Compound of the formula, where the following applies to the symbols and indices used: Ar 1 is a heteroaryl group comprising at least one nitrogen which is represented in formula, having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 1; Ar 2 stands for an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 2; Ar B is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 3; X stands, on each occurrence, identically or differently, for CR 2 or N; or two adjacent groups X stand for a group of formula (X-1), where the dashed bonds in formula (X-1) indicate the bonding of the corresponding adjacent groups X to the structure; V is on each occurrence, identically or differently, CR 2 or N; R 1, R 2, R 3 stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(=O)Ar 3, P(=O)(Ar 3) 2, S(=O)Ar 3, S(=O) 2 Ar 3, N(Ar 3) 2, NO 2, Si(R 4) 3, B(OR 4) 2, OSO 2 R 4, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 40 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 40 C atoms, each of which may be substituted by one or more radicals R 4, where in each case one or more non-adjacent CH 2 groups may be replaced by R 4 C=CR 4, C=C, Si(R 4) 2, Ge(R 4) 2, Sn(R 4) 2, C=O, C=S, C=Se, P(=O)(R 4), SO, SO 2, O, S or CONR 4 and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO 2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R 4, or an aryloxy groups having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 4; where two adjacent substituents R 1, and/or two adjacent substituents R 3 may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R 4; and where one substituent R 1 of the group Ar 1 and one substituent R 2 of the adjacent 6-membered ring comprising the groups X may form an aliphatic or aromatic ring system together; Ar 3 is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case also be substituted by one or more radicals R 4; and R 4 stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 20 C atoms or branched or cyclic alkyl, alkoxy or thioalkyl groups having 3 to 20 C atoms, where in each case one or more non-adjacent CH 2 groups may be replaced by SO, SO 2, O, S and where one or more H atoms may be replaced by D, F, Cl, Br or I, or an aromatic or heteroaromatic ring system having 5 to 24 C atoms. Ar 1 is a heteroaryl group comprising at least one nitrogen which is represented in formula, having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 1; Ar 2 stands for an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 2; Ar B is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 3; X stands, on each occurrence, identically or differently, for CR 2 or N; or two adjacent groups X stand for a group of formula (X-1), where the dashed bonds in formula (X-1) indicate the bonding of the corresponding adjacent groups X to the structure; V is on each occurrence, identically or differently, CR 2 or N; R 1, R 2, R 3 stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(=O)Ar 3, P(=O)(Ar 3) 2, S(=O)Ar 3, S(=O) 2 Ar 3, N(Ar 3) 2, NO 2, Si(R 4) 3, B(OR 4) 2, OSO 2 R 4, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 40 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 40 C atoms, each of which may be substituted by one or more radicals R 4, where in each case one or more non-adjacent CH 2 groups may be replaced by R 4 C=CR 4, C=C, Si(R 4) 2, Ge(R 4) 2, Sn(R 4) 2, C=O, C=S, C=Se, P(=O)(R 4), SO, SO 2, O, S or CONR 4 and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO 2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R 4, or an aryloxy groups having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 4; where two adjacent substituents R 1, and/or two adjacent substituents R 3 may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R 4; and where one substituent R 1 of the group Ar 1 and one substituent R 2 of the adjacent 6-membered ring comprising the groups X may form an aliphatic or aromatic ring system together; Ar 3 is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case also be substituted by one or more radicals R 4; and R 4 stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 20 C atoms or branched or cyclic alkyl, alkoxy or thioalkyl groups having 3 to 20 C atoms, where in each case one or more non-adjacent CH 2 groups may be replaced by SO, SO 2, O, S and where one or more H atoms may be replaced by D, F, Cl, Br or I, or an aromatic or heteroaromatic ring system having 5 to 24 C atoms.