Compound according to formula (10a), where the following applies to the symbols and indices used: X is B, P or P=O; Ar 2 In each occurrence, the group is either the same or different: an
aryl group with 6 to 10 aromatic ring atoms, which may be substituted with one or more R groups, or a heteroaryl group with 5 to 13 aromatic ring atoms, which may be substituted with one or more R groups; R is selected in each instance, either the same or different, from the group consisting of H, D, F, CN, a straight-chain
alkyl group with 1 to 10 C atoms, or a branched or cyclic
alkyl group with 3 to 10 C atoms, each with one or more R substituents. 2 may be substituted, with one or more H atoms being replaced by D or F, or an aromatic or heteroaromatic ring
system with 5 to 18 aromatic ring atoms, each with one or more R groups 2can be substituted, with optionally two or more adjacent substituents R forming a monocyclic or polycyclic, aliphatic, aromatic or heteroaromatic ring
system, which can be combined with one or more R groups 2 may be substituted; R 1 is the same or different R in each occurrence; two groups R can be used 1 , if n = 2, they also form a ring together; R 2 is selected in each occurrence, either the same or different, from the group consisting of H, D, F, a straight-chain
alkyl group with 1 to 40 C atoms, or a branched or cyclic alkyl group with 3 to 40 C atoms, where one or more H atoms may be replaced by D or F, or an aromatic or heteroaromatic ring
system with 5 to 60 aromatic ring atoms, each with one or more R groups 3can be substituted, optionally with two or more adjacent substituents R 2 can form a monocyclic or polycyclic, aliphatic, aromatic or heteroaromatic ring system, which may contain one or more R groups 3 may be substituted; R 3 is selected from the group consisting of H, D, F, CN or an
aliphatic hydrocarbon residue with 1 to 20 C atoms, either the same or different in each occurrence; n is 0 if X represents B or P=O, and is 0 or 2 if X represents P.