EP2399305A1 - Use of triarylamine derivatives as hole-conducting materials in organic solar cells and organic solar cells containing said triarylamine derivatives - Google Patents

Abstract

The present invention relates to the use of compounds of the general formula (I) as hole-conducting materials in organic solar cells, wherein A¹, A², A³ independently of each other mean divalent organic units, which can contain one, two, or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, two of said groups are bonded to each other by means of a chemical bond and/or by means of a divalent alkyl group in each case, R¹, R², R³ independently of each other mean substituents R, OR, NR₂, A³-OR, or A³-NR₂, R is alkyl, aryl, or a monovalent organic group, which can contain one, two, or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, two of said groups are bonded to each other by means of a chemical bond and/or by means of a divalent alkyl group or NR' group in each case, R' is alkyl, aryl, or a monovalent organic group, which can contain one, two, or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, two of said groups are bonded to each other by means of a chemical bond and/or by means of a divalent alkyl group in each case, and n independently for each occurrence in formula (I) is a value 0, 1, 2, or 3, with the stipulation that the sum of the individual values n is at least 2, and at least two of the groups R¹, R², and R³ mean substituents OR and/or NR₂. The present invention further relates to organic solar cells that contain said compounds.

Description

 Use of triarylamine derivatives as hole-conducting materials in organic solar cells and organic solar cells containing these triarylamine derivatives

description

The present invention relates to the use of compounds of general formula I.

in which mean

A ¹ , A ² , A ³ are each independently of one another divalent organic units which may contain one, two or three optionally substituted aromatic or heteroaromatic groups, where in the case of two or three aromatic or heteroaromatic groups, two of these groups are each bound by a chemical bond and / or are connected to each other via a divalent alkyl radical,

R ¹ , R ² , R ³ independently of one another are substituents R, OR, NR ₂ , A ³ -OR or A ³ -NR ₂ ,

R is alkyl, aryl or a monovalent organic radical which may contain one, two or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, any two of these groups by a chemical bond and / or via a bivalent Alkyl or NR ^' radical are joined together, R ^'is alkyl, aryl or a monovalent organic radical which may contain one, two or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, two of these groups by a chemical bond and / or via a divalent alkyl radical are linked together,

and

n is independently 0, 1, 2 or 3 for each occurrence in formula I,

with the proviso that the sum of the individual values n is at least 2 and at least two of the radicals R ¹ , R ² and R ^{3 are} substituents OR and / or NR 2,

as hole-conducting materials in organic solar cells.

Further, the present invention relates to organic solar cells containing these compounds.

Dye solar cells (also Dye Solar Cell, "DSC", or Dye Sensitized Solar Cell, "DSSC", these terms or abbreviations are used interchangeably below) currently represent one of the most efficient alternative solar cell technologies. In a liquid version of this technology so far efficiencies of Grätzel M. et al., J. Photochem., Photobio C, 2003, 4, 145; Chiba et al., Japanese Journal of Appl. Phys., 2006, 45; L638-L640).

The construction of a DSC is usually based on a glass substrate coated with a transparent, conductive layer, the working electrode. On this electrode or in the vicinity of the same usually an n-type metal oxide is applied, for example, an approximately 10-20 microns thick, nanoporous layer of titanium dioxide (TiO 2). On its surface, in turn, usually a monolayer of a light-sensitive dye, for example a ruthenium complex, adsorbed, which can be converted by light absorption in an excited state. Optionally, the counter electrode may comprise a catalytic layer of a metal, such as platinum, a few microns thick. The area between the two electrodes is covered with a redox electrolyte, z. As a solution of iodine (b) and lithium iodide (LiI) filled.

The function of the DSC is to absorb light from the dye, transfer electrons from the excited dye to the n-type semiconducting metal oxide semiconductor, and migrate to the anode, whereas the electrolyte ensures charge equalization across the cathode. Thus, the n-type semiconducting metal oxide, the dye and the (mostly liquid) electrolyte are the essential components of DSC, with cells containing liquid electrolyte in many cases suffering from a non-optimal seal resulting in stability problems. Therefore, various materials have been investigated for their suitability as solid electrolytes / p-type semiconductors.

For example, various inorganic p-type semiconductors such as CuI, CuBr ^• 3 (S (C ₄ Hg) ₂ ) or CuSCN have been used in solid state DSCs. For example, efficiencies of up to 3% have been reported with solid DSC based on CuI or CuSCN (Tennakone et al J. Phys D: Appl Phys, 1998, 31, 1492, O'Regan et al., Adv 200, 12, 1263, Kumara et al., Chem. Mater., 2002, 14, 954).

Organic polymers are also used as solid p-type semiconductors. Examples thereof include polypyrrole, poly (3,4-ethylenedioxythiophene), carbazole-based polymers, polyaniline, poly (4-undecyl-2,2'-bithiophene), poly (3-octylthiophene), poly (triphenyldiamine), and poly (N vinylcarbazole). The efficiencies reach up to 2% in the case of the poly (N-vinylcarbazole), and an efficiency of 2.9% has even been achieved on an in-situ polymerized PEDOT (poly (3,4-ethylenedioxythiophene) (Xia et al. Phys. Chem. C 2008, 1 12, 11569), where the polymers are typically not used in their pure form, but usually in admixture with additives, as well as a concept in which polymeric p-type semiconductors are bonded directly to a Ru dye (Peter, K., Appl. Phys. A 2004, 79, 65).

However, the highest efficiencies have so far been achieved with low molecular weight organic p-type semiconductors. For example, a vapor-deposited layer of triphenylamine (TPD) has been applied to the dye-sensitized layer as a replacement for the liquid electrolyte. The use of the organic compound 2,2'7,7'-tetrakis (N, N-di-p-methoxyphenyl-amine) -9,9'-spirobifluorene (spiro-MeOTAD) in dye-sensitized solar cells was reported in 1998. The methoxy groups adjust the oxidation potential of the spiro-MeOTAD so that the Ru complex can be efficiently regenerated. When using the Spiro-MeOTAD alone as a p-conductor, a maximum IPCE (incident photon to current conversion efficiency, external photon conversion efficiency) of 5% is achieved. With the addition of N (PhBr) sSbCl6 (as dopant) and Li [(CF ₃ SO ₂ ) 2N], an increase in IPCE to 33% and in efficiency to 0.74% was observed. By adding tert-butylpyridine, the efficiency could be increased to 2.56%, with an open circuit voltage (V _oc ) of about 910 mV and a short-circuit current Isc of about 5 mA with an active area of about 1.07 cm ² (Krüger et al., Appl. Phys. Lett., 2001, 79, 2085). Dyes which achieve better coverage of the TiO ₂ layer and which have good wetting on spiro-MeOTAD show efficiencies of over 4% (Schmidt-Mende et al., Adv. Mater. 17, p. 813-815 (2005). ). Even better efficiencies of 5.1% will be observed when a ruthenium complex with oxyethylene side chains is used (Snaith, H. et al., Nano Lett., 7, 3372-3376 (2007)).

Durrant et al., Adv. Func. Mater. 2006, 16, 1832-1838 describe that in many cases the photocurrent is directly dependent on the yield at the hole transition from the oxidized dye to the solid p-conductor. This depends essentially on two factors: on the one hand on the extent of penetration of the p-type semiconductor into the oxide pores and on the other hand on the thermodynamic driving force for the charge transfer, ie in particular on the difference in the free enthalpy ΔG between dye and p-conductor.

The best-performing efficiencies in fixed-hole DSCs are obtained with the previously mentioned compound Spiro-MeOTAD, whose chemical formula is listed below:

(Snaith, H.J., Moule, A.J. Klein, C; Meerholz, K., Friend, R.H., Grätzel, M. Nano Lett .; (Letter); 2007; 7 (11); 3372-3376)

Investigations by C. Jäger et al. (Proc. SPIE 4108, 104-110 (2001)) show that this compound is semicrystalline and thus there is the danger of its (re) crystallization in the processed form, ie in the DSC.

Furthermore, the solubility in conventional process solvents is relatively low, resulting in a correspondingly low pore filling level.

The object of the present invention was therefore to provide further compounds which can be used advantageously in solar cells, in particular in DSCs, as p-type semiconductors. In terms of their property profile, these compounds should have good hole-conducting properties, have no or only a very slight tendency to crystallize and good in the usual be used solvents to cause the highest possible degree of filling of the oxide pores.

Accordingly, the use of the compounds listed above in organic solar cells and organic solar cells containing these compounds has been found.

Alkyl is to be understood as meaning substituted or unsubstituted C 1 -C 20 -alkyl radicals. Preference is given to C 1 -C 10 -alkyl radicals, more preferably C 1 -C -alkyl radicals. The alkyl radicals can be both straight-chain and branched. Furthermore, the alkyl radicals may be substituted by one or more substituents selected from the group consisting of C 1 -C 20 -alkoxy, halogen, preferably F, and C 6 -C 8 -aryl, which in turn may be substituted or unsubstituted. Examples of suitable alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl and with C6-C3o-aryl, Ci-C2o-alkoxy and / or halogen, especially F, substituted derivatives of said alkyl groups, for Example CF3. Examples of linear and branched alkyl radicals are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl and isopropyl, isobutyl, isopentyl, sec-butyl, tert-butyl, neopentyl, 3,3-dimethylbutyl, 2-ethylhexyl ,

Divalent alkyl radicals in the units A ¹ , A ² , A ³ , R, R ^' , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ^{9 are} derived from the aforementioned alkyl by formal removal of another From the hydrogen atom.

Suitable aryls are Cβ-Cso-aryl radicals derived from monocyclic, bicyclic or tricyclic aromatics which contain no ring heteroatoms. Unless they are monocyclic systems, the term aryl for the second ring also means the saturated form (perhydroform) or the partially unsaturated form (for example the dihydroform or tetrahyroform), provided the respective forms are known and stable. Thus, for the purposes of the present invention, the term aryl also includes, for example, bicyclic or tricyclic radicals in which both both and all three radicals are aromatic, as well as bicyclic or tricyclic radicals in which only one ring is aromatic, and tricyclic radicals in which two Rings are aromatic. Examples of aryl are: phenyl, naphthyl, indanyl, 1, 2-dihydronaphthenyl, 1, 4-dihydronaphthenyl, fluorenyl, indenyl, anthracenyl, phenanthrenyl or 1, 2,3,4-tetrahydronaphthyl. Particularly preferred are Cβ-Cio-aryl radicals, for example phenyl or naphthyl, very particularly preferably Cβ-aryl radicals, for example phenyl.

Aromatic groups in the units A ¹ , A ² , A ³ , R, R ^' , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ^{9 are} derived from the aforementioned aryl by formal removal of one or more others Hydrogen atoms off. Heteroaromatic groups in the units A ¹ , A ² , A ³ , R, R ^' , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ^{9 are} derived from hetaryl radicals by formal removal of one or more others Hydrogen atoms off.

The underlying hetaryl radicals are unsubstituted or substituted here and contain 5 to 30 ring atoms. They may be monocyclic, bicyclic or tricyclic and may be derived, in part, from the abovementioned aryl, in which at least one carbon atom in the aryl skeleton is replaced by a heteroatom. Preferred heteroatoms are N, O and S. Particularly preferably, the

Hetaryl radicals 5 to 13 ring atoms. Especially preferred is the backbone of the heteroaryl radicals selected from systems such as pyridine and five-membered heteroaromatics such as thiophene, pyrrole, imidazole or furan. These backbones may optionally be fused with one or two six-membered aromatic radicals. Suitable fused heteroaromatics are carbazolyl, benzimidazolyl, benzofuryl, dibenzofuryl or dibenzothiophenyl. The backbone may be substituted at one, several or all substitutable positions, suitable substituents being the same as those already mentioned under the definition of Cβ-Cso-aryl. However, the hetaryl radicals are preferably unsubstituted. Suitable hetaryl radicals are, for example, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, thiophen-2-yl, thiophen-3-yl, pyrrol-2-yl, pyrrol-3-yl, furan-2 -yl, furan-3-yl and imidazol-2-yl and the corresponding benzanellierten radicals, in particular carbazolyl, benzimidazolyl, benzofuryl, dibenzofuryl or dibenzothiophenyl.

Further substituents of the one, two or three optionally substituted aromatic or heteroaromatic groups are alkyl radicals, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl and isopropyl, isobutyl, isopentyl, sec-butyl, tert Butyl, neopentyl, 3,3-dimethylbutyl and 2-ethylhexyl, aryl radicals, such as Cβ-C-io-Arvl radicals, in particular phenyl or naphthyl, most preferably Cβ-aryl radicals, for example phenyl, and hetaryl Radicals, such as, for example, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, thiophen-2-yl, thiophen-3-yl, pyrrol-2-yl, pyrrol-3-yl, furan 2-yl, furan-3-yl and imidazol-2-yl and the corresponding benzanellierten radicals, in particular carbazolyl, benzimidazolyl, benzofuryl, dibenzofuryl or dibenzothiophenyl in question. The degree of substitution can vary from simple substitution to the maximum number of possible substituents.

Preferred compounds of the formula I to be used according to the invention are characterized in that at least two of the radicals R ¹ , R ² and R ^{3 are} para-substituted OR and / or NR 2 substituents. Hiebei there may be at least two residues either only OR residues, only NR2 residues or at least one OR and act at least one NF ^ -Rest.

Particularly preferred compounds of the formula I to be used according to the invention are characterized in that at least four of the radicals R ¹ , R ² and R ^{3 are} para-containing OR and / or NR 2 substituents. Hiebei may be at least four residues either only OR residues, only NR2 residues or a mixture of OR and NR2 residues.

Very particularly preferred compounds of the formula I to be used according to the invention are distinguished by the fact that all radicals R ¹ , R ² and R ^{3 are} para-substituted OR and / or NR 2 substituents. These can be either only OR residues, only NR2 residues, or a mixture of OR and NR2 residues.

In all cases, the two Rs in the NR2 residues may be different from each other, but they are preferably the same.

Preferred bivalent organic units A ¹ , A ² and A ³ are selected from the group consisting of (CH ₂ ) _m , C (R ⁷ ) (R ⁸ ), N (R ⁹ ),

in which mean

m is an integer value from 1 to 18,

R ⁴ , R ^{9 is} alkyl, aryl or a monovalent organic radical which may contain one, two or three unsubstituted or substituted aromatic or heteroaromatic groups, where in the case of two or three aromatic or heteroaromatic groups, two of these groups are each bound by a chemical bond and / or are connected to each other via a divalent alkyl radical, R ⁵ , R ⁶ , R ⁷ , R ⁸ independently of one another are hydrogen atoms or radicals of the definition of R ⁴ and R ⁹ ,

and the aromatic and heteroaromatic rings of the units shown may be further substituted.

The degree of substitution of the aromatic and heteroaromatic rings can vary from simple substitution to the maximum number of possible substituents.

Preferred substituents in the case of a further substitution of the aromatic and heteroaromatic rings are the substituents already mentioned above for the one, two or three optionally substituted aromatic or heteroaromatic groups.

The compounds to be used according to the invention can be prepared by customary methods of organic synthesis known to those skilled in the art. References to relevant (patent) references can also be found in the Synthesis Examples below.

For the construction of a DSC, a single metal oxide or a mixture of different oxides can be used as the n-semiconducting metal oxide. It is also possible to use mixed oxides. The n-semiconducting metal oxide can be used in particular as a nanoparticulate oxide, in which context nanoparticles are to be understood as meaning particles having an average particle size of less than 0.1 micrometers.

A nanoparticulate oxide is usually applied to a conductive substrate (i.e., a substrate having a conductive layer as a first electrode) by a sintering process as a thin porous film having a large surface area.

As a substrate (hereinafter also referred to as a support) are in addition to metal foils especially plastic sheets or films and glass plates in particular. As electrode material, in particular for the first electrode according to the preferred structure described above, in particular conductive materials such. As transparent conductive oxides (transparent conducting oxides, TCO), for example, with fluorine and / or indium-doped tin oxide (FTO or ITO) and / or aluminum-doped zinc oxide (AZO), carbon nanotubes or metal films. Alternatively or additionally, however, it would also be possible to use thin metal films which still have sufficient transparency. The substrate may be coated with these conductive materials. Since in this structure usually only a single substrate is needed, the construction of flexible cells is possible. This allows a variety of applications that would not or only with realizable rigid substrates, such as the use in bank cards, garments, etc.

The first electrode, in particular the TCO layer, can additionally be coated or coated with a (for example 10 to 200 nm thick) solid buffer layer, in particular a metal oxide buffer layer, in order to direct contact of the p-type semiconductor with the TCO layer (see Peng et al., Coord. Chem. Rev. 248, 1479 (2004)). The buffer metal oxide which may be employed in the buffer layer may comprise, for example, one or more of the following materials: vanadium oxide; a zinc oxide; a tin oxide; a titanium oxide.

Thin layers or films of metal oxides are usually inexpensive solid semiconductor materials (n-type semiconductors), but their absorption is due to large band gaps usually not in the visible range of the solar spectrum, but predominantly in the ultraviolet spectral range. For use in solar cells, therefore, the metal oxides must generally, as is the case with the DSCs, be combined with a dye as a photosensitizer, which absorbs in the wavelength range of sunlight, ie at 300 to 2000 nm, and electrons in the electronically excited state injected into the conduction band of the semiconductor. With the aid of a solid p-type semiconductor which is additionally used in the cell and which in turn is reduced at the counterelectrode, electrons can be returned to the sensitizer so that it is regenerated.

Of particular interest for use in solar cells are the semiconductors zinc oxide, tin dioxide, titanium dioxide or mixtures of these metal oxides. The metal oxides can be used in the form of nanocrystalline porous layers. These layers have a large surface which is coated with the sensitizer, so that a high absorption of the sunlight is achieved. Metal oxide layers that are structured, such as. For example, nanorods (nanorods) offer advantages such as higher electron mobilities or improved pore filling by the dye and the p-type semiconductor.

The metal oxide semiconductors can be used alone or in the form of mixtures. It is also possible to coat a metal oxide with one or more other metal oxides. Furthermore, the metal oxides may also be used as a coating on another semiconductor, e.g. As GaP, ZnP or ZnS, be applied.

Particularly preferred semiconductors are zinc oxide and titanium dioxide in the anatase modification, which is preferably used in nanocrystalline form. In addition, the sensitizers can be advantageously combined with all the n-type semiconductors commonly used in these solar cells. Preferred examples are metal oxides used in the ceramic, such as titanium dioxide, zinc oxide, tin (IV) oxide, tungsten (VI) oxide, tantalum (V) oxide, niobium (V) oxide, cesium oxide, strontium titanate, zinc stannate, complex oxides of the perovskite type, e.g. As barium titanate, and called binary and ternary iron oxides, which may also be present in nanocrystalline or amorphous form.

Due to the strong absorption exhibited by common organic dyes as well as phthalocyanines and porphyrins, even thin layers or films of the dye-sensitized n-type semiconductive metal oxide are sufficient to obtain sufficient light absorption. Thin metal oxide films in turn have the advantage that the probability of undesired recombination processes decreases and that the internal resistance of the dye subcell is reduced. Layer thicknesses of from 100 nm to 20 micrometers can preferably be used for the n-semiconducting metal oxide, more preferably in the range between 500 nm to about 5 micrometers.

Numerous dyes that can be used in the context of the present invention are known from the prior art, so that for possible material examples, reference may also be made to the above description of the prior art for dye-sensitized solar cells. All listed and claimed dyes may in principle also be present as pigments. Dye-sensitized solar cells based on titanium dioxide as a semiconductor material are, for. In US-A-4,927,721, Nature 353, pp. 737-740 (1991) and US-A-5,350,644 and Nature 395, pp. 583-585 (1998) and EP-A-1 176 646 described. The dyes described in these documents can in principle also be used advantageously in the context of the present invention. These dye-sensitized solar cells contain monomolecular films of transition metal complexes, in particular ruthenium complexes, which are bonded to the titanium dioxide layer via acid groups as sensitizers.

Sensitizers, not least for reasons of cost, have repeatedly been proposed metal-free organic dyes which can also be used in the context of the present invention. High efficiencies of over 4%, especially in solid-dye solar cells, can be, for example, with

Indoline dyes achieve (see, for example, Schmidt-Mende et al., Adv., Mater., 2005, 17, 813). US Pat. No. 6,359,211 also describes the use, within the scope of the present invention, of cyanine, oxazine, thiazine and acridine dyes which have carboxyl groups bonded via an alkylene radical for attachment to the titanium dioxide semiconductor. JP-A-10-189065, 2000-243463, 2001-093589, 2000-100484 and 10-334954 describe various perylene skeleton unsubstituted perylene-3,4: 9,10-tetracarboxylic acid derivatives for use in semiconductor solar cells. Specifically, they are: perylenetetracarboxylic diimides which carry carboxyalkyl, carboxyaryl, carboxyarylalkyl or carboxyalkylaryl radicals on the imide nitrogen atoms and / or are imidated with p-diaminobenzene derivatives in which the nitrogen atom of the amino group is substituted by two further phenyl radicals in the p-position Part of a heteroaromatic tricyclic system; Perylene-3,4: 9,10-tetracarboxylic monoanhydride monoimides bearing on the imide nitrogen atom the radicals mentioned above or non-functionalized alkyl or aryl radicals, or

Semicondensates of perylene-3,4,9,10-tetracarboxylic dianhydride with 1,2-diamine-topazoles or 1,8-diaminonaphthalenes, which are converted by further reaction with primary amine into the corresponding diimides or double condensates; Condensates of perylene-3,4,9,10-tetracarboxylic dianhydride with 1,2-diamine-topazoles functionalized by carboxyl or amino radicals; and perylene-3,4: 9,10-tetracarboxylic diimides which are imidated with aliphatic or aromatic diamines.

New J. Chem. 26: 1 155-1160 (2002) investigates the sensitization of titanium dioxide with perylene derivatives which are unsubstituted in the perylene framework (bay positions). Specifically mentioned are 9-dialkylaminoperylene-3,4-dicarboxylic acid anhydride, perylene-3,4-dicarboximides, which are substituted in the 9-position by dialkylamino or carboxymethylamino and at the imide nitrogen atom have a carboxymethyl or a 2, 5 Di (tert-butyl) phenyl radical, and N-dodecylaminoperylene-3,4: 9,10-tetracarboxylic monoanhydride called mono-imide. However, the liquid-electrolyte solar cells based on these perylene derivatives showed significantly lower efficiencies than a solar cell sensitized for comparison with a ruthenium complex.

Particularly preferred as Sensibilisatorfabstoffe in the proposed dye solar cell are described in DE 10 2005 053 995 A1 or WO 2007/054470 A1 perylene derivatives, Terrylenderivate and Quaterrylenderivate. The use of these dyes leads to photovoltaic elements with high efficiencies and high stabilities.

The rylenes show strong absorption in the wavelength range of the sunlight and can, depending on the length of the conjugated system, a range of about 400 nm (perylene derivatives I from DE 10 2005 053 995 A1) up to about 900 nm (quaterrylene derivatives I from DE 10 2005 053 995 A1). Depending on their composition, terrylene-based rylene derivatives I absorb in a solid state adsorbed to titanium dioxide in a range from about 400 to 800 nm. In order to maximize the utilization of the irradiated sunlight from the visible to the near-infrared range, it is advantageous to use mixtures of various types Rylene derivatives I use. Occasionally, it may also be advisable to use different Rylenhomologe.

The rylene derivatives I can be easily and permanently fixed on the metal oxide film. Binding takes place via the anhydride function (x1) or the carboxyl groups -COOH or -COO- formed in situ or via the acid groups A contained in the imide or condensate radicals ((x2) or (x3)) Rylene derivatives I described in DE 10 2005 053 995 A1 are well suited for use in dye-sensitized solar cells in the context of the present invention.

Particularly preferably, the dyes have an anchor group at one end of the molecule, which ensures their fixation on the n-type semiconductor film. At the other end of the molecule, the dyes preferably contain electron donors which facilitate regeneration of the dye after electron donation to the n-type semiconductor and also prevent recombination with electrons already delivered to the semiconductor.

For further details on the possible selection of a suitable dye, reference may again be made, for example, to DE 10 2005 053 995 A1. Ruthenium complexes, porphyrins, other organic sensitizers and preferably rylenes can be used in particular for the solid-colorant solar cells described herein.

The fixation of the dyes on the metal oxide films can be done in a simple manner. For example, the n-type semiconductive metal oxide films in freshly sintered (still warm) condition may be contacted with a solution or suspension of the dye in a suitable organic solvent for a sufficient period of time (eg, about 0.5 to 24 hours). This can be done, for example, by immersing the substrate coated with the metal oxide in the solution of the dye.

If combinations of different dyes are to be used, they can be applied, for example, one after the other from one or more solutions or suspensions containing one or more of the dyes. Also possible is the use of two dyes separated by a layer of z. CuSCN (see eg Tennakone, K.J., Phys. Chem B. 2003, 107, 13758). The most appropriate method can be determined comparatively easily in individual cases.

In principle, the dye can be present as a separate element or applied in a separate step and applied separately to the remaining layers. Alternatively or additionally, however, the dye can also be combined with one or more of the other elements or applied together, for example with the solid p-type semiconductor. So can For example, a dye-p-semiconductor combination comprising an absorbent dye having p-type semiconductive properties or, for example, a pigment having absorbent and p-type semiconductive properties can be used.

In order to prevent recombination of the electrons in the n-type semiconducting metal oxide with the solid p-type conductor, it is possible to use a kind of passivating layer comprising a passivation material. This layer should be as thin as possible and, if possible, should only cover the hitherto uncovered areas of the n-semiconducting metal oxide. The passivation material may also be applied to the metal oxide in time before the dye. As passivation materials in particular the following substances are preferred: Al 2 O 3; an aluminum salt; Silanes, such as For example, CHsSiCb; an organometallic complex, in particular an Al ³⁺ complex; Al ³⁺ , in particular an Al ³⁺ complex; 4-tert-butyl pyridine in (TBP); MgO; 4-guanidinobutyric acid (GBA); an alkanoic acid; Hexadecylmalonic acid (HDMA).

As already mentioned above, solid p-type semiconductors are used in the solid-colorant solar cell. Solid p-type semiconductors can also be used in the dye-sensitized soot cells according to the invention without a large increase in cell resistance, in particular if the dyes absorb strongly and therefore require only thin n-type semiconductor layers. In particular, the p-type semiconductor should essentially have a closed, dense layer in order to reduce unwanted recombination reactions which could result from contact between the n-semiconducting metal oxide (in particular in nanoporous form) with the second electrode or the second half cell.

An important factor which influences the selection of the p-type semiconductor is the hole mobility, since this determines the hole diffusion length (see Kumara, G., Langmuir, 2002, 18, 10493-10495). A comparison of charge carrier mobilities in various spiro compounds can be found, for example, in Saragi, T., Adv. Funct. Mater. 2006, 16, 966-974.

Furthermore, reference is made to the comments on the p-semiconducting materials in the description of the prior art.

With regard to the other possible components and the possible structure of the dye-sensitized solar cell, reference is also made to the above-described. Examples:

Synthesis of the compounds of the formula to be used according to the invention

A) Syntheses:

Synthesis route I:

Synthesis step I-R1:

(R ¹ ) n

The synthesis in synthesis step I-R1 was carried out on the basis of the following references:

a) Liu, Yunqi; Ma, Hong; Jen, Alex K-Y .; CHCOFS; Chem. Commun .; 24; 1998; 2747-2748,

b) Goodson, Felix E .; Hauck, Sheila; Hartwig, John F .; J. Am. Chem. Soc. 121; 33; 1999; 7527 - 7539,

c) Shen, Jiun Yi; Lee, Chung Ying; Huang, Tai-Hsiang; Lin, Jiann T .; Tao, Yu Tai; Chien, Chin-Hsiung; Tsai, Chiitang; J. Mater. Chem .; 15; 25; 2005; 2455 - 2463,

d) Huang, Ping-Hsin; Shen, Jiun-yi; Pu, Shin-chien; Wen, Yuh Sheng; Lin, Jiann T .; Chou, Pi-Tai; Yeh, Ming-Chang P .; J. Mater. Chem .; 16; 9; 2006; 850-857,

e) Hirata, Narukuni; Kroeze, Jessica E .; Park, Taiho; Jones, David; Haque, Saif A .; Holmes, Andrew B .; Durrant, James R .; Chem. Commun .; 5; 2006; 535 - 537. Synthetic Step I-R2:

The synthesis in synthesis step I-R2 was carried out on the basis of the following references:

a) Huang, Qinglan; Evmenenko, Guennadi; Dutta, Pulak; Marks, Tobin J .; J. Am. Chem. Soα; 125; 48; 2003; 14704 - 14705,

b) Bacher, Erwin; Bayerl, Michael; Rudati, Paula; Reckefuss, Nina; Mueller, C. David; Meerholz, Klaus; Nuyken, Oskar; Macromolecules; EN; 38; 5; 2005; 1640-1647,

c) Li, Zhong Hui; Wong, Man Shing; Tao, Ye; D'Loro, Marie; J. Org. Chem. EN; 69; 3; 2004; 921 - 927.

Synthesis step I-R3:

The synthesis in synthesis step I-R3 was carried out on the basis of the following reference:

J. Grazulevicius; J. of Photochem. and Photobio., A: Chemistry 2004 162 (2-3), 249-252,

The compounds of the formula I can be prepared via the sequence of the synthesis steps of the synthesis route I shown above. The coupling of the reactants can be carried out, for example, by Ullmann reaction with copper as catalyst or under palladium catalysis. Synthesis route II:

Synthesis step I I-R1:

br

The synthesis in synthesis step II-R1 was carried out in accordance with the references listed under I-R2.

Synthesis step I I-R2:

(R ¹ ) n

The synthesis in synthesis step II-R2 was carried out on the basis of the following references:

a) Bacher, Erwin; Bayerl, Michael; Rudati, Paula; Reckefuss, Nina; Müller, C. David; Meerholz, Klaus; Nuyken, Oskar; Macromolecules; 38; 5; 2005; 1640-1647, b) Goodson, Felix E .; Hauck, Sheila; Hartwig, John F .; J. Am. Chem. Soc. 121; 33; 1999; 7527-7539; Hauck, Sheila I .; Lakshmi, KV; Hartwig, John F .; Org. Lett .; 1 ; 13; 1999; 2057-2060.

Synthesis Step I I-R3:

The compounds of the formula I can be prepared via the sequence of the synthesis steps of the synthesis route II shown above. The coupling of the reactants can, as in Synthesis Route I, for example, by Ullmann reaction with copper as catalyst or under palladium catalysis. Production of the starting amines:

If the diarylamines are not commercially available in the synthesis steps I-R2 and II-R1 of the synthesis routes I and II, they can be prepared, for example, by Ullmann reaction with copper as catalyst or under palladium catalysis in accordance with the following reaction:

The synthesis was based on the following review articles:

Palladium-catalyzed C-N coupling reactions: a) Yang, Buchwald; J. Organomet. Chem. 1999, 576 (1-2), 125-146,

b) Wolfe, Marcoux, Buchwald; Acc. Chem. Res. 1998, 31, 805-818,

c) Hartwig; Angew. Chem. Int. Ed. Engl. 1998, 37, 2046-2067.

Copper-catalyzed C-N coupling reactions: a) Goodbrand, Hu; Org. Chem. 1999, 64, 670-674,

b) Lindley; Tetrahedron 1984, 40, 1433-1456.

Example 1 Synthesis of Compound ID367 (Synthesis Route I)

Synthesis Step I-R1:

A mixture of 4,4'-dibromobiphenyl (93.6 g, 300 mmol), 4-methoxyaniline (133 g, 1.08 mol), Pd (dppf) Cl ₂ (Pd (1,1'-bis (diphenylphosphino) ferrocene) CI ₂ , 21, 93 g, 30 mmol), and t-BuONa (sodium tert-butoxide, 109.06 g, 1.136 mol) in toluene (1500 ml) was stirred under nitrogen atmosphere at 110 ^° C. for 24 hours , After cooling the mixture was diluted with diethyl ether and filtered through a pad of Celite® (Carl Roth). The filter bed was washed with 1500 ml each of ethyl acetate, methanol and methylene chloride. The product was obtained as a tan solid (36 g, yield: 30%).

¹ HNMR (400 MHz, DMSO): δ 7.81 (s, 2H), 7.34-7.32 (m, 4H), 6.99-6.97 (m, 4H), 6.90-6 , 88 (m, 4H), 6.81-6.79 (m, 4H), 3.64 (s, 6H).

Synthesis step I-R2:

Nitrogen was bubbled through a solution of dppf (1,1'-bis (diphenylphosphino) ferrocene, 0.19 g, 0.34 mmol) and Pd2 (dba) 3 (tris (dibenzylideneacetone) dipalladium (O) for 10 minutes). 0.15 g, 0.17 mmol) in toluene (220 ml). Then, t-BuONa (2.8 g, 29 mmol) was added and the reaction mixture was stirred for an additional 15 minutes. Successively 4,4'-dibromobiphenyl (25 g, 80 mmol) and 4,4'-dimethoxydiphenylamine (5.52 g, 20 mmol) were then added. The reaction mixture was heated for 7 hours at a temperature of 100 ⁰ C under a nitrogen atmosphere. After cooling to room temperature, the reaction mixture was quenched with ice-water, the precipitate filtered off and dissolved in ethyl acetate. The organic layer was washed with water, dried over sodium sulfate and purified by column chromatography (eluent: 5% ethyl acetate / hexane). A slightly yellow colored solid was obtained (7.58 g, yield: 82%).

¹ HNMR (300 MHz, DMSOd ₆ ): 7.60-7.49 (m, 6H), 7.07-7.04 (m, 4H), 6.94-6.91 (m, 4H), 6 , 83-6.80 (d, 2H), 3.75 (s, 6H). Synthesis Step I-R3:

N ⁴ , N ⁴ '-Bis (4-methoxyphenyl) biphenyl-4,4'-diamine (product from Synthesis Step I-R1, 0.4 g, 1.0 mmol) and product from Synthesis Step I-R2 (1, 0 2.2 mmol) were added under a nitrogen atmosphere to a solution of t-BuONa (0.32 g, 3.3 mmol) in o-xylene (25 mL). Then, palladium acetate (0.03 g, 0.14 mmol) and a solution of 10 wt% P (t-Bu) 3 (tris-t-butylphosphine) in hexane (0.3 mL, 0.1 mmol) were added. added to the reaction mixture and stirred for 7 hours at 125 ° C. Thereafter, the reaction mixture was diluted with 150 ml of toluene, filtered through Celite® and the organic layer was dried over Na 2 SO 4. The solvent was removed and the crude product was reprecipitated three times from a mixture of tetrahydrofuran (THF) / methanol. The solid was purified by column chromatography (eluent: 20% ethyl acetate / hexane) followed by precipitation with THF / methanol and charcoal purification. After removal of the solvent, the product was obtained as a pale yellow solid (1, 0g, yield: 86%).

¹ HNMR (400 MHz, DMSOd ₆ ): 7.52-7.40 (m, 8H), 6.88-7.10 (m, 32H), 6.79-6.81 (d, 4H), 3 , 75 (s, 6H), 3.73 (s, 12H).

Example 2 Synthesis of Compound ID447 (Synthesis Route II)

Synthesis Step I-R1:

p-Anisidine (5.7 g, 46.1 mmol), t-BuONa (5.5 g, 57.7 mmol) and P (t-Bu) ₃ (0.62 mL, 0.31 mmol) became of a solution of the product from Synthesis Step I-R2 (17.7 g, 38.4 mmol) in toluene (150 mL). After nitrogen was passed through the reaction mixture for 20 minutes, Pd 2 (dba) 3 (0.35 g, 0.38 mmol) was added. added. The resulting reaction mixture was allowed to stir at room temperature for 16 hours under a nitrogen atmosphere. It was then diluted with ethyl acetate and filtered through Celite®. The filtrate was washed twice with 150 ml each of water and saturated brine. Drying of the organic phase over Na 2 SO 4 and removal of the solvent gave a black solid. This was purified by column chromatography (eluent: 0-25% ethyl acetate / hexane). An orange solid was obtained (14 g, yield: 75%).

¹ HNMR (300 MHz, DMSO): 7.91 (s, 1H), 7.43-7.40 (d, 4H), 7.08-6.81 (m, 16H), 3.74 (s , 6H), 3.72 (s, 3H).

Synthesis Step I-R3:

t-BuONa (686 mg, 7.14 mmol) was heated at 100 ⁰ C under vacuum, then purged with nitrogen, the reaction flask and allowed to cool to room temperature. Then, 2,7-dibromo-9,9-dimethylfluorene (420 mg, 1.19 mmol), toluene (40 mL) and Pd [P ( ¹ Bu) ₃ ] (20 mg, 0.0714 mmol) were added and the

Reaction mixture stirred at room temperature for 15 minutes. This was followed by N, N, N'-p-Trimethoxytriphenylbenzidin (1, 5 g; 1 27 mmol) to the reaction mixture and stirred for 5 hours at 120 ⁰ C. The mixture was filtered through a Celite® / MgSO4- mixture with toluene washed. The crude product was purified by column chromatography twice (eluant: 30% ethyl acetate / hexane) and, after reprecipitation from THF / methanol twice, gave a pale yellow solid (200 mg, yield: 13%). ¹ H NMR: (400 MHz, DMSO-de): 7.60-7.37 (m, 8H), 7.02-6.99 (m, 16H), 6.92-6.87 (m, 20H ), 6.80-6.77 (d, 2H), 3.73 (s, 6H), 3.71 (s, 12H), 1, 25 (s, 6H)

Example 3 Synthesis of Compound ID453 (Synthesis Route I)

a) Preparation of the starting amine: Step 1:

NaOH (78 g, 4 eq) was added to a mixture of 2-bromo-9H-fluorene (120 g, 1 eq) and BnEt ₃ NCI (benzyltriethylammonium chloride, 5.9 g, 0.06 eq) in 580 ml of DMSO (dimethylformamide). sulfoxide). The mixture was cooled with ice-water and methyl iodide (MeI) (160 g, 2.3 eq) was slowly added dropwise. The reaction mixture was allowed to stir overnight, then poured into water and then extracted three times with ethyl acetate. The combined organic phases were washed with brine, dried over Na 2 SO 4 and the solvent removed. The crude product was purified by column chromatography on silica gel (eluent: petroleum ether). After washing with methanol, the product (2-bromo-9,9'-dimethyl-9H-fluorene) was obtained as a white solid (102 g).

¹ HNMR (400 MHz, CDCl3): δ 1, 46 (s, 6H), 7.32 (m, 2H), 7.43 (m, 2H), 7.55 (m, 2H), 7.68 (m, 1H)

Step 2:

p-Anisidine (1.23 g, 10.0 mmol) and 2-bromo-9,9'-dimethyl-9H-fluorene (3.0 g, 11.10 mmol) became a solution of t-BuONa under a nitrogen atmosphere (1.44 g, 15.0 mmol) in 15 ml of toluene. Pd2 (dba) 3 (92 mg, 0.1 mmol) and a 10 wt% solution of P (t-Bu) 3 in hexane (0.24 ml, 0.08 mmol) were added and the reaction mixture at room temperature Stirred for 5 hours. The mixture was then quenched with ice water, the precipitate filtered off and dissolved in ethyl acetate. The organic phase was washed with water and dried over Na2SO4. After purification by column chromatography of the crude product (eluent: 10% ethyl acetate / hexane) gave a slightly yellow colored solid (1, 5 g, yield: 48%).

¹ HNMR (300 MHz, C ₆ D ₆ ): 7.59-7.55 (d, 1 H), 7.53-7.50 (d, 1 H), 7.27-7.22 (t, 2H), 7.19 (s, 1H), 6.99-6.95 (d, 2H), 6.84-6.77 (m, 4H), 4.99 (s, 1H), 3 , 35 (s, 3H), 1, 37 (s, 6H).

b) Preparation of the compound to be used according to the invention

Synthesis step I-R2:

Product from a) (4.70 g, 10.0 mmol) and 4,4'-dibromobiphenyl (7.8 g, 25 mmol) were added to a solution of t-BuONa (1, 15 g, 12 mmol) in 50 mL Toluene added under nitrogen. Pd2 (dba) 3 (0.64 g; 0.7 mmol) and DPPF (0.78 g; 1, 4 mmol) were added and allowed the reaction mixture at 100 ⁰ C with stirring for 7 hours. After quenching the reaction mixture with ice water, the precipitated solid is filtered off and dissolved in ethyl acetate. The organic phase was washed with water and dried over Na 2 SO 4. After column chromatography purification of the crude product (eluent: 1% ethyl acetate / hexane) gave a slightly yellow colored solid (4.5 g, yield: 82%).

¹ HNMR (400 MHz, DMSO-d6): 7.70-7.72 (d, 2H), 7.54-7.58 (m, 6H), 7.47-7.48 (d, 1H) , 7.21-7.32 (m, 3H), 7.09-7.12 (m, 2H), 6.94-6.99 (m, 4H), 3.76 (s, 3H), 1 , 36 (s, 6H).

Synthesis Step I-R3:

N ⁴ , N ⁴ '-Bis (4-methoxyphenyl) biphenyl-4,4'-diamine (0.60 g, 1.5 mmol) and product from the previous Synthesis Step I-R2 (1. 89 g, 3.5 mmol) were added under nitrogen to a solution of t-BuONa (0.48 g, 5.0 mmol) in 30 ml of o-xylene. Palladium acetate (0.04 g, 0.18 mmol) and P (t-Bu) 3 in a 10 wt% solution in hexane (0.62 mL, 0.21 mmol) were added and the reaction mixture for 6 h stirred at 125 ° C. It was then diluted with 100 ml of toluene and filtered through Celite®. The organic phase was dried over Na 2 SO 4 and the resulting solid was purified by column chromatography (eluent: 10% ethyl acetate / hexane). It was reprecipitated from THF / methanol and gave a slightly yellow colored solid (1, 6 g, yield: 80%).

¹ HNMR (400 MHz, DMSOd ₆ ): 7.67-7.70 (d, 4H), 7.46-7.53 (m, 14H), 7.21-7.31 (m, 4H), 7 , 17-7.18 (d, 2H), 7.06-7.1 1 (m, 8H), 6.91-7.01 (m, 22H), 3.75 (s, 12H), 1, 35 (s, 12H).

Further compounds of the formula I to be used according to the invention:

The compounds listed below were obtained analogously to the previously described syntheses: Example 4: Connection ID320

¹ HNMR (300 MHz, THF-d ₈ ): δ 7.43-7.46 (d, 4H), 7.18-7.23 (t, 4H), 7.00-7.08 (m, 16H ), 6.81-6.96 (m, 18H), 3.74 (s, 12H)

Example 5: Connection ID321

¹ HNMR (300 MHz, THF-d ₈ ): δ 7.37-7.50 (t, 8H), 7.37-7.40 (d, 4H), 7.21-7.26 (d, 4H ), 6.96-7.12 (m, 22H), 6.90-6.93 (d, 4H), 6.81-6.84 (d, 8H), 3.74 (s, 12H)

Example 6: Compound ID366

¹ HNMR (400 MHz, DMS0-d6): δ 7.60-7.70 (t, 4H), 7.40-7.55 (d, 2H), 7.17-7.29 (m, 8H) , 7.07-7.09 (t, 4H), 7.06 (s, 2H), 6.86-7.00 (m, 24H), 3.73 (s, 6H), 1, 31 (s , 12H) Example 7: Connection ID368

¹ HNMR (400 MHz, DMSO-d6): δ 7.48-7.55 (m, 8H), 7.42-7.46 (d, 4H), 7.33-7.28 (d, 4H) , 6.98-7.06 (m, 20H), 6.88-6.94 (m, 8H), 6.78-6.84 (d, 4H), 3.73 (s, 12H), 1 , 27 (s, 18H)

Example 8: Compound ID369

¹ HNMR (400 MHz, THF-d8): δ 7.60-7.70 (t, 4H), 7.57-7.54 (d, 4H), 7.48-7.51 (d, 4H) , 7.39-7.44 (t, 6H), 7.32-7.33 (d, 2H), 7.14-7.27 (m, 12H), 7.00-7.10 (m, 10H), 6.90-6.96 (m, 4H), 6.80-6.87 (m, 8H), 3.75 (s, 12H), 1.42 (s, 12H)

¹ HNMR (400 MHz, dmso-de): δ 7.39-7.44 (m, 8H), 7.00-7.07 (m, 13H), 6.89-6.94 (m, 19H) , 6.79-6.81 (d, 4H), 3.73 (s, 18H)

Example 10: Connection ID450

¹ HNMR (400 MHz, dmso-de): δ 7.55-7.57 (d, 2H), 7.39-7.45 (m, 8H), 6.99-7.04 (m, 15H) , 6.85-6.93 (m, 19H), 6.78-6.80 (d, 4H), 3.72 (s, 18H), 1, 68-1, 71 (m, 6H), 1 , 07 (m, 6H), 0.98-0.99 (m, 8H), 0.58 (m, 6H)

Example 1 1: Compound ID452

¹ HNMR (400 MHz, DMSO-d6): δ 7.38-7.44 (m, 8H), 7.16-7.19 (d, 4H), 6.99-7.03 (m, 12H) , 6.85-6.92 (m, 20H), 6.77-6.79 (d, 4H), 3.74 (s, 18H), 2.00-2.25 (m, 4H), 1 , 25- 1, 50 (m, 6H)

Example 12: Connection ID480

¹ HNMR (400 MHz, DMS0-d6): δ 7.40-7.42 (d, 4H), 7.02-7.05 (d, 4H), 6.96-6.99 (m, 28H) , 6.74-6.77 (d, 4H), 3.73 (s, 6H), 3.71 (s, 12H)

Example 13: Connection ID518

¹ HNMR (400 MHz, DMSO-d6): 7.46-7.51 (m, 8H), 7.10-7.12 (d, 2H), 7.05-7.08 (d, 4H), 6.97-7.00 (d, 8H), 6.86-6.95 (m, 20H), 6.69-6.72 (m, 2H), 3.74 (s, 6H), 3, 72 (s, 12H), 1, 24 (t, 12H)

Example 14: Connection ID519

¹ HNMR (400 MHz, DMS0-d6): 7.44-7.53 (m, 12H), 6.84-7.1 1 (m, 32H), 6.74-6.77 (d, 2H) , 3.76 (s, 6H), 3.74 (s, 6H), 2.17 (s, 6H), 2.13 (s, 6H)

Example 15: Connection ID521

¹ HNMR (400 MHz, THF-d ₆ ): 7.36-7.42 (m, 12 H), 6.99-7.07 (m, 20 H), 6.90-6.92 (d, 4 H), 6.81-6.84 (m, 8 H), 6.66-6.69 (d, 4 H), 3.74 (s, 12 H), 3.36-3.38 ( q, 8 H), 1, 41-1, 17 (t, 12 H)

¹ HNMR (400 MHz, DMSOd ₆ ): 7.65 (s, 2H), 7.52-7.56 (t, 2H), 7.44-7.47 (t, 1H), 7, 37-7.39 (d, 2H), 7.20-7.22 (m, 10H), 7.05-7.08 (dd, 2H), 6.86-6.94 (m, 8 H), 6.79-6.80-6.86 (m, 12 H), 6.68-6.73, (dd, 8 H), 6.60-6.62 (d, 4 H) , 3.68 (s, 12H), 3.62 (s, 6H)

Example 17: Connection ID523

¹ HNMR (400 MHz, THF-d ₈ ): 7.54-7.56 (d, 2H), 7.35-7.40 (dd, 8H), 7.18 (s, 2H) 7 , 00-7.08 (m, 18H), 6.90-6.92 (d, 4H), 6.81-6.86 (m, 12H), 3.75 (s, 6H) , 3.74 (s, 12H), 3.69 (s, 2H)

¹ HNMR (400 MHz, THF-d8): 7.97-8.00 (d, 2H), 7.86-7.89 (d, 2H), 7.73-7.76 (d, 2H), 7.28-7.47 (m, 20H), 7.03-7.08 (m, 16H), 6.78-6.90 (m, 12H), 3.93-3.99 (q, 4H ), 3.77 (s, 6H), 1, 32-1, 36 (s, 6H)

Example 19: Compound ID568

¹ HNMR (400 MHz, DMS0-d6): 7.41-7.51 (m, 12H), 6.78-7.06 (m, 36H), 3.82-3.84 (d, 4H), 3.79 (s, 12H), 1, 60-1, 80 (m, 2H), 0.60-1, 60 (m, 28H)

Example 20: Compound ID569

¹ HNMR (400 MHz, DMS0-d6): 7.40-7.70 (m, 1OH), 6.80-7.20 (m, 36H), 3.92-3.93 (d, 4H), 2.81 (s, 12H), 0.60-1, 90 (m, 56H) Example 21: Connection ID572

¹ HNMR (400 MHz, THF-d8): 7.39-7.47 (m, 12H), 7.03-7.1 1 (m, 20H), 6.39-6.99 (m, 8H) , 6.83-6.90 (m, 8H), 3.78 (s, 6H), 3.76 (s, 6H), 2.27 (s, 6H)

Example 22: Connection ID573

¹ HNMR (400 MHz, THF-d8): 7.43-7.51 (m, 20H), 7.05-7.12 (m, 24H), 6.87-6.95 (m, 12H), 3.79 (s, 6H), 3.78 (s, 12H)

¹ HNMR (400 MHz, DMS0-d6): 7.35-7.55 (m, 8H), 7.15-7.45 (m, 4H), 6.85-7.10 (m, 26H), 6.75-6.85 (d, 4H), 6.50-6.60 (d, 2H), 3.76 (s, 6H), 3.74 (s, 12H)

¹ HNMR (400 MHz, THF-d ₈ ): 7.50-7.56 (dd, 8H), 7.38-7.41 (dd, 4H), 7.12-7.16 (d, 8H) 7.02-7.04 (dd, 8H), 6.91-6.93 (d, 4H), 6.82-6.84 (dd, 8H), 6.65-6 , 68 (d, 4H) 3.87 (s, 6H), 3.74 (s, 12H)

Example 25: Connection ID631

¹ HNMR (400 MHz, THF-d ₆ ): 7.52 (d, 2H), 7.43-7.47 (dd, 2H), 7.34-7.38 (m, 8H), 7.12-7.14 (d, 2H), 6.99-7.03 (m, 12H), 6.81-6.92 (m, 20H), 3.74 (s, 18H ), 2.10 (s, 6H)

For spiro-MeOTAD and the compounds of Examples 1 to 23 were respectively the glass transition temperature Tg ( ⁰ C) and the morphology M by DSC, the decomposition temperature Td by TGA ( ⁰ C) and the solubility L in chlorobenzene (mg / ml) -da this is one of the best known solvents for spiro-MeOTAD represents determined at room temperature and the data in Table 1 below. In the column "M" this means:

a: amorphous; during the DSC measurement, only one glass transition at Tg could be detected during initial heating;

a ^* : the amorphous state was additionally confirmed by X-ray diffraction;

sk: semi-crystalline; upon initial heating during the DSC measurement, after glass transition at Tg crystallization occurred;

Table 1

Table 1 shows that the compounds to be used according to the invention are consistently present in amorphous form. Therefore, they are expected to have a significantly lower tendency for crystallization and to provide more advantageous properties of the DSCs produced therewith in terms of extended life than DSCs based on the comparative compound spiro-MeOTAD. Furthermore The compounds to be used according to the invention have a significantly better solubility than the comparative compound spiro-MeOTAD, which has a positive effect on the pore filling level in the preparation of the DSCs.

Solubilities in other solvents:

Since chlorobenzene has low to moderate toxicity (LD50 of 2.9 g / kg according to Manfred Rossberg et al., "Chlorinated Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2006), the compounds were also exemplified by their solubility in investigated other solvents. How one

Table 2, these have in the majority of cases increased in comparison to spiro-MeOTAD increased solubility (all data in mg / ml). Ie. the application of the hole to be used according to the invention in high concentration is also possible from other solvents.

Table 2

"N.d." does not mean determined

">" in conjunction with a numerical value means that the solubility of the compound is greater than the specified numerical value. B) Test of the compounds to be used according to the invention in DSCs:

Building a DSC typically involves the following layers:

138 top contact (cathode)

124 hole-conducting material

123 hole-conducting material (in pores of layer 120/122)

122 sensitizing dye

120 n-semiconducting metal oxide 119 optional buffer layer

116 front contact (anode)

114 carriers

On the carrier 1 14 is a layer 16 of a transparent conductive oxide (TCO - transparent conducting oxide), such as FTO (fluorine-doped tin oxide) or ITO (indium tin oxide). This TCO layer represents the front contact (anode).

On the front contact, an optional buffer layer 119 can be applied, which should prevent or at least complicate the migration of the holes to the front electrode 116. The buffer layer 119 used is usually a single layer of (preferably non-nanoporous) titanium dioxide and generally has a thickness between 10 nm and 500 nm. Such layers can be produced, for example, by sputtering and / or spray pyrolysis.

The optional buffer layer 119 is followed by an approximately 1 μm to 20 μm thick layer 120 of a porous, n-semiconductive metal oxide, which is sensitized with a very thin, usually monomolecular layer 122 of a dye. Most commonly used as n-type semiconducting metal oxide titanium dioxide, but other oxides are conceivable.

The layer 120 of the n-type semiconducting metal oxide sensitized with the dye (layer 122) is followed by a layer 123 of hole-conducting material. This material fills the pores of the layer 120/122 (metal oxide / dye) usually more or less completely, with a possible complete degree of filling is desirable. This results in an interpenetrating layer / intimate penetration of hole-conducting material and n-type semiconducting metal oxide / dye. In addition, the hole-conducting material on the metal oxide / dye layer forms a supernatant layer 124, which is typically 10 nm to 500 nm thick and, inter alia, prevents electrons from the metal oxide from entering the cathode 138. On the layer 124, a counter electrode 138 is applied as a top contact (cathode).

In order to use the DSC, so to tap a photovoltage and remove a photocurrent, front contact (anode) 1 16 and the top contact (cathode) 138 are provided with corresponding conductive terminals, but not shown here for reasons of clarity were.

Dyes used:

D102:

Commercially available from Mitsubishi.

D205:

D205

Synthesizable according to Seigo Ito et al., "High-conversion-efficiency Organic Dye-sensitized Solar Cells with a Novel Indoline Dye", Chem.Commun. 41, 5194 - 5196 (2008). Peryleni:

The synthesis was carried out analogously to the synthesis of compound 17 from Example 7 on page 80 of WO 2007/054470 A1.

Perylen2:

A Equivalent Peryleni was reacted with 8 equivalents of glycine and one equivalent of anhydrous zinc acetate in N-methylpyrrolidone at 130 ⁰ C overnight. The product was purified over silica gel.

Perylen3:

One equivalent of the compound of Example I24 24 on page 109 of WO 2007/054470 A1 was reacted with 8 equivalents of glycine and one equivalent of anhydrous zinc acetate in N-methylpyrrolidone at 130 ⁰ C overnight. The product was purified over silica gel. The test DSCs were prepared as follows:

DSC 1:

The base material used was nippon sheet glass 25 mm x 15 mm x 3 mm glass plates coated with fluorine-doped tin oxide (FTO), which were treated successively with glass cleaner (RBS 35), demineralized water and acetone for 5 minutes each in an ultrasonic bath, then Boiled for 10 minutes in isopropanol and dried in a stream of nitrogen.

To prepare the solid TiO 2 buffer layer 119, a spray pyrolysis method was used, as described in L. Kavan and M. Grätzel, Electrochim. Acta 40, 643 (1995). Alternatively or additionally, however, it is also possible to use other methods, such as, for example, sputtering methods (see P. Frach et al., Thin Solid Films 445 (2003) 251-258, D. Glöß et al., Suf. Coat., Technol. 2005) 967-971).

On the buffer layer 1 19, a layer of an n-type semiconducting metal oxide 120 was applied. For this purpose, a Tiθ2 paste (Dyesol, DSL 18NR-T), spin coated with a spin coater at 4500 revolutions per minute and dried at 90 ⁰ C for 30 minutes. After 45 minutes of heating to 450 ⁰ C and 30-minute sintering at 450 ⁰ C, a TiO 2 layer thickness resulted from approximately 1, 8 microns.

The intermediates thus prepared were then treated with TiCU as described by Grätzel in, for example, Grätzel M. et al., Adv. Mater. 2006, 18, 1202.

After removal from the sintering furnace, the sample was cooled to 80 ⁰ C and immersed for 12 hours in a 0.5 mM solution of the dye D102 in acetonitrile / t-BuOH 1: 1. After removal from the solution, the sample was then rinsed with the same solvent and dried in a stream of nitrogen.

Next, the p-type semiconductor ID367 was deposited. To this was added a solution of 130 mM ID367, 12 mM LiN (SO ₂ CFs) ₂ (Aldrich), 47 mM 4-t-butylpyridine (Aldrich) in chlorobenzene. 75 μl of this solution was applied to the sample and allowed to act for 60 seconds. Thereafter, the supernatant solution was spun for 30 seconds at 2000 revolutions per minute and dried in ambient air for 3 hours.

The top contact (cathode) was applied by thermal metal evaporation in vacuo. For this purpose, the sample was provided with a mask to vaporize 4 individual, separate rectangular top contacts with dimensions of about 5 mm x 4 mm on the active region, each with an approximately 3 mm x 2 mm contact surface are connected. As the metal Ag came to be used, the s ⁵ mbar was evaporated at a pressure of 5 ^■ 10 "at a rate of 0.1 nm /, so that a layer of about 200 nm thickness was formed.

To determine the efficiency η, the respective current / voltage characteristic was measured with a Source Meter Model 2400 (Keithley Instruments Inc.) under irradiation with a xenon lamp (LOT-Oriel) as a solar simulator.

Current / voltage characteristics were measured at illuminances of 10 mW / cm ² (0.1 sun) and 100 mW / cm ² (1 sun). The current density at 0.1 sun was multiplied by a factor of 10 to obtain the direct comparison to the measurement at 1 sun.

At 0.1 sun or 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 1.01 mA / cm ² or 9.76 mA / cm ² , the terminal voltage Voc (OC stands in this case for "open circuit") with open circuit 0.78 V or 0.86 V, the fill factor (FF) 68% or 53% and the efficiency 5.3% and 4.4%, respectively.

Comparative Example to DSC 1: As described in example DSC 1, a solid DSC was produced with the hole conductor spiro-MeO-TAD. To this was added a solution of 163 mM spiro-MeO-TAD, 15 mM LiN (SO ₂ CFs) ₂ (Aldrich), 60 mM 4-t-butylpyridine (Aldrich) in chlorobenzene. At 0.1 sun or 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 1.10 mA / cm ² or 10.60 mA / cm ² , the terminal voltage Voc (OC stands here for "open circuit") with open circuit 0.74 V or 0.80 V, the fill factor (FF) 69% or 47% and the efficiency 5.6% and 4.0%.

DSC 2:

As described in example DSC 1, a solid DSC was prepared with the hole conductor ID447 and the dye D102 (hole conductor solution: 167 mM ID447, 15 mM LiN (SO ₂ CF ₃ ) ₂ , 61 mM 4-t-butylpyridine in chlorobenzene).

At 0.1 sun and 1 sun, the short-circuit current density Isc was 0.91 mA / cm ² and 6.95 mA / cm ² , respectively, and the terminal voltage Voc when the circuit was open was 0.72 V and 0.78 V, respectively , the fill factor (FF) 56% and 33% and the efficiency 3.8% and 1, 8%, respectively.

DSC 3:

As described in example DSC 1, a solid DSC was prepared with the hole conductor ID453 and the dye D102 (hole conductor solution: 151 mM ID453, 14 mM LiN (SO ₂ CF ₃ ) ₂ , 55 mM 4-t-butylpyridine in chlorobenzene). At 0.1 sun and 1 sun, the short-circuit current density Isc was 0.87 mA / cm ² and 7.75 mA / cm ² , respectively, and the terminal voltage Voc with the open circuit was 0.84 V and 0.90 V, respectively , the fill factor (FF) 61% and 34% and the efficiency 4.5% and 2.3%.

DSC 4:

As described in example DSC 1, a solid DSC was prepared with the hole conductor ID522 and the dye D102 (hole conductor solution: 161 mM ID522, 15 mM LiN (SO 2 CF 3) 2, 58 mM 4-t-butylpyridine in chlorobenzene). The thickness of the nanoporous Tiθ2 layer was this time about 2.2 microns instead of about 1, 8 microns.

At 0.1 sun and 1 sun, the short-circuit current density Isc was 0.83 mA / cm ² and 8.77 mA / cm ² , respectively, and the terminal voltage Voc with the circuit open was 0.76 V and 0.84 V, respectively , the fill factor (FF) 69% and 45% and the efficiency 4.4% and 3.3%, respectively.

Comparative example to DSC 4:

As described in example DSC 4, a solid DSC was prepared with the hole conductor spiro-MeO-TAD and the dye D102 (hole-conductor solution: 163 mM spiro-MeO-TAD, 15 mM LiN (SO ₂ CFs) ₂ (Aldrich), 60 mM 4-t-butylpyridine (Aldrich) in chlorobenzene). The thickness of the nanoporous TiO ₂ layer was about 2.2 μm, as in example DSC 4.

At 0.1 sun and 1 sun, the short-circuit current density Isc was 0.92 mA / cm ² and 9.10 mA / cm ² , respectively, and the terminal voltage Voc when the circuit was open was 0.74 V and 0.82 V, respectively , the fill factor (FF) 69% and 50% and the efficiency 4.7% and 3.7%, respectively.

DSC 5:

As described in example DSC 1, a solid DSC was prepared with hole-punch ID572 and dye D102 (hole-transfer solution: 178 mM ID572, 16 mM LiN (SO ₂ CFs) ₂ , 65 mM 4-t-butylpyridine in chlorobenzene). The thickness of the nanoporous TiO ₂ layer was about 1, 8 microns as in Example DSC 1.

At 0.1 and 1 sun sun, the short-circuit current density Isc was 0.91 mA / cm ² and 8.52 mA / cm ^2, the terminal voltage Voc open circuit 0.84 V and 0.92 V , the fill factor (FF) 58% and 40% and the efficiency 4.5% and 3.1%, respectively.

DSC 6:

As described in Example DSC 1, a solid DSC was prepared with the hole conductor ID367 and the dye D205 (hole conductor solution: 130 mM ID367, 12 mM LiN (SO ₂ CFs) ₂ , 47 mM 4-t-butylpyridine in chlorobenzene). Dye bath: 0.5 mM solution of dye D205 (as described in Schmidt-Mende et al., Adv. Mater. 2005, 17, 813) in acetonitrile / t-BuOH 1: 1. At 0.1 sun and 1 sun, the short-circuit current density Isc was 0.97 mA / cm ² and 8.92 mA / cm ² , respectively, and the terminal voltage Voc when the circuit was open was 0.80 V and 0.88 V, respectively , the fill factor (FF) 70% and 46% and the efficiency 5.4% and 3.7%, respectively.

Comparative example to DSC6

As described in the example DSC6, a solid DSC was prepared with the hole conductor spiro-MeO-TAD and the dye D205 (hole conductor solution: 123 mM spiro-MeO-TAD, 1 1 mM LiN (SO ₂ CFs) ₂ , 45 mM 4. t-butylpyridine in chlorobenzene).

At 0.1 sun or 1 sun, the short-circuit current density Isc was 0.96 mA / cm ² or

9.32 mA / cm ² , the terminal voltage Voc with open circuit 0.76 V or 0.86 V, the fill factor (FF) 68% or 49% and the efficiency 4.9% and 3.9 %.

DSC 7: As described in example DSC 6, a solid DSC was prepared with the hole conductor ID518 and the dye D205 (hole conductor solution: 202 mM ID518, 18 mM LiN (SO ₂ CFs) ₂ , 74 mM 4-t-butylpyridine in chlorobenzene ). The thickness of the nanoporous TiO ₂ layer was this time 3.2 microns instead of about 1, 8 microns.

At 0.1 sun or 1 sun, the short-circuit current density Isc was 0.81 mA / cm ² or

8.57 mA / cm ² , the terminal voltage Voc with open circuit 0.74 V and 0.82 V, the filling factor (FF) 63% and 33% and the efficiency of 3.8% and 2.3, respectively %.

Comparative Example to DSC 7: As described in example DSC 7, a solid DSC was prepared with the hole conductor spiro-MeO-TAD and the dye D205 (hole conductor solution: 204 mM spiro-MeO-TAD, 19 mM LiN (SO ₂ CF ₃ ). _2, 74 mM 4-t-butylpyridine in chlorobenzene). The thickness of the nanoporous TiO ₂ layer was 3.2 μm, as in DSC 7, instead of approximately 1.8 μm.

At 0.1 sun or 1 sun, the short-circuit current density Isc was 0.95 mA / cm ² or

10.0 mA / cm ² , the terminal voltage Voc with open circuit 0.72 V or 0.78 V, the fill factor (FF) 68% or 37% and the efficiency 4.7% and 2.9 %.

DSC 8: As described in example DSC 7, a solid DSC was prepared with the hole conductor ID522 and the dye D205 (hole conductor solution: 201 mM ID522, 18 mM LiN (SO ₂ CFs) ₂ , 73 mM 4-t-butylpyridine in chlorobenzene) , The thickness of the nanoporous TiO ₂ layer was 3.2 μm, as in DSC 7, instead of approximately 1.8 μm.

At 0.1 sun or 1 sun, the short-circuit current density Isc was 0.56 mA / cm ² or

6.57 mA / cm ² , the terminal voltage Voc with open circuit 0.74 V and 0.84 V, the fill factor (FF) 64% and 51% and the efficiency 2.7% and 2.8, respectively %. DSC 9:

As described in example DSC 7, a solid DSC was prepared with the hole conductor ID523 and the dye D205 (hole conductor solution: 214 mM ID523, 19 mM LiN (SO 2 CF 3) 2, 78 mM 4-t-butylpyridine in chlorobenzene). The thickness of the nanoporous TiO 2 layer was as in DSC 7 3.2 microns instead of about 1, 8 microns.

At 0.1 sun and 1 sun, the short-circuit current density Isc was 0.95 mA / cm ² and 6.76 mA / cm ² , respectively, and the terminal voltage Voc when the circuit was open was 0.74 V and 0.80 V, respectively , the fill factor (FF) 58% and 34% and the efficiency 4.1% and 1, 8%.

DSC 10:

As described in Example DSC 1, a solid DSC was prepared with the hole conductor ID367 and the dye Peryleni (dye bath: 0.5 mM solution of the dye Peryleni in dichloromethane). To this was added a solution of 130 mM ID367, 12 mM LiN (SO ₂ CF ₃ ) 2 (Aldrich), 47 mM 4-t-butylpyridine (Aldrich) in chlorobenzene.

At 0.1 sun and 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 0.38 mA / cm ² or 2.78 mA / cm ² , the terminal voltage Voc (OC stands in this case for "open circuit") with open circuit 0.66 V or 0.74 V, the fill factor (FF) 53% or 51% and the efficiency 1, 3% or 1, 1%.

Comparative Example DSC 10:

As described in example DSC 10, a solid DSC was prepared with the hole conductor spiro-MeO-TAD and the dye Peryleni (dye bath: 0.5 mM solution of the dye Peryleni in dichloromethane). To this was added a solution of 123 mM spiro-MeO-TAD, 1 lmM LiN (SO ₂ CFs) ₂ (Aldrich), 45 mM 4-t-butylpyridine (Aldrich) in chlorobenzene.

At 0.1 sun or 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 0.37 mA / cm ² or 2.58 mA / cm ² , the terminal voltage Voc (OC stands here for "open circuit") with open circuit 0.60 V or 0.68 V, the fill factor (FF) 55% or 54% and the efficiency 1, 2% and 0.9%.

DSC 11:

As described in Example DSC 1, a solid DSC was prepared with the hole conductor ID367 and the dye perylene 2 (dye bath: 0.5 mM solution of the dye perylene 2 in dichloromethane). To this was added a solution of 130 mM ID367, 12 mM LiN (SO ₂ CFs) ₂ (Aldrich), 47 mM 4-t-butylpyridine (Aldrich) in chlorobenzene.

At 0.1 sun or 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 0.42 mA / cm ² or 4.39 mA / cm ² , the terminal voltage Voc (OC stands in this case for "open circuit") with open circuit 0.78 V or 0.84 V, the fill factor (FF) 68% or 54% and the efficiency 2.3% or 2.0%.

Comparative Example DSC 11: As described in example DSC 10, a solid DSC was prepared with the hole conductor spiro-MeO-TAD and the dye perylene 2 (dye bath: 0.5 mM solution of the dye perylene 2 in dichloromethane). To this was added a solution of 123 mM spiro-MeO-TAD, 1 lmM LiN (SO ₂ CFs) ₂ (Aldrich), 45 mM 4-t-butylpyridine (Aldrich) in chlorobenzene.

At 0.1 sun or 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 0.52 mA / cm ² or 6.87 mA / cm ² , the terminal voltage Voc (OC stands in this case for "open circuit") with open circuit 0.74 V or 0.76 V, the fill factor (FF) 70% or 56% and the efficiency 2.7% and 2.9%.

DSC 12:

As described in example DSC 1, a solid DSC was prepared with the hole conductor ID523 and the dye perylene 3 (dye bath: 0.5 mM solution of the dye perylene 3 in dichloromethane). To this was added a solution of 214 mM ID523, 19 mM LiN (SO ₂ CF ₂ ) ₂ (Aldrich), 78 mM 4-t-butylpyridine (Aldrich) in chlorobenzene. The thickness of the nanoporous TiO ₂ layer was about 3.1 microns instead of about 1, 8 microns.

At 0.1 sun or 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 0.21 mA / cm ² or 3.40 mA / cm ² , the terminal voltage Voc (OC stands in this case for "open circuit") with open circuit 0.64 V or 0.66 V, the fill factor (FF) 64% or 59% and the efficiency 0.9% or 1.3%.

Comparative Example DSC 12:

As described in example DSC 12, a solid DSC was prepared with the hole conductor spiro-MeO-TAD and the dye perylene 3 (dye bath: 0.5 mM solution of the dye perylene 3 in dichloromethane). To this was added a solution of 204 mM spiro-MeO-TAD, 19 mM LiN (SO ₂ CF ₂ ) ₂ (Aldrich), 74 mM 4-t-butylpyridine (Aldrich) in chlorobenzene. The thickness of the nanoporous TiO ₂ layer was about 3.1 microns instead of about 1, 8 microns.

At 0.1 sun or 1 sun, the short-circuit current density Isc (SC stands for "short circuit") was 0.25 mA / cm ² or 3.97 mA / cm ² , the terminal voltage Voc (OC stands here for "open circuit") with open circuit 0.62 V or 0.66 V, the fill factor (FF) 66% or 57% and the efficiency 1, 0% and 1, 5%.

Claims

claims

1. Use of compounds of the general formula

in which mean

A ¹ , A ² , A ³ are each independently of one another divalent organic units which may contain one, two or three optionally substituted aromatic or heteroaromatic groups, where in the case of two or three aromatic or heteroaromatic groups, two of these groups are each bound by a chemical bond and / or are connected to each other via a divalent alkyl radical,

R ¹ , R ² , R ³ independently of one another are substituents R, OR, NR ₂ , A ³ -OR or A ³ -NR ₂ ,

R is alkyl, aryl or a monovalent organic radical which may contain one, two or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, each of these two groups by a chemical bond and / or a divalent alkyl or NR ^' radical are linked together, R ^'is alkyl, aryl or a monovalent organic radical which may contain one, two or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, two of these groups by a chemical bond and / or via a divalent alkyl radical are linked together,

and

n is independently 0, 1, 2 or 3 for each occurrence in formula I,

with the proviso that the sum of the individual values n is at least 2 and at least two of the radicals R ¹ , R ² and R ^{3 are} substituents OR and / or NR 2,

as hole-conducting materials in organic solar cells.

2. Use according to claim 1, characterized in that at least two of the radicals R ¹ , R ² and R ^{3 are} para-containing OR and / or NR 2 substituents.

3. Use according to claim 1, characterized in that at least four of the radicals R ¹ , R ² and R ^{3 are} paraständige OR and / or NR2 Substit.uent.en.

4. Use according to claim 1, characterized in that all radicals R ¹ , R ² and R ^{3 are} para-stable OR and / or NR 2 substituents.

5. Use according to one or more of claims 1 to 4, characterized in that the organic units A ¹ , A ² and A ^{3 are} selected from the group consisting of (CH ₂ ) _m , C (R ⁷ ) (R ⁸ ) , N (R ⁹ ),

in which mean

m is an integer value from 1 to 18,

R ⁴ , R ^{9 is} alkyl, aryl or a monovalent organic radical which may contain one, two or three optionally substituted aromatic or heteroaromatic groups, wherein in the case of two or three aromatic or heteroaromatic groups, two of these groups by a chemical bond and / or are connected to one another via a divalent alkyl radical,

R ⁵ , R ⁶ , R ⁷ , R ⁸ independently of one another are hydrogen atoms or radicals of the definition of R ⁴ and R ⁹ ,

and the aromatic and heteroaromatic rings of the units shown may be further substituted.

Use according to one or more of claims 1 to 5, characterized in that R in the radicals R ¹ , R ² and R ³ independently of one another is Cr to Cs-alkyl, cyclopentyl, cyclohexyl or aryl.

Solar cells containing compounds according to one or more of claims 1 to 6.