FR3011548A1 - PHOTOACTIVE ORGANIC COMPOUND - Google Patents

Abstract

The invention relates to a photoactive organic compound for use in a photoactive device, such as a photovoltaic cell for example. The compound is derived from thienyl triarylamines and characterized in that it is in the following general formula (III):

Description

The present invention relates to the field of photo-active organic compounds capable of emitting an electric current when they are subjected to light radiation. BACKGROUND OF THE INVENTION More particularly, the invention relates to a photoactive compound, to a photoactive composition comprising such a compound and to a photoactive device manufactured from such a compound. Such a photoactive device is for example in the form of an organic photovoltaic cell. BACKGROUND [0003] The photoactive organic compounds are intended to be used in photoactive devices such as photovoltaic cells for example. The photovoltaic effect results from the absorption of photons by a semiconductor material. The absorption of a photon can move an electron from a ground state to an excited state to form an exciton which can then dissociate into an electron-hole pair and produce a continuous electric current. Thus, photovoltaic cells can transform the light energy they receive into electrical energy. [0005] Silicon-based photovoltaic cells have been on the market for some years. Monocrystalline silicon, in particular, makes it possible to obtain very good yields of conversion of solar energy into electrical energy. This efficiency drops for cells made with polycrystalline silicon and drops even more with amorphous silicon. However, the production of mono- or poly-crystalline silicon requires a lot of energy and is very expensive. Moreover, its recycling remains difficult. Alternative solutions have been considered to lower the cost of manufacturing photovoltaic devices. Organic photovoltaic cells, in particular, based on organic materials, have been studied. [0007] Organic photovoltaic cells generally consist of two types of materials: electron donor materials on the one hand and acceptor materials on the other hand. A heterojunction is thus created and the intense electric Ref: 0384-ARK42 field prevailing at the acceptor donor interface will make it possible to dissociate the excitons into positive and negative charges. [0008] The electron-donor active materials most studied are conductive polymers with a small gap. They give good results in terms of performance with a conversion efficiency between incident solar energy and electrical energy restored of the order of 8%. However, the inherent polydispersity of polymers leads to a variability of parameters such as molecular weight, regio-regularity, the distribution of the different lengths of conjugated chains and the possible presence of terminal residual groups which pose the problem of reproducibility. the composition and performance of the resulting donor material. A possible solution to this problem is to replace the polymers with soluble organic molecules that have the advantage of a perfectly defined chemical structure, a reproducible synthesis and purification and to allow easier analysis of structure / performance correlations only in the case of polymers. [0011] Interesting results have been obtained with electron donor molecular compounds based on a wide variety of chemical structures such as triphenylamines (see "Triphenylamine-Thienylenevinylene Hybrid Systems with Internal Loading Charge as Donor Material for Heterojunction"). Solar Cells, S. Roquet, A. Cravino, P. Leriche, O. Alveque, P. Frere and J. Roncali, J. Am Chem Soc., 2006, 128, 3459), oligothiophenes (see document entitled Y. Sun, GCWelch, Leong Wong, Takacs CJ, GC Bazan and AJ

Heeger, Nat. Mater., 2011, 11,), squaraines (see document entitled "Arylamine-based squaraine donors for use in organic cells" G.Wei, X. Xiao, S. Wang, JDZimmerman, K.Sun, VVDiev, ME Thompson, SRForrest, Nona Lett. 2011, 11, 4261-4264), diketopyrrolopyrroles (see document entitled "Nanoscale phase separation and high photovoltaic efficiency in solution processed, small molecules bulk heterojunction solar cells", B. Walker, ABTamayo, XD Dang, P.Zalar, JH Seo, A.Garcia, M.Tantiniwat, TQNguyen, Advance Functional Material, Vol.19, Issue 19, 3063-3069) or borondipyrromethenes (see document entitled "A tailored hybrid BODIPY-oligothiophene [Rousse, A. Cravino, E. Ripaud, P. Leriche, S. Rihn, A. De Nicola, R. Zissel, J. Roncali, Chem, Heterojunction solar cells with Ref: 0384-ARK42 Commun 2010, 46, 5082-5084). Thus, a solar yield greater than 8% could be observed for an oligothiophene-type electron donor material (see in particular the document entitled "Solution-Processed and High-Performance Organic Solar Cells Using Small Molecules with a Benzodithiophene Unit", Jiaoyan Zhou, Yi Zuo, Xiangjian Wan, Long Guankui, Zhang Qian, Wang Ni, Yongsheng Liu, Li Zhi, Guangrui He, Li Chenxi, Bin Kan, Li Miaomiao, and Chen Yongsheng, J. Am., Soc Chem 2013, 135 , 8484). However, these compounds have high molecular weights, which can exceed 1500g.mo1-1, and their synthesis requires a large number of steps, sometimes greater than 12. In addition, synthetic processes generally require the use toxic reagents or solvents and expensive catalysts. Finally, the synthesis yield of these molecules is very low, sometimes less than 0.10%, which is incompatible with industrial production. There is therefore a need to industrially produce photo-active compounds, electron donors, low molecular weight (preferably less than 1500g.mo1-1), which can be synthesized simply, quickly and inexpensively, while limiting the use of toxic reagents or solvents and expensive catalysts. The compounds must in particular make it possible to obtain a good compromise between complexity and yield of synthesis, production cost and solar yield obtained. Such compounds, easy to synthesize and therefore inexpensive to manufacture, can indeed have a significant impact for industrial production of photo-active compositions for photovoltaic cells for example. Thus, a small molecule was synthesized and tested as a photo-active electron donor compound in a photovoltaic cell. A. Liege, C-H The Regent, M. Allain, P. Blanchard and J. Roncali, Chem. Commun, 2012, 48, 8907-8909 describes this compound of triphenylamine dicyanovinyl thiophene, noted DA in the following description, the formula (I) developed is the following: Ref: 0384-ARK42 ON (I) [0016] Ce compound has been tested as a donor material in a bilayer photovoltaic cell, whose acceptor material layer is C60 fullerene and the cathode is aluminum. The compound made it possible to obtain a solar yield of 2.53% in such a cell. This compound, of simple structure, is used as a reference compound to analyze the optical properties of compounds of more complex structures based on this reference structure. Based on the structure of this reference compound (I), another compound was synthesized with an α-naphthyl group to replace a phenyl group of the amine. This α-naphthyl dicyanovinylthiophene-diphenylamine compound, again denoted "a-DA", whose formula (II) developed is as follows: was used as a p-type organic semiconductor material in a solid-state transistor. organic field (see document entitled "Nonvolatile memory organic field effect transistor induced by the steric hindrance effects of organic molecules", Jung, Mi-Hee; Song, Kyu-Ho; Ko, Kyoung-Chul; Lee, Jin-Yong; Lee, Hyo-Young, Journal of Materials Chemistry, 2010, 20 (37), 8016-8020). The optical properties of this compound (II) were evaluated by the applicant and its solar yield was measured in a photovoltaic cell structure bilayer donor-acceptor. For this, the compound is deposited on an anode, in the form of a layer acting as an electron donor, and another layer, based on fullerene C60, acting as an electron acceptor, is deposited between the layer of electron donor and a Ref: 0384-ARK42 cathode. The solar yield was measured at 2.20%, which is lower than the yield obtained with the reference compound (I) previously described. TECHNICAL PROBLEM The object of the invention is therefore to remedy at least one of the drawbacks of the prior art. The invention aims in particular to produce other photoactive compounds, the synthesis of which is easy, fast, reproducible, compatible with an inexpensive industrial process, for use in a photovoltaic cell with a satisfactory solar yield. Brief description of the invention [0020] Surprisingly, it has been discovered that a photoactive compound derived from thienyl triarylamines, characterized in that it is in the following general formula (III): R 9 R Wherein: A represents an electron withdrawing block; R1 is selected from hydrogen, fluorine, alkyl or a cyano or trifluoromethyl functional group; R2, R3 are independently selected from one of the following substituents: hydrogen, a halogen, an alkyl or a cyano or trifluoromethyl functional group, R4 to R7 are independently selected from one of the following substituents: hydrogen, a halogen, an alkyl such as methyl, an alkoxy such as methoxy, a polyether, or a nitro, cyano or trifluoromethyl functional group; An is an aromatic functional group phenyl, naphthyl or anthracenyl, preferably phenyl, substituted or not by at least one of the following substituents: a halogen, an alkyl such as methyl, an alkoxy such as methoxy, by a polyether, or with a nitro, cyano or trifluoromethyl functional group, R8 to R13 are independently selected from at least one of the following substituents: hydrogen; a halogen; an alkyl such as methyl; an alkoxy such as Ref: 0384-ARK42 methoxy; a polyether; a nitro, cyano or trifluoromethyl functional group; or an aromatic phenyl, naphthyl or anthracenyl functional group, substituted or unsubstituted by at least one of the following substituents: a halogen, an alkyl such as methyl, an alkoxy such as methoxy, a polyether, or a nitro, cyano or trifluoromethyl functional group, at least two adjacent groups from R8 to R13 and also the carbon atoms of the 8-naphthyl functional group to which they are attached being capable of being fused, or not, into an aromatic ring attached to said 8-naphthyl functional group of said compound, has good optical and electrochemical properties and allows the realization of photovoltaic cells with a solar yield of the order of 3%. In addition, such a compound is easy and fast to synthesize, with an overall synthetic yield greater than 10%, compatible with industrial production. According to a feature of the invention, the electron withdrawing block A is in one of the following formulas (1) to (6): (1) (2) (3) (4) COOR (5) Where R is a hydrogen or alkyl group. According to another feature of the invention, the photoactive compound is in the following formula (IV): (IV) This compound (IV) is the simplest of the compounds of the family of formula general (III), where all substituents R1 to R13 are hydrogen, An1 Ref: 0384-ARK42 is an unsubstituted phenyl functional group, and the electron withdrawing block is a dicyanovinyl. This compound makes it possible to obtain good results, and in particular a satisfactory solar yield when integrated in a photovoltaic cell, since it has an average yield of 3% with a standard deviation of 0.155. According to another feature of the invention, the photoactive compound is in the following formula (V): (V) [0025] The invention also relates to a photoactive composition comprising at least one electron donor compound, characterized in that the electron donor compound is a compound as described above. The composition further comprises a solvent, in particular a chlorinated solvent and more particularly trichloromethane. The composition further comprises an electron acceptor compound chosen from at least one of the following compounds: a fullerene, such as C60 or C70, or a perylene diimide derivative. The invention finally relates to a photoactive device comprising at least one electron donor compound, characterized in that the electron donor compound is a compound as described above. More particularly, the electron donor compound is in the form of a layer capable of transporting holes to an electrode. This layer is advantageously obtained by evaporation or sublimation under vacuum of a composition as described above. According to a feature, the photo-active device constitutes an organic photovoltaic cell comprising an electron acceptor compound and said electron donor compound. The electron acceptor compound of the photovoltaic cell is chosen from at least one of the following compounds: a fullerene, such as C60 or C70, or a perylene derivative diim ide. Ref: 0384-ARK42 According to a particular feature, the electron donor compound forms a layer capable of transporting holes towards an anode, said layer being obtained by depositing the composition based on the electron donor compound described previously, by evaporation or sublimation under vacuum. According to one feature, the electron donor compound and the electron acceptor compound form a single layer in which the compounds form an interpenetrating network capable of transporting electrons to a cathode and holes to an anode, said layer being obtained by depositing the composition described above, comprising both the electron donor compound and the electron acceptor compound, by evaporation or by sublimation under vacuum. According to yet another particularity, the electron donor compound and the electron acceptor compound form a single layer in which the compounds form an interpenetrating network, capable of transporting electrons to a cathode and holes to an anode, said layer being obtained by co-evaporation deposition of two compositions respectively comprising the electron donor compound and the electron acceptor compound. Other features and advantages of the invention will appear on reading the description given by way of illustrative and non-limiting example, with reference to the appended figures which represent: - Figure 1, a sectional diagram of a bi-layer type heterojunction photovoltaic cell, - Figure 2, a sectional diagram of a volumetric heterojunction photovoltaic cell, - Figure 3, comparative absorption spectra, in the visible UV, of three solutions. comprising respectively the compound 13-DA (IV) according to the invention, the reference compound DA (I) and the compound a-DA (II), - Figure 4, comparative absorption spectra of films obtained by deposit at the spin of three compositions respectively comprising the compound 13 -DA (IV) according to the invention, the reference compound DA (I) and the compound a-DA (II), - Figure 5, comparative curves of current density according to the voltage, characteristics of u a photovoltaic cell manufactured in accordance with Example 2, starting from a compound 13-DA (IV) according to the invention and from the existing α-DA compound (II). Ref: 0384-ARK42 Detailed description of the invention] In the following description, the term "open circuit voltage", denoted Voc, the voltage measured at the terminals of a photovoltaic cell when it is in open circuit and the current is then zero. This voltage is usually expressed in volts. The term "short-circuit current density", denoted Jsc, the current that passes through this cell per unit area when it is short-circuited, and the voltage at its terminals is then zero. This current is usually expressed in mi I liam fathers / cm2. The term "fill factor", noted FF (acronym for "Fill Factor"), the ratio between the maximum electrical power output and the product of the short-circuit current and open circuit voltage. The fill factor is usually expressed as a percentage. It is essential to determine the solar yield (PCE) of photovoltaic cells. The solar yield of a photovoltaic cell, noted PCE (acronym for "Power Conversion Efficiency"), the ratio between the maximum electrical power restored and incident solar power. It is usually expressed as a percentage. It is calculated according to the following equation: PCE = (Voc * Jsc * FF) / Pi, [0040] where Voc represents the open circuit voltage (expressed in V), Jsc the short-circuit current density (expressed in mA.cm-2), FF the fill factor (expressed in%) and Pi the incident light power (expressed in mW.cm-2). Molecular organic compounds are developing more and more because they have a perfectly defined chemical structure with easier characterization and purification than polymers. Their synthesis is reproducible and the structure / performance correlations are easier to establish than in the case of poly-dispersed polymers which have many difficult to control parameters, such as the length of the chains and the possible presence of terminal residual groups. Surprisingly, a family of compounds has made it possible to obtain satisfactory results, when integrated as a layer, as an electron donor material, in a photovoltaic cell. This family of Ref: 0384-ARK42 compounds, derived from thienyl triarylamines, is in the following general formula (III): Block A represents an electron withdrawing block. This attractor block can for example be in one of the following formulas: r. N (2) (1) (4) (6) (5) (3) wherein R is a hydrogen or alkyl group. The substituent R1 is chosen from hydrogen, fluorine, an alkyl or a cyano or trifluoromethyl functional group. The substituents R 2 and R 3 are independently selected from one of the following substituents: hydrogen, a halogen, an alkyl or a cyano or trifluoromethyl functional group. Similarly, the substituents R4 to R7 are independently chosen from one of the following substituents: hydrogen, a halogen, an alkyl such as methyl, an alkoxy such as methoxy, a polyether, or a functional group nitro, cyano or trifluoromethyl. The triarylamine block forms an electron donor block, and the substituent An 1 is an aromatic functional group phenyl, naphthyl or anthracenyl, preferably phenyl, substituted or not by at least one of the following substituents: a halogen, by an alkyl such as methyl, an alkoxy such as methoxy, a polyether, or a nitro, cyano or trifluoromethyl functional group. Ref: 0384-ARK42 [0048] The substituents R8 to R13 are independently selected from at least one of the following substituents: hydrogen; a halogen; an alkyl such as methyl; an alkoxy such as methoxy; a polyether; a nitro, cyano or trifluoromethyl functional group; or an aromatic phenyl, naphthyl or anthracenyl functional group, substituted or unsubstituted by at least one of the following substituents: a halogen, an alkyl such as methyl, an alkoxy such as methoxy, a polyether, or a nitro, cyano or trifluoromethyl functional group. At least two adjacent groups, from R8 to R13, as well as the carbon atoms of the 13-naphthyl functional group to which they are attached, may optionally be fused to form an aromatic ring fused to the [3-naphthyl] functional group. This compound has the advantage of being easily put in solution in a chlorinated solvent, such as dichloromethane or trichloromethane (also known under the name "chloroform") for example, and it can be deposited easily in the form of layer, by spin coating and evaporation of the solvent, or by sublimation under vacuum. The mobility of the charges is greater than 10-4 cm.sup.2.sup.-1.s -1, that is to say sufficient to efficiently transport the electrons and the holes to their respective collecting electrodes, that is to say the cathode and the anode. A compound of this family has been more particularly studied and compared with the compounds (I) and (II) of the prior art. This is the compound of [3-naphthyl diphenylamine dicyanovinyl thiophene, also noted "[3-DA] in the following description, of general formula (IV): CN (IV) [0051] This compound can be synthesized by methods known to those skilled in the art. It can for example be synthesized in just 4 steps. A first step consists in synthesizing a brominated derivative of diphenylnaphthalene amine, and more particularly N- (4-bromophenyl) -N-phenylnaphthalen-2-amine, from phenylnaphthalenamine and dibromobenzene. In a second step, N-phenyl-N (-4 (thiophen-2-yl) phenyl) naphthalen-2-amine is synthesized by reaction of Ref: 0384-ARK42 Stille between N- (4-bromophenyl) -N -phenylnaphthalen-2-amine obtained in the first step and 2- (tri-n-butylstannyl) thiophene. The N-phenyl-N (-4 (thiophen-2-yl) phenyl) naphthalen-2-amine thus obtained is then subjected to a Vilsmeier formylation to give an aldehyde, more particularly 5- (4- (naphthalen-2 yl (phenyl) amino) phenyl) thiophene-2-carbaldehyde. This aldehyde is then subjected to Knoevenagel condensation by reacting it with malonitrile, so as to obtain the p-naphyl diphenylamine dicyanovinyl thiophene of formula (IV). Another compound of the family (III) is for example in the following formula (V): (V) The structure of an effective electron donor compound generally involves the combination, within this compound, an electron donor block and an electron withdrawing block to create an internal charge transfer, also noted ICT (acronym for "Internai Charge Transfer") which produces at the same time an extension of the spectrum of absorption at longer wavelengths and an increase in the open circuit voltage Voc of the photovalota cell. The compound (IV) has been characterized and compared with the first 2 compounds (I) and (II) already known. For this, each compound was solubilized in a chlorinated solvent, such as dichloromethane for example, at a rate of 5 mg of compound (IV) per ml of solvent. The solution obtained was subjected to UV-visible spectroscopic analyzes in order to determine the molar absorption maxima corresponding to each of the compounds (I), (II) and (IV). The absorbance curves (A) as a function of wavelength (λ) are reported in FIG. 3. Table I below summarizes the absorption maxima and the molar absorption coefficients E measured for each compound. (I), (II), (IV) in solution.

Ref: 0384-ARK42 Compound A max (nm) E (L.Mol.cm-1) DA (I) 500 27000 a-DA (II) 494 32500 [3-DA (IV) 500 36300 Table I [0055] All these compounds have a low energy internal charge transfer band (ICT), that is to say a wavelength λ greater than 400 nm. The molar absorption coefficient E of the compound [3-DA of formula (IV) is greater than the molar absorption coefficient of the other two compounds. This reflects a better ability to absorb light radiation that passes through the medium containing the compound. Advantageously, a composition comprising at least one compound of general formula (III) as described above is prepared for use as an electron donor material in a photovoltaic cell, for example. This composition may comprise a compound [3-DA of formula (IV) and / or optionally one or more other compounds of different formula, but all belonging to the same family of compounds of general formula (III), such as, for example, the compound of formula (V). Such a composition was thus prepared by dissolving the compound [3-DA of formula (IV) in a solvent, in particular a chlorinated solvent such as chloroform for example. Preferably 5 mg of compound (IV) is dissolved per ml of solvent. The composition may further comprise an electron acceptor compound, such as a fullerene, such as C60 or C70 for example, a perylene derivative, such as PTCDA (perylene dianhydride -3,4,9, 10-tetracarboxylic), for example, a perylene diimide derivative, such as Me-PTCDI (N, N'-dimethylperylene-3,4,9,10-tetracarboxylic diimide) for example, or PCBM ([6,6] In this case, the acceptor and electron donor compounds are mixed in the same composition, which can then be used to form a single layer both electron donor and electron acceptor within a single electron-donating and accepting compound. Photovoltaic cell type heterojunction volume or BHJ (acronym for "Bulk HeteroJunction"). According to the compound, the layer may have a flat morphology or a morphology comprising cylinders, spheres or lamellae for example. The composition comprising the compound [3-DA of Formula (IV) was then used to form thin films. Such a film is produced by depositing the composition on a glass substrate, either by sublimation under vacuum or by evaporation. In the latter case, the composition is deposited for example by spinning with a speed of between 6000 and 10000 revolutions per minute, for a few seconds and the solvent is evaporated at the time of deposition. In the same way, films based on the compounds (I) and (II) were made on glass substrates in order to be compared. The absorbance curves (A) as a function of the wavelength (λ) are illustrated in FIG. 4. Table II below collates the absorption maxima and the optical gaps measured for each film. Composition Film Amax (nm) Eg (eV) DA (I) 523 1.98a-DA (II) 510 2.06-AD (IV) 518 2.02 Table II [0063] For the various compounds, the transition to the solid state causes a bathochromic shift and broadening of the ICT band (see Figure 4 in relation to Figure 3). This result is generally explained by an improvement in the flatness of the molecules and the existence of stronger intermolecular interactions. The optical gap values of the films (in eV) were determined by the tilting method by applying Planck's law (E = hc / λ = 1240 / Å in nm). The value of the optical gap of the film formed with the compound [3-DA of formula (IV) is less than that of the optical gap of the film formed with the compound a-DA of formula (II). This result reflects a better ability of the compound [3-DA to absorb light radiation that passes through the film containing the compound. The composition may be used for the production of electron donor or electron donor / acceptor layers in photovoltaic cells. There are essentially two types of photovoltemic cells. A first so-called bi-layer heterojunction type, as schematized in FIG. 1, consists in depositing two distinct layers, one electron donor, Ref: 0384-ARK42 referenced 13, and the other electron acceptor , referenced 14, between two electrodes 11, 16. In this case, the dissociation of the exciton in separate charges occurs at the interface (or heterojunction) between the donor layer 13 and the acceptor layer 14. The anode 11 collects the holes, while the cathode 16 collects the electrons. The layer 10 corresponds to a glass substrate. The other type of so-called heterojunction volume cell, as shown diagrammatically in FIG. 2, consists in forming an active layer consisting of an interpenetrating network of donor and acceptor obtained by mixing the two donor and acceptor compounds. in the layer 15 between two electrodes 11 and 16. In this case, the donor / acceptor interface is much larger than in the case of bilayer cells because it is not limited to the surface of the cell. In this case, the active layer 15 is formed either by spin coating a composition comprising the donor compound and the electron acceptor compound, or by vacuum coevaporation of two compositions each comprising, respectively, the donor compound and the acceptor compound. The example described in the following description refers to a bilayer photovoltaic cell. However, the invention is not limited to this example and the electron-donor photoactive active compound according to the invention can also be integrated, in the form of a layer, in other photoactive devices such as transistors. field effect for example. EXAMPLE 1 - Preparation of Compound 13-DA of Formula (IV): Reaction (1): In a first step, N- (4-bromophenyl) -N-phenylnaphthalen-2-amine is synthesized at 0.degree. from dibromobenzene and N-phenylnaphthalen-2-amine. For this purpose, 2,69 g (ie 11.4 mmol) of 1,4-dibromobenzene, 1 g (ie 4.56 mmol) of N-phenylnaphthalen-2-amine and 1.75 g (18.2 mmol) of tert-butylate are used. sodium, noted NaOtBu, are dissolved in 40 ml of toluene. The mixture is degassed for about 10 minutes with argon. Then a palladium catalyst is introduced into the mixture. More precisely, 100mg (ie 3% by weight) of Pd (dppf) Cl 2 is introduced into the mixture, which is then heated at a temperature of 120 ° C. for 4 hours under an argon atmosphere. The sodium tert-butylate is then filtered and the solvent, that is to say toluene, is evaporated. The product obtained is purified by column chromatography Ref: 0384-ARK42 silica gel with an eluent comprising a mixture of cyclohexane and dichloromethane in proportions of 8.5: 1.5 respectively. The yield of this first reaction is 79%. 1.35 g (3.6 mmol) of N- (4-bromophenyl) -N-phenylnaphthalen-2-amine are thus obtained.

NaOtBu Br DPPFPdC12 Toluene - (1) [0072] Reaction (2) - Stille reaction: 920 mg (ie 2,45 mmol) of previously synthesized N- (4-bromophenyl) -N-phenylnaphthalen-2-amine and 1.18 ml ( or 3.75 mmol) of tributylstannylthiophene are dissolved in 40 ml of dry toluene. The solution obtained is degassed for 10 minutes. 143.3 mg (or 0.124 mmol) of (triphenylphosphine) palladium, which catalyzes the reaction, is then added to the mixture. The mixture obtained is refluxed for 24 hours. The solvent, that is to say toluene, is evaporated and the product is then purified by column chromatography on silica gel with an eluent comprising a mixture of cyclohexane and dichloromethane in respective proportions of 8: 2. 629 mg (ie 1.66 mmol) of N-phenyl-N (-4 (thiophen-2-yl) phenyl) naphthalen-2-amine are obtained. The reaction has a yield of 68%. This reaction is as follows: nBu - Pd (PPh3) Toluene Reflux, 24h (2) Reaction (3) - Vilsmeier reaction: In a third step, 200 mg (ie 0.53 mol) of N-phenyl-N (-4 (thiophen-2-yl) phenyl) naphthalen-2-amine previously synthesized in step 2 are introduced into a Schlenk tube filled with argon, then dissolved in 10 ml of dry THF and cooled to -78 ° C. vs. 224 μl (ie 0.6 mmol) of nBuLi is then added dropwise and the mixture is stirred for 30 minutes. A white precipitate is formed. 71p1 (ie 1.06mmol) of dimethylformamide is then added and the mixture is again stirred overnight. The solvent is then evaporated and the product obtained is purified by column chromatography on Ref: 0384-ARK42 silica gel with an eluent comprising a mixture of cyclohexane and dichloromethane in respective proportions of 4: 6. 100 mg (or 0.26 mmol) of a yellow powder of 5- (4- (naphthalen-2-yl (phenyl) amino) phenyl) thiophene-2-carbaldehyde are obtained in a yield of 49%. The reaction is as follows: nBuLi (3) DMF-THF Reaction (4) - Knoevenagel condensation reaction: Finally, a last step consists in mixing 100 mg (or 0.26 mmol) of 5- (4- (naphthalene) 2-yl (phenyl) amino) phenyl) thiophene-2-carbaldehyde synthesized in the previous step with 35 mg (ie 0.52 mmol) of malonitrile and dissolve the mixture in 5 ml of chloroform. A drop of triethylamine is added to the mixture and the mixture is refluxed for 2 hours. The product obtained is purified by column chromatography on silica gel with an eluent comprising a mixture of dichloromethane and cyclohexane in proportions of 9: 1. The yield of the reaction is 99%. 110 mg (or 0.25 mmol) of diphenylamine naphthyl thiophene dicyanovinyl or 13-D A are obtained. The reaction is as follows: C F12 (CN) 2 -Et 3 N Reflux, 2h (4) (IV) The overall yield of synthesis of this compound 13 -DA (IV) is 26% and compatible with an industrial production. EXAMPLE 2 Preparation and Characterization of Bilayer Solar Cells Two-layer solar cells, conforming to the cell shown diagrammatically in FIG. 1, were developed in order to evaluate the potential of a composition Ref: 0384 -ARK42 comprising an electron donor compound 13 -DA of formula (IV) previously described, relative to cells made from the compound α-DA (II) already known. On a glass substrate 10 is deposited a first layer of ITO 11 (Indium oxide and tin). This ITO layer is transparent and generally used as anode. It is generally covered by a layer 12 of about 40 nm of PEDOT-PSS. This transparent material combines the conductive character of the oxidized PEDOT (poly (3,4-ethylenedioxythiophene)) and the mechanical properties of the PSS (polystyrene sulfonate) to form an ohmic contact with the photoactive layer 13 deposited above to improve the collection of positive charges. The PEDOT-PSS also smoothes the surface of ITO layer 11. Because of its acid nature, PEDOT-PSS is increasingly replaced by transition metal oxides such as Mo03, V205 or NiO to increase the stability of the device and its performance. The photoactive organic layer 13 is then deposited by spinning, for example, from a composition comprising the compound 13-D electron donor of formula (IV) described above diluted in chloroform at a rate of 5 mg. of compound (IV) per ml of solvent. The deposit can also be made by sublimation under vacuum. The thickness of the layer 13 deposited is of the order of 20 nm. A acceptor layer 14 based on fullerene, such as C60 or C70 for example, or based on perylene diimide derivative for example, is then deposited on the photoactive layer, by evaporation under vacuum on a thickness of the order of 30 nm. Finally, a layer 16 of Al aluminum of the order of 100nm thick is deposited by evaporation under vacuum to form the cathode. Other complementary materials may also be deposited before the aluminum layer, for example Calcium Ca, Barium Ba, or Mg Magnesium, so as to stabilize the aluminum cathode. The cell thus produced is preferably subjected to a heat treatment at a temperature of about 140 ° C for 5 min to improve the solar conversion properties of the photovoltaic cell. The photovoltaic cells thus obtained are characterized by representing the curve of the current density J as a function of the voltage V applied under illumination and in the dark (see FIG. 5). The curve with empty round Ref: 0384-ARK42 represents the current density as a function of the voltage applied in the dark. The curve with the spotted circles represents the current density as a function of the voltage applied across a cell whose donor layer comprises the α-DA compound of formula (II). The curve with the gray circles represents the current density as a function of the voltage applied across a cell whose donor layer comprises the compound [3-DA of formula (IV) according to the invention. The performance of a solar cell is evaluated by measuring four main characteristics: the open circuit voltage (Voc), the short-circuit current density (Jsc), the curve fill factor (FF) and the efficiency of the solar cell. conversion (PCE). The open circuit voltage Voc corresponds to the voltage measured when the current generated by the device is zero. The parameter Jsc corresponds to the maximum current density generated by the device under illumination. Its value depends on the number of photons absorbed by the material and therefore on the thickness of the active layer 13 as well as on its absorption spectrum. The filling factor FF corresponds to the maximum power ratio on the theoretical power. It informs about the efficiency of the transport of the charges in the device and on the quality of the interface between the donor and the acceptor. The conversion efficiency PCE is determined by the ratio of the maximum power Pmax delivered by the device to the incident light power Pi. [0084] The measurements were carried out using a solar simulator under the AM1,5 conditions, ie that is to say a mass of air traversed by the sun's rays inclined relative to the earth at an angle of 48.2 ° (X = 1 / cosangle = 1.5), which corresponds to an incident power Pi received of 90mW.cm-2. For the compound [3-DA (IV), an average conversion yield of 3% is obtained, with a standard deviation of 0.155. This efficiency results from the combination of a mean Voc voltage of 0.82V, an average current density of 7.44mA.cm-2 and an average FF of 45.7%. [0086] Comparatively, the α-DA compound (II) integrated into bilayer solar cells has a yield of 2.20% due to the combination of a mean Voc voltage of 0.8V, a mean current density. of 6.22mA.cm-2, and an average FF of 40.3%. Ref: 0384-ARK42 Cell Voc (V) Jsc (mA.cm-2) FF (`) / 0) PCE (`) / 0) a 0.88 6.68 47 3.08 b 0.78 7.75 43 2 , 93 c 0.83 7.7 47 3.21 d 0.81 7.63 46 3.15 Table III: characterization of bilayer cells whose donor layer comprises a compound 13 -DA of formula (IV). The photoactive compounds which have just been described have the advantage of being less expensive than the compounds studied so far. They can be synthesized easily and quickly with an overall yield compatible with industrial production. They can be easily deposited in the form of a layer by deposition of a composition by spinning and evaporation of the solvent, or by sublimation under vacuum, thus making it possible to develop two-layer or interpenetrating photovoltaic cells. They make it possible to obtain a satisfactory average solar yield in a photovoltaic cell of the bilayer type. Ref: 0384-ARK42