Compounds of the formula, where the following applies to the symbols and indices used: Ar 1, Ar 3 are on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 6 to 20 aromatic ring atoms, which may be substituted by one or more radicals R; Ar 2 is on each occurrence, identically or differently, a condensed aryl or heteroaryl group having 14 to 40 aromatic ring atoms, which may be substituted by one or more radicals R, where the condensed aryl or heteroaryl groups Ar 2 contain three, four, five or six aromatic or heteroaromatic units selected from benzene, pyrimidine, pyrazine and pyridazine, which are in each case condensed onto one another via one or more common edges and thus form a common aromatic system, or Ar 2 is acridine, which may be substituted by one or more radicals R, with the proviso that the two groups Ar 1 and Ar 3 are not linked via adjacent positions or peri positions on Ar 2; L 1, L 2 are on each occurrence, identically or differently, a divalent organic bridge containing 1 to 60 C atoms which is selected from the groups of the alkenes, aromatic groups containing 6 to 40 C atoms, heteroaromatic groups containing 2 to 40 C atoms, imines, alkoxy groups, thioalkoxy groups, aryloxy groups, thioaryl groups, amines, arylamines, alkylenes and arylboranes, or combinations of one or more of these systems, which may be substituted by one or more radicals R; R is on each occurrence, identically or differently, H, F, Cl, Br, I, CN, NO 2, COOR 1, B(OR 1) 2, B(R 1) 2, Si(R 1) 3, a straight-chain alkyl or alkoxy chain having 1 to 40 C atoms or a branched or cyclic alkyl or alkoxy chain having 3 to 40 C atoms, each of which may be substituted by R 1 and in which, in addition, one or more non-adjacent C atoms may be replaced by N-R 1, O, S, O-CO-O, CO-O, -CR 1 =CR 1 - or -C≡C- and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R 1, or a combination of two, three or four of these systems; two or more radicals R here may also form a further mono- or polycyclic, aliphatic or aromatic ring system with one another; R 1 is on each occurrence, identically or differently, H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 C atoms; two or more radicals R 1 here may also form a ring system with one another; x is on each occurrence, identically or differently, 0 or 1, where x = 0 means that bridge L 2 is not present. Ar 1, Ar 3 are on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 6 to 20 aromatic ring atoms, which may be substituted by one or more radicals R; Ar 2 is on each occurrence, identically or differently, a condensed aryl or heteroaryl group having 14 to 40 aromatic ring atoms, which may be substituted by one or more radicals R, where the condensed aryl or heteroaryl groups Ar 2 contain three, four, five or six aromatic or heteroaromatic units selected from benzene, pyrimidine, pyrazine and pyridazine, which are in each case condensed onto one another via one or more common edges and thus form a common aromatic system, or Ar 2 is acridine, which may be substituted by one or more radicals R, with the proviso that the two groups Ar 1 and Ar 3 are not linked via adjacent positions or peri positions on Ar 2; L 1, L 2 are on each occurrence, identically or differently, a divalent organic bridge containing 1 to 60 C atoms which is selected from the groups of the alkenes, aromatic groups containing 6 to 40 C atoms, heteroaromatic groups containing 2 to 40 C atoms, imines, alkoxy groups, thioalkoxy groups, aryloxy groups, thioaryl groups, amines, arylamines, alkylenes and arylboranes, or combinations of one or more of these systems, which may be substituted by one or more radicals R; R is on each occurrence, identically or differently, H, F, Cl, Br, I, CN, NO 2, COOR 1, B(OR 1) 2, B(R 1) 2, Si(R 1) 3, a straight-chain alkyl or alkoxy chain having 1 to 40 C atoms or a branched or cyclic alkyl or alkoxy chain having 3 to 40 C atoms, each of which may be substituted by R 1 and in which, in addition, one or more non-adjacent C atoms may be replaced by N-R 1, O, S, O-CO-O, CO-O, -CR 1 =CR 1 - or -C≡C- and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R 1, or a combination of two, three or four of these systems; two or more radicals R here may also form a further mono- or polycyclic, aliphatic or aromatic ring system with one another; R 1 is on each occurrence, identically or differently, H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 C atoms; two or more radicals R 1 here may also form a ring system with one another; x is on each occurrence, identically or differently, 0 or 1, where x = 0 means that bridge L 2 is not present.