Organic colorants for dye-sensitized solar cells (DSSC)

Abstract

The present invention relates to new organic colorants of general formula (I) and their use as photosensitizer or light absorbing material, wherein: R1 is selected from the group comprising C 4_15 arylamine or (C 4-15 polyaryl) 2-3 amine or C 4-15 heteroarylamine or (C 4-15 polyheteroaryl) 2-3 amine; L is selected from the group comprising: (II), (III), (IV). The compounds are suitable for indoor use in a dye-sensitized solar cell (DSSC).

Description

[0001] 1 Title: NEW COMPOUNDS Field of the invention The present invention relates to new organic colorants and their use as photosensitizer or 5 light absorbing material. Background Dye-sensitized solar cells (DSSC) are well known in the art, and work on similar principles as photosynthesis. Unlike silicon solar cells, these cells obtain energy from sunlight using dyes, 10 which can be manufactured cheap and environmentally friendly. A dye-sensitized solar cell has a light absorbing layer comprising a porous metal oxide, for example a few µm thick porous TiO2 electrode layer, dyed by adsorbing dye molecules and forming a working electrode. Sunlight is harvested by the dye, producing photo-excited electrons that are injected into the conduction band of the metal oxide particles. Other words 15 for dye in this context are chromophore, sensitizer and photosensitizer. There exist different types of dye-sensitized solar cells, such as sandwich dye-sensitized solar cells and monolithic solar cells. There are several thousands of known types of dyes with the ability to absorb photons and generate photo-excited electron. The dye molecules, colorant, can be organic dye molecules, 20 organometallic dye molecules, or natural dye molecules. Metal organic dyes are well known photovoltaic materials having good light absorption and which can be tailor made for efficient absorption of visible light. In recent years, there has been an increasing interest in organic dyes for usage in DSSCs since it has been found that organic dyes in combination with metal complex-based electrolytes 25 improve the performance of DSSC devices, in particular for indoor applications. There exist a large number of different types of dyes with different abilities to absorb light. The following are some examples of organic dyes: tetrahydroquinolines, pyrolidine, diphenylamine, triphenylamine (TPA), coumarin dyes, indole dyes, aryl amine dyes, porphyrine dyes, fluorine dyes, carbazole dyes (CBZ), phenothiazine dyes (PTZ), phenoxazine dyes (POZ), hemicyanine 30 dyes, merocyanine dyes, squaraine dyes, perylene dyes, anthraquinone dyes, boradiazaindacene (BODIPY) dyes, oligothiophene dyes, and polymeric dyes, fluorinated quinoxaline dyes. There is a desire to improve the properties of the dye in order to provide a more efficient and stable DSSC. 35 Kimura et al., Chem. Lett., 2012, Nov., Vol.41, No. 12, pp.1613-1615 discloses compounds wherein a fluorene as the π-conjugated spacer. Kimura et al. recommend not to use sulfur in the spacer and not to substitute the aryl groups in the arylamine. WO 2017191466, US 2017288156, CN 113429383 and US 2022275277 disclose large lists of alternative compounds and parts of compounds that may be useful as organic sensitizers for 40 DSSCs. No incentive is given which (parts of) compounds may be most favorable. 2 Summary of the invention. It is an object of the present invention to at least partly overcome the above-mentioned problems, and to provide an improved colorant, with improved stability and low production cost, providing improved characteristics in photovoltaic conversion devices, such as a high 5 energy conversion efficiency. The compounds are preferably suitable for indoor use in a DSSC. The compounds do not aggregate and have improved crystallinity. Preferably, the compounds of the invention have a strong extinction coefficient. The invention relates to the compounds as defined in claim 1. In some aspects, the invention relates to compounds of formula (I) 10 wherein R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or C4-15heteroarylamine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, OH, SH, -C1-20alkyl, -N-(C1-20alkyl)1-2, -O-(C1-20alkyl)1-2, and -S-(C1-20alkyl)1-2,wherein R11is optionally 15 substituted by one or more substituents R13, R13is selected from the group comprising H, O, N, S, NH, OH, SH, -C(O)OH, -C(O)C1-10alkyl, -N- (C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, Z is on each occurrence, identically or differently O or S, A is selected from the group comprising C5-15aryl, C4-15heteroaryl, -C2-4alkynyl, -C2-4alkynylC5- 2015aryl and -C2-4alkynylC4-15heteroaryl, substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising H, OH, - C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2- 4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2-25 10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1- 10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C(O)NH2, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, - C1-10alkylC(S)-OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, 30 -C2-10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, L is selected from the group comprising 3 , Y is C, Z2is O or S, and R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group 5 comprising H, -C1-10alkyl, -C2-10alkenyl and -C1-10alkyl-C5-15aryl, -C5-10aryl, -C5-10aryl-(C1-10alkyl)1-3. In some aspects, the compound of formula (I) comprises or consists of R1is selected from the group comprising or consisting of C4-15arylamine or (C4-15polyaryl)2- 3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, 10 R11is on each occurrence, identically or differently selected from the group comprising or consisting of H, -C1-20alkyl, -N-(C1-10alkyl)0-2, -O-(C1-20alkyl)1-2, and -S-(C1-10alkyl)1-2wherein R11is optionally substituted by one or more substituents R13, R13is selected from the group comprising or consisting of H, O, N, S, NH, OH, SH, -C(O)OH, - C(O)C1-10alkyl, -N-(C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, 15 Z is on each occurrence, identically or differently O or S, A is selected from the group comprising or consisting of C5-15aryl, C2-4alkynyl, -C2-4alkynylC5- 15aryl and -C2-4alkynylC4-15heteroaryl, substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -20 C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2- 4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2- 10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1- 10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-2510alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)- OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2- 10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, L is selected from the group comprising or consisting of , 30 Y is C, Z2is S, and 4 R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group comprising or consisting of H, -C1-10alkyl and -C2-10alkenyl. In some aspects, the compound of formula (I) comprises or consists of R1comprises or consists of an aromatic amine, or heteroaromatic amine, optionally substituted by one or more R11, 5 R11is on each occurrence, identically or differently selected from the group comprising or consisting of H, -C1-20alkyl, -N-(C1-20alkyl)0-2, -O-(C1-20alkyl)0-2, and -S-(C1-20alkyl)0-1, wherein R11may be substituted by one or more substituents R13, R13is selected from the group comprising or consisting of H, O, N, S, -C(O)OH, -C(O)C1-10alkyl, -N-(C1-10alkyl)0-2, -O-(C1-10alkyl)0-2, and -S-(C1-10alkyl)0-2, 10 wherein in each alkyl of R11and R13, independently, one or more CH2 groups may be replaced by O, S, N, C=C, C≡C, or -Si-(C1-10alkyl)0-2, Z is on each occurrence, identically or differently O, S or Se, A is selected from the group comprising or consisting of C5-15aryl, C4-15heteroaryl, -C2-4alkynyl -C2-4alkynylC5-15aryl and -C2-4alkynylC4-15heteroaryl, optionally substituted by one or more R4, 15 R5and R6, R4, R5and R6are independently of each other selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-10alkylC(O)O-C0-10alkyl, -C2-10alkenylC(O)O-C0-10alkyl, -C0-10alkyl- (C(O)OH)2, -C2-4alkynylC(O)OH, -C1-10alkylC(O)-C0-10alkyl, -C2-10alkenylC(O)-C0-10alkyl, -C1- 10alkylO-C0-10alkyl, -C2-10alkenylO-C0-10alkyl, -C0-10alkyl-PO3H2, -C0-10alkenyl-PO3H2, -C0-2010alkyl−C(O)−NH−OH, -C0-10alkenyl−C(O)−NH−OH, -C0-10alkyl-C(O)NH2, -C0-10alkenyl-C(O)NH2, - C1-10alkylC(S)-C0-10alkyl, -C2-10alkenylC(S)-C0-10alkyl, -C0-10alkylC(S)-OH, -C2-10alkenylC(S)-OH, -C0-10alkylC(S)-OC0-10alkyl, -C2-10alkenylC(S)-OC0-10alkyl, and -C2-10alkenylC(CN)PO3H2, L is selected from the group comprising or consisting of , 25 Y is C or Si, Z2is O or S, and R2, R3, R7, R8, R9R18and R19are independently of each other selected from the group comprising or consisting of H, -C1-20alkyl, -C2-20alkenyl and -C0-20alkyl-C5-15aryl, -C5-10aryl-C0- 10alkyl, -C5-10aryl-(C0-10alkyl)2-3. 30 In some aspects, A is selected from the group comprising C5-15aryl, C2-4alkynyl and -C2-4alkynylC5-15aryl substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising H, OH, - C(O)OH, -C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH -C2-4alkynylC(O)OH -PO3H2, -C2- 10alkenyl-PO3H2, −C(O)−NH−OH, 35 R2and R3are independently of each other selected from the group comprising H and -C1- 10alkyl. 5 In some aspects, the compound of formula (I) comprises or consists of R1is selected from the group comprising or consisting of C4-15arylamine or (C4-15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising or 5 consisting of H, -C1-20alkyl and -O-(C1-20alkyl)1-2, Z is on each occurrence, identically or differently O or S, A is selected from the group comprising or consisting of C5-15aryl, C2-4alkynyl and -C2-4alkynylC5-15aryl-, substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising or consisting10 of H, OH, -C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, - C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2- 4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2- 10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1-10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH,15 -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)- OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2- 10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, L is selected from the group comprising or consisting of 20 , Y is C, Z2is S, and R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group comprising or consisting of H, -C1-10alkyl and -C2-10alkenyl. 25 In some aspects, the compound of formula (I) comprises or consists of R1is selected from the group comprising or consisting of C4-15arylamine or (C4-15polyaryl)2- 3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising or consisting of H, -C1-20alkyl and -O-(C1-20alkyl)1-2, 30 Z is on each occurrence, identically or differently O or S, A is selected from the group comprising or consisting of C5-15aryl, C2-4alkynyl and -C2-4alkynylC5-15aryl substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH -C2-4alkynylC(O)OH -PO3H2, 35 -C2-10alkenyl-PO3H2, −C(O)−NH−OH, L is selected from the group comprising or consisting of 6 , Y is C, Z2is S, and R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group 5 comprising or consisting of H and -C1-10alkyl. The compounds of the invention as defined anywhere herein, possess photosensitizing and light absorbing qualities that can be used in a solar cell, especially solar cells that can be used indoors. The compounds are metal-free and environmentally friendly compared to conventional colorants. The compounds of the invention as defined anywhere herein can be 10 used in large scale production in a cost-effective manner. The compounds of the invention have a strong extinction coefficient In one aspect, one or more compounds of the invention as defined anywhere herein are in crystalline form. In dye-sensitized solar cells (DSSCs), the crystallinity of the dye layer may be crucial for performance, with higher crystallinity generally leading to improved efficiency. 15 Crystalline dyes may facilitate better electron transport and reduce energy losses, resulting in higher power conversion efficiencies. Crystallinity of the dye has an impact is on the production cost, as it enables the use of crystallization as a purification method. In some aspects, the compound of formula (I) is represented by formula (II) 20 wherein R1is selected from the group comprising or consisting of C4-15arylamine or (C4- 15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising or consisting of H, -C1-20alkyl, -N-(C1-10alkyl)0-2, -O-(C1-20alkyl)1-2, and -S-(C1-10alkyl)1-2,wherein R11is optionally substituted by one or more substituents R13, 25 R13is selected from the group comprising or consisting of H, O, N, S, NH, OH, SH, -C(O)OH, - C(O)C1-10alkyl, -N-(C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, R4, R5and R6are independently of each other selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, - C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2-304alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2-10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1- 7 10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)- OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2- 5 10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, and R2and R3are independently of each other selected from the group comprising or consisting of H, -C1-10alkyl and -C2-10alkenyl. In some aspects, the compound of formula (I) is represented by a compound of formula (II) wherein 10 R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or (C4- 15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1- 20alkyl and -O-(C1-20alkyl)1-2, In some aspects, the compound of formula (I) is represented by formula (III) 15 wherein R1is selected from the group comprising or consisting of C4-15arylamine or (C4- 15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising or consisting of H, -C1-20alkyl, -N-(C1-10alkyl)0-2, -O-(C1-20alkyl)1-2, and -S-(C1-10alkyl)1-2,wherein R1120 is optionally substituted by one or more substituents R13, R13is selected from the group comprising or consisting of H, O, N, S, NH, OH, SH, -C(O)OH, - C(O)C1-10alkyl, -N-(C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, R4is selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-10alkyl, -C1- 10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH, -C2- 2510alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2-4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2-10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1-10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-30 10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)-OH, -C2-10alkenylC(S)-OH, - C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2-10alkenylC(S)-OH, -C2-10alkenylC(S)- OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, R8and R9are independently of each other selected from the group comprising or consisting of H, -C1-10alkyl and -C2-10alkenyl. 8 In some aspects, R4is selected from the group comprising or consisting of H, OH, -C(O)OH, - C1-10alkyl, -C2-4alkynylC(O)OH, -PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, and R8and R9are independently of each other selected from the group comprising or consisting of H, -C1-10alkyl and -C2-10alkenyl. 5 In some aspects, R1is a substituent of formula (IV): wherein m is 0 or 1, n is 2, o is 0 or 1, and wherein each Ar is independently of each other a C4-15aryl or C4-15heteroaryl, optionally substituted by one or more R11. In some aspects, m is 1, n is 2, o is 1, and each Ar is C4-10aryl 10 optionally substituted by one or more R11. In some aspects, Ar is independently of each other a C4-15aryl or C4-15heteroaryl substituted by one or more R11. In some aspects, R1is an aromatic amine or a (poly-)C5-15arylamine, or C4-15arylamine or (C4-15polyaryl)2-3amine, where the aryl on each occurrence, identically or differently, is selected from the group comprising or consisting of phenyl, diphenyl, 1-aryl-4-penten, tropylium, 15 naphthalene, anthracene, phenanthrene, as-indacene, s-indacene, biphenylene, indene, acenaphthene, flourene, cyclopropene, cyclobutene, cyclobutadiene, cyclopentene, cyclopentadiene cyclohexene and cyclohexadiene. In some aspects, R1is an aromatic amine or (poly-)C5-15arylamine or C4-15arylamine or (C4- 15polyaryl)2-3amine, where the aryl on each occurrence, identically or differently, is selected 20 from phenyl, diphenyl or naphthalene. In some aspects, the aryl in R1is phenyl or diphenyl. The compounds of the invention wherein R1is an aromatic amine or a (poly-)C5-15arylamine, or C4-15arylamine or (C4-15polyaryl)2-3amine possess photosensitizing and light absorbing qualities that can be used in a solar cell, even indoors. The compounds of the invention as defined anywhere herein can be used in large scale production in a cost-effective manner.25 In some aspects, R1is a heteroaromatic amine or a (poly-)C4-15heteroarylamine or C4-15heteroarylamine or (C4-15polyheteroaryl)2-3amine, where the heteroaryl on each occurrence, identically or differently, is selected from the group comprising or consisting of thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl, 1,2,3-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-triazolyl, 1,2,4-thiadiazolyl, 1,2,4- 30 oxadiazolyl, 1,3,4-triazolyl, 1,3,4-thiadiazolyl, and 1,3,4- oxadiazolyl or pyridyl, pyrazinyl, pyrimidinyl, triazinyl and pyridazinyl or phenanthrene, or benzofuran, dibenzofuran, zanthenonyl, quinolinyl, carbazolyl, dibenzothiophenyl, isoquinolinyl, indolyl, purinyl, pteridine, xanthenyl, chromanyl, chromenyl, coumarinyl, dihydrodibenzooxepinyl, naphthyridinyl, cabolines, quinoxalinyl, lorcaserinyl and benzoazepinonyl. In some aspects, 35 heteroaryl is indolyl or carbazolyl. Any aryl and heteroaryl may be attached to the compound of formula (I) by a carbon atom or any other atom. In some aspects, the substitution is a carbon-carbon link. 9 In some aspects, R1is an aromatic amine, heteroaromatic amine, (poly-)C5-15arylamine or (poly-)C4-15heteroarylamine, which are C4-15arylamine or (C4-15polyaryl)2-3amine or C4-15heteroarylamine or (C4-15polyheteroaryl)2-3amine, optionally substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising or 5 consisting of H, -C1-10alkyl, -N-(C1-10alkyl)0-2, -O-(C1-10alkyl)0-2, and -S-(C1-10alkyl)0-2, wherein R11may be substituted by one or more substituents R13, and R13is selected from the group comprising or consisting of H, O, N, S, -C(O)OH, -C(O)C1-10alkyl, -N-(C1-10alkyl)0-2, -O-(C1-10alkyl)0-2, and -S-(C1-10alkyl)0-2, and wherein in each alkyl of R11and R13, independently, one or more CH2groups may be replaced 10 by O, S, N, C=C, C≡C, or -Si-(C1-10alkyl)0-2. In some aspects, R1is selected from the group comprising C4-15arylamine or (C4-15diaryl)2- 3amine or (C4-15diheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1-15alkyl, -N-(C1-15alkyl)1-2, -O-(C1-15alkyl)1-2, and -S-(C1-15alkyl)1-2wherein R11is optionally 15 substituted by one or more substituents R13, R13is selected from the group comprising H, O, N, S, NH, OH, SH, -C(O)OH, -C(O)C1-10alkyl, -N- (C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2. R11is important for the solubility of the dye and aggregation. In some aspects, R1is an aromatic amine or C4-10arylamine and R11is on each occurrence,20 identically or differently selected from the group comprising or consisting of H, -C2-6alkyl, -N- C2-6alkyl, -O-C2-6alkyl, and -S-C2-6alkyl, wherein R11may be substituted by one or more substituents R13, and R13is selected from the group comprising or consisting of H, O, N, S, -C(O)OH, -C(O)C1-10alkyl, -N-(C1-6alkyl)0-2, -O-(C1-6alkyl)0-2, and -S-(C1-6alkyl)0-2, and 25 wherein in each alkyl of R11and R13, independently, one or more CH2 groups may be replaced by C=C or C≡C. In some aspects, R1is C6arylamine substituted by more than one R11, which R11is on each occurrence, identically or differently -O-C2-6alkyl, wherein R11is substituted by one or more substituents R13, and R13is H. 30 All R1groups defined anywhere above are suitable electron donor groups, especially those where nitrogen contributes its lone pair to the aromatic system. These R1groups possess stable redox properties and allow the colorant to be reduced more easily by the electrolyte, especially in combination with the R11substituents as defined anywhere herein. Compounds in which R1is C4-15arylamine or (C4-15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine35 substituted by one or more R11selected from the group comprising or consisting of H, -C1-15alkyl, -N-(C1-15alkyl)0-2 and -O-(C1-15alkyl)1-2, or R11selected from the group comprising or consisting of H, -C1-15alkyl and -O-(C1-15alkyl)1-2, improve reduction of colorant in a stable manner. All R1groups defined anywhere above can be combined with any group defined herein under L, Z, Z2, Y, A and any R. 40 In some aspects, R1is selected from: 10 wherein R11is on each occurrence, identically or differently selected from the group comprising or consisting of H, -C1-10alkyl, -N-(C1-10alkyl)0-2, -O-(C1-10alkyl)0-2, and-S-(C1-10alkyl)0- 2. In some aspects, R11is on each occurrence, identically or differently selected from the group 5 comprising or consisting of H, -C1-15alkyl, -NH2, -N-(C1-10alkyl)1-2, -OH, -O-(C1-15alkyl)1-2, -SH2 and -S-(C1-10alkyl)1-2. In some aspects, All R1groups defined anywhere above are suitable electron donor groups, prevent aggregation and are suitable for large scale production of the colorant in a cost-effective 10 manner. Compounds wherein R1is (poly-)C6arylamine or C4-15arylamine or (C4-15polyaryl)2-3amine substituted by more than one R11as defined anywhere above are suitable electron donor groups. These R1groups possess stable redox properties and allow the colorant to be reduced more easily by the electrolyte. Compounds wherein R1is (poly-)C6arylamine, such as a15 diphenyl, especially those wherein R1substituted by more than one C2-6alkyl, C10-15alkyl, -O-C2- 6alkyl or -O-C10-15alkyl, are suitable for large scale production, improve crystallization and prevent or reduce aggregation In some aspects, Z is on each occurrence, identically or differently O or S. In some aspects, Z is S. 20 In some aspects, L is selected from the group comprising or consisting of 11 , R2, R3, R7, R8, R9R18and R19are independently of each other selected from the group comprising or consisting of H, -C1-10alkyl, -C2-10alkenyl and -C0-10alkyl-C5-15aryl, -C5-10aryl-C0- 10alkyl, -C5-10aryl-(C0-10alkyl)2-3, and 5 Y is C or Si, Z2is O or S. In some aspects, R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group comprising or consisting of H, -C5-9alkyl and -C5-9alkenyl, and Y is C, or N, Z2is O or S. In some aspects, R2, R3, R7, R8, R9, R18and R19are independently of each other selected from 10 the group comprising or consisting of H, -C5-9alkyl and -C5-9alkenyl. In some aspects, Y is C. In some aspects, Y is N. In some aspects, Z2is S. In some aspects, L is selected from R2, R3, R8and R9are independently of each other selected from the group comprising or15 consisting of H, -C1-10alkyl, -C2-10alkenyl and -C0-10alkyl-C5-15aryl, -C5-10aryl-C0-10alkyl, -C5-10aryl- (C0-10alkyl)2-3. In some aspects, R2, R3, R8and R9are independently of each other selected from the group comprising or consisting of H, -C5-9alkyl, which alkyl may be branched or straight. In some aspects, the alkyl on R2and R3are branched. R2and R3may be different or identical and both branched C4-10alkyl. In some aspects, the alkyl on R8and R9are straight. In some 20 aspects, R8and R9are identical and straight C4-10alkyl. The alkyl chain of R2and R3and R8and R9, straight or branched, improve solubility of the dye and prevent aggregation. The alkyl chain may be up to 20 or 10 carbon atoms. The alkyl chain may be straight. The alkyl chain may be single branched with a C1-3alkyl group. Compound of the invention having the L group as defined above provide for symmetry in the 25 molecule. Without wanting to be bound by any theories, this symmetry may play a role in the crystallization of the colorant. This L group also has an electron donor function, which together with R1improves the effectiveness of the colorant. In some aspects, A is selected from the group comprising or consisting of C5-15aryl, C4-15heteroaryl, -C2-4alkynyl, -C2-4alkynylC5-15aryl and -C2-4alkynylC4-15heteroaryl, optionally 30 substituted by one or more R4, R5and R6. In some aspects, A is selected from the group comprising or consisting of C5-15aryl, C4-15heteroaryl and -C2-4alkynylC5-15aryl. In some aspects, A is an C5-15aryl selected from the group comprising or consisting of phenyl, diphenyl, 1-aryl- 4-penten, tropylium, naphthalene, anthracene, phenanthrene, as-indacene, s-indacene, 12 biphenylene, indene, acenaphthene, flourene, cyclopropene, cyclobutene, cyclobutadiene, cyclopentene, cyclopentadiene cyclohexene and cyclohexadiene. In some aspects, the C5-15aryl is selected from phenyl or naphthalene. In some aspects, A is selected from the group comprising or consisting of C4-15heteroaryl or 5 (C4-15heteroaryl)2-3 or (C4-15polyheteroaryl)2-3 selected from the group comprising or consisting of thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl, 1,2,3- triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-triazolyl, 1,2,4-thiadiazolyl, 1,2,4-oxadiazolyl, 1,3,4-triazolyl, 1,3,4-thiadiazolyl, and 1,3,4- oxadiazolyl or pyridyl, pyrazinyl, pyrimidinyl, triazinyl and pyridazinyl or phenanthrene, or benzofuran, dibenzofuran, 10 zanthenonyl, quinolinyl, carbazolyl, dibenzothiophenyl, isoquinolinyl, indolyl, purinyl, pteridine, xanthenyl, chromanyl, chromenyl, coumarinyl, dihydrodibenzooxepinyl, naphthyridinyl, cabolines, quinoxalinyl, lorcaserinyl and benzoazepinonyl. Any aryl and heteroaryl may be attached to the compound of formula (I) by a carbon atom or any other atom. The nitrogen atom in the heteroaromatic aryls may be sp2hybridized to 15 improve anchoring and electron acceptor function. In some aspects, R4, R5and R6are independently selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-5alkylC(O)O-C0-5alkyl, -C2-5alkenylC(O)O-C0-5alkyl, -C2- 4alkynylC(O)OH, -C1-5alkylC(O)-C0-3alkyl, and -C2-5alkenylC(O)-C0-5alkyl. In some aspects, R4, R5and R6are independently of each other selected from the group comprising or consisting of 20 H, OH, -C(O)OH, -C1-5alkyl, -C2-3alkynylC(O)OH, -PO3H2, -C2-5alkenyl-PO3H2and −C(O)−NH−OH. All R4, R5and R6as defined anywhere herein are suitable electron acceptor portions and / or anchoring portions of the colorant. In some aspects, R4, R5and R6are independently selected from the group comprising or consisting of H, OH, -C(O)OH, methyl, -C2-3alkenylC(O)H, -PO3H2 and -C2-3alkenyl-PO3H2 and−C(O)−NH−OH. 25 These substituents are especially suitable for anchoring the colorant to titanium dioxide, prevent or reduce aggregation are especially suitable for large scale production of the colorant. In some aspects, R4and R6are H. In some aspects, R5are independently selected from the group comprising or consisting of H, OH, -C(O)OH, -C2-5alkenylC(O)H. These substituents are 30 especially suitable for anchoring the colorant to titanium dioxide, prevent or reduce aggregation are especially suitable for large scale production of the colorant. All R4, R5, R6are preferably shorter chain substituents. This reduces the complexity of the colorant molecule and improves suitability for large scale production in a cost-effective manner. The shorter chains have no impact on the crystallization properties of the 35 compounds. R4, R5, R6are important for the adsorption of the compound to the TiO2. In some aspects, R1is (poly-)C5-10arylamine or C4-15arylamine or (C4-15polyaryl)2-3amine and R11is on each occurrence, identically or differently selected from the group comprising or consisting of H, C2-6alkyl, -N-C2-6alkyl, -O-C2-6alkyl, and -S-C2-6alkyl, wherein R11may be substituted by one or more substituents R13, and 40 R13is selected from the group comprising or consisting of H, O, N, S, -C(O)OH, -C(O)C1-10alkyl, -N-(C1-6alkyl)0-2, -O-(C1-6alkyl)0-2, and -S-(C1-6alkyl)0-2, and 13 R4and R6are H, and R5are independently selected from the group comprising or consisting of H, OH, -C(O)OH, -C2-5alkenylC(O)H. In some aspects, R1is (poly-)C5-10arylamine or C4-15arylamine or (C4-15polyaryl)2-3amine substituted by more than one R11, which R11is on each occurrence, identically or differently 5 C4-15alkyl or -C4-12alkyl, -O-C2-6alkyl, -O-C4-15alkyl or -O-C4-12alkyl wherein R11is substituted by one or more substituents R13, and R13is H, R4and R6are H, and R5are independently selected from the group comprising or consisting of H, OH, -C(O)OH, -C2-4alkenylC(O)H. The invention relates to compounds of formula (I), selected from the group comprising or consisting of compounds EXY3, EXY4, EXY5, EXY6, EXY9, EXY10, EXY11, and EXY15 to EXY22 as 10 illustrated below. The invention also relates to a use of the as defined anywhere herein as photosensitizer or as light absorbing material. In some aspects, the compound is selected from the group comprising or consisting of , 15 , 17 The invention also relates to a use of one or more of intermediate compound in the preparation of the compounds as defined above, wherein the intermediate compounds are 5 selected from the group comprising or consisting of catalysts such as Pd XPhos G2 (Chloro(2-dicyclohexylphosphino-2′,4′,6′- triisopropyl-1,1′-biphenyl)[2-(2′-amino-1,1′-biphenyl)]palladium(II)) such as Pd XPhos G3 ((2-Dicyclohexylphosphino-2′,4′,6′-triisopropyl- 10 1,1′-biphenyl)[2-(2′-amino-1,1′-biphenyl)]palladium(II) methanesulfonate). In some aspects the intermediate compounds are anchor boronic acids (or boronic acid ester) selected from the group comprising or consisting of 18 In some aspects the intermediate compounds are donor boronic acids (or boronic acid ester) selected from the group comprising or consisting of 5 In some aspects the intermediate compounds are an anchor aryl halide used in the preparation of phenyl propiolic acid derivatives, selected from the group comprising or consisting of 19 In some aspects the intermediate compounds are an anchor halide used in the preparation of phenyl(ethynyl)benzoic acid derivatives, such as 5 In some aspects the intermediate compounds are a benzoic acid used in the synthesis of phenyl phosphonic acid, such as In some aspects the intermediate compounds are an alkenyl acid used in the synthesis of vinyl 10 In some aspects the intermediate compounds are a methyl benzoate derivative used in the synthesis of hydroxamic acid, such as 20 Brief description of the drawings The invention will now be explained more closely by the description of different aspects of the invention and with reference to the appended figures. Fig.1 shows an H NMR spectrum of dye EXY4. 5 Fig.2 shows an H NMR spectrum of dye EXY5. Fig.3 shows a UV-vis absorption spectra of EXY4 and EXY5 in the DCM solution. Fig.4 shows a cyclic Voltammetry of EXY4 and EXY5 on TiO2 film. Fig.5 shows a ideality factor of EXY4 and EXY5 based devices. Fig.6 shows an IPCE spectra of EXY4 and EXY5 based devices. 10 Fig.7 shows an H NMR spectrum of purified dye EXY4. Detailed description of the invention. The definitions set forth in this application are intended to clarify terms used throughout this application. The term "herein" means the entire application. 15 As used herein, the term “colorant” is intended to include photosensitizers and any light absorbing material. As used herein, the term “compounds of the invention” refers to the compound of formula I, II or III, or or any mixture thereof, or a salt thereof. As used herein, the term "C1-20-alkyl", used alone or as a suffix or prefix, is intended to include 20 both branched and straight chain saturated aliphatic hydrocarbon groups having from 1 to 20 carbon atoms. Examples of C1-20-alkyl include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, pentyl, hexyl, ethyl-hexyl, decyl and dodecyl, etc.. As used herein, the term "C2-20-alkenyl", used alone or as a suffix or prefix, is intended to include both branched and straight chain aliphatic hydrocarbon groups having from 1 to 2025 carbon atoms, which contains at least one carbon-carbon double bond. Examples of C2-20- alkenyl include ethene, 1-pentene, 4-pentene, 1-octene and 5-dodecyl-2-hexene. As used herein, the term "C2-20-alkynyl", used alone or as a suffix or prefix, is intended to include both branched and straight chain aliphatic hydrocarbon groups having from 1 to 20 carbon atoms, which contains at least one carbon-carbon triple bond. Examples of C2-20- 30 alkynyl include ethyne, 1-pentyne, 4-pentyne, 1-octyne and 5-dodecyl-2-propyne. As used herein, the term “C1-20-alkoxy”, used alone or as a suffix and prefix, refers to a C1-20- alkyl radical, which is attached to the remainder of the molecule through an oxygen atom. Examples of C1-20-alkoxy include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, sec-butoxy, tert-butoxy, nonoxy, decoxy and dodecoxy. 35 As used herein, the term “C4-15-aryl” refers to a cyclic aromatic ring having 5 to 15 ring members. Examples of aryls may be phenyl, diphenyl, 1-aryl-4-penten, tropylium, naphthalene, anthracene, phenanthrene, as-indacene, s-indacene, biphenylene, indene, acenaphthene, flourene, cyclopropene, cyclobutene, cyclobutadiene, cyclopentene, cyclopentadiene cyclohexene and cyclohexadiene, etc.. Other examples of suitable aryls may 40 be pyrene, acenaphtylene and fluoranthene. 21 As used herein, the term “C4-15-heteroaryl” refers to a cyclic heteroaromatic ring wherein 1, 2 or 3 ring atoms are independently selected from N, O and S. Examples include heteroaryls are thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl, 1,2,3-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-triazolyl, 1,2,4- 5 thiadiazolyl, 1,2,4-oxadiazolyl, 1,3,4-triazolyl, 1,3,4-thiadiazolyl, and 1,3,4- oxadiazolyl or pyridyl, pyrazinyl, pyrimidinyl, triazinyl and pyridazinyl or phenanthrene, or benzofuran, dibenzofuran, thienylphenyl, zanthenonyl, quinolinyl, carbazolyl, dibenzothiophenyl, isoquinolinyl, indolyl, purinyl, pteridine, xanthenyl, chromanyl, chromenyl, coumarinyl, dihydrodibenzooxepinyl, naphthyridinyl, cabolinyl, quinoxalinyl, lorcaserinyl and 10 benzoazepinonyl, etc.. The term “poly-C4-4-15(hetero)aryl or (C4-15polyheteroaryl)2-3amine” refers to (hetero)aryl-rings linked to each other, such as biphenyl and thienylphenyl. The aryl or heteroaryls may be directly linked to each other or a linker, e.g. a methylene or ethylene group or a bridge (e.g. as with fluorene) may be present between the (hetero)aryl groups. 15 The term “poly-C4-15(hetero)aryl or heteroaromatic amine or C4-15heteroarylamine or (C4-15polyheteroaryl)2-3amine” may refer to a combination comprising or consisting of an aryl and a heteroaryl. The term “aromatic amine or heteroaromatic amine” includes any (poly-)C5-30arylamine or (poly-)C5-30heteroarylamine or C4-15arylamine or (C4-15polyaryl)2-3amine or C4- 2015heteroarylamine or (C4-15polyheteroaryl)2-3amine. The terms “aromatic amine or heteroaromatic amine or (poly-)C5-15arylamine and (poly-)C4-15heteroarylamine or C4-15arylamine or (C4-15polyaryl)2-3amine or C4-15heteroarylamine or (C4-15polyheteroaryl)2-3amine” refer to an amine, wherein the nitrogen atom is substituted by C4- 15aryl and / or C4-15heteroaryl and / or poly-C4-15aryl and / or poly-C4-15heteroaryl, such as 25 thienylphenyl. Brackets indicate that the feature between the brackets is optional. (Poly-)C4-15(hetero)arylamine may be a phenyl or a diphenyl or pyrazolyl or a phenyl-cabolinyl group. The term “S-C1-20alkyl” refers to an alkylsulfanyl. Exemplary alkylsulfanyl includes methylsulfanyl, ethylsulfanyl and dodecylsulfanyl. 30 The term “N-C1-20alkyl” refers to an alkylamine. Exemplary alkylamine includes methylamine, ethylamine and hexylamine. The term “-C1-10alkylC(O)O-C0-10alkyl” refers to an ester or a carboxy group. Examples of such an ester group may be ethyl butyrate, isopentyl acetate, nonyl acetate, acetic acid, octanoic acid.35 The term “-C1-10alkylC(O)-C0-10alkyl” refers to an aldehyde or keton group. Examples of such an ether group may be benzaldehyde, propanal, butenal, propanone and octanone. The term --C1-10alkylO-C0-10alkyl” refers to an ether group. Examples of such an ether group may be methoxyethane (methyl-ethyl-ether), ethoxyoctane (diethyl-ether), 2-methoxy-2- nonylpropane. 22 As used herein, the term “optional” or “optionally” means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not. A variety of compound of the invention as defined above may exist in particular geometric or 5 stereoisomeric forms. The present invention takes into account all such compounds, including tautomers, R- and S- enantiomers, diastereomers, (D)-isomers, (L)-isomers, the racemic mixtures thereof, and other mixtures thereof, as being covered within the scope of this invention. Additional asymmetric carbon atoms may be present in a substituent such as an alkyl group. All chiral, diastereomeric and racemic forms are intended, to be included in the 10 scope of the invention, unless the specific stereochemistry or isomeric form is specifically indicated. As used herein, “tautomer” means other structural isomers that exist in equilibrium resulting from the migration of a hydrogen atom. For example, keto-enol tautomerism occurs where the resulting compound has the properties of both a ketone and an unsaturated alcohol. 15 The invention relates to a compound of a formula (I) wherein R1comprises or consists of an aromatic amine or heteroaromatic amine or in other words C4-15arylamine or (C4-15polyaryl)2-3amine or C4-15heteroarylamine or (C4- 15polyheteroaryl)2-3amine. 20 The compounds may be in crystalline form. The compound of formula (I) may be represented by a compound of formula (II) is The compound of formula (I) may be represented by a compound of formula (III) 25 The compounds may be in crystalline form. 23 R1may be an aromatic amine or a (poly-)C4-15arylamine or C4-15arylamine or (C4-15polyaryl)2-3amine optionally substituted by one or more R11. R1may be a heteroaromatic amine or a (poly-)C4-15heteroarylamine or C4-15heteroarylamine or (C4-15polyheteroaryl)2-3amine optionally substituted by one or more R11. The number of aryl or heteroaryl units on the 5 nitrogen atom may be 2 to 10, or 3 to 7, or 3 to 5. The aryl or heteroaryl groups may be the same or different and the number of aryl or heteroaryl groups on the nitrogen atom may be the same or different. R1may be a substituent of formula (IV): 10 wherein m is 0 or 1, n is 2, o is 0 or 1, and wherein each Ar is independently of each other a C4-15aryl or C4-15heteroaryl optionally substituted by one or more R11. Or each Ar is independently of each other a C4-15aryl or C4-15heteroaryl substituted by one or more R11. m may be 1 and n may be 2 and o may be 1. The aryl groups may be the same or different. 15 The (poly-)C4-15aryl or C4-15aryl or (C4-15polyaryl)2-3on the aromatic amine of R1may be on each occurrence, identically or differently selected from the group comprising or consisting of phenyl, diphenyl, 1-aryl-4-penten, tropylium, naphthalene, anthracene, phenanthrene, as- indacene, s-indacene, biphenylene, indene, acenaphthene, flourene, cyclopropene, cyclobutene, cyclobutadiene, cyclopentene, cyclopentadiene cyclohexene and 20 cyclohexadiene. The (poly-)C5--15aryl or C4-15aryl or (C4-15polyaryl)2-3on the aromatic amine of R1may be on each occurrence, identically or differently, phenyl or naphthalene. The (poly-)C4-15aryl on the aromatic amine of R1may be phenyl or diphenyl. The (poly-)C4-15heteroaryl or C4-15heteroaryl or (C4-15polyheteroaryl)2-3 on the heteroaromatic 25 amine of R1may be on each occurrence, identically or differently, selected from the group comprising or consisting of thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl, 1,2,3-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,2,4- triazolyl, 1,2,4-thiadiazolyl, 1,2,4-oxadiazolyl, 1,3,4-triazolyl, 1,3,4-thiadiazolyl, and 1,3,4- oxadiazolyl or pyridyl, pyrazinyl, pyrimidinyl, triazinyl and pyridazinyl or phenanthrene, or 30 benzofuran, dibenzofuran, zanthenonyl, quinolinyl, carbazolyl, dibenzothiophenyl, isoquinolinyl, indolyl, purinyl, pteridine, xanthenyl, chromanyl, chromenyl, coumarinyl, dihydrodibenzooxepinyl, naphthyridinyl, cabolines, quinoxalinyl, lorcaserinyl and benzoazepinonyl. The (poly-)C4-15heteroaryl or C4-15heteroaryl or (C4-15polyheteroaryl)2-3on the heteroaromatic amine of R1may be indolyl. The (poly-)C4-15heteroaryl or C4-15heteroaryl35 or (C4-15polyheteroaryl)2-3 on the heteroaromatic amine of R1may be carbazolyl. The (poly-)C4- 15heteroaryl or C4-15heteroaryl or (C4-15polyheteroaryl)2-3 on the heteroaromatic amine of R1may be a combination of a heteroaryl and an aryl, such as phenyl-pyrazolyl or thienylphenyl. 24 R1may be Each aromatic amine or heteroaromatic amine or (poly-)aryl or (poly-)heteroaryl of R1may be substituted independently by one or more R11. R11may be on each occurrence, identically or 5 differently selected from the group comprising or consisting of H, -C1-20alkyl, -N-(C1-20alkyl)0-2, -O-(C1-20alkyl)0-2, and -S-(C1-20alkyl)0-1. In each alkyl in R11may independently, one or more CH2 groups be replaced by O, S, N, C=C, C≡C, or -Si-(C1-10alkyl)0-2. R1may comprise C4-12arylamine or (C4-12polyaryl)2-3amine or C4-12heteroarylamine or (C4- 12polyheteroaryl)2-3amine substituted by one or more R11, 10 R11may on each occurrence, identically or differently be selected from the group comprising or consisting of H, OH, SH, -C3-15alkyl, -N-(C3-15alkyl)0-2, -O-(C3-15alkyl)1-2, and -S-(C3-15alkyl)1-2,wherein R11is optionally substituted by one or more substituents R13, R13may be selected from the group comprising or consisting of H, O, N, S, NH, OH, SH, - C(O)OH, -C(O)C1-5alkyl, -N-(C1-5alkyl)1-2, -O-(C1-5alkyl)1-2, and -S-(C1-5alkyl)1-2. 15 R1may comprise C4-15arylamine or (C4-15polyaryl)2-3amine or C4-15heteroarylamine or (C4- 15polyheteroaryl)2-3amine substituted by one or more R11, R11may on each occurrence, identically or differently be selected from the group comprising or consisting of H, OH, SH, -C3-15alkyl and -O-(C3-15alkyl)1-2, wherein R11is substituted by substituents R13, and R13is H. 20 R1may be a phenyl, diphenyl or naphthalene and R11may on each occurrence, identically or differently be selected from the group comprising or consisting of H, OH, SH, -C3-15alkyl, -N- (C3-15alkyl)1-2, -O-(C3-15alkyl)1-2, and -S-(C3-15alkyl)1-2 wherein R11is optionally substituted by one or more substituents R13. R1may be a thienyl or thienylphenyl and R11may on each occurrence, identically or differently 25 be selected from the group comprising or consisting of H, OH, SH, -C3-15alkyl, -N-(C3-15alkyl)1-2, -O-(C3-15alkyl)1-2, and -S-(C3-15alkyl)1-2 wherein R11is optionally substituted by one or more substituents R13. Each R11may be substituted by one or more substituents R13. R13may be selected from the group comprising or consisting of H, O, N, S, -C(O)OH, -C(O)C1-3010alkyl, -N-(C1-10alkyl)0-2, -O-(C1-10alkyl)0-2, and -S-(C1-10alkyl)0-2. In each alkyl in R13may independently, one or more CH2groups be replaced by O, S, N, C=C, C≡C, or -Si-(C1-10alkyl)0-2. 25 R11may on each occurrence, identically or differently be selected from the group comprising or consisting of H, -C1-10alkyl, -N-(C1-10alkyl)0-2, -O-(C1-10alkyl)0-2, and-S-(C1-10alkyl)0-2. R11may on each occurrence, identically or differently be selected from the group comprising or consisting of H, OH, SH, -C3-15alkyl, -N-(C3-15alkyl)1-2, -O-(C3-15alkyl)1-2, and -S-(C3-15alkyl)1-2 5 Each aromatic amine or heteroaromatic amine C4-15arylamine or (C4-15polyaryl)2-3amine or C4- 15heteroarylamine or (C4-15polyheteroaryl)2-3amine on R1may be substituted independently by more than one R11, which is substituted by R13is H. Each aryl on R1may be substituted independently by more than one -C1-15alkyl, -C1-6alkyl, -O-C1-15alkyl or -O-C1-6alkyl, which is substituted by R13is H. R11may be butanyl, butoxyl, hexoxyl, octoxyl, or dodecyl. The more 10 than one R11may be the same on each aryl or heteroaryl of R1. R1may be Z is on each occurrence, identically or differently O, S or Se. Z may be O. Z may be S. 15 A may be selected from the group comprising or consisting of C4-15aryl, C4-15heteroaryl, -C2- 4alkynyl, -C2-4alkynylC4-15aryl and -C2-4alkynylC4-15heteroaryl, substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -20 C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2-4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2- 10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1- 10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C(O)NH2, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-2510alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, - C1-10alkylC(S)-OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2-10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2. A may be selected from the group comprising or consisting of C4-15aryl, C4-15heteroaryl, -C2-4alkynyl, -C2- 4alkynylC4-15aryl and -C2-4alkynylC4-15heteroaryl, optionally substituted by one or more R4, R530 and R6. A may be selected from the group comprising or consisting of C5-15aryl, C4-15heteroaryl 26 and , -C2-4alkynylC4-15aryl, optionally substituted by one or more R4, R5and R6. A may be or ethynylphenyl. The C4-15aryl may be selected from the group comprising or consisting of phenyl, diphenyl, 1-aryl-4-penten, tropylium, naphthalene, anthracene, phenanthrene, as- indacene, s-indacene, biphenylene, indene, acenaphthene, flourene, cyclopropene, 5 cyclobutene, cyclobutadiene, cyclopentene, cyclopentadiene cyclohexene and cyclohexadiene. The C4-15aryl may be phenyl or naphthalene. The C4-15aryl may be phenyl. The C4-15heteroaryl may be selected from the group comprising or consisting of thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl, 1,2,3-triazolyl,10 tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-triazolyl, 1,2,4-thiadiazolyl, 1,2,4- oxadiazolyl, 1,3,4-triazolyl, 1,3,4-thiadiazolyl, and 1,3,4- oxadiazolyl or pyridyl, pyrazinyl, pyrimidinyl, triazinyl and pyridazinyl or phenanthrene, or benzofuran, dibenzofuran, zanthenonyl, quinolinyl, carbazolyl, dibenzothiophenyl, isoquinolinyl, indolyl, purinyl, pteridine, xanthenyl, chromanyl, chromenyl, coumarinyl, dihydrodibenzooxepinyl, 15 naphthyridinyl, cabolines, quinoxalinyl, lorcaserinyl and benzoazepinonyl. L may be selected from the group comprising or consisting of , Y is C or Si, and Z2is O or S. Y is C, and Z2is S. 20 L may be selected from R2, R3, R7, R8, R9, R18and R19may independently of each other be selected from the group comprising or consisting of H, -C1-15alkyl, -C2-15alkenyl and -C0-15alkyl-C5-15aryl, -C5-10aryl-C1- 10alkyl, -C5-10aryl-(C1-10alkyl)2-3. R2, R3, R7, R8, R9, R18and R19may independently of each other25 be selected from the group comprising or consisting of H, -C1-10alkyl, -C2-10alkenyl and -C1-10alkyl-C4-15aryl, -C4-10aryl and, -C4-10aryl-(C1-10alkyl)1-3. R2, R3, R7, R8, R9, R18and R19may independently of each other be selected from the group comprising or consisting of H, -C1-15alkyl. R2, R3, R7, R8and R9may independently of each other be C5-10alkyl. 30 The alkyl on R2and R3may be branched. R2and R3may be different but both branched C5- 10alkyl. R2and R3may be identical and both branched C5-10alkyl. The alkyl on R8and R9may be straight. R8and R9may be identical and straight C5-10alkyl. 27 R4, R5and R6may independently of each other be selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-5alkyl, -C1-5alkylC(O)OH, -C1-5alkylC(O)O-C1-5alkyl, C(O)O-C1-5alkyl, -C2-5alkenylC(O)OH, -C2-5alkenylC(O)O-C1-5alkyl, C(O)OH)2, -C1-5alkyl-(C(O)OH)2, -C2-5alkynylC(O)OH, -C1-5alkylC(O)H, -C1-5alkylC(O)-C1-5alkyl, -C2-5alkenylC(O)H, -C2-5alkenylC(O)-C1- 5 5alkyl, -C1-5alkylOH, -C1-5alkylO-C1-10alkyl, -C2-5alkenylOH, -C2-5alkenylO-C1-5alkyl, -PO3H2, -C1- 5alkyl-PO3H2, -C2-5alkenyl-PO3H2, −C(O)−NH−OH, -C1-5alkyl−C(O)−NH−OH, -C2- 5alkenyl−C(O)−NH−OH, -C1-5alkyl-C(O)NH2, -C2-5alkenyl-C(O)NH2, -C1-5alkylC(S)H, -C1-5alkylC(S)- C1-5alkyl, -C2-5alkenylC(S)H, -C2-5alkenylC(S)-C1-5alkyl, -C(S)-OH, -C1-5alkylC(S)-OH, -C2-5alkenylC(S)-OH, -C(S)-OH, -C1-5alkylC(S)-OH, -C1-5alkylC(S)-OC1-5alkyl, -C2-5alkenylC(S)-OH, -C2-10 5alkenylC(S)-OC1-5alkyl, and -C2-5alkenylC(CN)PO3H2. R4and R6may be H. R5and R7may be selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-3alkyl and -C1-3alkylC(O)OH. R4, R5and R6may independently of each other be selected from the group comprising or consisting of H, OH, -C(O)OH, -C1-3alkyl, C(O)O-C1-3alkyl, -C2-3alkenylC(O)OH, -C2-154alkynylC(O)OH, -PO3H2, -C2-3alkenyl-PO3H2and −C(O)−NH−OH. The compound of formula (II) may be compound EXY4 The compound EXY4 may be in crystalline form. The compound of formula (II) may be compound EXY5 20 The compound EXY5 may be in crystalline form. 28 Preparation of the compounds Abbreviations NMR nuclear magnetic resonance HPLC High pressure liquid chromatography 5 TLC thin layer chromatography THF tetrahydrofuran NBS N-Bromosuccinimide DCM dichloromethane NHE normal hydrogen electrode 10 NMB N-Methylbenzimidazole Alkylation of cyclopenta[2,1-b:3,4-b']dithiophene was performed according to: Gao, P., Cho, D., Yang, X., Enkelmann, V., Baumgarten, M. and Müllen, K. (2010), Heteroheptacenes with Fused Thiophene and Pyrrole Rings. Chemistry – A European Journal, 16: 5119- 5128. https: / / doi.org / 10.1002 / chem.200903562. 15 The synthesis of 2',4'-dibutoxy-N-(2',4'-dibutoxy-[1,1'-biphenyl]-4-yl)-N-(4-(4,4,5,5- tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-[1,1'-biphenyl]-4-amine is described in Gabrielsson, E., Ellis, H., Feldt, S., Tian, H., Boschloo, G., Hagfeldt, A. and Sun, L. (2013), Convergent / Divergent Synthesis of a Linker-Varied Series of Dyes for Dye-Sensitized Solar Cells Based on the D35 Donor. Adv. Energy Mater., 3: 1647- 20 1656. https: / / doi.org / 10.1002 / aenm.201300367. General procedure for the synthesis of 2,6-bis(7-bromobenzo[c][1,2,5]thiadiazol-4-yl)-4H- cyclopenta[2,1-b:3,4-b']dithiophenes: To a stirred 0.2M solution of 4,4-dialkyl-4H-cyclopenta[2,1-b:3,4-b']dithiophene in THF at -78 °C, n-hexyllithium (2.3 M in hexanes, 2.2 eq) was slowly added under nitrogen. The reaction 25 mixture was allowed to warm to -40 °C over 180 minutes, then further warmed to 0 °C over 15 minutes after which it was brought back down to -78 °C within 10 minutes for the addition of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2.2 eq). The reaction mixture was allowed to slowly warm to room temperature over the course of 19 hours, after which it was quenched with water (5 eq). 30 To the reaction mixture was then added 4-bromobenzo[c][1,2,5]thiadiazole (2 eq) which was allowed to dissolve before the addition of XPhos Pd G2 (0.02 eq) and K3PO4 (2M, 4 eq). The reaction mixture was then heated to 40 °C for 24 hours. Water (4 mq) was added and the phases separated. The organic phase was dried over MgSO4 and filtered. The solvent was then removed by rotary evaporation followed by high vacuum. The resulting material was used 35 without further purification. To a stirred 0.2M solution of the above 4,4'-(4,4-dialkyl-4H-cyclopenta[2,1-b:3,4- b']dithiophene-2,6-diyl)bis(benzo[c][1,2,5]thiadiazole) in DCM at -50 °C, NBS (2 eq) was added as a solid in one portion. The temperature was gradually raised to -15 °C over the course of 140 minutes at which point TLC and HPLC indicate completion of the reaction. The reaction 40 was then quenched by addition of (4 eq) of 1M Na2S2O3 (aq) and stirred for 10 minutes. The 29 crude product was purified by flash chromatography (toluene / hexanes, gradient from 5 to 100% toluene). General procedure for Suzuki-Miyuara cross-coupling: 5 To a stirred solution of the above 2,6-bis(7-bromobenzo[c][1,2,5]thiadiazol-4-yl)-4H- cyclopenta[2,1-b:3,4-b']dithiophene, XPhos Pd G3 (0.02 eq) and the donor and anchor boronic acids (1.2 eq each) in THF (30 mq) under nitrogen, aqueous K3PO4 (1M, 4 eq) was added. The reaction mixture was kept at 60 °C for 17 hours. After cooling to room temperature, the reaction mixture was dried over anhydrous Na2SO4 and filtered through Celite. The solvent 10 was removed by rotary evaporation. The crude product was purified by flash chromatography (toluene / hexanes, gradient from 50 to 100% toluene). General procedure for saponification: The above ester (1 eq, 8.4 mmol) was refluxed in a mixture of THF / methanol / 1M aqueous 15 KOH (10:1:1 volume ratio, 180 ml) for 2 hours. After cooling the mixture to room temperature, aqueous HCl (5M, 5 ml) was added. The solvent was then removed using rotary evaporation and the product filtered and washed with water and consequently dried under vacuum. Example: Synthesis of 7,7'-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene-2,6- 20 diyl)bis(4-bromobenzo[c][1,2,5]thiadiazole). To a stirred solution of 4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene (10 g, 24.8 mmol) in THF (120 ml) at -78 °C, n-hexyllithium (2.3 M in hexanes, 2.2 eq, 24 ml) was 25 slowly added under nitrogen. The reaction mixture was allowed to warm to -40 °C over 180 minutes, then further warmed to 0 °C over 15 minutes after which it was brought back down to -78 °C within 10 minutes for the addition of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2- dioxaborolane (2.2 eq, 54.6 mmol, 11.2 ml). The reaction mixture was allowed to slowly warm to room temperature over the course of 19 hours, after which it was quenched with water (1 30 ml). 30 To the reaction mixture was then added 4-bromobenzo[c][1,2,5]thiadiazole (2 eq, 49.7 mmol, 10.7 g) which was allowed to dissolve before the addition of XPhos Pd G2 (0.02 eq, 0.5 mmol, 420 mg) and K3PO4 (2M, 4 eq, 50 ml). The reaction mixture was then heated to 40 °C for 24 hours. Water (100 ml) was added and the phases separated. The organic phase was dried over 5 MgSO4 and filtered. The solvent was then removed by rotary evaporation followed by high vacuum. The resulting material was used in the next step without further purification. To a stirred solution of the above 4,4'-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4- b']dithiophene-2,6-diyl)bis(benzo[c][1,2,5]thiadiazole) in DCM (100 ml) at -50 °C, NBS (2 eq, 50 mmol, 8.84 g) was added as a solid in one portion. The temperature was gradually raised 10 to -15 °C over the course of 140 minutes at which point TLC and HPLC indicate completion of the reaction. The reaction was then quenched by addition of 10 ml of 1M Na2S2O3 (aq) and 1 ml of 0.2 g / ml KI (aq) and stirred for 10 minutes. Ethanol (100 ml) was added, and the reaction mixture was evaporated on a rotary evaporator down to 60 mbar at 25 °C upon which the product precipitated. The precipitate was filtered 15 and the retentate washed sequentially with copious amounts of ethanol, water, methanol and finally ethanol again. The product 7,7'-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4- b']dithiophene-2,6-diyl)bis(4-bromobenzo[c][1,2,5]thiadiazole) was isolated as a dark red- purple solid in 81% yield (over 3 steps). Example: Synthesis of methyl 4-(7-(6-(7-(4-(bis(2',4'-dibutoxy-[1,1'-biphenyl]-4-20 yl)amino)phenyl)benzo[c][1,2,5]thiadiazol-4-yl)-4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1- b:3,4-b']dithiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)benzoate. 31 Example: Synthesis of 4-(7-(6-(7-(4-(bis(2',4'-dibutoxy-[1,1'-biphenyl]-4- yl)amino)phenyl)benzo[c][1,2,5]thiadiazol-4-yl)-4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1- b:3,4-b']dithiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid. 5 To a stirred solution of the above 7,7'-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4- b']dithiophene-2,6-diyl)bis(4-bromobenzo[c][1,2,5]thiadiazole) (240 mg, 0.29 mmol), XPhos Pd G3 (0.02 eq, 5.8 µmol, 4.9 mg), 2',4'-dibutoxy-N-(2',4'-dibutoxy-[1,1'-biphenyl]-4-yl)-N-(4- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-[1,1'-biphenyl]-4-amine (1.2 eq, 0.35 mmol, 282 mg) and (4-(methoxycarbonyl)phenyl)boronic acid (1.2 eq, 0.35 mmol, 63 mg) in 10 THF (10 ml) under nitrogen, K3PO4 (1M, 4 eq, 1.2 ml) was added. The reaction mixture was kept at 60 °C for 17 hours. After cooling to room temperature, the reaction mixture was dried over anhydrous Na2SO4 and filtered through Celite. The solvent was removed by rotary evaporation. The crude product was purified by flash chromatography (toluene / hexanes, gradient from 50 to 100% toluene) to yield 220 mg (51% yield) of dark purple solid. 15 yl)amino)phenyl)benzo[c][1,2,5]thiadiazol-4-yl)-4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1- b:3,4-b']dithiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)benzoate (12.5 g, 8.4 mmol) was refluxed in a mixture of THF / methanol / 1M aqueous KOH (10:1:1 volume ratio, 180 ml) for 2 20 hours. After cooling the mixture to room temperature, aqueous HCl (5M, 5 ml) was added. 32 The solvent was then removed using rotary evaporation and the product filtered and washed with water and consequently dried under vacuum to yield a dark purple solid (12 g, 97% yield). Example: Crystallization of 4-(7-(6-(7-(4-(bis(2',4'-dibutoxy-[1,1'-biphenyl]-4- 5 yl)amino)phenyl)benzo[c][1,2,5]thiadiazol-4-yl)-4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1- b:3,4-b']dithiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid To a round bottomed flask was charged 4-(7-(6-(7-(4-(bis(2',4'-dibutoxy-[1,1'-biphenyl]-4- yl)amino)phenyl)benzo[c][1,2,5]thiadiazol-4-yl)-4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1- b:3,4-b']dithiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid (5 g) and propylene glycol 10 methyl ether (30 mL). The heterogeneous mixture was heated to inner temperature (Ti=140 °C) and agitated to give a homogeneous mixture. The mixture was clear filtered through a membrane filter (PTFE, Pore size: 0.2 µm). The filter, round bottomed flask and receiver flask was washed with propylene glycol methyl ether (10 mL). The solution was transferred to a 50 mL round bottomed flask. The RB-content was heated to inner temperature (Ti=140 °C) and 15 agitated for 10 minutes. The mixture was cooled to inner temperature (Ti=75 °C) and agitated for 15 minutes. To the round bottom-flask was charged seeds (0.5 g) followed by stirring at Ti=75 °C for 2 h. The mixture was allowed to reach 20 °C during 5 hours and then stirred for 36 hours. The mixture was filtered through a glass sintered filter (Robur Por 3; 100 mL). The filter cake was pulled dry and compressed. The filter cake was washed with MeOH (50 mL) 20 and then pulled dry for 1 h. The material was dried in a vacuum oven for 24 h at (10 mbar, 90 °C) which gave product as a violet / black solid (4.5 g; 82 %). Chromatographic purity: 98 area- % (330 nm), 98.5 area-% (360 nm), and 99.1 area-% (560 nm). Other examples of compounds of the invention are

[0002] 34 The EXY15 compound is synthesized using same strategy EXY4. The donor group is synthesized 5 reacting (4-dodecylthiophen-2-yl)boronic acid and 4-bromo-N-(4-bromophenyl)-N- phenylaniline in a Pd-catalysed Suzuki-Miyaura cross-coupling reaction. The resulting product is brominated (electrophilic aromatic substitution) followed by Pd-catalysed Miyaura borylation. The donor, acceptor, and central fragment were coupled in a three component Suzuki Miyaura cross-coupling reaction followed by flash chromatography purification and 10 subsequent saponification and isolation. 35 The EXY16 compound is synthesized using same strategy as for EXY4. The central fragment is synthesized by using same method as for EXY4 however 4-Bromobenzo[c][1,2,5] oxadiazole is used as a building block in the Suzuki-Miyaura cross-coupling chemistry. 5 The EXY17 compound is synthesized via a Pd-catalysed C6-decarboxylative cross-coupling as a key step. The central fragment is synthesised by C2-selective metalation, borylation followed by C6-metalation and reaction of the metalated specie with methyl chloroformate. The C2- borylated building block is reacted with 4-bromobenzo[c][1,2,5] thiadiazole followed by10 bromination and Suzuki-Miyaura cross-coupling to instal the donor. The Pd-catalysed C6- decarboxylative cross-coupling involved reaction between the C6 carboxylic acid and methyl 3-(4-(7-chlorobenzo[c][1,2,5]thiadiazol-4-yl)phenyl)propiolate. The EXY18 compound is synthesized via Pd-catalysed C6-decarboxylative cross-coupling as a 15 key step. The central fragment is synthesised by C2-selective metalation, borylation followed by C6-metalation and reaction of the metalated specie with methyl chloroformate. The C2- borylated building block is reacted with 4-bromobenzo[c][1,2,5] thiadiazole followed by bromination and Suzuki-Miyaura cross-coupling to instal the donor. The Pd-catalysed C6- decarboxylative cross-coupling involved reaction between the C6 carboxylic acid methyl 4-((4- 20 (7-chlorobenzo[c][1,2,5]thiadiazol-4-yl)phenyl)ethynyl)benzoate 36 The EXY19 compound is synthesised employing C2selective metalation, borylation, and Suzuki-Miyaura cross-coupling reaction followed by bromination and SMC-coupling to install donor. The C6 functionalization is performed using direct C6-arylation chemistry followed by 5 hydrolysis and decarboxylative phosphorylation to instal anchor group. The EXY20 compound is synthesised employing C2 selective metalation, borylation, and Suzuki-Miyaura cross-coupling reaction followed by bromination and SMC-coupling to install donor. The C6functionalization is performed using direct C6-arylation chemistry followed by 10 hydrolysis and Nickel-Catalysed decarboxylative C−P Cross-Coupling of alkenyl acids to enable instalment of anchor group. The EXY21 compound is synthesized using same strategy EXY4. The donor group is synthesized reacting (2,4-dibutylphenyl)boronic acid and 4-bromo-N-(4-bromophenyl)-N-phenylaniline in 15 a Pd-catalysed Suzuki-Miyaura cross-coupling reaction. The resulting product is brominated (electrophilic aromatic substitution) followed by Pd-catalysed Miyaura borylation. The donor, acceptor, and central fragment were coupled together in a three component Suzuki Miyaura cross-coupling reaction followed by flash chromatography purification and subsequent saponification and isolation. 37 The EXY22 compound is synthesized using same strategy as for EXY4. The central fragment, donor and anchor groups were coupled employing a three component Suzuki Miyaura cross- coupling reaction followed by flash chromatographic purification and subsequent formation 5 of hydroxamic acid. Equivalents Materials also can be specified in units relative to the reactant, i.e. as equivalents. 10 Donor and anchor boronic acids Pd XPhos G2 (Chloro(2-dicyclohexylphosphino-2′,4′,6′-triisopropyl-1,1′-biphenyl)[2-(2′-amino- 1,1′-biphenyl)]palladium(II)) 15 Pd XPhos G3 ((2-Dicyclohexylphosphino-2′,4′,6′-triisopropyl-1,1′-biphenyl)[2-(2′-amino-1,1′- biphenyl)]palladium(II) methanesulfonate) 38 Example anchor boronic acids (or boronic acid ester): Example donor boronic acids (or boronic acid ester): 5 39 Example of anchor aryl halide used in the preparation of phenyl propiolic acid derivatives de used in the preparation of phenyl(ethynyl)benzoic acid derivatives 5 Example of benzoic acid used in the synthesis of phenyl phosphonic acid Example of alkenyl acid used in the synthesis of vinyl phosphonic acid 10 Example of methyl benzoate derivative used in the synthesis of hydroxamic acid 40 Results 1.1 Characterization of EXY4 and EXY5 5 Two new dyes, EXY4 and EXY5, were received from Exeger. H NMR analysis was carried out to check the purity of the two dyes. The dye structures are shown above. The H NMR spectra in figures 1 and 2 of as-received EXY4 and EXY5 show some small impurity peaks in the aromatic region. Integration of the main peaks shows 10% and 30% mismatch, respectively, indicating that the purity of EXY4 and EXY5 is not very high. 10 1.2 Optical and electrochemical properties of EXY4 and EXY5 The UV-vis absorption spectra of EXY4 and EXY5 in DCM are shown in figure 3. The absorption maximum of EXY4 is at 565 nm, with a molar extinction coefficient of 57300 M-1cm- 1. While the absorption maximum of EXY5 is blue-shifted to 472 nm, with a much lower molar extinction coefficient of 35300 M-1cm- 1. The cyclic voltammograms of 15 EXY4 and EXY5 are shown in figure 4. The corresponding parameters are shown in Table 1. The HOMO energy level of EXY4 is 1.10 V vs. NHE, which is 70 mV higher than EXY5. The LUMO energy level of EXY4 is -0.83 V vs. NHE, and EXY5 shows a 330 mV more negative LUMO energy level of -1.16 V vs. NHE. These results illustrate that there is enough driving force for dye regeneration and electron injection for both EXY4 and EXY5. 20 Table 1. Optical and electrochemical properties of EXY4 and EXY5 1.3 Device performance of raw EXY4 and EXY5 Large-area cells of EXY4, EXY5 were prepared with a film thickness of 4 + 4 μm (18 NRT paste) and an active area of 2.8 cm2, PEDOT was used as the counter electrode, and the composition of the copper electrolyte was 0.1 M Cu(tmby)2TFSI, 0.04 M Cu(tmby)2TFSI2, 25 0.1 M LiTFSI, 0.6 M NMB in distilled MPN. The photovoltaic data is shown in Tables 2-3. The EXY4 based device shows a power output Pmax of 71.79 µW cm-2under 1000 lux, with an Isc of 362.13 µA, Voc of 784.0 mV and fill factor of 0.708. While the EXY5 based device shows the highest Voc of 911.0 as well as the highest FF of 0.796, but the Isc is only 305.70 µ A because of the narrow spectral response. The EXY5 based device shows a higher output 30 power of 79.13 µW cm-2under 1000 lux compared with EXY4. The evolution of EXY4 and EXY5 based cells are recorded in Tables 4 and 5. Both EXY4 and EXY5 show the best 41 performance on the 2ndday, with the output power of EXY4 and EXY5 increasing to 74.43 µW cm-2and 81.92 µW cm-2, respectively. The performances start to decrease after 2 days, and after 5 days the output power of EXY4 and EXY5 decreased to 67.97 µW cm-2and 66.92 µW cm-2, respectively. 5 Table 2. Photovoltaic performance of EXY4. Table 3. Photovoltaic performance of EXY5. Table 4. Evolution of EXY4 after 5 days under 1000 lux. 42 Table 5. Evolution of EXY5 after 5 days under 1000 lux. Devices with dyes EXY4 and EXY5 were prepared with a film thickness of 4 + 4 μm and an active 5 area of 0.28 cm2, PEDOT was used as the counter electrode, the composition of the copper electrolyte was 0.2 M Cu(tmby)2TFSI, 0.09 M Cu(tmby)2TFSI2, 0.1 M LiTFSI, 0.6 M NMB. The photovoltaic data is shown in Table 6. The PCE of EXY4-based devices is 8.48% under 1 sun, with a Jsc of 12.34 mA / cm2, Voc of 938.5 mV and fill factor of 0.737. While the device using EXY5 exhibits a higher Voc of 1018 mV, its Jsc of 11.05 mA / cm2is significantly lower, resulting 10 in a slightly lower PCE of 8.25% under 1 sun. Furthermore, EXY4 and EXY5-based device show ideality factors of 1.84 and 2.15 (Figure 5), resepctively. Figure 6 shows the IPCE spectra of EXY4 and EXY5-based devices. The IPCE of EXY4-based devices is much broader than that of EXY5-based devices, which is in good agreement with the higher Jsc value obtained from the IV measurement. 15 Table 6. Photovoltaic performance of EXY4 and EXY5 based devices. 1.4 Purification of EXY4 43 A column purification of dye EXY4 was performed, because the NMR spectrum of EXY4 had shown that there was a 10% impurity in the raw EXY4 sample.25 mg EXY4 was dissolved in DCM and loaded onto the silica gel column. DCM with 1% MeOH was used as the eluent, and the main band was collected, concentrated, and recrystallized from DCM and MeOH.15 5 mg solid were collected and checked by NMR (Figure 7). The small peaks have disappeared, and the integration of the main peaks is correct following purification, indicating high purity of EXY4.

Claims

44 Claims 1. A compound of formula (I)wherein R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or 5 C4-15heteroarylamine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, OH, SH, -C1-20alkyl, -N-(C1-20alkyl)1-2, -O-(C1-20alkyl)1-2, and -S-(C1-20alkyl)1-2wherein R11is optionally substituted by one or more substituents R13, R13is selected from the group comprising H, O, N, S, NH, OH, SH, -C(O)OH, -C(O)C1-20alkyl, -N- 10 (C,0alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, Z is on each occurrence, identically or differently O or S, A is selected from the group comprising C4-15aryl, C4-15heteroaryl, -C2-4alkynyl, -C2-4alkynylC4- 15aryl and -C2-4alkynylC4-15heteroaryl, substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising H, OH, -15 C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2-4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2- 10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1- 10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH,20 -C2-10alkenyl−C(O)−NH−OH, -C(O)NH2, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, - C1-10alkylC(S)-OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2-10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, L is selected from the group comprising25 , Y is C, Z2is O or S, and R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group comprising H, -C1-10alkyl, -C2-10alkenyl and -C1-10alkyl-C5-15aryl, -C5-10aryl, -C5-10aryl-(C1-10alkyl)1- 303.45 2. The compound of formula (I) according to claim 1, wherein wherein R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1- 5 20alkyl, -N-(C1-10alkyl)1-2, -O-(C1-20alkyl)1-2, and -S-(C1-10alkyl)1-2, wherein R11is optionally substituted by one or more substituents R13, R13is selected from the group comprising H, O, N, S, NH, OH, SH, -C(O)OH, -C(O)C1-10alkyl, -N- (C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, Z is on each occurrence, identically or differently O or S, 10 A is selected from the group comprising C5-15aryl, C2-4alkynyl, -C2-4alkynylC5-15aryl and -C2- 4alkynylC4-15heteroaryl, substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising H, OH, - C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2-154alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2-10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1-10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1- 10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)-20 OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2-10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, L is selected from the group comprising, Y is C, 25 Z2is S, and R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group comprising H, -C1-10alkyl and -C2-10alkenyl.

3. The compound of formula (I) according to claim 1, wherein 30 wherein R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1-20alkyl and -O-(C1-20alkyl)1-2, Z is on each occurrence, identically or differently O or S, 35 A is selected from the group comprising C5-15aryl, C2-4alkynyl and -C2-4alkynylC5-15aryl , substituted by one or more R4, R5and R6,46 R4, R5and R6are independently of each other selected from the group comprising H, OH, - C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2-4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2- 5 10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1- 10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)- OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2-10 10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, L is selected from the group comprising, Y is C, Z2is S, and 15 R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group comprising H, -C1-10alkyl and -C2-10alkenyl.

4. The compound of formula (I) according to claim 1, wherein wherein R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or 20 (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1- 20alkyl and -O-(C1-20alkyl)1-2, Z is on each occurrence, identically or differently O or S, A is selected from the group comprising C5-15aryl, C2-4alkynyl and -C2-4alkynylC5-15aryl 25 substituted by one or more R4, R5and R6, R4, R5and R6are independently of each other selected from the group comprising H, OH, - C(O)OH, -C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH -C2-4alkynylC(O)OH -PO3H2, -C2- 10alkenyl-PO3H2, −C(O)−NH−OH, L is selected from the group comprising30 , Y is C,47 Z2is S, and R2, R3, R7, R8, R9, R18and R19are independently of each other selected from the group comprising H and -C1-10alkyl. 5 5. The compound according to any one of claims 1 to 4, represented by formula (II)wherein R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1- 10 20alkyl, -N-(C1-10alkyl)1-2, -O-(C1-20alkyl)1-2, and -S-(C1-10alkyl)1-2, wherein R11is optionally substituted by one or more substituents R13, R13is selected from the group comprising H, O, N, S, NH, OH, SH, -C(O)OH, -C(O)C1-10alkyl, -N- (C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, R4, R5and R6are independently of each other selected from the group comprising H, OH, -15 C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH, -C2-10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2- 4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2- 10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1-10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1- 10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2-10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH,20 -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-10alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)- OH, -C2-10alkenylC(S)-OH, -C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2- 10alkenylC(S)-OH, -C2-10alkenylC(S)-OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, R2and R3are independently of each other selected from the group comprising H, -C1-10alkyl 25 and -C2-10alkenyl.

6. The compound according to any one of claims 1 to 4, represented by formula (III)48 wherein R1is selected from the group comprising C4-15arylamine or (C4-15polyaryl)2-3amine or (C4-15polyheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1-20alkyl, -N-(C1-10alkyl)1-2, -O-(C1-20alkyl)1-2, and -S-(C1-10alkyl)1-2, wherein R11is optionally 5 substituted by one or more substituents R13, R13is selected from the group comprising H, O, N, S, NH, OH, SH, -C(O)OH, -C(O)C1-10alkyl, -N- (C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2, wherein R4is selected from the group comprising H, OH, -C(O)OH, -C1-10alkyl, -C1-10alkylC(O)OH, -C1-10alkylC(O)O-C1-10alkyl, C(O)O-C1-10alkyl, -C2-10alkenylC(O)OH, -C2-10 10alkenylC(O)O-C1-10alkyl, C(O)OH)2, -C1-10alkyl-(C(O)OH)2, -C2-4alkynylC(O)OH, -C1-10alkylC(O)H, -C1-10alkylC(O)-C1-10alkyl, -C2-10alkenylC(O)H, -C2-10alkenylC(O)-C1-10alkyl, -C1-10alkylOH, -C1- 10alkylO-C1-10alkyl, -C2-10alkenylOH, -C2-10alkenylO-C1-10alkyl, -PO3H2, -C1-10alkyl-PO3H2, -C2- 10alkenyl-PO3H2, −C(O)−NH−OH, -C1-10alkyl−C(O)−NH−OH, -C2-10alkenyl−C(O)−NH−OH, -C1-10alkyl-C(O)NH2, -C2-10alkenyl-C(O)NH2, -C1-10alkylC(S)H, -C1-10alkylC(S)-C1-10alkyl, -C2-1510alkenylC(S)H, -C2-10alkenylC(S)-C1-10alkyl, -C(S)-OH, -C1-10alkylC(S)-OH, -C2-10alkenylC(S)-OH, - C(S)-OH, -C1-10alkylC(S)-OH, -C1-10alkylC(S)-OC1-10alkyl, -C2-10alkenylC(S)-OH, -C2-10alkenylC(S)- OC1-10alkyl, and -C2-10alkenylC(CN)PO3H2, R8and R9are independently of each other selected from the group comprising H, -C1-10alkyl and -C2-10alkenyl. 20 7. The compound according to any one of the preceding claims, wherein R1is a substituent of formula (IV)wherein m is 0 or 1, n is 2, o is 0 or 1, and 25 wherein each Ar is independently of each other a C4-15aryl or C4-15heteroaryl substituted by one or more R11.

8. The compound according to any one of the preceding claims, wherein wherein R1is selected from the group comprising C4-15arylamine or (C4-15diaryl)2-3amine or (C4- 30 15diheteroaryl)2-3amine substituted by one or more R11, R11is on each occurrence, identically or differently selected from the group comprising H, -C1- 15alkyl, -N-(C1-15alkyl)1-2, -O-(C1-15alkyl)1-2, and -S-(C1-15alkyl)1-2wherein R11is optionally substituted by one or more substituents R13, R13is selected from the group comprising H, O, N, S, NH, OH, SH, -C(O)OH, -C(O)C1-10alkyl, -N- 35 (C1-10alkyl)1-2, -O-(C1-10alkyl)1-2, and -S-(C1-10alkyl)1-2.49 9. The compound according to any one of the preceding claims, wherein R1is an C4-15arylamine or (C4-15diaryl)2-3amine , where the aryl on each occurrence, identically or differently, is selected from the group comprising phenyl, diphenyl, 1-aryl-4-penten, tropylium, naphthalene, anthracene, phenanthrene, as-indacene, s-indacene, biphenylene, 5 indene, acenaphthene, flourene, cyclopropene, cyclobutene, cyclobutadiene, cyclopentene, cyclopentadiene cyclohexene and cyclohexadiene.

10. The compound according to any one of the preceding claims, wherein R1is C4-15heteroarylamine or (C4-15heterodiaryl)2-3amine, where the heteroaryl on each occurrence, 10 identically or differently, is selected from the group comprising thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl, 1,2,3-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-triazolyl, 1,2,4-thiadiazolyl, 1,2,4-oxadiazolyl, 1,3,4- triazolyl, 1,3,4-thiadiazolyl, and 1,3,4- oxadiazolyl or pyridyl, pyrazinyl, pyrimidinyl, triazinyl and pyridazinyl or phenanthrene, or benzofuran, dibenzofuran, zanthenonyl, quinolinyl, 15 carbazolyl, dibenzothiophenyl, isoquinolinyl, indolyl, purinyl, pteridine, xanthenyl, chromanyl, chromenyl, coumarinyl, dihydrodibenzooxepinyl, naphthyridinyl, cabolines, quinoxalinyl, lorcaserinyl and benzoazepinonyl.

11. The compound according to any one of the preceding claims, wherein R1is selected from: 20wherein R11is on each occurrence, identically or differently selected from the group comprising H, -C1-15alkyl, -N-(C1-10alkyl)1-2, -O-(C1-15alkyl)1-2, and-S-(C1-15alkyl)1-2.50 12. The compound according to any one of the claims 1 to 9, wherein R1is13. The compound according to any one of the preceding claims, wherein R4, R5and R6are 5 independently of each other selected from the group comprising H, OH, -C(O)OH, -C1-5alkyl, - C(O)O-C1-5alkyl, -C2-5alkenylC(O)OH, -C2-3alkynylC(O)OH, -PO3H2and -C2-5alkenyl-PO3H2, −C(O)−NH−OH-.

14. The compound according to any one of the preceding claims, wherein R2, R3, R7, R8, R9, 10 R18and R19are independently of each other selected from the group comprising H, -C5-9alkyl and -C5-9alkenyl.

15. The compound according to any one of claims 1 to 4, wherein L is selected from15 R2, R3, R8and R9are independently of each other selected from the group comprising H, -C5-9alkyl, which alkyl may be branched or straight.

16. The compound according to any one of claims 1 to 4, wherein the compound is selected from the group comprising 205517. A use of the compound according to any one of the preceding claims as photosensitizer 5 or light absorbing material.

18. A use of one or more of intermediate compound in the preparation of the compounds according to any one of the preceding claims, wherein the intermediate compounds are selected from the group comprising 10,

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