A polyfullerene consisting of di- or polyvalent units of formula I1 and divalent units of formula I2 *-Ar-* I2 wherein the individual radicals, independently of each other, and on each occurrence identically or differently, have the following meanings C n a fullerene composed of n carbon atoms, optionally with one or more atoms trapped inside, R n alkyl with 1 to 12 C-atoms, g 0 or an integer ≥ 1, Ar is selected of formula 17 R 11 , R 14 H, R 12 , R 13 halogen, CN, an alkyl group with 1 to 50 C atoms, which is straight-chain, branched or cyclic, and in which one or more CH 2 groups are optionally replaced by -O-, -S-,-C(=O)-, -C(=S)-, -C(=O)-O-, -O-C(=O)-, -NR 0 -, -C(=O)-NR 0 -, -NR 0 -C(=O)-, -SiR 0 R 00 -, -CF 2 -, -CR 0 =CR 00 -,-CR 0 =N-, -N=N- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and/or in which one or more H atoms are optionally replaced by F, Cl or CN, and/or in which one or more C or H atoms are optionally replaced by a cationic or anionic group, a saturated or unsaturated carbo- or heterocyclic group, or an aryl, heteroaryl, aryloxy or heteroaryloxy group, wherein each of the aforementioned cyclic groups is mono- or polycyclic, does optionally contain fused rings, and is optionally substituted by one or more identical or different groups L, L F, Cl, -CN, or an alkyl group with 1 to 20 C atoms, which is straight-chain, branched or cyclic, and in which one or more CH 2 groups are optionally replaced by -O-, -S-,-C(=O)-, -C(=S)-, -C(=O)-O-, -O-C(=O)-, -NR 0 -, -C(=O)-NR 0 -, -NR 0 -C(=O)-, -SiR 0 R 00 -, -CF 2 -, -CR 0 =CR 00 -,-CR 0 =N-, -N=N- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and/or in which one or more H atoms are optionally replaced by F, Cl or CN, and/or in which one or more C or H atoms are optionally replaced by a cationic or anionic group, R 0 and R 00 H or alkyl with 1 to 12 C-atoms, Ad 2 a second adduct, or a combination of second adducts, appended to the fullerene C n with any connectivity, r 0, an integer ≥ 1, or a non-integer > 0, C n a fullerene composed of n carbon atoms, optionally with one or more atoms trapped inside, R n alkyl with 1 to 12 C-atoms, g 0 or an integer ≥ 1, Ar is selected of formula 17 R 11 , R 14 H, R 12 , R 13 halogen, CN, an alkyl group with 1 to 50 C atoms, which is straight-chain, branched or cyclic, and in which one or more CH 2 groups are optionally replaced by -O-, -S-,-C(=O)-, -C(=S)-, -C(=O)-O-, -O-C(=O)-, -NR 0 -, -C(=O)-NR 0 -, -NR 0 -C(=O)-, -SiR 0 R 00 -, -CF 2 -, -CR 0 =CR 00 -,-CR 0 =N-, -N=N- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and/or in which one or more H atoms are optionally replaced by F, Cl or CN, and/or in which one or more C or H atoms are optionally replaced by a cationic or anionic group, a saturated or unsaturated carbo- or heterocyclic group, or an aryl, heteroaryl, aryloxy or heteroaryloxy group, wherein each of the aforementioned cyclic groups is mono- or polycyclic, does optionally contain fused rings, and is optionally substituted by one or more identical or different groups L, L F, Cl, -CN, or an alkyl group with 1 to 20 C atoms, which is straight-chain, branched or cyclic, and in which one or more CH 2 groups are optionally replaced by -O-, -S-,-C(=O)-, -C(=S)-, -C(=O)-O-, -O-C(=O)-, -NR 0 -, -C(=O)-NR 0 -, -NR 0 -C(=O)-, -SiR 0 R 00 -, -CF 2 -, -CR 0 =CR 00 -,-CR 0 =N-, -N=N- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and/or in which one or more H atoms are optionally replaced by F, Cl or CN, and/or in which one or more C or H atoms are optionally replaced by a cationic or anionic group, R 0 and R 00 H or alkyl with 1 to 12 C-atoms, Ad 2 a second adduct, or a combination of second adducts, appended to the fullerene C n with any connectivity, r 0, an integer ≥ 1, or a non-integer > 0, <EOS>