TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Solar Cell: The solar cell is in the form of a component cell of a tandem cell. In the compounds of the general Formula (I), the Ra and Rb radicals are each independently selected from hydrogen, deuterium, 1-12C-alkyl, 7-22C-aralkyl, 4-7C-cycloalkyl, 6-10C-aryl and 7-22C-alkaryl; or the Ra and Rb radicals are both hydrogen, are both deuterium or are both 1-6C-alkyl or are both phenyl or are both 1-12C-alkylphenyl or are both naphthyl. Also, in the compounds of the general Formula (I), the R1-R12 radicals are each independently selected from hydrogen, F, Cl, hydroxyl, 1-18C-alkyl, 1-12C-alkoxy, 1-6C-alkylthio, 7-22C-aralkyl, 7-22C-aralkyloxy, 7-22C-aralkylthio, 4-7C-cycloalkyl, 6-10C-aryl, 7-22C-alkaryl, 7-22C-alkaryloxy, 7-22C-alkarylthio, amino, mono(1-12C-alkyl)amino, di(1-12C-alkyl)amino, NH(6-10C-aryl), N(6-10C-aryl)2, hetaryl and oligohetaryl, where hetaryl and the hetaryl groups of oligohetaryl may each independently be unsubstituted or substituted by 1,2,3 or 4 radicals selected from 1-12C-alkyl and 1-12C-alkoxy. Likewise, in the compounds of the general Formula (I), 0, 1, 2, 3 or 4 of the R1-R12 radicals have a definition other than hydrogen. The indanthrene compound is selected from compounds of the general formula (I.1).Ra and Rb=each independently selected from hydrogen, deuterium, 1-6C-alkyl, phenyl and naphthyl;R1 and R9=each independently selected from phenyl, phenyloxy, phenylthio, naphthyl, naphthyloxy, naphthylthio, (1-12C-alkyl)phenyl, (1-12C-alkyl)phenyloxy, (1-12C-alkyl)phenylthio, (1-12C-alkyl)naphthyl, (1-12C-alkyl)naphthyloxy and (1-12C-alkyl)naphthylthio; andR5 and R8=each independently selected from hydrogen, hydroxyl and 1-12C-alkoxy.The photoactive region comprises, as the fullerene compound, at least one fullerene and/or fullerene derivative. The photoactive region comprises, as the fullerene compound, C60 or (6,6)-phenyl-C61-butyric acid methyl ester. Moreover, at least one photoactive donor-acceptor transition is present in the form of a bulk heterojunction. Preferred Compound: The compound is used in an organic solar cell which comprises at least one photoactive region which comprises at least one compound of the general Formula (I) and at least one fullerene compound, where the fullerene compound used is C60 or (6,6)-phenyl-C61-butyric acid methyl ester. Alternatively, a compound of the Formula (I).R1 and R9=both phenoxy; andRa, Rb, R2, R3, R4, R5, R6, R7, R8, R10, R11 and R12 radicals=all hydrogen; or R5 and R8 are both methoxy and the Ra, Rb, R1, R2, R3, R4, R6, R7, R9, R10, R11 and R12 radicals are all hydrogen. EXAMPLE - No suitable example given.