-dodecyleicosanyl, 2-undecyleicosanyl, 2-decyleicosanyl, 2-nonyleicosanyl, 2-octyleicosanyl,

2-heptyleicosanyl, 2-hexyleicosanyl, 2-pentyleicosanyl, 2-butyleicosanyl,

2-propyleicosanyl, 2-ethyleicosanyl, 2-methyleicosanyl, 2-octadecylhenicoeicosanyl, 2-eicosanyldocosanyl, 2-nonadecyldocosanyl, 2-octadecyldocosanyl,

2-heptadecyldocosanyl, 2-hexadecyldocosanyl, 2-pentadecyldocosanyl,

2-tetradecyldocosanyl, 2-tridecyldocosanyl, 2-undecyldocosanyl, 2-decyldocosanyl, 2-nonyldocosanyl, 2-octyldocosanyl, 2-heptyldocosanyl, 2-hexyldocosanyl,

2-pentyldocosanyl, 2-butyldocosanyl, 2-propyldocosanyl, 2-ethyldocosanyl,

2-methyldocosanyl, 2-tricosanyltetracosanyl, 2-docosanyltetracosanyl,

2-nonadecyltetracosanyl, 2-octadecyltetracosanyl, 2-heptadecyltetracosanyl,

2-hexadecyltetracosanyl, 2-pentadecyltetracosanyl, 2-pentadecyltetracosanyl,

2-tetradecyltetracosanyl, 2-tridecyltetracosanyl, 2-dodecyltetracosanyl,

2-undecyltetracosanyl, 2-decyltetracosanyl, 2-nonyltetracosanyl, 2-octyltetracosanyl, 2-heptyltetracosanyl, 2-hexyltetracosanyl, 2-pentyltetracosanyl, 2-butyltetracosanyl, 2-propyltetracosanyl , 2-ethyltetracosanyl , 2-methyltetracosanyl , 2-heptacosanyloctacosanyl, 2-hexacosanyloctacosanyl, 2-pentacosanyloctacosanyl, 2-tetracosanyloctacosanyl, 2-tricosanyloctacosanyl, 2-docosanyloctacosanyl,

2-nonadecyloctacosanyl, 2-octadecyloctacosanyl, 2-heptadecyloctacosanyl,

2-hexadecyloctacosanyl, 2-hexadecyloctacosanyl, 2-pentadecyloctacosanyl,

2-tetradecyloctacosanyl, 2-tridecyloctacosanyl, 2-dodecyloctacosanyl,

2-undecyloctacosanyl, 2-decyloctacosanyl, 2-nonyloctacosanyl, 2-octyloctacosanyl, 2-heptyloctacosanyl, 2-hexyloctacosanyl, 2-pentyloctacosanyl, 2-butyloctacosanyl, 2-propyloctacosanyl, 2-ethyloctacosanyl, 2-methyloctacosanyl; in which q is 2, such as

3-methylbutyl, 3-ethylpentyl, 3-methylpentyl, 3-propylhexyl, 3-ethylhexyl, 3-methylhexyl, 3-butylheptyl, 3-propylheptyl, 3-ethylheptyl, 3-methylheptyl, 3-heptyloctyl, 3-hexyloctyl, 3-pentyloctyl, 3-butyloctyl, 3-propyloctyl, 3-ethyloctyl, 3-methyloctyl, 3-hexylnonyl, 3-pentylnonyl, 3-butylnonyl, 3-propylnonyl, 3-ethylnonyl, 3-methylnonyl, 3-heptyldecyl, 3-hexyldecyl, 3-pentyldecyl, 3-butyldecyl, 3-propyldecyl, 3-ethyldecyl, 3-methyldecyl, 3-octylundecyl, 3-heptylundecyl, 3-hexylundecyl, 3-pentylundecyl, 3-butylundecyl, 3-propylundecyl, 3-ethylundecyl, 3-methylundecyl, 3-undecyldodecyl, 3-octyldodecyl, 3-heptyldodecyl, 3-hexyldodecyl, 3-pentyldodecyl, 3-butyldodecyl, 3-propyldodecyl, 3-ethyldodecyl, 3-methyldodecyl, 3-dodecyltridecyl, 3-undecyltridecyl, 3-decyltridecyl, 3-nonyltridecyl, 3-octyltridecyl, 3-heptyltridecyl, 3-hexyltridecyl, 3-pentyltridecyl,

3-butyltridecyl, 3-propyltridecyl, 3-ethyltridecyl, 3-methyltridecyl, 3-tridecyltetradecyl, 3-undecyltetradecyl, 3-decyltetradecyl, 3-nonyltetradecyl, 3-octyltetradecyl,

3-hetyltetradecyl, 3-hexyltetradecyl, 3-pentyltetradecyl, 3-butyltetradecyl,

3-propyltetradecyl, 3-ethyltetradecyl, 3-methyltetradecyl, 3-pentadecylhexadecyl, 3-tetradecylhexadecyl, 3-tridecylhexadecyl, 3-dodecylhexadecyl, 3-undecylhexadecyl, 3-decylhexadecyl, 3-nonylhexadecyl, 3-octylhexadecyl, 3-heptylhexadecyl,

3-hexylhexadecyl, 3-pentylhexadecyl, 3-butylhexadecyl, 3-propylhexadecyl,

3-ethylhexadecyl, 3-methylhexadecyl, 3-hexadecyloctadecyl, 3-pentadecyloctadecyl, 3-tetradecyloctadecyl, 3-tridecyloctadecyl, 3-dodecyloctadecyl, 3-undecyloctadecyl, 3-decyloctadecyl, 3-nonyloctadecyl, 3-octyloctadecyl, 3-heptyloctadecyl,

3-hexyloctadecyl, 3-pentyloctadecyl, 3-butyloctadecyl, 3-propyloctadecyl,

3-ethyloctadecyl, 3-methyloctadecyl, 3-nonadecyleicosanyl, 3-octadecyleicosanyl, 3-heptadecyleicosanyl, 3-hexadecyleicosanyl, 3-pentadecyleicosanyl,

3-tetradecyleicosanyl, 3-tridecyleicosanyl, 3-dodecyleicosanyl, 3-undecyleicosanyl, 3-decyleicosanyl, 3-nonyleicosanyl, 3-octyleicosanyl, 3-heptyleicosanyl,

3-hexyleicosanyl, 3-pentyleicosanyl, 3-butyleicosanyl, 3-propyleicosanyl,

3-ethyleicosanyl, 3-methyleicosanyl, 3-eicosanyldocosanyl, 3-nonadecyldocosanyl, 3-octadecyldocosanyl, 3-heptadecyldocosanyl, 3-hexadecyldocosanyl,

3-pentadecyldocosanyl, 3-tetradecyldocosanyl, 3-tridecyldocosanyl,

3-undecyldocosanyl, 3-decyldocosanyl, 3-nonyldocosanyl, 3-octyldocosanyl,

3-heptyldocosanyl, 3-hexyldocosanyl, 3-pentyldocosanyl, 3-butyldocosanyl,

3-propyldocosanyl, 3-ethyldocosanyl, 3-methyldocosanyl, 3-tricosanyltetracosanyl, 3-docosanyltetracosanyl, 3-nonadecyltetracosanyl, 3-octadecyltetracosanyl,

3-heptadecyltetracosanyl, 3-hexadecyltetracosanyl, 3-pentadecyltetracosanyl, 3-pentadecyltetracosanyl, 3-tetradecyltetracosanyl, 3-tridecyltetracosanyl,

3-dodecyltetracosanyl, 3-undecyltetracosanyl, 3-decyltetracosanyl,

3-nonyltetracosanyl, 3-octyltetracosanyl, 3-heptyltetracosanyl, 3-hexyltetracosanyl, 3-pentyltetracosanyl, 3-butyltetracosanyl, 3-propyltetracosanyl, 3-ethyltetracosanyl, 3-methyltetracosanyl, 3-heptacosanyloctacosanyl, 3-hexacosanyloctacosanyl, 3-pentacosanyloctacosanyl, 3-tetracosanyloctacosanyl, 3-tricosanyloctacosanyl, 3-docosanyloctacosanyl, 3-nonadecyloctacosanyl, 3-octadecyloctacosanyl,

3-heptadecyloctacosanyl, 3-hexadecyloctacosanyl, 3-hexadecyloctacosanyl,

3-pentadecyloctacosanyl, 3-tetradecyloctacosanyl, 3-tridecyloctacosanyl,

3-dodecyloctacosanyl, 3-undecyloctacosanyl, 3-decyloctacosanyl, 3-nonyloctacosanyl, 3-octyloctacosanyl, 3-heptyloctacosanyl, 3-hexyloctacosanyl, 3-pentyloctacosanyl,

3- butyloctacosanyl, 3-propyloctacosanyl, 3-ethyloctacosanyl, 3-methyloctacosanyl, in which q is 3, such as

4- methylpentyl, 4-ethylhexyl, 4-methylhexyl, 4-propylheptyl, 4-ethylheptyl,

4-methylheptyl, 4-butyloctyl, 4-propyloctyl, 4-ethyloctyl, 4-methyloctyl, 4-pentylnonyl, 4-butylnonyl, 4-propylnonyl, 4-ethylnonyl, 4-methylnonyl, 4-nonyldecyl, 4-pentyldecyl, 4-butyldecyl, 4-propyldecyl, 4-ethyldecyl, 4-methyldecyl, 4-decylundecyl,

4-nonylundecyl, 4-octylundecyl, 4-heptylundecyl, 4-hexylundecyl, 4-pentylundecyl, 4-butylundecyl, 4-propylundecyl, 4-ethylundecyl, 4-methylundecyl, 4-undecyldodecyl, 4-decyldodecyl, 4-nonyldodecyl, 4-octyldodecyl, 4-heptyldodecyl, 4-hexyldodecyl, 4-pentyldodecyl, 4-butyldodecyl, 4-propyldodecyl, 4-ethyldodecyl, 4-methyldodecyl, 4-dodecyltridecyl, 4-undecyltridecyl, 4-decyltridecyl, 4-nonyltridecyl, 4-octyltridecyl, 4-heptyltridecyl, 4-hexyltridecyl, 4-pentyltridecyl, 4-butyltridecyl, 4-propyltridecyl, 4-ethyltridecyl, 4-methyltridecyl, 4-tridecyltetradecyl, 4-undecyltetradecyl,

4-decyltetradecyl, 4-nonyltetradecyl, 4-octyltetradecyl, 4-hetyltetradecyl,

4-hexyltetradecyl, 4-pentyltetradecyl, 4-butyltetradecyl, 4-propyltetradecyl,

4-ethyltetradecyl, 4-methyltetradecyl, 4-pentadecylhexadecyl, 4-tetradecylhexadecyl, 4-tridecylhexadecyl, 4-dodecylhexadecyl, 4-undecylhexadecyl, 4-decylhexadecyl, 4-nonylhexadecyl, 4-octylhexadecyl, 4-heptylhexadecyl, 4-hexylhexadecyl,

4-pentylhexadecyl, 4-butylhexadecyl, 4-propylhexadecyl, 4-ethylhexadecyl,

4-methylhexadecyl, 4-hexadecyloctadecyl, 4-pentadecyloctadecyl,

4-tetradecyloctadecyl, 4-tridecyloctadecyl, 4-dodecyloctadecyl, 4-undecyloctadecyl, 4-decyloctadecyl, 4-nonyloctadecyl, 4-octyloctadecyl, 4-heptyloctadecyl,

4-hexyloctadecyl, 4-pentyloctadecyl, 4-butyloctadecyl, 4-propyloctadecyl,

4-ethyloctadecyl, 4-methyloctadecyl, 4-nonadecyleicosanyl, 4-octadecyleicosanyl, 4-heptadecyleicosanyl, 4-hexadecyleicosanyl, 4-pentadecyleicosanyl,

4-tetradecyleicosanyl, 4-tridecyleicosanyl, 4-dodecyleicosanyl, 4-undecyleicosanyl, 4-decyleicosanyl, 4-nonyleicosanyl, 4-octyleicosanyl, 4-heptyleicosanyl,

4-hexyleicosanyl, 4-pentyleicosanyl, 4-butyleicosanyl, 4-propyleicosanyl, 4-ethyleicosanyl, 4-methyleicosanyl, 4-eicosanyldocosanyl, 4-nonadecyldocosanyl, 4-octadecyldocosanyl, 4-heptadecyldocosanyl, 4-hexadecyldocosanyl,

4-pentadecyldocosanyl, 4-tetradecyldocosanyl, 4-tridecyldocosanyl,

4-undecyldocosanyl, 4-decyldocosanyl, 4-nonyldocosanyl, 4-octyldocosanyl,

4-heptyldocosanyl, 4-hexyldocosanyl, 4-pentyldocosanyl, 4-butyldocosanyl,

4-propyldocosanyl, 4-ethyldocosanyl, 4-methyldocosanyl, 4-tricosanyltetracosanyl, 4-docosanyltetracosanyl, 4-nonadecyltetracosanyl, 4-octadecyltetracosanyl,

4-heptadecyltetracosanyl, 4-hexadecyltetracosanyl, 4-pentadecyltetracosanyl,

4-pentadecyltetracosanyl, 4-tetradecyltetracosanyl, 4-tridecyltetracosanyl,

4-dodecyltetracosanyl, 4-undecyltetracosanyl, 4-decyltetracosanyl,

4-nonyltetracosanyl, 4-octyltetracosanyl, 4-heptyltetracosanyl, 4-hexyltetracosanyl, 4-pentyltetracosanyl, 4-butyltetracosanyl, 4-propyltetracosanyl, 4-ethyltetracosanyl, 4-methyltetracosanyl, 4-heptacosanyloctacosanyl, 4-hexacosanyloctacosanyl,

4-pentacosanyloctacosanyl, 4-tetracosanyloctacosanyl, 4-tricosanyloctacosanyl, 4-docosanyloctacosanyl, 4-nonadecyloctacosanyl, 4-octadecyloctacosanyl,

4-heptadecyloctacosanyl, 4-hexadecyloctacosanyl, 4-hexadecyloctacosanyl,

4-pentadecyloctacosanyl, 4-tetradecyloctacosanyl, 4-tridecyloctacosanyl,

4-dodecyloctacosanyl, 4-undecyloctacosanyl, 4-decyloctacosanyl, 4-nonyloctacosanyl, 4-octyloctacosanyl, 4-heptyloctacosanyl, 4-hexyloctacosanyl, 4-pentyloctacosanyl, 4-butyloctacosanyl, 4-propyloctacosanyl, 4-ethyloctacosanyl, 4-methyloctacosanyl,

More preferably, the branched C3-C3o-alkyl groups are selected from

1 -methylethyl, 1 -methylpropyl, 2-methylpropyl, 1 -methylbutyl, 2-methylbutyl,

3-methylbutyl, 1 -methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl,

1 -methylhexyl, 1 -methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl,

1 -methylheptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5-methylheptyl, 6-methylheptyl, 1 -methyloctyl, 2-methyloctyl, 1 -ethylpropyl, 1 -ethylbutyl, 1 -ethylpentyl, 1 -ethylhexyl, 1 -ethylheptyl, 1 -ethyloctyl, 1 -propylbutyl, 1 -propylpentyl, 1 -propylhexyl,

1 - propylheptyl, 1 -propyloctyl, 1 -butylpentyl, 1 -butylhexyl, 1 -butylheptyl, 1 -butyloctyl, 1 -pentylhexyl, 1 -pentylheptyl, 1 -pentyloctyl, 1 -hexylheptyl, 1 -hexyloctyl, 1 -heptyloctyl,

2- ethylbutyl, 2-ethylpentyl, 2-ethylhexyl, 2-ethylheptyl, 2-ethyloctyl, 2-ethylnonyl,

2- ethyldecyl, 3-ethylpentyl, 3-ethylhexyl, 3-ethylheptyl, 3-ethyloctyl, 3-ethylnonyl or

3- ethyldecyl . In a preferred embodiment at least one of the radicals R¹ and R² is selected from

1 - methylpentyl and 2-ethylhexyl. R¹ and R² are preferably both 1 -methylpentyl or

2- ethylhexyl.

In a preferred embodiment one of the radicals X¹ and X² is selected from

1 -methylpentyl and 2-ethylhexyl and the other is selected from F, CI and Br. Preferably, X¹ or X² is 1 -methylpentyl or 2-ethylhexyl and the other is CI. In a preferred embodiment, the R¹ and R² radicals are each independently perfluoro- Ci-C₂₀-alkyl or 1 H,1 H-perfluoro-C2-C₂o-alkyl or 1 H,1 H,2H,2H-perfluoro-C₃-C₂o-alkyl.

In particular, the R¹ and R² radicals are each independently perfluoro-Ci-Cio-alkyl or 1 H,1 H-perfluoro-C₂-Cio-alkyl or 1 H,1 H,2H,2H-perfluoro-C₃-Cio-alkyl.

In a preferred embodiment, at least one of the radicals R¹ and R² is selected from CF₃, C₂F₅, n-C₃F₇, n-C₄F₉, n-CsFn .n-CeFis, CF(CF₃)₂, C(CF₃)₃, CF₂CF(CF₃)₂, CF(CF₃)(C₂F₅), CH₂-CF₃, CH₂-C₂F₅, CH₂-(n-C₃F₇), CH₂-(n-C₄F₉), CH₂-(n-C₅Fn), CH₂-(n-C₆Fi3), CH₂-CF(CF₃)₂,CH₂-C(CF₃)₃,CH₂-CF₂CF(CF₃)₂, CH₂-CF(CF₃)(C₂F₅), CH₂-CH₂-CF₃, CH₂-CH₂-C₂F₅, CH₂-CH₂-(n-C₃F₇), CH₂-CH₂-(n-C₄F₉),

CH₂-CH₂-(n-C5Fii),CH₂-CH₂-(n-C6Fi₃), CH₂-CH₂-CF(CF₃)₂, CH₂-CH₂-C(CF₃)₃, CH₂-CH₂-CF₂CF(CF₃)₂ and CH₂-CH₂-CF(CF₃)(C₂F₅). In a special embodiment, the afore-mentioned fluorinated radicals R¹ and R² have the same meaning.

R¹ and R² are preferably both CH₂-CF₃, CH₂-C₂F₅ or CH₂-(n-C₃F₇). In a preferred embodiment, the X¹ and X² radicals are each independently perfluoro- C₃-C₂₀-alkyl or 1 H,1 H-perfluoro-C₂-C₂₀-alkyl or 1 H,1 H,2H,2H-perfluoro-C₃-C₂₀-alkyl.

In particular, the X¹ and X² radicals are each independently perfluoro-C₃-Cio-alkyl or 1 H,1 H-perfluoro-C₂-Cio-alkyl or 1 H,1 H,2H,2H-perfluoro-C₃-Cio-alkyl.

In a preferred embodiment, at least one of the radicals X¹ and X² is selected from n-C₃F₇, n-C₄F₉, n-CsFn .n-CeFis, CF(CF₃)₂, C(CF₃)₃, CF₂CF(CF₃)₂,

CF(CF₃)(C₂F₅), CH₂-CF₃, CH₂-C₂F₅, CH₂-(n-C₃F₇), CH₂-(n-C₄F₉), CH₂-(n-C₅Fn), CH₂-(n-C₆Fi3), CH₂-CF(CF₃)₂,CH₂-C(CF₃)₃,CH₂-CF₂CF(CF₃)₂, CH₂-CF(CF₃)(C₂F₅), CH₂-CH₂-CF₃, CH₂-CH₂-C₂F₅, CH₂-CH₂-(n-C₃F₇), CH₂-CH₂-(n-C₄F₉),

CH₂-CH₂-(n-C5Fii),CH₂-CH₂-(n-C6Fi₃), CH₂-CH₂-CF(CF₃)₂, CH₂-CH₂-C(CF₃)₃,

CH₂-CH₂-CF₂CF(CF₃)₂, CH₂-CH₂-CF(CF₃)(C₂F₅),

NH(n-C₃F₇), NH(n-C₄F₉), NH(n-C₅Fn),

NH(n-C₆Fi₃), NH(CF(CF₃)₂), NH( C(CF₃)₃), NH(CF₂CF(CF₃)₂),

NH(CF(CF₃)(C₂F₅)), NH(CH₂-CF₃), NH(CH₂-C₂F₅), NH(CH₂-(n-C₃F₇)),

NH(CH₂-(n-C₄F₉)), NH(CH₂-(n-C₅Fn)), NH(CH₂-(n-C₆Fi3)), NH( CH₂-CF(CF₃)₂), NH(CH₂-C(CF₃)₃), NH(CH₂-CF₂CF(CF₃)₂), NH(CH₂-CF(CF₃)(C₂F₅)),

NH(CH₂-CH₂-CF₃), NH(CH₂-CH₂-C₂F₅), NH(CH₂-CH₂-(n-C₃F₇)),

NH(CH₂-CH₂-(n-C₄F₉)), NH(CH₂-CH₂-(n-C5Fn)), NH(CH₂-CH₂-(n-C6Fi3)), NH(CH₂-CH₂-CF(CF₃)2), NH(CH₂-CH₂-C(CF₃)3),

NH(CH₂-CH₂-CF₂CF(CF₃)₂) and NH(CH₂-CH₂-CF(CF₃)(C₂F₅)).

In a special embodiment, the afore-mentioned fluorinated radicals X¹ and X² have the same meaning.

In a further special embodiment one of the radicals X¹ or X² is selected from perfluoro- C₃-C₂₀-alkyl or 1 H,1 H-perfluoro-C₂-C₂₀-alkyl or 1 H,1 H,2H,2H-perfluoro-C₃-C₂₀-alkyl and the other radical X¹ or X² is selected from F, CI or Br.

X¹ and X² are preferably both n-C₄F₉ or CH₂-(n-C₄F₉)or NH-CH₂-(n-C₄F₉).

In a preferred embodiment, at least one of the radicals R¹ and R² is a phenylalkyl group, wherein the benzene ring of the phenylalkyl group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI, Br, CN and perfluoro-Ci-C₃o-alkyl.

More preferably, at least one of the radicals R¹ and R² is a group of the formula III

in which

# represents the bonding site to the imide nitrogen atom, r is an integer of 1 to 10, x is 1 , 2, 3, 4 or 5, and the R^f radicals are each independently selected from F, CI, Br, CN and perfluoro- Ci-C₃₀-alkyl.

In the groups of the formula (III), q is preferably 1 .

In the groups of the formula (III), x is preferably 1 , 2 or 3. In particular x is 1.

In the groups of the formula (III), the R^f radicals are preferably each independently selected from F, CI and perfluoro-Ci-C₃o-alkyl. More preferably, in the groups of the formula (III), the R^f radicals are selected from perfluoro-Ci-C₃o-alkyl. Examples of preferred perfluoro-Ci-C₃o-alkyl groups are CF₃, C₂F₅, n-C₃F₇, n-C₄F9, n-CsFn , n-C₆Fi_3j CF(CF₃)₂, C(CF₃)₃, CF₂CF(CF₃)₂ and CF(CF₃)(C₂F₅). In particular, at least one of the radicals R¹ and R² is a benzyl group, wherein the benzene ring of the benzyl group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI and perfluoro-Ci-C3o-alkyl. In a special embodiment, at least one of the radicals R¹ and R² is a substituent of the formula IV

in which

# represents the bonding site to the imide nitrogen atom, and

R^f is selected from CF₃, C₂F₅, n-C₃F₇, n-C₄F₉, n-CsFn , n-CeFis, CF(CF₃)₂, C(CF₃)₃, CF₂CF(CF₃)₂, or CF(CF₃)(C₂F₅).

In a more special embodiment, at least one of the radicals R¹ and R² is a group of the formula

in which

# represents the bonding site to the imide nitrogen atom.

Preference is given to the following compounds:

CF_gCH

(n-C₃F₇)-CH₂—

(4)

The invention further provides a process for preparing compounds of the formula I. Suitable starting materials are 3,6-dichloropyromellitic dianhydride (V.a) or 3,6-dibromopyromellitic dianhydride (V.b):

The synthesis of (V.a) and (V.b) is described in "Die Angewandte Makromolekulare Chemie" 254 (1998), pages 33-38 and the literature cited therein.

It has been found that substituted pyromellitic diimides of the formula (I) can be obtained when 3,6-dichloropyromellitic dianhydride (V.a) or 3,6-dibromopyromellitic dianhydride (V.b) is subjected first to an imidation and subsequently optionally to a substitution of the chlorine or bromine substituents by groups different from chlorine or bromine.

It has also been found that the imidation can be connected with a (partial) substitution of the chlorine or bromine groups bound to the benzene ring by the amine employed in the imidation reaction. It has further been found, that a substitution of the chlorine or bromine groups bound to the benzene ring by cyano groups optionally can combined with a partial or total hydrolysis to give amides or carboxylic acids.

The invention provides a process for preparing compounds of the formula (I)

(1)

wherein

R¹ and R² are each independently selected from branched C3-C3o-alkyl, linear or

branched perfluoro-Ci-C3o-alkyl, linear or branched 1 H,1 H-perfluoro-C2-C3o-alkyl, linear or branched 1 H,1 H,2H,2H-perfluoro-C3-C3o-alkyl or a phenyl-(Ci-C3o)-alkyl group, wherein the benzene ring of the phenylalkyl group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI, Br, CN and perfluoro-Ci-C3o- alkyl,

linear or branched perfluoro-C3-C3o-alkyl,

linear or branched 1 H,1 H-perfluoro-C2-C3o-alkyl,

linear or branched 1 H,1 H,2H,2H-perfluoro-C3-C3o-alkyl,

branched NH(C₃-C₃₀-alkyl),

linear or branched NH(perfluoro-Ci-C3o-alkyl),

linear or branched NH(1 H,1 H-perfluoro-C2-C3o-alkyl) or

linear or branched NH(1 H,1 H,2H,2H-perfluoro-C₃-C₃o-alkyl),

R^a, R^b and R^c are each independently hydrogen or Ci-C3o-alkyl, by a) subjecting a compound of the formula (V.a) or (V.b)

(V.a) (V.b)

to a reaction with an amine of the formula R¹-NH2 and optionally, if R¹ and R² have different meanings, an amine of the formula R²-NH2, b) optionally subjecting the product obtained in step a) to a substitution of at least one of the chlorine or bromine substituents bound to the benzene ring by groups X¹ and/or X² different from chlorine or bromine.

Step a)

The imidation of the carboxylic anhydride groups in reaction step a) is known in principle (see e.g. Macromolecules 1992, 25, 3540 - 3545). Preference is given to effecting the reaction of the dianhydride with (an) primary amine(s) in the presence of a polar aprotic solvent. Suitable polar aprotic solvents are nitrogen heterocycles, such as pyridine, pyrimidine, quinoline, isoquinoline, quinaldine, N-methylpiperidine,

N-methylpiperidone and N-methylpyrrolidone. A preferred solvent is

N-methylpyrrolidone.

The reaction in step a) is preferably undertaken in the presence of an imidation catalyst. Suitable imidation catalysts are organic and inorganic acids, for example formic acid, acetic acid, propionic acid and phosphoric acid. Suitable imidation catalysts are also organic and inorganic salts of transition metals such as zinc, iron, copper and magnesium. These include, for example, zinc acetate, zinc propionate, zinc oxide, iron(ll) acetate, iron(lll) chloride, iron(ll) sulfate, copper(ll) acetate, copper(ll) oxide and magnesium acetate. The molar ratio of imidation catalyst to dianhydride (V.a) or (V.b) is preferably from about 2:1 to 20:1 , more preferably from 2.1 :1 to 10:1.

The molar ratio of amine R¹-NH2 and, if present, R²-NH2 to dianhydride is preferably from about 2:1 to 10:1 , more preferably from 2.1 :1 to 5:1 . Usually, the molar ratio of amine R¹-NH2 and, if present, R²-NH2 to dianhydride is preferably from about 5:1 to 10:1 for the amino-substituted pyrromellitic diimide compound.

The reaction temperature in step a) is generally from 0°C to 200°C, preferably from 20 to 180°C. The reaction in step a) may be performed under a protective gas atmosphere, for example nitrogen or argon. Reaction step a) may be effected at standard pressure or, if desired, under elevated pressure. A suitable pressure range is in the range from about 0.8 to 10 bar. When volatile amines are used (boiling point < 180°C), preference is given to working under elevated pressure. In general, the diimides obtained in reaction step a) may be used for the subsequent reactions without further purification. For use of the products as semiconductors, it may, however, be advantageous to subject the products to further purification. This includes, for example, column chromatography processes, where the products are preferably dissolved in a halogenated hydrocarbon such as methylene chloride, chloroform or tetrachloroethane and are subjected to a separation or filtration on silica gel. Finally, the solvent is removed. The reaction products of step a) may also be purified by sublimation.

Step b)

In a first embodiment of step b), the product obtained in step a) is subjected to a substitution of at least one of the chlorine or bromine atoms bound to the benzene ring by fluorine. Preferably, both chlorine or both bromine atoms bound to the benzene ring are substituted by fluorine.

Suitable process conditions for the aromatic nucleophilic substitution of chlorine atoms or bromine atoms by fluorine atoms (halo-dehalogenation) are known in principle. Suitable conditions for halo-dehalogenation are described, for example, in J. March, Advanced Organic Chemistry, 4th edition, John Wiley & Sons publishers (1992), p. 659 and also in DE-A-32 35 526. Reference is made here to this disclosure.

To introduce the fluorine groups, preference is given to using an alkali metal fluoride, in particular KF, NaF or CsF. Preferred solvents for the halogen exchange in step b) are aprotic polar solvents such as acetonitrile, dimethylformamide, N-methylpyrrolidone, (Cl- ^SO, dimethyl sulfone or sulfolane. Preference is given to subjecting the solvents before use to drying to remove water by customary methods known to those skilled in the art. For the halogenic exchange in step b), it is additionally possible to use a complexing agent, for example, a crown ether. These include, for example, [12]crown-4, [15]crown- 5, [18]crown-6, [21]crown-7, [24]crown-8, etc. The complexing agent is selected according to its capability of complexing the alkali metals of the alkali metal halides used for the halogen exchange. When KF is used to introduce the fluorine groups, the complexing agent used is preferably [18]crown-6. Further suitable phase transfer catalysts for use in step b) are, for example, selected from 2-azaallenium compounds, carbophosphazenium compounds, aminophosphonium compounds and

diphosphazenium compounds. In a preferred embodiment, 2-azaallenium compounds such as (N,N-dimethylimidazolidino)tetramethylguanidinium chloride (CNC⁺) are used. A. Pleschke, A. Marhold, M. Schneider, A. Kolomeitsev and G. V. Roschenthaler give, in Journal of Fluorine Chemistry 125, 2004, 1031 -1038, a review of further suitable phase transfer catalysts. Reference is made to the disclosure of this document. The use amount of the aforementioned phase transfer catalysts is preferably from 0.1 to 20% by weight, more preferably from 1 to 10% by weight, based on the weight of the compound from step a) used. In a further embodiment of step b), the product obtained in step a) is subjected to a substitution of at least one of the chlorine or bromine atoms bound to the benzene ring by cyano. Preferably, both chlorine or both bromine atoms bound to the benzene ring are substituted by cyano. If appropriate, this reaction can be combined with a partial or total hydrolysis to give amides or carboxylic acids. The carboxylic acids can be further subjected to an esterification.

Suitable process conditions for the cyano-dehalogenation are likewise described in J. March, Advanced Organic Chemistry, 4th edition, John Wiley & Sons publishers (1992), pp. 660 - 661 and also in WO 2004/029028. These include, for example, the reaction with copper cyanide. Also suitable are alkali metal cyanides, such as KCN and NaCN, and also zinc cyanide in polar aprotic solvents in the presence of Pd(ll) salts or copper or nickel complexes. Preferred polar aprotic solvents are those mentioned above for the halogen exchange. In a further embodiment of step b), the product obtained in step a) is subjected to a substitution of at least one of the chlorine or bromine atoms bound to the benzene ring by perfluoroalkyl. Preferably, both chlorine or both bromine atoms bound to the benzene ring are substituted by perfluoroalkyl. According to this embodiment, the product of step a)

wherein

R¹ and R² have the afore-mentioned meaning and X¹ and X² are each independently selected from CI and Br, is subjected to a reaction with a linear or branched perfluoro-Ci-C3o-alkyl iodide in the presence of a copper catalyst.

A preferred copper catalyst is copper(l)oxide (CU2O).

Preferably the substitution of chlorine or bromine by perfluoroalkyl is performed in the presence of a polar aprotic solvent. Suitable polar aprotic solvents are aprotic polar solvents such as acetonitrile, dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, dimethyl sulfone or sulfolane. A preferred solvent is dimethyl sulfoxide.

The reaction temperature is generally from 20°C to 200°C, preferably from 50 to 180°C.

In addition to the imidation reaction in step a), at least one of the chlorine or bromine atoms bound to the benzene ring may be substituted by the amine R¹-NH2 and/or, if present, R²-NH2. Preferably, only one chlorine or bromine atom bound to the benzene ring is substituted by R¹-NH₂ or R²-NH₂.

The compounds of the formula (I) are particularly advantageously suitable as organic semiconductors. They generally function as n-semiconductors. When the compounds of the formula (I) used in accordance with the invention are combined with other semiconductors and the position of the energy levels results in the other

semiconductors functioning as n-semiconductors, the compounds (I) may also function as p-semiconductors in exceptional cases.

The compounds of the formula (I) have at least one of the following advantages over known organic semiconductor materials: high charge transport mobility,

air stability,

high on/off ratio.

The compounds of the formula (I) are particularly advantageously suitable for organic field-effect transistors. They may be used, for example, for the production of integrated circuits (ICs), for which customary n-channel MOSFETs (metal oxide semiconductor field-effect transistors) have been used to date. These are then CMOS-like

semiconductor units, for example for microprocessors, microcontrollers, static RAM and other digital logic circuits. For the production of semiconductor materials, the compounds of the formula (I) can be processed further by one of the following processes: printing (offset, flexographic, gravure, screenprinting, inkjet,

electrophotography), evaporation, laser transfer, photolithography, drop-casting. They are especially suitable for use in displays (specifically large-surface area and/or flexible displays), RFID tags, smart labels and sensors.

The compounds of the formula (I) are particularly advantageously suitable as electron conductors in organic field-effect transistors, organic solar cells and in organic light- emitting diodes. They are also particularly advantageous as an exciton transport material in excitonic solar cells.

Some of the compounds of the formula (I) are fluorescent and are also particularly advantageously suitable as fluorescent dyes in a display based on fluorescence conversion. Such displays comprise generally a transparent substrate, a fluorescent dye present on the substrate and a radiation source. Typical radiation sources emit blue (color by blue) or UV light (color by UV). The dyes absorb either the blue or the UV light and are used as green emitters. In these displays, for example, the red light is generated by exciting the red emitter by means of a green emitter which absorbs blue or UV light. Suitable color-by-blue displays are described, for example, in

WO 98/28946. Suitable color-by-UV displays are described, for example, by W. A. Crossland, I. D. Sprigle and A. B. Davey in Photoluminescent LCDs (PL-LCD) using phosphors, Cambridge University and Screen Technology Ltd., Cambridge, UK. The compounds of the formula (I) are also particularly suitable in displays which, based on an electrophoretic effect, switch colors on and off via charged pigment dyes. Such electrophoretic displays are described, for example, in US 2004/0130776.

The invention further provides organic field-effect transistors comprising a substrate with at least one gate structure, a source electrode and a drain electrode, and at least one compound of the formula (I) as defined above as a semiconductor, especially as an n-semiconductor.

The invention further provides substrates having a plurality of organic field-effect transistors, wherein at least some of the field-effect transistors comprise at least one compound of the formula (I) as defined above. The invention also provides semiconductor units which comprise at least one such substrate.

A specific embodiment is a substrate with a pattern (topography) of organic field-effect transistors, each transistor comprising

- an organic semiconductor disposed on the substrate;

a gate structure for controlling the conductivity of the conductive channel; and conductive source and drain electrodes at the two ends of the channel, the organic semiconductor consisting of at least one compound of the formula (I) or comprising a compound of the formula (I). In addition, the organic field-effect transistor generally comprises a dielectric. A specific embodiment is a substrate with a pattern (topography) of organic field-effect transistors, each transistor comprising

an organic semiconductor disposed on a buffer layer on a substrate;

a gate structure for controlling the conductivity of the conductive channel; and conductive source and drain electrodes at the two ends of the channel, the organic semiconductor consisting of at least one compound of the formula (I) or comprising a compound of the formula (I). In addition, the organic field-effect transistor generally comprises a dielectric.

As a buffer layer, any dielectric material is suitable, for example anorganic materials such LIF, AIOx, S1O2 or silicium nitride or organic materials such as polyimides or polyacrylates, e.g. polymethylmethacrylate (PMMA).

A further specific embodiment is a substrate having a pattern of organic field-effect transistors, each transistor forming an integrated circuit or being part of an integrated circuit and at least some of the transistors comprising at least one compound of the formula (I).

Suitable substrates are in principle the materials known for this purpose. Suitable substrates comprise, for example, metals (preferably metals of groups 8, 9, 10 or 1 1 of the Periodic Table, such as Au, Ag, Cu), oxidic materials (such as glass, ceramics, S1O2, especially quartz), semiconductors (e.g. doped Si, doped Ge), metal alloys (for example based on Au, Ag, Cu, etc.), semiconductor alloys, polymers (e.g. polyvinyl chloride, polyolefins, such as polyethylene and polypropylene, polyesters,

fluoropolymers, polyamides, polyimides, polyurethanes, polyethersulfones, polyalkyl (meth)acrylates, polystyrene and mixtures and composites thereof), inorganic solids (e.g. ammonium chloride), paper and combinations thereof. The substrates may be flexible or inflexible, and have a curved or planar geometry, depending on the desired use. A typical substrate for semiconductor units comprises a matrix (for example a quartz or polymer matrix) and, optionally, a dielectric top layer.

Suitable dielectrics are S1O2, polystyrene, poly-a-methylstyrene, polyolefins (such as polypropylene, polyethylene, polyisobutene), polyvinylcarbazole, fluorinated polymers (e.g. Cytop), cyanopullulans (e.g. CYMM), polyvinylphenol, poly-p-xylene, polyvinyl chloride, or polymers crosslinkable thermally or by atmospheric moisture. Specific dielectrics are "self-assembled nanodielectrics", i.e. polymers which are obtained from monomers comprising SiCI functionalities, for example C SiOSiC , Cl3Si-(CH2)6-SiCl3, Cl3Si-(CH2)i2-SiCl3, and/or which are crosslinked by atmospheric moisture or by addition of water diluted with solvents (see, for example, Faccietti Adv. Mat. 2005, 17, 1705-1725). Instead of water, it is also possible for hydroxyl-containing polymers such as polyvinylphenol or polyvinyl alcohol or copolymers of vinylphenol and styrene to serve as crosslinking components. It is also possible for at least one further polymer to be present during the crosslinking operation, for example polystyrene, which is then also crosslinked (see Facietti, US patent application 2006/0202195). The substrate may additionally have electrodes, such as gate, drain and source electrodes of OFETs, which are normally localized on the substrate (for example deposited onto or embedded into a nonconductive layer on the dielectric). The substrate may additionally comprise conductive gate electrodes of the OFETs, which are typically arranged below the dielectric top layer (i.e. the gate dielectric).

In a specific embodiment, an insulator layer (gate insulating layer) is present on at least part of the substrate surface. The insulator layer comprises at least one insulator which is preferably selected from inorganic insulators, such as S1O2, silicon nitride (S13N4), etc., ferroelectric insulators, such as AI2O3, Ta20s, La20s, T1O2, Y2O3, etc., organic insulators such as polyimides, benzocyclobutene (BCB), polyvinyl alcohols,

polyacrylates, etc., and combinations thereof.

Suitable materials for source and drain electrodes are in principle electrically conductive materials. These include metals, preferably metals of groups 6, 7, 8, 9, 10 or 1 1 of the Periodic Table, such as Pd, Au, Ag, Cu, Al, Ni, Cr, etc. Also suitable are conductive polymers, such as PEDOT (=poly(3,4-ethylenedioxythiophene)):PSS (= poly(styrenesulfonate)), polyaniline, surface-modified gold, etc. Preferred electrically conductive materials have a specific resistance of less than 10 ^"3 ohm x meter, preferably less than 10 -⁴ ohm x meter, especially less than 10 ^"6 or 10 ^"7 ohm x meter.

In a specific embodiment, drain and source electrodes are present at least partly on the organic semiconductor material. It will be appreciated that the substrate may comprise further components as used customarily in semiconductor materials or ICs, such as insulators, resistors, capacitors, conductor tracks, etc.

The electrodes may be applied by customary processes, such as evaporation or sputtering, lithographic processes or another structuring process, such as printing techniques.

The semiconductor materials may also be processed with suitable auxiliaries

(polymers, surfactants) in disperse phase by printing. In a first preferred embodiment, the deposition of at least one compound of the general formula (I) (and if appropriate further semiconductor materials) is carried out by a gas phase deposition process (physical vapor deposition, PVD). PVD processes are performed under high-vacuum conditions and comprise the following steps:

evaporation, transport, deposition. It has been found that, surprisingly, the compounds of the general formula (I) are suitable particularly advantageously for use in a PVD process, since they essentially do not decompose and/or form undesired by-products. The material deposited is obtained in high purity. In a specific embodiment, the deposited material is obtained in the form of crystals or comprises a high crystalline content. In general, for the PVD, at least one compound of the general formula (I) is heated to a temperature above its evaporation temperature and deposited on a substrate by cooling below the crystallization temperature. The temperature of the substrate in the deposition is preferably within a range from about 20 to 250°C, more preferably from 50 to 200°C. It has been found that, surprisingly, elevated substrate temperatures in the deposition of the compounds of the formula (I) can have advantageous effects on the properties of the semiconductor elements achieved.

The resulting semiconductor layers generally have a thickness which is sufficient for forming a semiconductor channel which is in contact with the source/drain electrodes. The deposition can be effected under an inert atmosphere, for example, under nitrogen, argon or helium.

The deposition is effected typically at ambient pressure or under reduced pressure. A suitable pressure range is from about 10^-7 to 1 .5 bar.

The compound of the formula (I) is preferably deposited on the substrate in a thickness of from 10 to 1000 nm, more preferably from 15 to 250 nm. In a specific embodiment, the compound of the formula (I) is deposited at least partly in crystalline form. For this purpose, especially the above-described PVD process is suitable. Moreover, it is possible to use previously prepared organic semiconductor crystals. Suitable processes for obtaining such crystals are described by R. A. Laudise et al. in "Physical Vapor Growth of Organic Semi-Conductors", Journal of Crystal Growth 187 (1998), pages 449-454, and in "Physical Vapor Growth of Centimeter-sized Crystals of a-Hexathiophene", Journal of Crystal Growth 1982 (1997), pages 416-427, which are incorporated here by reference.

In a second preferred embodiment, the deposition of at least one compound of the general formula (I) (and if appropriate further semiconductor materials) is effected by spin-coating. Surprisingly, it is thus also possible to use the compounds of the formula (I) used in accordance with the invention in a wet processing method to produce semiconductor substrates. The compounds of the formula (I) should thus also be suitable for producing semiconductor elements, especially OFETs or based on OFETs, by a printing process. It is possible for this purpose to use customary printing or coating processes (inkjet, flexographic, offset, gravure; intaglio printing, nanoprinting, slot die). Preferred solvents for the use of compounds of the formula (I) in a printing process are aromatic solvents, such as toluene, xylene, etc. It is also possible to add thickening substances, such as polymers, for example polystyrene, etc., to these "semiconductor inks". In this case, the dielectrics used are the aforementioned compounds.

In a preferred embodiment, the inventive field-effect transistor is a thin-film transistor (TFT). In a customary construction, a thin-film transistor has a gate electrode disposed on the substrate or buffer layer (the buffer layer being part of the substrate), a gate insulation layer disposed thereon and on the substrate, a semiconductor layer disposed on the gate insulator layer, an ohmic contact layer on the semiconductor layer, and a source electrode and a drain electrode on the ohmic contact layer. In a preferred embodiment, the surface of the substrate, before the deposition of at least one compound of the general formula (I) (and if appropriate of at least one further semiconductor material), is subjected to a modification. This modification serves to form regions which bind the semiconductor materials and/or regions on which no semiconductor materials can be deposited. The surface of the substrate is preferably modified with at least one compound (C1 ) which is suitable for binding to the surface of the substrate and to the compounds of the formula (I). In a suitable embodiment, a portion of the surface or the complete surface of the substrate is coated with at least one compound (C1 ) in order to enable improved deposition of at least one compound of the general formula (I) (and if appropriate further semiconductive compounds). A further embodiment comprises the deposition of a pattern of compounds of the general formula (C1 ) on the substrate by a corresponding production process. These include the mask processes known for this purpose and so-called "patterning" processes, as described, for example, in US 1 1/353,934, which is incorporated here fully by reference.

Suitable compounds of the formula (C1 ) are capable of a binding interaction both with the substrate and with at least one semiconductor compound of the general formula (I). The term "binding interaction" comprises the formation of a chemical bond (covalent bond), ionic bond, coordinative interaction, van der Waals interactions, e.g. dipole- dipole interactions etc.), and combinations thereof. Suitable compounds of the general formula (C1 ) are: silane, phosphonic acids, carboxylic acids, hydroxamic acids, such as

alkyltrichlorosilanes, e.g. n-octadecyltrichlorosilane; compounds with

trialkoxysilane groups, e.g. alkyltrialkoxysilanes such as

n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane,

n-octadecyltri(n-propyl)oxysilane, n-octadecyltri(isopropyl)oxysilane; trialkoxyaminoalkylsilanes, such as triethoxyaminopropylsilane and

N[(3-triethoxysilyl)propyl]ethylenediamine; trialkoxyalkyl 3-glycidyl ether silanes, such as triethoxypropyl 3-glycidyl ether silane; trialkoxyallylsilanes, such as allyltrimethoxysilane; trialkoxy(isocyanatoalkyl)silanes;

trialkoxysilyl(meth)acryloyloxyalkanes and trialkoxysilyl(meth)acrylamidoalkanes, such as 1 -triethoxysilyl-3-acryl-oyl-oxypropane. amines, phosphines and sulfur-comprising compounds, especially thiols. The compound (C1 ) is preferably selected from alkyltrialkoxysilanes, especially n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane; hexaalkyldisilazanes, and especially hexamethyldisilazane (HMDS); Cs-Cso-alkylthiols, especially

hexadecanethiol; mercaptocarboxylic acids and mercaptosulfonic acids, especially mercaptoacetic acid, 3-mercaptopropionic acid, mercaptosuccinic acid, 3-mercapto-1 - propanesulfonic acid and the alkali metal and ammonium salts thereof.

Various semiconductor architectures comprising the inventive semiconductors are also conceivable, for example top contact, top gate, bottom contact, bottom gate, or else a vertical construction, for example a VOFET (vertical organic field-effect transistor), as described, for example, in US 2004/0046182.

The layer thicknesses are, for example, from 10 nm to 5 μηη in semiconductors, from 50 nm to 10 μηη in the dielectric; the electrodes may, for example, be from 20 nm to 10 μπΊ. The OFETs may also be combined to form other components, such as ring oscillators or inverters.

A further aspect of the invention is the provision of electronic components which comprise a plurality of semiconductor components, which may be n- and/or

p-semiconductors. Examples of such components are field-effect transistors (FETs), bipolar junction transistors (BJTs), tunnel diodes, converters, light-emitting

components, biological and chemical detectors or sensors, temperature-dependent detectors, photodetectors, such as polarization-sensitive photodetectors, gates, AND, NAND, NOT, OR, TOR and NOR gates, registers, switches, timer units, static or dynamic stores and other dynamic or sequential, logical or other digital components including programmable switches.

A specific semiconductor element is an inverter. In digital logic, the inverter is a gate which inverts an input signal. The inverter is also referred to as a NOT gate. Real inverter switches have an output current which constitutes the opposite of the input current. Typical values are, for example, (0, +5V) for TTL switches. The performance of a digital inverter reproduces the voltage transfer curve (VTC), i.e. the plot of input current against output current. Ideally, it is a staged function and, the closer the real measured curve approximates to such a stage, the better the inverter is. In a specific embodiment of the invention, the compounds of the formula (I) are used as organic n-semiconductors in an inverter. The compounds of the formula (I) are also particularly advantageously suitable for use in organic photovoltaics (OPVs). Preference is given to their use in solar cells which are characterized by diffusion of excited states (exciton diffusion). In this case, one or both of the semiconductor materials utilized is notable for a diffusion of excited states (exciton mobility). Also suitable is the combination of at least one semiconductor material which is characterized by diffusion of excited states with polymers which permit conduction of the excited states along the polymer chain. In the context of the invention, such solar cells are referred to as excitonic solar cells. The direct conversion of solar energy to electrical energy in solar cells is based on the internal photo effect of a semiconductor material, i.e. the generation of electron-hole pairs by absorption of photons and the separation of the negative and positive charge carriers at a p-n transition or a Schottky contact. An exciton can form, for example, when a photon penetrates into a semiconductor and excites an electron to transfer from the valence band into the conduction band. In order to generate current, the excited state generated by the absorbed photons must, however, reach a p-n transition in order to generate a hole and an electron which then flow to the anode and cathode. The photovoltage thus generated can bring about a photocurrent in an external circuit, through which the solar cell delivers its power. The semiconductor can absorb only those photons which have an energy which is greater than its band gap. The size of the semiconductor band gap thus determines the proportion of sunlight which can be converted to electrical energy. Solar cells consist normally of two absorbing materials with different band gaps in order to very effectively utilize the solar energy. Most organic semiconductors have exciton diffusion lengths of up to 10 nm. There is still a need here for organic semiconductors through which the excited state can be passed on over very large distances. It has now been found that, surprisingly, the compounds of the general formula (I) described above are particularly advantageously suitable for use in excitonic solar cells.

Suitable organic solar cells generally have a layer structure and generally comprise at least the following layers: anode, photoactive layer and cathode. These layers generally consist of a substrate customary therefore. The structure of organic solar cells is described, for example, in US 2005/0098726 A1 and US 2005/0224905 A1 , which are fully incorporated here by reference.

The invention provides an organic solar cell comprising a substrate with at least one cathode, at least one anode and at least one compound of the formula I as defined above as a photoactive material. The organic solar cell according to the invention comprises at least one photoactive region. A photoactive region can comprise two layers that each have a homogeneous composition and form a flat donor-acceptor heterojunction or a mixed layer forming a donor-acceptor bulk heterojunction.

Suitable substrates are, for example, oxidic materials (such as glass, ceramic, S1O2, especially quartz, etc.), polymers (e.g. polyvinyl chloride, polyolefins, such as polyethylene and polypropylene, polyesters, fluoropolymers, polyamides,

polyurethanes, polyalkyl (meth)acrylates, polystyrene and mixtures and composites thereof) and combinations thereof. Suitable electrodes (cathode, anode) are in principle metals (preferably of groups 2, 8, 9, 10, 1 1 or 13 of the Periodic Table, e.g. Pt, Au, Ag, Cu, Al, In, Mg, Ca),

semiconductors (e.g. doped Si, doped Ge, indium tin oxide (ITO), gallium indium tin oxide (GITO), zinc indium tin oxide (ZITO), etc.), metal alloys (e.g. based on Pt, Au, Ag, Cu, etc., especially Mg/Ag alloys), semiconductor alloys, etc. The anode used is preferably a material essentially transparent to incident light. This includes, for example, ITO, doped ITO, ZnO, T1O2, Ag, Au, Pt. The cathode used is preferably a material which essentially reflects the incident light. This includes, for example, metal films, for example of Al, Ag, Au, In, Mg, Mg/AI, Ca, etc. For its part, the photoactive region comprises at least one or consists of at least one layer which comprises, as an organic semiconductor material, at least one compound of the formula I as defined above. In addition to the photoactive region, there may be one or more further layers. These include, for example, layers with electron-conducting properties (electron transport layer, ETL) layers which comprise a hole-conducting material (hole transport layer, HTL) which need not absorb,

exciton- and hole-blocking layers (e.g. EBLs) which should not absorb, and multiplication layers.

Compounds of the formula I can be used as electron transport material in an electron transport layer in organic solar cells in combination with other donor photoactive materials and fullerenes, especially C60. Suitable organic solar cell architectures include bulk heterojunction, bilayer and tandem which are discussed below.

Suitable exciton- and hole-blocking layers are described, for example, in US 6,451 ,415.

Suitable exciton blocker layers are, for example, bathocuproins (BCPs),

4,4',4"-tris[3-methylphenyl(phenyl)amino]triphenylamine (m-MTDATA) or

polyethylenedioxythiophene (PEDOT), as described in US 7,026,041. The preferred solar cells according to the invention comprise at least one photoactive donor-acceptor heterojunction. Upon optical excitation of an organic material, excitons are generated. For photocurrent to occur, the electron-hole pair has to be separated, typically at a donor-acceptor interface between two dissimilar contacting materials. At such an interface, the donor material forms a heterojunction with an acceptor material. If the charges do not separate, they can recombine in a geminate recombination process, also known as quenching, either radiatively, by the emission of light of a lower energy than the incident light, or non-radiatively, by the production of heat. Either of these outcomes is undesirable. Preferably, at least one compound of the formula I is used as electron acceptor material.

Charge generating (donor) as well as HTM (hole transport material), and/or the corresponding electron accepting ETM (electron transport material) must be selected such that, after excitation of the compounds, a rapid electron transfer to the ETM takes place. Further suitable ETMs are, for example, C60 and other fullerenes, perylene- 3,4;9,10-bis(dicarboximides) (PTCDIs), etc. (see in the following).

In a first embodiment, the heterojunction may have a flat (smooth) configuration (cf. Two layer organic photovoltaic cell, C. W. Tang, Appl. Phys. Lett., 48 (2), 183-185 (1986) or N. Karl, A. Bauer, J. Holzapfel, J. Marktanner, M. Mobus, F. Stolzle, Mol. Cryst. Liq. Cryst, 252, 243-258 (1994).).

In a second embodiment, the heterojunction may be implemented as a mixed (bulk) heterojunction or interpenetrating donor-acceptor network. Organic photovoltaic cells with a bulk heterojunction are e.g. described by C. J. Brabec, N. S. Sariciftci, J. C.

Hummelen in Adv. Funct. Mater., 1 1 (1 ), 15 (2001 ) or by J. Xue, B. P. Rand, S. Uchida and S. R. Forrest in J. Appl. Phys. 98, 124903 (2005). Bulk heterojunctions are discussed in details below. The compounds of the formula I can be used as a photoactive material in solar cells with MiM, pin, pn, Mip or Min structure (M = metal, p = p-doped organic or inorganic semiconductor, n = n-doped organic or inorganic semiconductor, i = intrinsically conductive system of organic layers; cf., for example, J. Drechsel et al., Org. Electron., 5 (4), 175 (2004) or Maennig et al., Appl. Phys. A 79, 1 -14 (2004)).

The compounds of the formula I can also be used as a photoactive material in tandem cells. Suitable tandem cells are described e.g. by P. Peumans, A. Yakimov, S. R.

Forrest in J. Appl. Phys, 93 (7), 3693-3723 (2003) (cf. patents US 4,461 ,922,

US 6,198,091 and US 6,198,092) and are discussed in details below.

The compounds of the formula I can also be used as a photoactive material in tandem cells composed of two or more MiM, pin, Mip or Min diodes stacked on one another (cf. patent application DE 103 13 232.5) (J. Drechsel et al., Thin Solid Films, 451452, 515- 517 (2004)).

The layer thicknesses of the M, n, i and p layers are typically from 10 to 1000 nm, preferably from 10 to 400 nm. Thin layers can be produced by vapor deposition under reduced pressure or in inert gas atmosphere, by laser ablation or by solution- or dispersion-processible methods such as spin-coating, knife-coating, casting methods, spraying, dip-coating or printing (e.g. inkjet, flexographic, offset, gravure; intaglio, nanoimprinting).

In order to improve efficiency of an organic solar cell the average distance an exciton must diffuse from its generation to its dissociation site (donor-acceptor interface) can be reduced in an interpenetrating network of the donor and acceptor materials. A preferred morphology of a bulk-heterojunction is characterized by a great donor- acceptor interface area and continuous carrier conducting pathways to the opposing electrodes.

Bulk heterojunctions may be produced by a gas phase deposition process (physical vapor deposition, PVD). Suitable methods are described in US 2005/0227406, to which reference is made here. To this end, typically at least one electron donor and at least one electron acceptor material may be subjected to a vapor phase deposition by cosublimation. PVD processes are performed under high-vacuum conditions and comprise the following steps: evaporation, transport, deposition. The deposition is effected preferably at a pressure range from about 10^-2 mbar to 10^-7 mbar, e.g. from 10^"5 to 10^"7 mbar. The deposition rate is preferably in a range from 0.01 to 10 nm/s. The deposition rate of the metal top contact is preferably in a range from 0.01 to 10 nm/s. The deposition can be effected under an inert atmosphere, for example, under nitrogen, argon or helium. The temperature of the substrate in the deposition is preferably within a range from about -100 to 300°C, more preferably from -50 to 250°C.

The other layers of the solar cell can be produced by known methods. These include vapor deposition under reduced pressure or in inert gas atmosphere, by laser ablation or by solution- or dispersion-processible methods such as spin-coating, knife-coating, casting methods, spraying, dip-coating or printing (e.g. inkjet, flexographic, offset, gravure; intaglio, nanoimprinting). The complete solar cell is preferably produced by a gas phase deposition process.

The photoactive region (homogeneous layers or mixed layer) can be subjected to a thermal treatment directly after its preparation or after the preparation of other layers being part of the solar cell. Annealing may improve the morphology of the photoactive region. The temperature is preferably in the range of from 60 to 300°C and the processing time ranges from 1 minute to 3 hours. In addition or alternatively to a thermal treatment, the photoactive region may be subjected to a treatment using a solvent-containing gas. According to a suitable embodiment saturated solvent vapors in air at ambient temperature are used. Suitable solvents are toluene, xylene,

chlorobenzene, trichloromethane, dichloromethane, N-methylpyrrolidone,

Ν,Ν-dimethylformamide, ethyl acetate and mixtures thereof. The processing time usually ranges from 1 minute to 3 hours.

According to a preferred embodiment of the invention, the solar cell according to the present invention is a flat-heterojunction single cell having a normal structure.

Figure 1 illustrates a solar cell with normal structure according to the present invention. According to a specific embodiment the cell has the following structure: a transparent conducting layer (anode) (1 1 )

- hole transport layer (HTL) (12)

layer comprising a donor material (13)

layer comprising an acceptor material (14)

exciton blocking layer and/or electron transport layer (15)

electrode (back electrode, cathode) (16)

Preferably, the acceptor material comprises or consists of a compound of the formula I. HTL and ETL can be either undoped or doped. Suitable dopants are discussed below.

The transparent conducting layer (1 1 ) comprises a carrier substrate, such as glass or a polymer (e.g. polyethylene terephthalate) and a transparent conducting material as anode. Suitable anode materials are the aforementioned materials that are essentially transparent to incident light, for example, ITO, doped ITO, FTO, ZnO, AZO, etc. The anode material may be subjected to a surface treatment, e.g. with UV light, ozone, oxygen plasma, Br2, etc. The transparent conducting layer (1 1 ) should be thin enough to ensure minimal light absorption, but thick enough to ensure good lateral charge transport through the layer. The layer thickness of the transparent conducting layer is preferably in the range of from 20 to 200 nm.

The solar cell with normal structure according to figure 1 optionally comprises a hole transport layer (12). This layer comprises at least one hole transport material (HTM). Layer 12 can be a single layer of essentially homogeneous composition or can comprise two or more sublayers. Suitable hole transport materials and the

corresponding hole transport layer (HTL) are characterized by a high work function or ionization energy. The ionization energy is preferably at least 5.0 eV, more preferably at least 5.5 eV. The HTM can be at least one organic compound, such as

poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate)(PEDOT-PSS), Ir-DPBIC (Tris-N,N'-Diphenylbenzimidazol-2-yliden-iriddium(lll)), N,N'-diphenyl-N,N'-bis (3-methylphenyl)-1 ,1 '-diphenyl-4, 4'-diamine (a-NPD), 2,2',7,7'-tetrakis(N,N-di-p- methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeOTAD), etc. The HTM can also be at least one inorganic compound, such as WO3, M0O3, etc. The thickness of layer (12) is preferably in a range of from 0 to 1 μηη, more preferably from 0 to 100 nm. Organic compounds employed as HTM can be doped with p-dopant, which has LUMO similar or deeper than the HOMO of the HTM, such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano- quino-dimethane (F4TCNQ), W0₃, M0O3, etc.

Layer 13 comprises at least one compound, selected from compounds of the formula I. The thickness of the layer should be thick enough to absorb as much light as possible, but still thin enough to extract charges efficiently. The thickness of layer (13) is preferably in a range of from 5 nm to 1 μηη, more preferably from 5 to 80 nm.

Layer (14) comprises at least one acceptor material. Preferred acceptor materials are the compounds of the formula I. Further suitable acceptor materials are mentioned in the following. The thickness of the layer should be thick enough to absorb as much light as much as possible, but still thin enough to extract charges efficiently. The thickness of layer (14) is preferably in a range of from 5 nm to 1 μηη, more preferably 5 to 80 nm.

The solar cell with normal structure according to figure 1 optionally comprises an exciton blocking layer and/or electron transport layer (15). The exciton blocking layer should have a larger optical gap than the materials of layer (14) to reflect the excitons and still enable good electron transport through the layer. Preferably layer (15) comprises at least one compound selected from 2,9-dimethyl-4,7-diphenyl-1 ,10- phenanthroline (BCP), (4,7-diphenyl-1 ,10-phenanthroline) Bphen, 1 ,3-bis[2-(2,2'- bupyridine-6-yl)1 ,3,4-oxadizo-5-yl]benzene (BPY-OXD), zinc oxide, titanium oxide, etc. Organic compounds employed in layer (15) can be doped with an n-dopant, which has HOMO similar or smaller than the LUMO of the electron-transport layer, such as CS2CO3, pyronin B (PyB), rhodamine B, cobaltocene, etc. The thickness of layer (15) is preferably in a range of from 0 to 500 nm, more preferably from 0 to 60 nm.

Layer (16) is the cathode and comprises at least one material with low work function such as Ag, Al, Ca, Mg or a mixture thereof. The thickness of layer (16) is preferably in a range of from 10 nm to 10 μηη, e.g. 10 nm to 60 nm.

According to further preferred embodiment of the invention, the solar cell is a flat- heterojunction single cell having an inverse structure. Figure 2 illustrates a solar cell with inverse structure according to the present invention. According to a further preferred embodiment of the invention, the solar cell according to the present invention is a bulk-heterojunction single cell having a normal structure. Figure 3 illustrates a solar cell with normal structure according to the present invention. According to a specific embodiment the cell has the following structure: a transparent conducting layer (anode) (21 )

hole transport layer (HTL) (22)

mixed layer of a hole-conducting material and electron transport material in form of a bulk heterojunction (23)

electron transport layer (ETL) (24)

exciton blocking layer/ electron transport layer (25)

electrode (back electrode, cathode) Preferably, the mixed layer comprises a compound of formula I as the acceptor material. HTL and ETL can be either undoped or doped. Suitable dopants are discussed below.

With regard to layer 21 , reference is made to layer 1 1 mentioned before.

With regard to layer 22, reference is made to layer 12 mentioned before.

Layer 23 is a mixed layer of at least one compound of formula I as the acceptor material and a donor material. The mixed layer can be prepared by co-evaporation as mentioned before or by solution processing using common solvents. The mixed layer comprises preferably from 10 to 90 wt%, more preferably from 20 to 80 wt%, of at least one compound of formula I based on the total weight of the mixed layer. The mixed layer comprises preferably from 10 to 90 wt%, more preferably from 20 to 80 wt%, of at least one acceptor material based on the total weight of the mixed layer. The thickness of layer (23) should be thick enough to absorb as much light as possible, but still thin enough to extract charges efficiently. The thickness of layer (23) is preferably in a range of from 5 nm to 1 μηη, more preferably 5 to 200 nm, specially from 5 to 80 nm.

The bulk-heterojunction solar cell with normal structure according to figure 3 comprises an electron transport layer (24). This layer comprises at least one electron transport material (ETM). Layer 24 can be a single layer of essentially homogeneous

composition or can comprise two or more sublayers. Suitable electron transport materials and the corresponding electron transport layer (ETL) are characterized by a low work function or ionization energy. The ionization energy is preferably less than 3.5 eV. The ETM can be at least one organic compound, such as C60, BCP, Bphen, BPY-OXD. The ETM also can be at least one inorganic compound, such as zinc oxide, titanium oxide etc. Organic compounds employed in layer (24) can be doped with an n-dopant, which has HOMO similar or smaller than the LUMO of the electron-transport layer, such as CS2CO3, pyronin B (PyB), rhodamine B, cobaltocene, etc. The thickness of layer (24) is preferably in a range of from 0 to 1 μηη, more preferably from 0 to 60 nm.

With regard to layer 25, reference is made to layer 15 mentioned before.

With regard to layer 26, reference is made to layer 16 mentioned before. The organic solar cell with bulk heterojunctions may be produced by a gas phase deposition process as mentioned before. With regard to the deposition rate, the temperature of the substrate in the deposition and thermal treatment (annealing) reference is made to the disclosure above. According to a further preferred embodiment of the invention, the solar cell according to the present invention is a bulk-heterojunction single cell having an inverse structure. Figure 4 illustrates a solar cell with inverse structure according to the present invention.

According to further preferred embodiment of the invention, the solar cell according to the present invention is a tandem cell.

A tandem cell comprises two or more than two, e.g. 3, 4, 5, etc., subcells. A single subcell, some of the subcells or all subcells may comprise a donor-acceptor heterojunction based on a compound of formula I. Each donor-acceptor heterojunction can in form of a flat heterojunction or a bulk heterojunction. In a preferred embodiment, at least one of the donor-acceptor heterojunctions of the tandem cell are in form of a bulk heterojunction.

The subcells forming the tandem cell may be connected in series or parallel.

Preference is given to those tandem cells, wherein the subcells are connected in series. Preferably, an additional recombination layer is between the single subcells. Both normal structure and inverse structure can be used as subcell. However, the polarity of all subcells should be in one direction, i.e. all cells have a normal structure or all cells have an inverse structure.

Figure 5 illustrates a tandem cell according to the present invention. Layer 31 is a transparent conducting layer. Suitable materials are those mentioned herein for the single cells.

With regard to layer 31 , reference is made to layers 1 1 and 21 mentioned before. Layer 32 and 34 are the individual subcells. Here, subcell refers to functional layers of a single cell, excluding cathode and anode. Reference is made to layers 12 to 15 for cells with flat heterojunction and to layers 22 to 25 for cells with bulk heterojunction. In one embodiment, all of the subcells can comprise at least one compound of formula I. In a further embodiment, at least one subcell that comprises at least one compound of formula I is combined with at least one subcell based on a different semiconductor material. Thus, C60 can be combined with a phthalocyanine, such as zinc

phthalocyanine or copper phthalocyanine. Further, C60 can be combined with dibenzotetraphenylperiflanthene, oligothiophenes such as a,a'-bis(2,2-dicyanovinyl)- quinquethiophene (DCV5T) and the like.

In all cases, the best case is a combination of materials such a combination that the absorption of each subcell does not overlap too much, but is distributed over the solar spectrum, which in turns contributes to the higher photocurrent. For example, a second subcell with longer wavelength absorption is placed next to a first subcell having a shorter wavelength absorption than the first subcell to increase the absorption range. Preferably, the tandem cell can absorb in the region from 400 to 800 nm. Another subcell that can absorb from 800 nm and on can be placed next to the cell to increase the absorption to near infra red range. For best performance, the subcell with absorption in shorter wavelength is placed closer to the metal top contact than the subcell with the longer wavelength absorption.

Layer 33 is a recombination layer. The recombination layer enables one type of charge produced in one subcell to recombine to the other type of charge generated from adjacent subcells. Small metal clusters such as Ag, Au or combinations of highly doped n- and p-dopant layers can be used. In case of metal clusters, the thickness ranges from 0.5 to 5 nm. In the case of n- and p-dopant layers the thickness ranges from 5 to 40 nm. The recombination layer usually connects an electron transport layer of one subcell with the hole transport layer of the another subcell. In so doing this, further subcells may be combined to a tandem cell.

Layer 36 is the top electrode. The material of the top electrode depends on the polarity direction of the subcells. When the subcells take normal structure, the top metal is preferably made from low work function materials, such as Ag, Mg, Ca or Al. When the subcells take inverse structure, the top metal is preferably made from high work function materials such as Au, Pt, PEDOT-PSS.

In tandem structure connected in series, the overall voltage is the sum of the single subcells. The overall current is limited by the lowest current amongst the single subcells. For this reason, the thickness of each subcell should be re-optimized so that all subcell show similar current. Examples of various types of donor-acceptor heterojunctions are a donor-acceptor bilayer forming a planar heterojunction or a hybrid planar-mixed heterojunction or a gradient bulk heterojunction or an annealed bulk heterojunction.

The preparation of a hybrid planar-mixed heterojunction is described in Adv. Mater. 17, 66-70 (2005). Coevaporated mixed heterojunction layers are sandwiched between homogenous donor and acceptors materials. According to a specific embodiment of the invention, the donor-acceptor heterojunction is a gradient bulk heterojunction. The bulk heterojunction layer has a gradual change in donor - acceptor ratio. The cell can have stepwise gradient (Figure 6 (a)), where layer 01 consists of 100% donor, layer 02 has donor/acceptor ratio > 1 , layer 03 has donor/acceptor ratio = 1 , layer 04 has donor/acceptor ratio <1 , and layer 05 consists of 100% acceptor. It can also have smooth gradient. (Figure 6 (b)) where layer 01 consists of 100% donor, layer 02 has decreasing ratio of donor / acceptor as the layer is distanced from the layer 01 , and layer 03 consists of 100% acceptor. Different donor- acceptor ratio can be controlled by deposition rate of each material. Such structure can enhance the percolation path of charges.

According to a further specific embodiment of the invention, the donor-acceptor heterojunction is an annealed bulk heterojunction as described for example in Nature 425, 158-162, 2003. The method of fabricating said type of solar cell comprises an annealing step before or after metal deposition. With annealing, donor and acceptor materials can segregate which leads to larger percolation paths.

According to a further specific embodiment of the invention, the solar cells are prepared by organic vapor phase deposition in either a planar or controlled

heterojunction architecture. Solar cells of this type are described in Materials, 4, 2005, 37.

In addition to the compounds of the general formula (I), the following semiconductor materials are suitable for use in organic photovoltaics: Acenes, such as anthracene, tetracene, pentacene and substituted acenes.

Substituted acenes comprise at least one substituent selected from electron-donating substituents (e.g. alkyl, alkoxy, ester, carboxylate or thioalkoxy), electron-withdrawing substituents (e.g. halogen, nitro or cyano) and combinations thereof. These include 2,9-dialkylpentacenes and 2,10-dialkylpentacenes, 2,10-dialkoxypentacenes,

1 ,4,8,1 1 -tetraalkoxypentacenes and rubrene (5,6,1 1 ,12-tetraphenylnaphthacene).

Suitable substituted pentacenes are described in US 2003/0100779 and US 6,864,396. A preferred acene is rubrene (5,6,1 1 ,12-tetraphenylnaphthacene). Phthalocyanines, such as hexadecachlorophthalocyanines and

hexadecafluorophthalocyanines, metal-free phthalocyanine and phthalocyanine comprising divalent metals, especially those of titanyloxy, vanadyloxy, iron, copper, zinc, especially copper phthalocyanine, zinc phthalocyanine and metal-free phthalocyanine, copper hexadecachlorophthalocyanine, zinc

hexadecachlorophthalocyanine, metal-free hexadecachlorophthalocyanine, copper hexadecafluorophthalocyanine, hexadecafluorophthalocyanine or metal-free hexadecafluorophthalocyanine.

Porphyrins, for example 5,10,15,20-tetra(3-pyridyl)porphyrin (TpyP).

Liquid-crystalline (LC) materials, for example hexabenzocoronene (HBC-PhC12) or other coronenes, coronenediimides, or triphenylenes, such as

2,3,6,7,10,1 1 -hexahexylthiotriphenylene (HTT6) or 2,3,6,7,10,1 1 -hexakis(4-n- nonylphenyl)triphenylene (PTP9), 2,3,6,7,10,1 1 -hexakis(undecyloxy)triphenylene (HAT1 1 ). Particular preference is given to LCs which are discotic.

Thiophenes, oligothiophenes and substituted derivatives thereof. Suitable

oligothiophenes are quaterthiophenes, quinquethiophenes, sexithiophenes, a,co-di(Ci-C8)alkyloligothiophenes, such as a,co-dihexylquaterthiophenes,

α,ω-dihexylquinquethiophenes and α,ω-dihexylsexithiophenes, poly(alkylthiophenes) such as poly(3-hexylthiophene), bis(dithienothiophenes), anthradithiophenes and dialkylanthradithiophenes such as dihexylanthradithiophene, phenylene-thiophene (P-T) oligomers and derivatives thereof, especiallya,co-alkyl-substituted phenylene- thiophene oligomers.

Preferred thiophenes, oligothiophenes and substituted derivatives thereof, are poly-3-hexylthiophene (P3HT) or compounds of the a a'-bis(2,2-dicyanovinyl)quin- quethiophene (DCV5T) type, poly(3-(4-octylphenyl)-2,2'-bithiophene) (PTOPT), poly(3-(4'-(1 ",4",7"-trioxaoctyl)phenyl)thiophene) (PEOPT), poly(3-(2'-methoxy-5'- octylphenyl)thiophenes) (POMeOPTs), poly(3-octylthiophene) (P30T), pyridine- containing polymers such as poly(pyridopyrazine vinylene), poly(pyridopyrazine vinylene) modified with alkyl groups e.g. EHH-PpyPz, PTPTB copolymers, polybenzimidazobenzophenanthroline (BBL), poly(9,9-dioctylfluorene-co-bis-

N,N'-(4-methoxyphenyl)-bis-N,N'-phenyl-1 ,4-phenylenediamine) (PFMO); see Brabec C, Adv. Mater., 2996, 18, 2884. (PCPDTBT) poly[2,6-(4,4-bis(2-ethylhexyl)-4H- cyclopenta[2,1 -b;3,4-b']-dithiophene)-4,7-(2,1 ,3-benzothiadiazoles)]. Paraphenylenevinylene and paraphenylenevinylene-comprising oligomers and polymers, for example polyparaphenylenevinylene (PPV), MEH-PPV (poly(2-methoxy- 5-(2'-ethylhexyloxy)-1 ,4-phenylenevinylene)), MDMO-PPV (poly(2-methoxy-5-(3',7'- dimethyloctyloxy)-1 ,4-phenylenevinylene)), cyano-paraphenylenevinylene (CN-PPV), CN-PPV modified with alkoxy groups.

PPE-PPV hybrid polymers (phenylene-ethynylene/phenylene-vinylene hybrid polymers).

Polyfluorenes and alternating polyfluorene copolymers, for example with 4,7-dithien- 2'-yl-2,1 ,3-benzothiadiazoles, and also poly(9,9'-dioctylfluorene-cobenzothiadiazole) (F₈BT), poly(9,9'-dioctylfluorene-co-bis-A/,A/ '-(4-butylphenyl)-bis-A/,A/ '-phenyl- 1 ,4-phenylenediamine) (PFB).

Polycarbazoles, i.e. carbazole-comprising oligomers and polymers, such as (2,7) and (3,6). Polyanilines, i.e. aniline-comprising oligomers and polymers.

Triarylamines, polytriarylamines, polycyclopentadienes, polypyrroles, polyfuran, polysilols, polyphospholes, N,N'-Bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine (TPD), 4,4'-bis(carbazol-9-yl) biphenyl (CBP), 2,2',7,7'-tetrakis-(N,N-di-p-methoxy- phenyl-amine)-9,9'-spirobifluorene (spiro-MeOTAD).

Fullerenes, especially C60 and derivatives thereof such as PCBM (= [6,6]-phenyl- C6i-butyric acid methyl ester). In such cases, the fullerene derivative would be a hole conductor.

Copper(l) iodide, copper(l) thiocyanate. p-n-Mixed materials, i.e. donor and acceptor in one material, polymer, block copolymers, polymers with C60s, C60 azo dyes, trimeric mixed material which comprises compounds of the carotenoid type, porphyrin type and quinoid liquid- crystalline compounds as donor/acceptor systems, as described by Kelly in S. Adv. Mater. 2006, 18, 1754.

All aforementioned semiconductor materials may also be doped. Examples of dopants: Br2, tetrafluorotetracyanoquinodimethane (F4-TCNQ), etc.

The invention further provides an electroluminescent (EL) arrangement comprising an upper electrode, a lower electrode, wherein at least one of said electrodes is transparent, an electroluminescent layer and optionally an auxiliary layer, wherein the electroluminescent arrangement comprises at least one compound of the formula I as defined above. An EL arrangement is characterized by the fact that it emits light when an electrical voltage is applied with flow of current. Such arrangements have been known for a long time in industry and technology as light-emitting diodes (LEDs). Light is emitted on account of the fact that positive charges (holes) and negative charges (electrons) combine with the emission of light. In the sense of this application the terms electroluminescing arrangement and organic light-emitting diode (OLEDs) are used synonymously. As a rule, EL arrangements are constructed from several layers. At least on of those layers contains one or more organic charge transport compounds. The layer structure is in principle as follows:

1. Carrier, substrate

2. Base electrode (anode)

3. Hole-injecting layer

4. Hole-transporting layer

5. Light-emitting layer

6. Electron-transporting layer

7. Electron-injecting layer

8. Top electrode (cathode)

9. Contacts

10. Covering, encapsulation. This structure represents the most general case and can be simplified by omitting individual layers, so that one layer performs several tasks. In the simplest case an EL arrangement consists of two electrodes between which an organic layer is arranged, which fulfils all functions, including emission of light. The structure of organic light- emitting diodes and processes for their production are known in principle to those skilled in the art, for example from WO 2005/019373. Suitable materials for the individual layers of OLEDs are disclosed, for example, in WO 00/70655. Reference is made here to the disclosure of these documents. In principle OLEDs according to the invention can be produced by methods known to those skilled in the art. In a first embodiment, an OLED is produced by successive vapor deposition of the individual layers onto a suitable substrate. For vapor deposition, it is possible to use customary techniques such as thermal evaporation, chemical vapor deposition and others. In an alternative embodiment, the organic layers may be coated from solutions or dispersions in suitable solvents, for which coating techniques known to those skilled in the art are employed.

Suitable as substrate 1 are transparent carriers, such as glass or plastics films (for example polyesters, such as polyethylene terephthalate or polyethylene naphthalate, polycarbonate, polyacrylate, polysulphone, polyimide foil). Suitable as transparent and conducting materials are a) metal oxide, for example indium-tin oxide (ITO), tin oxide (NESA), etc. and b) semi-transparent metal films, for example Au, Pt, Ag, Cu, etc. The compounds of the formula (I) preferably serve as a charge transport material (electron conductor). Thus, at least one compound of the formula I as defined above is preferably used in a hole-injecting layer, hole transporting layer or as part of a transparent electrode.

In the EL applications according to the invention low molecular weight or oligomeric as well as polymeric materials may be used as light-emitting layer 5. The substances are characterized by the fact that they are photoluminescing. Accordingly, suitable substances are for example fluorescent dyes and fluorescent products that are forming oligomers or are incorporated into polymers. Examples of such materials are coumarins, perylenes, anthracenes, phenanthrenes, stilbenes, distyryls, methines or metal complexes such as Alq3 (Tris(8-hydroxyquinolinato)aluminium), etc. Suitable polymers include optionally substituted phenylenes, phenylene vinylenes or polymers with fluorescing segments in the polymer side chain or in the polymer backbone. A detailed list is given in EP-A-532 798. Preferably, in order to increase the luminance, electron-injecting or hole-injecting layers (3 and/or 7) can be incorporated into the EL arrangements. A large number of organic compounds that transport charges (holes and/or electrons) are described in the literature. Mainly low molecular weight substances are used, which are for example vacuum evaporated in a high vacuum. A comprehensive survey of the classes of substances and their use is given for example in the following publications: EP-A 387 715, US 4,539,507, US 4,720,432 and

US 4,769,292. A preferred material is PEDOT (poly-(3,4-ethylenedioxythiophene)) which can also be employed in the transparent electrode of the OLEDs. As a result of the inventive use of the compounds (I), it is possible to obtain OLEDs with high efficiency. The inventive OLEDs can be used in all devices in which electroluminescence is useful. Suitable devices are preferably selected from stationary and mobile visual display units. Stationary visual display units are, for example, visual display units of computers, televisions, visual display units in printers, kitchen appliances and advertising panels, illuminations and information panels. Mobile visual display units are, for example, visual display units in cell phones, laptops, digital cameras, vehicles and destination displays on buses and trains. Moreover, the compounds (I) may be used in OLEDs with inverse structure. The compounds (I) in these inverse OLEDs are in turn preferably used in the light-emitting layer. The structure of inverse OLEDs and the materials typically used therein are known to those skilled in the art.

Before they are used as charge transport materials or exciton transport materials, it may be advisable to subject the compounds of the formula (I) to a purification process. Suitable purification processes comprise conventional column techniques and conversion of the compounds of the formula (I) to the gas phase. This includes purification by sublimation or PVD (physical vapor deposition).

The invention is illustrated in detail with reference to the following nonrestrictive examples.

Examples

I. Preparation of compounds of the general formula I

To a suspension of 1 ,4-dichloro-2,3,5,6-tetracarboxylic acid dianhydride (0.9 g, prepared as described in "Die Angewandte Makromolekulare Chemie" 254 (1998), pages 33-38) in 10 mL of 1 -methylpyrrolidone was added 1 mL of concentrated acetic acid (AcOH). After stirring for 15 minutes 0.58 g (2.25 eq) of 1 H,1 H-trifluoroethylamine (2,2,2-trifluoroethylamine) were added. The reaction mixture warmed up to 30°C and the colour changed to yellow. The reaction mixture was slowly warmed up to 120°C and stirred for 3 hours at this temperature. A clear, yellow solution was formed. TLC showed complete reaction. After cooling to room temperature, 150 mL of 1 M HCI were added and the precipitate was sucked off after 30 minutes. After drying in vacuo at 70°C, 1 g of the title compound with a purity of 85% was obtained (yield: 72.4%).

Column chromatography on silica gel using dichloromethane followed by crystallisation using tetrahydrofuran (THF) gave 0.5 g (43%) of the title compound in a purity of 99.5%.

H-NMR (THF-d₈, 400 MHz, 300 K) δ = 4.38-4.50 (t, 4H, CH₂);

3C-NMR (THF-d₈, 125 MHz, 300 K) δ = 162.73, 135.70, 127.70, 124.52, 39.86.

The compounds of the following examples 2 to 4 were prepared in a manner analogous to the preparation of Example 1 .

Example 2:

3.0 g of 1 ,4-dichloro-2,3,5,6-tetracarboxylic acid dianhydride in 30 mL of

1 -methylpyrrolidone were reacted with 5.0 g (2.4 eq) of 1 H, 1 H-heptafluorobutylamine (2,2,3,3,4,4,4-heptafluorobutylamine) in the presence of 3 mL of concentrated acetic acid. Crude yield: 6 g (75.2%); purity: 85%. Column chromatography on silica gel using dichloromethane followed by crystallisation using tetrahydrofuran (THF) gave 4.4 g of the title compound in a purity of 99.5% (yield: 64.2%).

H-NMR (THF-d₈, 400 MHz, 300 K) δ = 4.45-4.60 (t, 4H, CH₂).

3C-NMR (THF-de, 125 MHz, 300 K) δ = 164.0, 137.8, 128.9, 1 17.7, 1 15.3, 109.8, 42.9.

Example

2.0 g of 1 ,4-dichloro-2,3,5,6-tetracarboxylic acid dianhydride in 30 mL of

1 -methylpyrrolidone were reacted with 3.35 g (2.75 eq) of 4-trifluoromethylbenzylamine in the presence of 3 mL of concentrated acetic acid. Crude yield: 2.1 g (42.4%); purity of 85%. Column chromatography on silica gel using dichloromethane followed by crystallisation using tetrahydrofuran (THF) gave the title compound in a purity of 99%. H-NMR (THF-de, 500 MHz, 300 K) δ = 7.65 (s, 8H, phenyl); 4.9 (s, 4H, CH₂).

3C-NMR (THF-de, 125 MHz, 300 K) δ = 164.0, 137.8, 133.5, 128.9, 128.7, 128.3, 125.2, 124.3, 41 .2.

Following the procedure analogous to that used in Examples 1 -3, but using 4 equivalents of (R)-l -methylpentylamine as amine, compounds 4a and 4b were obtained.

Compound 4a: Yield: 60.6 % in a purity of 99%

H-NMR (THF-de, 500 MHz, 300 K) δ = 4,3-4,42 (m, 2H, CH); 1 ,95-2,1 und 1 ,7-1 ,8 (m, 4H, CH₂); 1 ,45 (d, 6H, CH₃); 1 ,12-1 ,4 (8H, CH₂-CH₂); 1 ,85 (t, 6H, CH₃); ³C-NMR (THF-de, 125 MHz, 300 K) δ = 163.60, 134.76, 127.04, 49.12, 33.59, 29.31 ,

22.71 , 18.57, 14.10;

MS (MALDI-TOF): m/z (M⁺) = 452.

Compound 4b (by-product)

Yield: 14.5% in a purity of greater 95%.

H-NMR (THF-de, 500 MHz, 300 K) δ = 7,25-7,35 (d, 1 H, NH); 4,7-4,8 (m, 1 H, CH); 4,21 -4,36 (m, 2H, CH); 1 ,95-2,1 und 1 ,7-1 ,8 und 1 ,45-1 ,6 (m, 6H, CH₂); 1 ,4 und 1 ,2 (d, 9H, CH₃); 1 ,25-1 ,35 (12H, CH₂-CH₂); 0,85 (t, 9H, CH₃)

Example 5:

To a solution of 1 ,4-dibromo-2,3,5,6-tetracarboxylic acid dianhydride (1 .7 g, prepared as described in Angewandte Molekulare Chemie; 1998, Vol. 254, Iss. 1 , S. 33-38) in 25 ml. of 1 -methylpyrrolidone were added 1 .3 ml. of concentrated acetic acid. After stirring for 15 minutes 2.7 g (3.35 eq) of 1 H, 1 H-heptafluorobutylamine were added. The reaction mixture warmed up to 30°C. The reaction mixture was slowly warmed up to 120°C and stirred for 3 hours at this temperature. An orange-red solution was formed. TLC showed complete reaction. At 100°C, a thick precipitate was formed. After cooling to room temperature, 150 mL of 1 M HCI were added and the precipitate was sucked off after 30 minutes. After drying the title compound is crystallized from dichloromethane and tetrahydrofuran. The residue gave 2.4 g of the dibromo compound 5a (purity: 95%, yield: 68.3). 0.8 g of the monobromo compound 5b were isolated from the filtrate in a purity of 90% (yield: 68.3%).

Compound 5a:

H-NMR (THF-de, 400 MHz, 300 K) δ = 4.45-4.55 (t, 4H, CH₂).

MS (MALDI-TOF): m/z (M-) = 735.

Compound 5b:

H-NMR (THF-de, 400 MHz, 300 K) δ = 7.9-8.0 (t, 1 H, NH); 5.05-5.2 (m, 2H, CH₂); 4.40-

4.58 (t, 4H, CH₂).

MS (MALDI-TOF): m/z (M-) = 854.

0.6 g of compound 4a from example 4 were solved in 50 mL of acetonitrile at 60°C. Then 0.38 g of KF were added and the mixture was refluxed for 72 hours. The acetonitrile was distilled off, 30 mL of 1 -methylpyrrolidone were added and the reaction mixture was heated to 120°C. After stirring for 6 hours at 120°C, the mixture was cooled to room temperature, 150 mL of 1 M HCI were added and the precipitate was sucked off after 30 minutes. The residue was dissolved in dichloromethane, dried over MgSC and filtered over silica gel. 0.23 g (37.2% yield) of the title compound with a purity of 90% were obtained. Recrystallization (twice) from n-hexane gave 0.17 g of the title compound with a purity of 98%.

H-NMR (CD2CI2, 500 MHz, 300 K) δ = 4.27-4.38 (m, 2H, CH); 1 .97-2,07 and 1.69-1 .79 (m, 4H, CH₂); 1.45 (d, 6H, CH₃); 1.12-1 .35 (8H, CH₂-CH₂); 0.82-0.88 (6H, CH₃).

3C-NMR (THF-de, 125 MHz, 300 K) δ = 162.77, 149.07, 126.18, 49.23. 33.53, 29.27,

22.68, 18.55, 14.10;

MS (MALDI-TOF): m/z (M-) = 420. Example

1 .0 g of N,N-bis-(1 ,1 -H,H-perfluorobutyl)-1 ,4-dichloro-2,3,5,6-tetracarboxylic acid diimide were solved in 50 mL of dimethylformamide (DMF) at room temperature. Then 0.4 g of KF were added and the mixture was stirred at 120°C for 8 hours. After cooling to room temperature, 200 mL of 1 M HCI were added and the precipitate was sucked off after 30 minutes. The residue was solved in tert-butyl methyl ether and charcoal was added. The solution was dried with MgSC . After removing of the solvent, 0.4 g (29.5%) of the title compound with a purity of 70% were obtained.

MS (MALDI-TOF): m/z (M-) = 616.

To a solution of 1.05 g of N,N-bis-(1 ,1 -H,H-perfluorobutyl)-1 ,4-dibromo-2, 3,5,6- tetracarboxylic acid diimide in 15 mL of 1 -methylpyrrolidione were added 0.38 g of CuCN at room temperature and the mixture was stirred at 120°C for 5 hours. The reaction mixture was cooled to room temperature and 150 mL of methanol were added. Methanol is distilled off at 60°C/30 mbar. The thus obtained solution was mixed with 5% H2SO4 and the precipitate is sucked off after 60 minutes. The residue was dissolved in dichloromethane, the obtained solution was dried with MgSC and filtered. After removing of the solvent, 0.8 g of title compound (72.7% yield ) were obtained in a purity of 90%. Chromatography on silica gel using cyclohexane/ethyl acetate afforded 0.55 g of a yellow solid.

H-NMR (CD2CI2, 500 MHz, 300 K) δ = 4.30-4.55 (m, 4H, CH₂); 4.0 (s, 6H, CH₃).

3C-NMR (THF-ds, 125 MHz, 300 K) δ = 167.6, 165.0, 130.3, 126.5, 1 18.9, 1 12.6, 108.0, 53.3, 42.2.

MS (MALDI-TOF): m/z (M⁺) = 696.

Example 9:

0.5 g of the compound 4a from example 4-were dissolved in 50 mL of acetonitrile at 60°C. 0.36 g of KCN were added and the mixture was refluxed under stirring for 22 hours. After cooling to room temperature, the precipitate was filtered off. The solvent was removed and the obtained residue was dissolved in dichloromethane. Upon addition of n-hexane was added a precipitate was formed. The thus obtained

precipitate was sucked off and dried to give 0.2 g of the title compound.

MS (MALDI-TOF): m/z (M^") = 434.

0.6 g of N,N-bis-(1 ,1 -H,H-perfluorobutyl)-1 ,4-dibromo-2,3,5,6-tetracarboxylic acid diimide were dissolved in 25 mL of 1 -methylpyrrolidone at room temperature. 0.3 g of KCN were added and the reaction mixture was stirred at 130°C for 8 hours. After cooling to room temperature, 200 mL of 1 M HCI were added and the precipitate was sucked off after 30 minutes. The precipitate was dissolved in tert-butyl methyl ether, charcoal was added, dried with MgSC and sucked off. After removing of the solvent 0.4 g of the title compound (62,5% yield) with a purity of 80% were obtained.

MS (MALDI-TOF): m/z (M-) = 630.

Example 1 1 :

1 .0 g of N,N-Bis-(1 ,1 -H,H-perfluorobutyl)-1 ,4-dichloro-2,3,5,6-tetracarboxylic acid diimide were dissolved in 50 mL of dimethylformamide at room temperature. 0.4 g of KCN were added and the reaction mixture was stirred at 120°C for 8 hours. After cooling to room temperature, 200 mL of 1 M HCI were added. After 30 minutes, the precipitate was sucked off. The precipitate was dissolved in tert-butyl methyl ether, charcoal was added, dried with MgSC and sucked off. The solvent was removed to give 0.16 g of the title compound with a purity of 50 %.

MS (MALDI-TOF): m/z (M-) = 630.

To 8.8 g of copper(l) oxide in 20 mL of dimethyl sulfoxide were added dropwise 10.7 g of nonafluorobutyliodide at 100-1 10°C so that the reaction mixture was scarcely refluxed. After 30 minutes, the reaction mixture was cooled to 80°C and 1 .0 g of N,N-bis-(1 ,1 -H,H- perfluorobutyl)-1 ,4-dichloro-2,3,5,6-tetracarboxlic acid were added in one portion. The reaction mixture was heated at 125°C and stirring was continued for 20 hours. After cooling to room temperature, 200 mL of tetrahydrofuran were added and the insoluble copper salts were filtered off. After concentrating the reaction mixture in a rotary evaporator 300 mL of 1 M HCL were added, the mixture was stirred for 2 hours and decanted. The residue was stirred with water, dissolved in tert.-butyl methyl ether and filtrated over silica gel. The solvent was removed to give 0.5 g of the title compound with a purity of 25 % of compound 12a and 50% of compound 12b.

Compound 12a:

MS (MALDI-TOF): m/z (M-) = (1016)

Compound 12b:

MS (MALDI-TOF): m/z (M-)

II. General method for determining the transistor characteristics Production of semiconductor substrates by means of physical vapor deposition (PVD) Device preparation: bottom-gate top-contact configuration

The substrates used for the devices were heavily doped p-type doped silicon wafers.

Aluminum was deposited on the silicon substrate by vacuum evaporation as the gate electrode with a thickness of 20 nm. The aluminum surface was briefly exposed to an oxygen plasma to create an AIO_x layer with a thickness of 3.6 nm. The substrate was then immersed for 1 h in a 2-propanol solution of n-tetradecylphosphonic acid to form a 1 .7-nm-thick densely packed self-assembled monolayer (SAM) on the surface of the oxidized gate. The AIO_x/SAM gate dielectric had a total thickness of 5.3 nm. A thin layer of the organic semiconductor was deposited onto the gate dielectric surface by sublimation in a vacuum evaporator (Leybold UNIVEX 300) at a background pressure of 10^"6 mbar. During the deposition of the organic semiconductor layer, the substrate was held at a specified temperature between 20 and 150°C, typically 20°C. The

deposition rate was about 0.1 A/s and the final semiconductor film thickness was about 30 nm. Thin-film transistors were completed by depositing gold source and drain

contacts through a shadow mask onto the surface of the organic semiconductor layer by thermal evaporation in vacuum (typical channel length was 20 μηη with width/length ratios of about 10).

The current-voltage (l-V) characteristics of the devices were measured in ambient air at room temperature using a Agilent semiconductor parameter analyzer (4156C). Key device parameters, such as charge electron mobility (μ) and on-to-off current ratio

(lon/loff) were extracted from the drain current (Id) vs. gate voltage-source (V_g) characteristics employing standard procedures. Figure 7 shows the schematic cross section of the organic TFT.

11.1 OFET comprising 4,8-dichloro-2,6-bis-(2,2,3,3,4,4,4-heptafluorobutyl)-pyrrolo[3,4- f]isoindole-1 ,3,5,7-tetraone

Figure 8 shows the current-voltage characteristics of a 4,8-dichloro-2,6-bis- (2,2,3,3,4,4,4-heptafluorobutyl)-pyrrolo[3,4-f]isoindole-1 ,3,5,7-tetraone TFT on a Si wafer recorded shortly after device fabrication, measured in ambient air at room temperature. The TFT had a mobility of 0.008 cm s.

For comparison, the mobility of a 2,6-bis-(2,2,3,3,4,4,4-heptafluorobutyl)- pyrrolo[3,4-f]isoindole-1 ,3,5,7-tetraone TFT on a Si wafer recorded shortly after device fabrication was measured (figure 9).

The comparison TFT had a mobility of 5.1 x 10^"4 cmWs, measured in ambient air at room temperature.

Claims

1 . The use of compounds of the general formula I

wherein

R¹ and R² are each independently selected from branched C3-C3o-alkyl,

linear or branched perfluoro-Ci-C3o-alkyl,

linear or branched 1 H,1 H-perfluoro-C2-C3o-alkyl,

linear or branched 1 H,1 H,2H,2H-perfluoro-C3-C3o-alkyl

or a phenyl-(Ci-C3o)-alkyl group, wherein the benzene ring of the phenylalkyi group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI, Br, CN and perfluoro-Ci-C3o-alkyl,

X¹ and X² are each independently selected from F, CI, Br, CN, COOR^a, CONR^bR^c, branched C₃-C₃₀-alkyl,

linear or branched perfluoro-C3-C3o-alkyl,

linear or branched 1 H,1 H-perfluoro-C2-C3o-alkyl,

linear or branched 1 H,1 H,2H,2H-perfluoro-C3-C3o-alkyl, branched NH(C₃-C₃₀-alkyl),

linear or branched NH(perfluoro-Ci-C3o-alkyl),

linear or branched NH(1 H,1 H-perfluoro-C2-C3o-alkyl) or linear or branched NH(1 H,1 H,2H,2H-perfluoro-C₃-C₃o-alkyl),

The use according to claim 1 , where at least one of the radicals R¹ , R², X¹ or X² is selected from a group of the formula (II)

wherein

3. The use according to claim 2, wherein in the group of the formula (II), q is 0 or 1 .

4. The use according to claim 2 or 3, wherein at least one of the radicals R¹, R², X¹ or X² is 1 -methylethyl, 1 -methylpropyl, 2-methylpropyl, 1 -methylbutyl,

2-methylbutyl, 3-methylbutyl, 1 -methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1 -methylhexyl, 1 -methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 1 -methylheptyl, 1 -methylheptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 4-methylheptyl, 1 -methyloctyl, 1 -ethylpropyl, 1 -ethylbutyl, 1 -ethylpentyl, 1 -ethylhexyl, 1-ethylheptyl, 1 -ethyloctyl, 1 -propyl butyl,

1 -propylpentyl, 1 -propylhexyl, 1 -propylheptyl, 1 -propyloctyl, 1 -butylpentyl, 1 -butylhexyl, 1 -butylheptyl, 1-butyloctyl, 1 -pentylhexyl, 1 -pentylheptyl,

1 -pentyloctyl, 1 -hexylheptyl, 1 -hexyloctyl or 1 -heptyloctyl.

5. The use according to any of the preceding claims, wherein at least one of the radicals R¹ and R² is selected from CF3, C2F5, n-C3F₇, n-C4F9, n-CsFn ,

n-C₆Fi3, CF(CF₃)₂, C(CF₃)₃, CF₂CF(CF₃)₂, CF(CF₃)(C₂F₅), CH₂-CF₃, CH₂-C₂F₅, CH₂-(n-C₃F₇), CH₂-(n-C₄F₉), CH₂-(n-C₅Fn), CH₂-(n-C₆Fi₃), CH₂-CF(CF₃)₂, CH₂-C(CF₃)₃, CH₂-CF₂CF(CF₃)₂, CH₂-CF(CF₃)(C₂F₅), CH₂-CH₂-CF₃,

CH₂-CH₂-C₂F₅, CH₂-CH₂-(n-C₃F₇), CH₂-CH₂-(n-C₄F9), CH₂-CH₂-(n-C5Fn), CH₂-CH₂-(n-C6Fi₃), CH₂-CH₂-CF(CF₃)₂, CH₂-CH₂-C(CF₃)₃,

CH₂-CH₂-CF₂CF(CF₃)₂ or CH₂-CH₂-CF(CF₃)(C₂F₅).

6. The use according to any of the preceding claims, wherein at least one of the radicals X¹ and X² is selected from n-C₃F₇, n-C₄F9, n-CsFn ,

n-CeFis, CF(CF₃)₂, C(CF₃)₃, CF₂CF(CF₃)₂, CF(CF₃)(C₂F₅), CH₂-CF₃, CH₂-C₂F₅, CH₂-(n-C₃F₇), CH₂-(n-C₄F₉), CH₂-(n-C₅Fi i), CH₂-(n-C₆Fi3), CH₂-CF(CF₃)₂, CH₂-C(CF₃)₃, CH₂-CF₂CF(CF₃)₂, CH₂-CF(CF₃)(C₂F₅), CH₂-CH₂-CF₃,

CH₂-CH₂-C₂F₅, CH₂-CH₂-(n-C₃F₇), CH₂-CH₂-(n-C₄F₉), CH^CH^n-CsFn), CH₂-CH₂-(n-C6Fi₃), CH₂-CH₂-CF(CF₃)₂, CH₂-CH₂-C(CF₃)₃,

CH₂-CH₂-CF₂CF(CF₃)₂, CH₂-CH₂-CF(CF₃)(C₂F₅),

NH(n-C₃F₇), NH(n-C₄F₉), NH(n-C5Fn),NH(n-C6Fi₃), NH(CF(CF₃)₂),

NH( C(CF₃)₃), NH(CF₂CF(CF₃)₂), NH(CF(CF₃)(C₂F₅)), NH(CH₂-CF₃),

NH(CH₂-C₂F₅), NH(CH₂-(n-C₃F₇)), NH(CH₂-(n-C₄F₉)), NH(CH₂-(n-C₅Fi i)), NH(CH₂-(n-C6Fi₃)), NH( CH₂-CF(CF₃)₂), NH(CH₂-C(CF₃)₃),

NH(CH₂-CF₂CF(CF₃)₂), NH(CH₂-CF(CF₃)(C₂F₅)), NH(CH₂-CH₂-CF₃),

NH(CH₂-CH₂-C₂F₅), NH(CH₂-CH₂-(n-C₃F₇)), NH(CH₂-CH₂-(n-C₄F₉)),

NH(CH₂-CH₂-(n-C5Fn)),

NH(CH₂-CH₂-(n-C6Fi₃)), NH(CH₂-CH₂-CF(CF₃)₂), NH(CH₂-CH₂-C(CF₃)₃), NH(CH₂-CH₂-CF₂CF(CF₃)₂) or NH(CH₂-CH₂-CF(CF₃)(C₂F₅)).

7. The use according to any of the preceding claims, wherein at least one of the radicals R¹ and R² is a group of the formula III

in which

The use according to claim 7, wherein at least one of the radicals R¹ and R² is a benzyl group, wherein the benzene ring of the benzyl group bears 1 , 2, 3, 4 or 5 substituents, independently selected from F, CI and perfluoro-Ci-C₃o-alkyl.

The use according to claim 8, wherein at least one of the radicals R¹ and R² is a substituent of the formula IV

in which

# represents the bonding site to the imide nitrogen atom, and

R^f is selected from CF₃, C₂F₅, n-C₃F₇, n-C₄F9, n-CsFn , n-CeFi 3, CF(CF₃)2, C(CF₃)₃, CF₂CF(CF₃)₂, or CF(CF₃)(C₂F₅). 10. The use according to claim 9, where at least one of the radicals R¹ and R² is a group of the formula

in which

# represents the bonding site to the imide nitrogen atom.

1 1 . The use according to any of the preceding claims, where X¹ and X² are both F, or both CI, or both Br or both CN.

12. The use according to any of the preceding claims as an n-semiconductor in

organic field-effect transistors. 13. An organic field-effect transistor comprising a substrate having at least one gate structure, a source electrode and a drain electrode and at least one compound of the formula I as defined in any of claims 1 to 1 1 as a semiconductor material. 14. A substrate comprising a plurality of organic field-effect transistors, at least some of the field-effect transistors comprising at least one compound of the formula I as defined in any of claims 1 to 1 1.

15. A semiconductor unit comprising at least one substrate as defined in claim 14. 16. An electroluminescent arrangement comprising an upper electrode, a lower electrode, wherein at least one of said electrodes is transparent, an

electroluminescent layer and optionally an auxiliary layer, wherein the electroluminescent arrangement comprises at least one compound of the formula I as defined in any of claims 1 to 1 1 .

17. An electroluminescent arrangement as claimed in claim 16 comprising at least one compound of the formula I as defined in any of claims 1 to 1 1 in a hole- injecting layer or as part of a transparent electrode.

18. An electroluminescent arrangement as claimed in claim 16 or 17 in form of an organic light-emitting diode (OLED).

19. An organic solar cell comprising at least one compound of the formula (I) as

defined in any of claims 1 to 1 1 .

20. A compound of the general formula (I) as defined in any of claims 1 to 1 1.