WO2014011483A1

WO2014011483A1 - Oxadiazole and triazole meta-linked n-phenyl carbazole ambipolar host materials

Info

Publication number: WO2014011483A1
Application number: PCT/US2013/049329
Authority: WO
Inventors: Carlos Zuniga; Seth R. Marder; Wojciech HASKE; Bernard Kippelen
Original assignee: Georgia Tech Research Corporation
Priority date: 2012-07-09
Filing date: 2013-07-03
Publication date: 2014-01-16

Abstract

Ambipolar compounds comprising, for example, carbazole moieties and oxadiazole moieties. Can be used for organic electronics including OLEDs including electron transfer layers and emitter hosts. The compounds can have an electron deficient core having a substituent comprising a first phenyl group which is substituted with a second phenyl group that is substituted with a relatively electron rich moiety.

Description

OXADIAZOLE AND TRIAZOLE META-LINKED N-PHENYL CARBAZOLE

AMBIPOLAR HOST MATERIALS

BACKGROUND

Considerable research has been directed toward the synthesis of organic light-emitting diodes (OLEDs), in view of their potential applications in full-color flat panel displays and solid-state lighting. Such OLEDs often contain a light emissive layer comprising a luminescent material as a guest, dispersed and/or dissolved in a mixture of host/carrier materials capable of transporting holes, electrons, and/or excitons into contact with the luminescent guest. The light emissive layer is typically disposed between an anode and a cathode.

Compounds comprising the carbazole group have been utilized as hole transporter and/or electron blocking materials in OLED applications, and in some cases as hole- transporting hosts for luminescent guests. In addition, small-molecule 2,5-diaryl oxadiazoles are known as suitable electron transport materials for use in making electron transport layers for OLED devices, and have also been used as electron transport hosts for luminescent guests.

Identifying host materials that can efficiently perform important functions can be difficult, especially for use with guest materials that emit at relatively high photon energy at the blue part of the visible spectrum. In order to maximize energy transfer from the host materials to the guest emitters, the energies of both the singlet and triplet states of the hole and/or electron transport materials in the host should be at least somewhat higher than the energies of the corresponding singlet and triplet states of the guest emitters. To achieve such high energy excited states, the conjugation of the organic host materials must be limited, in order to provide for singlet and triplet energy levels higher than those of the guest emitters. This can be challenging for OLEDs employing high photon energy guest emitters.

In some cases, mixtures of hole transport and electron transport materials have been used to form a host material for phosphorescent guests in the emissions layers of multi-layer OLEDs. However, devices based on such mixtures of hole transport and electron transport materials in their emission layers can undergo undesirable phase separations, partial crystallizations, and/or otherwise degrade upon extended OLED device operation, decreasing OLED device efficiency and/or lifetimes over time. Progress on efficient hosts for higher photon energy phosphorescent emitters has been significantly slower, and the efficiencies and lifetimes of such PhOLEDs remain in need of significant improvement. Accordingly, there remains an unmet need in the art for improved host materials that can efficiently and stably transport holes and electrons into contact with phosphorescent emitters in OLED emission layers.

SUMMARY

Embodiments described herein include compounds and compositions, and methods of making and using the same. Also described are articles and devices.

For example, one embodiment provides a compound represented by formula (I):

(I), wherein:

a) one or two of R₂, R₃, P and R₅ are represented by

and the remaining of R₂, R₃, R4 and R₅ are independently selected from hydrogen, halogen and a Ci_₂o organic group;

b) for each

one or two of R5, R₇, Rs, R and Rio are optionally substituted carbazole groups; and the remaining of R5, R₇, Rs, R and Rio are independently selected from hydrogen, halogen and a Ci_₂o organic group;

c) RI is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group; and

^R11 ^R12

d) Y is selected from— O— ,— - N— --, N=N— - and— -N=c— -, wherein Rn is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group, and wherein Ri₂ is hydrogen, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group.

Another embodiment provides that: (i) the remaining of R₂, R3, R4 and R₅ are independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide group; (ii) the carbazole group is unsubstituted or is substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide, fluoroalkoxide and an optionally substituted carbazole; (iii) the remaining of R₆, R7, R₈, R and Rio are

independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; (iv) Ri, Rn and R₁₂ are unsubstituted or substituted with one or more groups selected from hydroxyl, fluoro, cyano, alkyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

Another embodiment provides that

is present at R3 and/or R4 but not at R₂ or R₅, and wherein the optionally substituted carbazole group is present at R₇ and/or R₉ but not at R₆, R₈ or R₁₀.

Another embodiment provides that the optionally substituted carbazole group is selected from formulae II III IV V and VI :

wherein each R13, R14, Ri₅, Ri₆ and Rn is independently hydrogen, fluoro, cyano, a Ci_₂o linear or branched alkyl, a Ci_₂o linear or branched fluoroalkyl, a Ci_₂o linear or branched alkoxide, or a Ci_₂o linear or branched fluoroalkoxide group. Another embodiment provides that

is selected from formulae (VII) and

wherein each Rig and R₁ is independently hydrogen, fluoro, cyano, a Ci_₂o linear or branched alkyl, a Ci_₂o linear or branched fluoroalkyl, a Ci_₂₀ linear or branched alkoxide, a Ci_₂₀ linear or branched fluoroalkoxide group, or an optionally substituted carbazole.

Another embodiment provides that the compound is selected from formulae (IX) and

N— N N— N

II \

Another embodiment provides that I Y >- is o

N-N

J \Y_

N— N

Another embodiment provides that I Y >- IS R ^■.11

Another embodiment provides that

Another embodiment provides that the compound comprises at least one triscarbazole group represented by

Another embodiment provides a method for making the compounds described herein, comprising reacting a first compound with a second compound, wherein: (a) the first compound is represented by

wherein

(i) one or two of R₂, R₃, R₄ and R₅ are Br, and the remaining of R₂, R₃, R₄ and R₅ in the formula representing the first compound have the same definition as their R₂, R3, R₄ and R₅ homologues as described herein;

(ii) Ri in the formula representing the first compound has the same definition as its Ri homologues contained in the formula of the compound described herein; and

^R11 ^R12

(iii) Y is selected from— O— ,— --N-— , N=N— - and— --N=C— -, wherein Rn and

R₁₂ in the formula representing the first compound have the same definition as their Rn and R₁₂ homologues contained in the formula of the compound described herein;

(b) the second compound is represented by

R₆, R₇, R₈, R and Rio in the formula representing the second compound have the same definition as their R₆, R₇, R₈, R₉ and Rio homologues contained in the formula of the compound described herein.

Other embodiments provide for a composition comprising the compounds described herein or made by the methods described herein.

Another embodiment is an electroluminescence device, comprising an anode, a cathode, and an emissive layer, wherein the emissive layer comprises the compound as described herein or made by the methods as described herein, or the composition as described herein.

Another embodiment provides that the emissive layer comprises at least one phosphorescent emitter, and wherein the external quantum efficiency of the

electroluminescence device at a luminance of 1,000 cd/m is at least 5%. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows performance of OLED devices with spin-coated Compound H hole transport layer and evaporation-deposited Compound A: Ir(ppy)3 emitting layer.

FIG. 2 shows performance of OLED devices with spin-coated Compound H hole transport layer and evaporation-deposited Compound A: FIrpic emitting layer.

DETAILED DESCRIPTION

INTRODUCTION

All references described herein are hereby incorporated by reference in their entireties. Various terms are further described herein below:

"A", "an", and "the" refers to "at least one" or "one or more" unless specified otherwise.

"Optionally substituted" groups can refer to, for example, functional groups that may be substituted or unsubstituted by additional functional groups. For example, when a group is unsubstituted, it can be referred to as the group name, for example alkyl or aryl. When a group is substituted with additional functional groups, it may more generically be referred to as substituted alkyl or substituted aryl.

"Alkyl" can refer to, for example, linear, branched, or cyclic alkyl groups. This term is exemplified by groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-pentyl, ethylhexyl, dodecyl, isopentyl, etc.

"Aryl" can refer to, for example, aromatic carbocyclic groups having one or more single rings (e.g., phenyl or biphenyl) or multiple condensed rings (e.g., naphthyl or anthryl).

"Heteroalkyl" can refer to, for example, an alkyl group wherein one or more carbon atoms are substituted with heteroatoms.

"Heteroaryl" can refer to, for example, an aryl group wherein one or more carbon atoms are substituted with heteroatoms.

"Alkoxide" can refer to, for example, the group "alkyl-O-". This term is exemplified by groups such as methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, t-butyloxy, etc.

"Fluoroalkyl" can refer to, for example, an alkyl group wherein one or more hydrogen atoms are substituted with fluorine. Fluoroalkyl described herein include partially fluorinated alkyl groups as well as perfluoroalkyl groups.

"Fluoroalkoxide" can refer to, for example, an alkoxide group wherein one or more hydrogen atoms are substituted with fluorine. Fluoroalkoxide described herein include partially fluorinated alkoxide groups as well as perfluoroalkoxide groups. "Triscarbazole" can refer to, for example, three or more carbazole groups connected to each other through aryl carbon-nitrogen bond and/or aryl carbon-carbon bond.

AMBIPOLAR HOST COMPOUND

Ambipolar host compounds are described in, for example, WO 2010149618,

WO 2010149620, WO 2010149622, and PCT/US2011/066597, all of which are incorporated herein by reference in their entireties.

embodiments described herein relate to a compound represented by formula (I):

(I), wherein:

(a) Ri is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group;

(b) one or two of R₂, R₃, R₄ and R₅ are represented by

and the remaining of R₂, R₃, R₄ and R₅ are independently selected from hydrogen, halogen and a Ci_₂o organic group;

(c) for each

one or two of R5, R7, Rs, R and Rio are optionally substituted carbazole groups; and the remaining of R₆, R7, Rs, R and Rio are independently selected from hydrogen, halogen and a Ci_₂o organic group; and (d) Y is selected from from

11 12

— Q— _{^ -----N----- -----N=N---- an(}j _{-----N=c----j wnerem} R_u i_{s an} optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group, and wherein R12 is hydrogen, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group. Ri can be, for example, an optionally substituted C₅_3o aryl or heteroaryl group, or an optionally substituted C₅_2o aryl or heteroaryl group, or an optionally substituted C₅_i4 aryl or heteroaryl group, including the optional substituent. Ri can be, for example, an optionally substituted Ci_₃o linear or branched alkyl or heteroalkyl group, or an optionally substituted Ci_ 20 linear or branched alkyl or heteroalkyl group, or an optionally substituted C_1-12 linear or branched alkyl or heteroalkyl group, or an optionally substituted Ci_₆ linear or branched alkyl or heteroalkyl group, including the optional substituent. Ri can be, for example, an optionally substituted Ci_₃o monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, or an optionally substituted Ci_₂o monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, or an optionally substituted C_1-12 monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, or an optionally substituted Ci_₆ monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, including the optional substituent.

Ri can be, for example, unsubstituted. Ri can be, for example, substituted with one or more substituents selected from fluoro, cyano, hydroxyl, alkyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

In one embodiment, Ri comprises at least one crosslinkable or polymerizable group. In one embodiment, Ri comprises at least two crosslinkable or polymerizable groups.

In one embodiment, Ri is an optionally substituted phenyl group. In one embodiment, Ri is a phenyl group substituted with at least one or at least two crosslinkable or

polymerizable groups.

In one embodiment, Y is— O— , and the ambipolar host material comprises an

xadiazole moiety represented by O . In another embodiment, Y is

ambipolar host material comprises a triazole moiety represented by ^Rn . In a further

R 12

embodiment, Y is— --N— C— -, and the ambipolar host material comprises a triazine moiety

represented by

. In an additional embodiment, Y is N=N— -, and the

N— N

< >^■-- ambipolar host material comprises a tetrazine moiety represented by N— N Rii and R12 can be, for example, an optionally substituted Ci_₃o alkyl or heteroalkyl group, or an optionally substituted Ci_₂o alkyl or heteroalkyl group, or an optionally substituted Ci_₆ alkyl or heteroalkyl group, including the optional substituent. Rn and R12 can also be, for example, an optionally substituted C5-30 aryl or heteroaryl group, or an optionally substituted C₅_₂o aryl or heteroaryl group, or an optionally substituted C₅_i4 aryl or heteroaryl group, including the optional substituent. Rn and R12 can be, for example, unsubstituted. Rn and R12 can also be, for example, substituted with one or more substituents selected from fluoro, cyano, hydroxyl, alkyl, fluoroalkyl, alkoxide, and fluoro alkoxide.

In one embodiment, the

moiety is present at R₃ or R₄. In another

moiety is present at R₂ or R₅. In a further embodiment, the

moiety is present at both R₃ and R₄. In an additional embodiment, the

moiety is not present at R₂ or R₅.

The remaining of R₂, R₃, R₄ and R5 can be, for example, independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoro alkoxide.

In one embodiment, wherein the

moiety is present at R₃, and wherein R₂, R₄ and R5 are each hydrogen, the ambipolar host compound is represented by formula (IX):

In another embodiment, wherein the ^Re ^R7 moiety is present at both R₃ and R4, and wherein R₂ and R₅ are each hydrogen, the ambipolar host compound is represented by formul

In one embodiment, R₇ or R is an optionally substituted carbazole group. In another embodiment, R₈ is an optionally substituted carbazole group. In a further embodiment, R₆ or Rio is an optionally substituted carbazole group. In an additional embodiment, both R₇ and R are optionally substituted carbazole groups.

Other than the optionally substituted carbazole groups, the remaining of R₆, R₇, R₈, R9 and Rio can be, for example, hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide. In a particular embodiment, the remaining of R₆, R₇, R₈, R9 and Rio are each hydrogen.

In some embodiments, the

moiety is present at R₃ and/or R₄ but not at

R₂ or R₅, and wherein the optionally substituted carbazole group is present at R₇ and/or R9 but not at R₆, R₈ or R₁₀. CARBAZOLE GROUP

The optionally substituted carbazole groups can comprise, for example, a

monocarbazole group or triscarbazole group. The synthesis of triscarbazole group is described in, for example, Jiang et al., J. Mater. Chem. 21 :4918-4926 (201 1) and Brunner et al. , J. Am. Chem. Soc. 126:6035-6042 (2004), both of which are incorporated herein by reference in their entireties. The monocarbazole group or triscarbazole group can be unsubstituted. The monocarbazole group or triscarbazole group can also be substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide, fluoroalkoxide, and carbazole.

The optionally substituted carbazole groups described herein can be represented by, for example, formulae (II), (III), (IV), (V) and (VI).

wherein each of R13, R14, R15, Ri6 and Rn is independently hydrogen, fluoro, cyano, a Ci_2o or Ci_6 linear or branched alkyl, a Ci_₂o or Ci_₆ linear or branched fluoroalkyl, a Ci_₂o or Ci_6 linear or branched alkoxide, or a Ci_₂o or Ci_₆ linear or branched fluoroalkoxide group. In one embodiment, each of R13, R14, R15, Ri₆ and Rn is hydrogen.

In some embodiments, wherein R is an optionally substituted carbazole group, and

R₆, R7, Re and Rio are each hydrogen, the ^Re ^R/ moiety is represented by formula (VII):

(VII), wherein Rig is independently hydrogen, fluoro, cyano, a Ci_₂o or Ci_₆ linear or branched alkyl, a Ci_₂o or Ci_6 linear or branched perfluoroalkyl, a Ci_₂o or Ci_6 linear or branched alkoxide, a Ci_₂o or Ci_₆ linear or branched fluoroalkoxide group, or an optionally substituted carbazole.

In one embodiment, the carbazole gro position is an unsubstituted

monocarbazole, and the

moiety is

In another embodiment, the carbazole group at the R₉ position is an unsubstituted

triscarbazole, and the

moiety is

In some embodiments, wherein R₇ and R₉ are each an optionally substituted carbazole

group, and R₆, gen, the ^Re ^R/ moiety is represented by

formula (VIII):

wherein R13 is independently hydrogen, carbazole, fluoro, cyano, a Ci_₂₀ or Ci_₆ linear or branched alkyl, a Ci_₂₀ or Ci_₆ linear or branched perfluoroalkyl, a Ci_₂₀ or Ci_₆ linear or branched alkoxide, a Ci_₂₀ or Ci_₆ linear or branched fluoroalkoxide group, or an optionally substituted carbazole. In one embodiment, the carbazole group at the R₇ and R position are each an

unsubstituted monocarbazole, and the

moiety is

In another embodiment, the carbazole group at the R₇ and R position are each an

unsubstituted triscarbazole, and the ^Re ^R/ moiety is

In one embodiment, the ambipolar host material described herein comprises at least one optionally substituted triscarbazole group. In a further embodiment, the ambipolar host material described herein comprises at least one unsubstituted triscarbazole group represented

Specific examples of the ambipolar host compounds described herein include the folio wings:

MATERIAL PROPERTIES OF THE AMBIPOLAR HOST COMPOUND

Many of the ambipolar host compounds described herein are either sublimable under high vacuum or readily soluble in common organic solvent, and therefore can be readily processed to form compositions useful in organic electronic devices, especially when mixed and/or co-deposited with phosphorescent guest emitters to form the emissive layers of OLED devices.

Further, many of the ambipolar host compounds described herein have high glass transition temperature which is advantageous for OLED applications. For example, the glass transition temperature can be at least 120°C, or at least 130°C, or at least 140°C, or at least 150°C, or at least 160°C, or at least 170°C, or at least 180°C, or at least 190°C, or at least

200°C.

METHODS FOR MAKING AMBIPOLAR HOST COMPOUND

Methods for making the ambipolar host compound described herein are disclosed in detail in the Working Examples. For example, a first compound can be reacted with a second compound, wherein the first compound is represented by

one or two of R₂, R₃,

R₄ and R₅ are halogen such as Br or I, and second compound is represented by

Ri, R5, R7, Re, R9, Rio, as well as the remaining of R₂, R3 and R₄ and R_5, have been defined in the foregoing sections.

Methods for synthesizing triazine and tetrazine-based compounds are disclosed in Yang et al, Angew. Chem. Int. Ed. 51 :5222-5225 (2012) and Phucho et al, ARKIVOC 2008 (xv):79-87, both of which are hereby incorporated by reference in their entireties.

In some embodiments, the ambipolar host compound described herein are synthesized according to the following general schemes.





 ELECTROLUMINESCENCE DEVICES COMPRISING AMBIPOLAR HOST COMPOUND

The solution-processed ambipolar transport layer described herein can be used in various electronic devices, including electroluminescence devices such as OLED devices.

Although other alternatives are known in the art, in many embodiments, the OLED devices comprise at least an anode layer, a hole transport layer, an emission layer, an electron transport layer, and a cathode layer. Such devices are illustrated in the diagram below.

Cathode Layer

Electron Transporting Layer

Emission Layer

Hole Transporting Layer

- Anode Layer

^~ Glass

The thickness of the anode layer, the cathode layer, the emissive layer, the hole transport layer, and the electron transport layer can be, for example, about 0.001-100 μιη, about 0.005-10 μιη, or about 0.01-1 μιη, or about 0.02-0.1 μιη.

Many suitable materials for anode in electroluminescence devices are known in the art and include, for example, ITO, which can be applied, for example, as a vacuum-deposited layer over an inert and transparent substrate such as glass. Other examples include metal oxide with high work function, such as zinc oxide and indium zinc oxide.

Many suitable materials for cathode in electroluminescence devices are known in the art and include, for example, a combination of LiF as electron injecting material coated with a vacuum deposited layer of Al, and optionally an additional layer of Ag.

Many suitable materials for the hole transporting or hole injection layer of

electroluminescence devices are known in the art. Suitable hole transporting materials include, for example, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)

(PEDOT:PSS), hole transporting materials described in WO 2009/080799, US 61/579394, US 61/579402 and US 61/579418, all of which are incorporated herein by reference in their entireties, as well as other hole transporting materials known in the art. In one embodiment, the hole transport layer is fabricated by solution processing (e.g., spin coating) from a solution comprising the hole transporting material. Many suitable materials for the electron transport layer of electroluminescence devices are known in the art and include, for example, 2,9-Dimethyl-4,7-diphenyl-l,10- phenanthroline (BCP), as well as those described in WO 2012/024132, WO 2009/080796 and WO 2009/080797, all of which are incorporated herein by reference in their entireties. In one embodiment, the electron transport layer is fabricated by solution processing (e.g., spin coating) from a solution comprising the electron transporting material (see

WO 2012/024132).

Many suitable guest emitters for the emissive layer of electroluminescence devices are known in the art and include, for example, Iridium complexes such as Tris(5-phenyl- 10,10-dimethyl-4-aza- tricycloundeca-2,4,6-triene)Iridium(III) (Ir(pppy)₃), Tris(2- phenylpyridine)iridium(III) (Ir(ppy)₃) and Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2- carboxypyridyl)iridium (III) (Flr(pic)), guest materials described in US 2006/0127696, WO 2009/026235, WO 2011000873 and PCT/US2011/066597, all of which are incorporated herein by reference in their entirety, as well as other guest materials known in the art. The emissive layer can comprise at least one blue emitter, at least one green emitter, at least one red emitter, or a combination thereof.

In one embodiment, the OLED devices described herein comprise a solution- processed hole transport layer and a solution-processed emissive layer. In another embodiment, the OLED devices described herein comprise a solution-processed hole transport layer and a vacuum-deposited emissive layer. In a further embodiment, the OLED devices described herein comprise a solution-processed hole transport layer, a solution- processed emissive layer, and a solution-processed electron transport layer.

In some embodiments, the OLED device described herein comprises an emitter having wavelengths between, for example, 400-700 nm including red, green, and blue phosphorescent emitters. The external quantum efficiency of said OLED device at 1,000 cd/m can be, for example, at least 5%, or at least 8%, or at least 10%, or at least 12%, or at least 15%, or at least 18%, or at least 20%. In some embodiments, the OLED device described herein comprises a green phosphorescent emitter. The external quantum efficiency of said OLED device at 1 ,000 cd/m can be, for example, at least 5%, or at least 8%, or at least 10%, or at least 12%, or at least 15%, or at least 18%, or at least 20%.

In some embodiments, the OLED device described herein comprises a blue phosphorescent emitter. The external quantum efficiency of said OLED device at 1 ,000 cd/m can be, for example, at least 5%, or at least 8%, or at least 10%, or at least 12%, or at least 15%, or at least 18%, or at least 20%.

Additional embodiments are provided by the following non-limiting working examples.

WORKING EXAMPLES

- Synthesis of Compound A

S4.13: Synthesized according to the literature. 1H NMR was consistent with the literature.

S4.14: S4.13 (3.990 g, 18.6 mmol) was dissolved in a mixture of THF and N,N- dimethylformamide (20 mL: 20 mL) under inert atmosphere. 3-methoxybenzoyl chloride was added dropwise and reaction was stirred overnight. A precipitate that formed overnight was collected by filtration and addition of water to the filtrate produced more solids. Solids were combined and dried to afford a white powder (3.53 g, 54.4%). 1H (300 MHz, DMSO- ¾: δ 10.64 (s, 1H), 10.55 (s, 1H), 8.07 (t, J= 1.7 Hz, 1H), 7.95-7.88 (m, 1H), 7.84-7.77 (m, 1H), 7.53-7.39 (m, 4H), 7.18-7.12 (m, 1H), 3.81 (s, 3H). ¹³C {1H} (75 MHz, DMSO-¾: δ 165.9, 164.9, 159.7, 135.1, 134.2, 131.4, 130.6, 130.2, 127.0, 122.3, 120.1, 118.3, 112.9, 55.8. MS (EI) m/z = 348.0 [M+]. Anal, calcd. for Ci₅Hi₃BrN₂0₃: C, 51.60; H, 3.75; N, 8.02. Found: C, 51.74; H, 3.67; N, 8.08

S4.15: S4.14 (1.501 g, 4.30 mmol) was combined with POCl₃ (15 mL) under inert atmosphere and heated to 100 °C overnight. DCM (200 mL) was added to the cooled mixture and phases were separated and solvents removed in vacuo. The crude was purified by column chromatography (silica gel ; hexanes:ethyl acetate = 70:30) to afford a white powder

(1.039 g, 73.2%). 1H (300 MHz, DMSO-^): δ 8.27 (t, J= 1.6 Hz, 1H), 8.14-8.09 (dm, 1H), 7.85-7.80 (dm, 1H), 7.73-7.68 (dm, 1H), 7.64-7.61 (m, 1H), 7.59-7.48 (m, 2H), 7.19 (dd, J = 8.4, 2.6, 0.9 Hz, 1H), 3.85 (s, 3H). ¹³C{1H} (75 MHz, DMSO-^): δ 164.7, 163.3, 160.1, 135.2, 132.0, 131.1, 129.5, 126.2, 125.9, 124.7, 122.9, 119.6, 118.6, 112.1, 56.0. MS (EI) m/z = 330.0 [M+]. Anal, calcd. for Ci₅HnBrN₂0₂: C, 54.40; H, 3.35; N, 8.46. Found: C, 54.55;

4.35 (Compound A): S4.15 (0.900 g, 2.72 mmol), 9-(3-(4,4,5,5-tetramethyl-l,3,2- dioxaborolan-2-yl)phenyl)-9H-carbazole (1.206 g, 3.27 mmol), and Pd(PPh₃)₄ (0.127 g, 0.110 mmol) were dissolved in a solution of anhydrous toluene (80 mL) and absolute ethanol (40 mL). In a separate flask, K₂C0₃ (11.06 g, 80.0 mmol) was dissolved in deionized water (40 mL) and the resulting solution was added to the reaction mixture, which was then refluxed for 27 hours. Upon cooling, the reaction mixture was diluted with deionized water (150 mL) and brine (50 mL) were added and the organic layer was extracted once chloroform (200 mL) then twice more with 50 mL portions of chloroform. The organic layers were combined, washed with brine (100 mL), dried over magnesium sulfate, and concentrated in vacuo to afford a dark oily solid. The crude material was purified by column chromatography (silica ; dichloromethane: ethyl acetate = 90: 10) as a white solid and was then washed with pentane to give the final product (0.945 g, 70%). 1H (300 MHz, CDC1₃): δ 8.40 (t, J= 1.5 Hz, 1H), 8.19- 8.15 (m, 3H), 7.89-7.61 (m, 8H), 7.61-7.41 (m, 5H), 7.34-7.29 (m, 2H), 7.12-7.08 (m, 1H), 3.90 (s, 3H). ¹³C{1H} NMR (75 MHz, CDC1₃): δ 164.83, 164.53, 160.10, 141.97, 141.33, 140.94, 138.58, 130.69, 130.59, 130.37, 129.94, 126.69, 126.38, 126.19, 125.90, 125.68, 125.03, 124.77, 123.59, 120.53, 120.23, 119.52, 118.35, 111.81, 109.86, 55.70. MS (EI) m/z = 492.9 [M+]. Anal, calcd. for C₃₃H₂₃N₃0₂: C, 83.31; H, 4.70; N, 8.51. Found: C, 83.01; H, 4.64; N, 8.47. EXAMPLE 2 - Synthesis of Compound B

S4.8: Synthesized according to the literature. 1H NMR was consistent with the literature.

S4.9: S4.8 (5.002 g, 17.0 mmol) was dissolved in anhydrous THF (40 mL) under inert atmosphere. Due to poor solubility, anhydrous N,N-dimethylformamide (40 mL) was added and the mixture cooled to 0 °C in an ice-water bath. After cooling, 3-methoxybenzoyl chloride (3.304 g, 19.4 mmol) was added dropwise. After 24 h, the mixture was added to deionized water and a precipitate formed, was collected, and dried to afford a white powder (2.291 g, 31.5%). 1H (300 MHz, DMSO-¼): δ 10.75 (s, 1H), 10.61 (s, 1H), 8.14-8.10 (m, 1H), 8.09-8.07 (m, 2H), 7.51-7.39 (m, 3H), 7.18-7.12 (m, 1H), 3.81 (s, 3H). ¹³C{1H} NMR (75MHz, DMSC i): δ 165.89, 163.53, 159.68, 137.18, 136.38, 134.05, 130.21, 129.88, 123.31, 120.16, 118.37, 112.95, 55.77. MS (EI) m/z = 425.9 [M+]. Anal, calcd. for

.09; H, 2.83; N, 6.54. Found: C, 42.28; H, 2.63; N, 6.48.

S4.10: S4.9 (2.365 g, 5.526 mmol) in neat POCl₃ (15.0 mL) was stirred under nitrogen atmosphere at 100 C for 2 hours. Upon cooling, the reaction mixture was poured slowly into ca. 400 mL of an ice-water mixture, resulting in the formation of a white precipitate, which was collected by filtration and washed with deionized water. Chromatography of the crude material (silica ; dichloromethane: ethyl acetate = 95:5) yielded the final product as a white solid (1.471 g, 65%).¹H (300 MHz, CDC1₃): δ 8.18 (d, J= 1.7 Hz, 2H), 7.81 (t, J= 1.7 Hz, 1H), 7.70-7.65 (m, 1H), 7.64-7.60 (m, 1H), 7.41 (t, J= 8.0 Hz, 1H), 7.08 (ddd, J, = 8.3, J₂ = 2.6, J₃ = 0.8 Hz, 1H), 3.88 (s, 3H). ¹³C{1H} NMR (75 MHz, CDC1₃): δ 165.14, 162.14, 160.04, 137.05, 130.34, 128.43, 128.40, 126.95, 124.45, 123.71, 119.47, 118.62, 11.71, 55.60. MS (EI) m/z = 409.9 [M+]. Anal, calcd. for Ci₅Hi₀Br₂N₂O₂: C, 43.94; H, 2.46; N, 6.83. Found: C, 43.64; H, 2.32; N, 6.75.

4.33 (Compound B): S4.10 (1.302 g, 3.175 mmol), 9-(3-(4,4,5,5-tetramethyl-l,3,2- dioxaborolan-2-yl)phenyl)-9H-carbazole (2.815 g, 7.623 mmol), and Pd(PPh₃)₄ (0.148 g, 0.128 mmol) were dissolved in a solution of anhydrous toluene (100 mL) and absolute ethanol (50 mL) under nitrogen atmosphere. In a separate flask, K₂C0₃ (13.84 g, 100.1 mmol) was dissolved in deionized water (50 mL) and the resulting solution was added to the reaction mixture, which was then refluxed with stirring for 24 hours. Upon cooling, the reaction mixture was diluted with 150mL of deionized water, 50 mL of brine were added, and the organic layer was extracted once with 400mL of chloroform, then twice more with 100 mL portions of chloroform. The organic layers were combined, washed with brine (1 x 250 mL) then dried over magnesium sulfate, and concentrated in vacuo to yield a dark yellow, oily solid. The oil was purified by column chromatography (silica gel; dichloromethane: ethyl acetate = 95:5) and then precipitated in methanol to afford a white solid (1.648 g, 72%).1H

(300 MHz, CDC1₃): δ 8.42 (s, 1H), 8.41 (s, 1H), 8.18-8.15 (m, 4H), 8.06 (t, J= 1.7 Hz, 1H), 7.93 (t, J= 1.7 Hz, 2H), 7.94-7.63 (m, 8H), 7.50-7.39 (m, 9H), 7.33-7.28 (m, 4H), 7.12-7.08 (m, 1H), 3.89 (s, 3H). ¹³C{1H} NMR (75 MHz, CDC1₃): δ 164.90, 164.29, 160.05, 142.08, 141.68, 140.84, 138.56, 130.67, 130.26, 129.32, 126.87, 126.42, 126.09, 126.03, 125.95, 125.36, 124.85, 124.81, 123.47, 120.44, 120.13, 119.47, 118.27, 111.82, 109.74, 55.68. MS (EI) m/z = 734.2 [M+]. Anal, calcd. for C₅iH₃₄N₄0₂: C, 83.36; H, 4.66; N, 7.62. Found: C, 83.22; H, 4.55; N, 7.68. - Synthesis of Compound C

S4.19: Aniline (4.499 g, 11.7 mmol) and anhydrous o-dichlorobenzene (50 mL) were combined and cooled in ice-water bath under inert atmosphere. After the mixture was cooled to 0 °C, phenyl phosphorodichloridate (2.508 g, 11.9 mmol) was added dropwise and the ice- water bath removed. S4.10 (3.759 g, 5.79 mmol) was added portion-wise and then the mixture was heated to 195 °C. Additional o-dichlorobenzene was added (25 mL) to achieve complete dissolution of solids. After 24 h, heating was stopped and 2N HC1 (100 mL) was added to the cooled mixture followed by dichloromethane (200 mL). The phases were separated and the aqueous layer was extracted with dichloromethane (2 x 200 mL). The combined organic phases were washed with deionized water (200 mL), dried over magnesium sulfate, filtered, and solvents were removed in vacuo to afford an oil that was purified by column chromatography (silica gel ; gradient from 100% dichloromethane to 100% ethyl acetate). The product was precipitated with deionized water, filtered, and dried to obtain a white powder (2.972 g, 52.4%).1H (300 MHz, DMSO-^): δ 7.94 (t, J= 1.8 Hz, 1H), 7.62-7.52 (m, 7H), 7.31 (t, J= 7.9 Hz, 1H), 7.05-6.98 (m, 2H), 6.94-6.92 (m, 1H), 3.65 (s, 3H). ¹³C{1H} (75 MHz, DMSO-^): δ 159.3, 154.8, 152.2, 135.0, 131.0, 130.7, 130.5, 130.2, 128.8, 128.2, 122.9, 121.1, 116.1, 114.2, 55.5. MS (EI) m/z = 486.0 [M+]. Anal, calcd. for

H, 3.12; N, 8.66. Found: C, 51.80; H, 3.04; N, 8.72.

4.38 (Compound C): 9-(3-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenyl)-9H- carbazole (2.677 g, 7.21 mmol), S4.19 (1.412 g, 2.89 mmol), 2.0 M aq. potassium carbonate solution (50 mL), and toluene (100 mL) were combined under inert atmosphere and nitrogen was bubbled through the solution for ~ 30 min. Pd (PPh₃)4 (0.169 g, 0.14 mmol) was added and the mixture was set to reflux overnight. The reaction mixture was cooled, deionized water (200 mL) was added, and then the mixture was extracted with chloroform (3 x 200 mL). The organic phase was washed with brine (1 x 200 mL), dried over magnesium sulfate, filtered, and solvents removed in vacuo. The crude was purified by column chromatography (silica gel ; gradient from 100% dichloromethane to dichloromethane: ethyl acetate = 75:25) and recrystallized from acetone to afford a white powder (0.827 g, 35.3%). 1H (300 MHz,

DMSC i): δ 8.25 (d, J= 7.4 Hz, 4H), 8.17 (s, 1H), 7.82 (d, J= 7.5 Hz, 2H), 7.76-7.69 (m, 6H), 7.61 (d, J= 7.5 Hz, 2H), 7.48-7.35 (m, 10H), 7.33-7.20 (m, 5H), 7.08 (t, J= 7.5 Hz, 2H), 7.02-6.87 (m, 3H), 6.82 (t, J= 7.5 Hz, 1H), 3.58 (s, 3H). ¹³C{¹H} (75 MHz, DMSO-^): δ 159.29, 154.57, 154.39, 141.61, 140.64, 138.04, 135.56, 131.3, 130.18, 130.15, 130.0, 129.91, 128.96, 128.72, 128.44, 126.95, 126.77, 125.65, 123.22, 121.0, 120.56, 115.98, 114.07, 110.20, 55.42. MS (EI) m/z = 809.4 [M+]. Anal, calcd. for

C, 84.52; H, 4.85; N, 8.65. Found: C, 84.26; H, 4.85; N, 8.58.

EXAMPLE 4 - Synthesis of Com ound D

38(16), 6755-6758) was dissolved in a mixture of THF and DMF (20 mL: 20 mL) under inert atmosphere. 3,5-dimethoxybenzoyl chloride was added portion-wise and the reaction was stirred overnight. A precipitate that formed overnight was collected by filtration and addition of water to the filtrate produced more solids. Solids were combined and dried to afford a pale yellow powder (5.764 g, crude). 1H (300MHz, DMSO-d₆): δ 10.74 (s, 1H), 10.59 (s, 1H), 8.12-8.06 (m, 3H), 7.09-7.02 (m, 3H), 6.73-6.69 (m, 2H), 3.78 (s, 6H), 3.76 (s, 3H).

(2.009 g, 4.37 mmol) was combined with

POCI₃ (15 mL) under inert atmosphere and heated to 100 °C overnight. DCM (200 mL) was added to the cooled mixture followed by deionized water (200 mL) and phases were separated and solvents removed in vacuo from the organic phase. The crude was purified by column chromatography (silica gel ; (8:2) = Hexanes:EtOAc) and recrystallization from ethanol to afford a white powder (0.695 g, 36.1%). 1H (300MHz, DMSO-d₆): δ 8.29 (s, 2H), 8.01 (s, 1H), 7.27 (s, 2H), 6.75 (s, 1H), 3.85 (s, 6H). ¹³C{¹H} (75MHz, DMSO-d₆): 5165.0, 161.5, 128.7, 127.3, 125.0, 123.9, 105.2, 104.6, 56.2. EI-MS (m/z): M⁺ calcd for

Ci₆Hi₂Br₂N203, 437.9; found 437.9. Elemental anal, calcd. for CieH^B^Os: C, 43.67; H,

C, 43.65; H, 2.65; N, 6.32.

Aniline (2.520 g, 27.1 mmol) and anhydrous o-dichlorobenzene (40 mL) were combined with phenyl phosphorodichloridate (1.513 g, 7.17 mmol) under inert

atmosphere and the mixture was heated at 100 °C for 1 h.

(2.9983 g,

6.55 mmol) was added portion- wise and then the mixture was heated to 195°C. After 24h, heating was stopped and 2N HC1 (100 mL) and then DCM (200 mL) was added to the cooled mixture. Phases were separated and aqueous layer was extracted with dichloromethane (2 x 200 mL) then solvents were removed in vacuo. The crude oil was purified (silica gel ; (8:2) = DCM:EtoAC to (1 : 1) = DCM:EtOAc) to afford a white powder (1.677, 49.8%). 1H

(300MHz, DMSO-d6): δ 7.88 (t, J = 1.8 Hz, 1H), 7.58-7.47 (m, 7H), 6.51 (s, 3H), 3.60 (s, 6H).

(2.704 g, 7.32 mmol) (also available from Aquila Pharmatech), and toluene (100 mL) were combined under inert atmosphere. Pd(PPh3)4 and 2M K2C03 (50 mL) were added and the mixture was heated to reflux for 24 h. After cooling, the solution was added to deionized water (200 mL) and stirred. The phases were separated and the aqueous phase was extracted with chloroform (2 x 200 mL). The combined organic phases were washed with brine (200 mL), dried over magnesium sulfate, and filtered. Solvents were removed in vacuo and the crude was purified by column chromatography (silica gel; (8:2) = DCM:EtOAc) to afford a white powder (2.128 g, 86.9%). 1H (300MHz, DMSO-d6): δ 8.26 (d, J = 7.5 Hz, 4H), 8.18 (s, 1H), 7.82 (d, J = 7.5 Hz, 2H), 7.78-7.68 (m, 6H), 7.62 (d, J = 7.5 Hz, 2H), 7.51-7.36 (m, 10H), 7.32-7.24 (m, 4H), 7.07 (t, J = 7.8 Hz, 2H), 6.80 (t, J = 7.3 Hz, 1H), 6.52-6.47 (m, 3H), 3.56 (s, 6H). 13C{1H} (75MHz, DMSO-d6): δ 160.6, 154.1, 141.6, 140.6, 138.0, 135.6, 131.3, 130.1, 129.0, 128.8, 128.7, 127.0, 126.8, 125.6, 123.2, 121.0, 120.6, 110.2, 106.8, 55.6. EI-MS (m/z): M+ calcd for C58H41N502, 839.3; found 839.4. Elemental anal, calcd. for C58H41N502: C, 82.93; H, 4.92; N, 8.34. Found: C, 82.83; H, 4.75; N, 8.26. - Synthesis of Compound E

dissolved in anhydrous dichloromethane (15 mL) and set to cool to -78 °C in a dry ice/aceton bath. After cooling, 1M boron tribromide in dichloromethane (10 mL) was added dropwise. After stirring overnight, the solution was dropped into ice-water (100 mL) and a white precipitate was obtained that was collected and dried to afford a crude powder that was subjected to column chromatography (silica gel; gradient (1 : 1) = DCM:EtOAC to 100% EtOAc) to afford a powder (0.311 g, crude). [The final product is labeled "crude" as impurities were still present]. 1H (300MHz, CDC13): δ 9.43 (s, 2H), 8.26 (d, J = 7.6 Hz, 4H), 8.16 (s, 1H), 7.82 (d, J = 7.7 Hz, 2H), 7.77-7.69 (m, 6H), 7.63 (d, J = 7.7 Hz, 2H), 7.48-7.35 (m, 10H), 7.33-7.25 (m, 4H), 7.12-7.03 (m, 2H), 6.80 (t, J = 7.5 Hz, 1H), 6.25 (d, J = 2.0 Hz, 2H), 6.20 (t, J = 2.0 Hz, 1H). (Compound E):

(0.294 g, 0.36 mmol), potassium carbonate (0.624 g, 4.5 mmol), and DMF (10 mL) were combined. 4-vinylbenzyl chloride (0.155 g, 1.0 mmol) was added dropwise and reaction was covered with foil. After 24 h, deionized water (100 mL) was added and the solution was extracted with dichloromethane (2 x 200 mL). The organic phase was concentrated in vacuo and purified by column chromatography (silica gel; gradient 100% DCM to (8:2) = DCM:EtOAc) to afford a nearly white powder.

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq were used as substrates for the OLEDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor (1 :3 by volume, HNO₃: HCl) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ITO substrates were 0₂ plasma treated for 2 min.

Polymer H

Polymer H was synthesized according to US provisional serial no. 61/579394 filed December 22, 2011, incorporated by reference in its entirety. Polymer H was processed in the glove box under nitrogen. 10 mg of Compound H was dissolved in 1ml of anhydrous chlorobenzene (Aldrich). 35 nm thick films of the hole-transport material were spin-coated at 1500 rpm, acceleration 1,000 rpm/sec for 60 sec. The films were then heated on a hot plate at 120 °C for 20 minutes.

The emissive layer, consisting of a host, Compound A, and an emitter, Ir(ppy)₃ (Lumtec), was deposited by co-evaporation of the two components at 0.94 A/s and 0.06 A/s respectively. The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF (Aldrich) and aluminum were thermally evaporated at 1 A/s, 0.2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 x 10^"7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen. The performance of the device is shown in Figure 1.

With an external quantum efficiency (EQE) of 25.1 % at a luminance of 100 cd/m , an EQE of 23.3% at a luminance of 1,000 cd/m , and an EQE of 18.2% at a luminance of 10,000 cd/m , the performance of these devices is among the best ever reported in the field for devices comprised of just an HTL, an emissive layer doped with Ir(ppy)₃, and an ETL. The high efficiency was achieved without any light extraction mechanism.

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq were used as substrates for the OLEDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor (1 :3 by volume, ΗΝ0₃: HC1) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ITO substrates were 0₂ plasma treated for 2 min.

Compound H was processed in the glove box under nitrogen. 10 mg of Compound H was dissolved in 1ml of anhydrous chlorobenzene (Aldrich). 35 nm thick films of the hole- transport material were spin-coated at 1500 rpm, acceleration 1,000 rpm/sec for 60 sec. The films were then heated on a hot plate at 120 °C for 20 minutes.

c

The emissive layer, consisting of a host, Compound A, and an emitter, FIrpic (Lumtec), was deposited by co-evaporation of the two components at 0.88 A/s and 0.12 A/s respectively. The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF (Aldrich) and aluminum were thermally evaporated at 1 A/s, 0.2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 x 10^"7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen. The performance of the device is shown in Figure 2. The performance of the device is shown in Figure 2. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (EQE) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd/m is above 10% and maximum luminance shown is around 10,000 cd/m . This high level of performance in terms of efficiency and luminance proves the suitability of these compositions for blue-emitting organic light-emitting diode applications.

Claims

WHAT IS CLAIMED IS: d represented by formula (I):

a) one or two of R₂, R₃, R and R5 are represented by ^R He ^R7 , and the remaining of R₂, R₃, R₄ and R₅ are independently selected from hydrogen, halogen and a Ci_₂o organic group;

b) for each

one or two of R₆, R₇, R₈, R₉ and Rio are optionally substituted carbazole groups; and the remaining of R5, R₇, R₈, R₉ and Rio are independently selected from hydrogen, halogen and a Ci_₂o organic group;

^R11 ^R12

d) Y is selected from— O— ,— -- N— --, N=N— - and— -N=C— wherein Rn is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group, and wherein Ri₂ is hydrogen, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group.

2. The compound of claim 1 , wherein: (i) the remaining of R₂, R₃, R₄ and R5 are independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide group; (ii) the carbazole group is unsubstituted or is substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide, fluoroalkoxide and optionally substituted carbazole; (iii) the remaining of R₆, R₇, R₈, R and Rio are independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; (iv) Ri, Rn and R12 are unsubstituted or substituted with one or more groups selected from hydroxyl, fluoro, cyano, alkyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

3. The compound of claim 1 or 2, wherein

is present at R3 and/or R4 but not at R₂ or R5, and wherein the optionally substituted carbazole group is present at R₇ and/or R but not at R₆, R₈ or R₁₀.

The compound of any of claims 1-3, wherein the optionally substituted carbazole

(V) and (VI):

wherein each R 3, R14, R15, Ri₆ and Rn is independently hydrogen, fluoro, cyano, a Ci_₂o linear or branched alkyl, a Ci_₂₀ linear or branched fluoroalkyl, a Ci_₂₀ linear or branched alkoxide, or a Ci_₂₀ linear or branched fluoroalkoxide group.

5. The compound of any of claims 1-3, wherein

is selected from formulae (VII) and (VIII):

wherein each Rig and R1 is independently hydrogen, fluoro, cyano, a Ci_₂₀ linear or branched alkyl, a Ci_₂o linear or branched fluoroalkyl, a Ci_₂₀ linear or branched alkoxide, a Ci_₂₀ linear or branched fluoroalkoxide group, or an optionally substituted carbazole.

6. The compound of any of claims 1-5, wherein the compound is selected from formulae (IX) and (X):

The compound of any of claims 1-6, wherein

10. The compound of claim 1, wherein the compound comprises at least one triscarbazole group represented by

11. The compound of any of claims 1-10, wherein Ri comprises at least one crosslinkable group.

12. The compound of claim 1, wherein the compound is selected from:

13. A method for making the compounds of any of claims 1-12, comprising reacting a first compound with a second compound, wherein:

(a) the first compound is represented by

, wherein

(i) one or two of R₂, R₃, R₄ and R5 are Br, and the remaining of R₂, R₃, R₄ and R5 in the formula representing the first compound have the same definition as their R₂, R₃, R₄ and R₅ homologues contained in the formula of the compound claimed in any of claims 1-12;

(ii) Ri in the formula representing the first compound has the same definition as its Ri homologues contained in the formula of the compound claimed in any of claims 1-12; and R^■.11 R^■.12

(iii) Y is selected from— O— ,— --N-— , N=N— - and— -N=C— -, wherein Rn and

Ri2 in the formula representing the first compound have the same definition as their Rn and Ri2 homologues contained in the formula of the compound claimed in any of claims 1-12;

(b) the second compound is represented by

wherein R₆, R₇, R₈, R9 and Rio in the formula representing the second compound have the same definition as their R₆, R₇, R₈, R9 and Rio homologues contained in the formula of the compound claimed in any of claims 1-12.

14. A composition comprising the compound of any of claims 1-12 or made by the method of claim 13.

15. An electroluminescence device, comprising an anode, a cathode, and an emissive layer, wherein the emissive layer comprises the compound of any of the claims 1-12 or made by the method of claim 13, or the composition of claim 14.

16. The electroluminescence device of claim 15, wherein the emissive layer comprises at least one phosphorescent emitter, and wherein the external quantum efficiency of the electroluminescence device at 1 ,000 cd/m is at least 5%.