A color converter comprising in a polymeric matrix material at least one fluorescent dye, wherein the at least one fluorescent dye is a perylene bisimide compound of the formula or a mixture thereof wherein R 1 and R 2, independently of each other, are selected from 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 4, R 5, R 6, R 7, R 8, R 9, R 10 R 11 R 12, R 13, R 14, R 15, R 16, R 17 and R 18 independently of each other, are selected from hydrogen, halogen, cyano, hydroxyl, mercapto, nitro, -NE 1 E 2, -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 3 and R 4, R 4 and R 5, R 5 and R 6, R 6 and R 7, R 7 and R 8, R 8 and R 9, R 9 and R 10, R 11 and R 12, R 12 and R 13, R 13 and R 14, R 14 and R 15, R 15 and R 16, R 16 and R 17 and/or R 17 and R 18 together with the carbon atoms of the biphenylyl moiety to which they are bonded, may also form a further fused aromatic or non-aromatic ring system wherein the fused ring system is unsubstituted or substituted; where E 1 and E 2, independently of each other, are hydrogen, unsubstituted or substituted C 1 -C 18 -alkyl, unsubstituted or substituted C 2 -C 18 -alkenyl, unsubstituted or substituted C 2 -C 18 -alkynyl, unsubstituted or substituted C 3 -C 20 -cycloalkyl or unsubstituted or substituted C 6 -C 10 -aryl; R Ar1 and R Ar2, each independently of each, 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 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 4, R 5, R 6, R 7, R 8, R 9, R 10 R 11 R 12, R 13, R 14, R 15, R 16, R 17 and R 18 independently of each other, are selected from hydrogen, halogen, cyano, hydroxyl, mercapto, nitro, -NE 1 E 2, -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 3 and R 4, R 4 and R 5, R 5 and R 6, R 6 and R 7, R 7 and R 8, R 8 and R 9, R 9 and R 10, R 11 and R 12, R 12 and R 13, R 13 and R 14, R 14 and R 15, R 15 and R 16, R 16 and R 17 and/or R 17 and R 18 together with the carbon atoms of the biphenylyl moiety to which they are bonded, may also form a further fused aromatic or non-aromatic ring system wherein the fused ring system is unsubstituted or substituted; where E 1 and E 2, independently of each other, are hydrogen, unsubstituted or substituted C 1 -C 18 -alkyl, unsubstituted or substituted C 2 -C 18 -alkenyl, unsubstituted or substituted C 2 -C 18 -alkynyl, unsubstituted or substituted C 3 -C 20 -cycloalkyl or unsubstituted or substituted C 6 -C 10 -aryl; R Ar1 and R Ar2, each independently of each, 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. 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 3 and R 4, R 4 and R 5, R 5 and R 6, R 6 and R 7, R 7 and R 8, R 8 and R 9, R 9 and R 10, R 11 and R 12, R 12 and R 13, R 13 and R 14, R 14 and R 15, R 15 and R 16, R 16 and R 17 and/or R 17 and R 18 together with the carbon atoms of the biphenylyl moiety to which they are bonded, may also form a further fused aromatic or non-aromatic ring system wherein the fused ring system is unsubstituted or substituted; where E 1 and E 2, independently of each other, are hydrogen, unsubstituted or substituted C 1 -C 18 -alkyl, unsubstituted or substituted C 2 -C 18 -alkenyl, unsubstituted or substituted C 2 -C 18 -alkynyl, unsubstituted or substituted C 3 -C 20 -cycloalkyl or unsubstituted or substituted C 6 -C 10 -aryl; R Ar1 and R Ar2, each independently of each, 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.