Materials for Electronic Devices

A compound of formula (I):

• wherein
• Ar1 is on each occurrence, identically or differently, an aryl or heteroaryl group having 6 to 18 aromatic ring atoms, which are optionally substituted by one or more radicals R1;
• Ar2 is on each occurrence, identically or differently, an aryl or heteroaryl group having 6 aromatic ring atoms, which are optionally substituted by one or more radicals R2;
• X1 is on each occurrence, identically or differently, BR3, C(R3)2, —C(R3)2—C(R3)2—, —C(R3)2—O—, —C(R3)2—S—, —R3C═CR3—, —R3C═N—, Si(R3)2, —Si(R3)2—Si(R3)2—, C═O, O, S, S═O, SO2, NR3, PR3, or P(═O)R3;
• R1, R2, and R3 are on each occurrence, identically or differently, H, D, F, Cl, Br, I, C(═O)R4, CN, Si(R4)3, N(R4)2, P(═O)(R4)2, OR4, S(═O)R4, S(═O)2R4, a straight-chain alkyl or alkoxy group having 1 to 20 C atoms, a branched or cyclic alkyl or alkoxy group having 3 to 20 C atoms, or an alkenyl or alkynyl group having 2 to 20 C atoms, wherein the above-mentioned groups are optionally substituted by one or more radicals R4 and wherein one or more CH2 groups in the above-mentioned groups are optionally replaced by —R4C═CR4—, —C≡C—, Si(R4)2, C═O, C═NR4, —C(═O)O—, —C(═O)NR4—, NR4, P(═O)(R4), —O—, —S—, SO, or SO2, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which is optionally substituted by one or more radicals R4, and wherein two or more radicals R3 are optionally linked to one another so as to define a ring;
• R4 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, C(═O)R5, CN, Si(R5)3, N(R5)2, P(═O)(R5)2, ORS, S(═O)R5, S(═O)2R5, a straight-chain alkyl or alkoxy group having 1 to 20 C atoms, a branched or cyclic alkyl or alkoxy group having 3 to 20 C atoms, or an alkenyl or alkynyl group having 2 to 20 C atoms, wherein the above-mentioned groups are optionally substituted by one or more radicals R5 and wherein one or more CH2 groups in the above-mentioned groups are optionally replaced by —R5C═CR5—, —C≡C—, Si(R5)2, C═O, C═NR5, —C(═O)O—, —C(═O)NR5—, NRS, P(═O)(R5), —O—, —S—, SO, or SO2, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which is optionally substituted by one or more radicals R5, and wherein two or more radicals R4 are optionally linked to one another so as to define a ring;
• R5 is on each occurrence, identically or differently, H, D, F, or an aliphatic, aromatic, or heteroaromatic organic radical having 1 to 20 C atoms, wherein one or more H atoms are optionally replaced by D or F, and wherein two or more substituents R5 are optionally linked to one another so as to define a ring;
• wherein at least one of the two groups Ar1 must contain 10 or more aromatic ring atoms;
• and
• wherein, if one of the two groups Ar1 is a phenyl group, the other of the two groups Ar1 must not contain more than 14 aromatic ring atoms.