A perylene bisimide compound of the formula wherein R 1 and R 2, independently of each other, are selected from the group consisting of hydrogen, in each case unsubstituted or substituted C 1 -C 30 -alkyl, polyalkyleneoxy, C 1 -C 30 -alkoxy, C 1 -C 30 -alkylthio, C 3 -C 20 -cycloalkyl, C 3 -C 20 -cycloalkyloxy, C 6 -C 24 -aryl and C 6 -C 24 -aryloxy; R 3, R 10, R 11 and R 18, independently of each other, are selected from phenyl and phenyl, which is substituted by one, two, three, four or five radicals L, wherein L is selected from halogen, cyano, hydroxyl, mercapto, -NR Ar1 COR Ar2, unsubstituted or substituted C 1 -C 30 -alkyl, polyalkyleneoxy, C 1 -C 30 -alkoxy, C 1 -C 30 -alkylthio, C 3 -C 20 -cycloalkyl, C 3 -C 20 -cycloalkoxy, C 6 -C 24 -aryl, C 6 -C 24 -aryloxy and C 6 -C 24 -arylthio; R 4, R 5, R 6, R 7, R 8, R 9, R 12, R 13, R 14, R 15, R 16, and R 17 independently of each other, are selected from the group consisting of hydrogen, halogen, cyano, hydroxyl, mercapto, -NR Ar1 COR Ar2, -CONR Ar1 R Ar2, -SO 2 NR Ar1 R Ar2, -COOR Ar1, -SO 3 R Ar2, in each case unsubstituted or substituted C 1 -C 30 -alkyl, polyalkyleneoxy, C 1 -C 30 -alkoxy, C 1 -C 30 -alkylthio, C 3 -C 20 -cycloalkyl, C 3 -C 20 -cycloalkoxy, C 6 -C 24 -aryl, C 6 -C 24 -aryloxy and C 6 -C 24 -arylthio, where R 4 and R 5, R 5 and R 6, R 7 and R 8, R 8 and R 9, R 12 and R 13, R 13 and R 14, R 14 and R 15, R 15 and R 16, and/or R 16 and R 17 together with the carbon atoms to which they are bonded, may also form a fused aromatic or nonaromatic carbon ring system wherein the fused ring system is unsubstituted or substituted; where R Ar1 and R Ar2, independently of each other, are hydrogen, unsubstituted or substituted C 1 -C 18 -alkyl, unsubstituted or substituted C 3 -C 20 -cycloalkyl, unsubstituted or substituted heterocyclyl, unsubstituted or substituted C 6 -C 20 -aryl or unsubstituted or substituted heteroaryl. R 1 and R 2, independently of each other, are selected from the group consisting of hydrogen, in each case unsubstituted or substituted C 1 -C 30 -alkyl, polyalkyleneoxy, C 1 -C 30 -alkoxy, C 1 -C 30 -alkylthio, C 3 -C 20 -cycloalkyl, C 3 -C 20 -cycloalkyloxy, C 6 -C 24 -aryl and C 6 -C 24 -aryloxy; R 3, R 10, R 11 and R 18, independently of each other, are selected from phenyl and phenyl, which is substituted by one, two, three, four or five radicals L, wherein L is selected from halogen, cyano, hydroxyl, mercapto, -NR Ar1 COR Ar2, unsubstituted or substituted C 1 -C 30 -alkyl, polyalkyleneoxy, C 1 -C 30 -alkoxy, C 1 -C 30 -alkylthio, C 3 -C 20 -cycloalkyl, C 3 -C 20 -cycloalkoxy, C 6 -C 24 -aryl, C 6 -C 24 -aryloxy and C 6 -C 24 -arylthio; R 4, R 5, R 6, R 7, R 8, R 9, R 12, R 13, R 14, R 15, R 16, and R 17 independently of each other, are selected from the group consisting of hydrogen, halogen, cyano, hydroxyl, mercapto, -NR Ar1 COR Ar2, -CONR Ar1 R Ar2, -SO 2 NR Ar1 R Ar2, -COOR Ar1, -SO 3 R Ar2, in each case unsubstituted or substituted C 1 -C 30 -alkyl, polyalkyleneoxy, C 1 -C 30 -alkoxy, C 1 -C 30 -alkylthio, C 3 -C 20 -cycloalkyl, C 3 -C 20 -cycloalkoxy, C 6 -C 24 -aryl, C 6 -C 24 -aryloxy and C 6 -C 24 -arylthio, where R 4 and R 5, R 5 and R 6, R 7 and R 8, R 8 and R 9, R 12 and R 13, R 13 and R 14, R 14 and R 15, R 15 and R 16, and/or R 16 and R 17 together with the carbon atoms to which they are bonded, may also form a fused aromatic or nonaromatic carbon ring system wherein the fused ring system is unsubstituted or substituted; where R Ar1 and R Ar2, independently of each other, are hydrogen, unsubstituted or substituted C 1 -C 18 -alkyl, unsubstituted or substituted C 3 -C 20 -cycloalkyl, unsubstituted or substituted heterocyclyl, unsubstituted or substituted C 6 -C 20 -aryl or unsubstituted or substituted heteroaryl.