Compound of Formula wherein L 1 is a direct bond or C 6 to C 12 arylene; Ar 1 is selected from substituted or unsubstituted C 6 to C 24 aryl; wherein Ar 2 is selected from the following groups C1 to C8, wherein the asterisk symbol "*" represents the binding position to the moiety L 1; wherein R 7, R 8 and R 9 are independently selected from H, C 1 to C 12 alkyl, perhalogenated C 1 to C 12 alkyl, C 1 to C 12 alkoxy, perhalogenated C 1 to C 12 alkoxy, C 6 to C 24 aryl, perhalogenated C 6 to C 24 aryl, C 3 to C 24 heteroaryl, CN halogen P(=O)R'R", C(=O)R' or C(=O)OR', wherein R' and R" are independently selected from C 1 to C 16 alkyl, C 6 to C 24 aryl, or C 3 to C 24 heteroaryl; R 6 is selected from H, substituted or unsubstituted C 1 to C 12 alkyl, substituted or unsubstituted C 1 to C 12 alkoxy, substituted or unsubstituted C 6 to C 36 aryl, substituted or unsubstituted C 3 to C 36 heteroaryl, substituted or unsubstituted C 2 to C 6 alkenyl, CN or halogen; and the one or more substituent(s), if present, is/are independently selected from C 1 to C 12 alkyl, perhalogenated C 1 to C 12 alkyl, C 1 to C 12 alkoxy, perhalogenated C 1 to C 12 alkoxy, substituted or unsubstituted C 6 to C 24 aryl, substituted or unsubstituted C 3 to C 24 heteroaryl, CN, halogen, P(=O)R'R", C(=O)R' or C(=O)OR'; wherein R' and R" are independently selected from C 1 to C 16 alkyl, C 6 to C 24 aryl, C 3 to C 24 heteroaryl; the substituted or unsubstituted C 6 to C 24 aryl substituents may be connected via a direct bond; and the one or more substituent(s) of the substituted C 6 to C 24 aryl and substituted C 3 to C 24 heteroaryl are independently selected from C 1 to C 6 alkyl, C 1 to C 6 alkoxy, CN, halogen, P(=O)R'R", C(=O)R' or C(=O)OR'. L 1 is a direct bond or C 6 to C 12 arylene; Ar 1 is selected from substituted or unsubstituted C 6 to C 24 aryl; wherein Ar 2 is selected from the following groups C1 to C8, wherein the asterisk symbol "*" represents the binding position to the moiety L 1; wherein R 7, R 8 and R 9 are independently selected from H, C 1 to C 12 alkyl, perhalogenated C 1 to C 12 alkyl, C 1 to C 12 alkoxy, perhalogenated C 1 to C 12 alkoxy, C 6 to C 24 aryl, perhalogenated C 6 to C 24 aryl, C 3 to C 24 heteroaryl, CN halogen P(=O)R'R", C(=O)R' or C(=O)OR', wherein R' and R" are independently selected from C 1 to C 16 alkyl, C 6 to C 24 aryl, or C 3 to C 24 heteroaryl; R 6 is selected from H, substituted or unsubstituted C 1 to C 12 alkyl, substituted or unsubstituted C 1 to C 12 alkoxy, substituted or unsubstituted C 6 to C 36 aryl, substituted or unsubstituted C 3 to C 36 heteroaryl, substituted or unsubstituted C 2 to C 6 alkenyl, CN or halogen; and the one or more substituent(s), if present, is/are independently selected from C 1 to C 12 alkyl, perhalogenated C 1 to C 12 alkyl, C 1 to C 12 alkoxy, perhalogenated C 1 to C 12 alkoxy, substituted or unsubstituted C 6 to C 24 aryl, substituted or unsubstituted C 3 to C 24 heteroaryl, CN, halogen, P(=O)R'R", C(=O)R' or C(=O)OR'; wherein R' and R" are independently selected from C 1 to C 16 alkyl, C 6 to C 24 aryl, C 3 to C 24 heteroaryl; the substituted or unsubstituted C 6 to C 24 aryl substituents may be connected via a direct bond; and the one or more substituent(s) of the substituted C 6 to C 24 aryl and substituted C 3 to C 24 heteroaryl are independently selected from C 1 to C 6 alkyl, C 1 to C 6 alkoxy, CN, halogen, P(=O)R'R", C(=O)R' or C(=O)OR'. R' and R" are independently selected from C 1 to C 16 alkyl, C 6 to C 24 aryl, C 3 to C 24 heteroaryl; the substituted or unsubstituted C 6 to C 24 aryl substituents may be connected via a direct bond; and the one or more substituent(s) of the substituted C 6 to C 24 aryl and substituted C 3 to C 24 heteroaryl are independently selected from C 1 to C 6 alkyl, C 1 to C 6 alkoxy, CN, halogen, P(=O)R'R", C(=O)R' or C(=O)OR'.