Organic semiconducting compounds

A compound selected from formulae IA and IB

• wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings
• one of Z1 and Z2 is O or S and the other is CR1R2, SiR1R2 or C═CR1R2,
• one of Z3 and Z4 is O or S and the other is CR1R2, SiR1R2 or C═CR1R2,
• wherein Z2 and Z3 are not at the same time O,
• Ar1 is selected from the following formulae
• Ar2, Ar3 are trivalent arylene or heteroarylene which has from 5 to 20 ring atoms, which is mono- or polycyclic, which optionally contains fused rings, and which is unsubstituted or substituted by one or more identical or different groups L, or CY1═CY2 or —C≡C—,
• Ar4-7 are divalent arylene or heteroarylene which has from 5 to 20 ring atoms, which is mono- or polycyclic, which optionally contains fused rings, and which is unsubstituted or substituted by one or more identical or different groups L, or CY1═CY2 or —C≡C—,
• Y1, Y2 are H, F, Cl or CN,
• W1, W2, W3 are S, O, Se or C═O,
• W4 is S, O or NR0,
• R1, R2 are RW, H, F, Cl, CN, or straight-chain, branched or cyclic alkyl with 1 to 30 C atoms, in which one or more CH2 groups are each optionally replaced by —O—, —S—, —C(═O)—, —C(═S)—, —C(═O)—O—, —O—C(═O)—, —NR0—, —SiR0R00—, —CF2—, —CR0═CR00—, —CY1═CY2— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are each optionally replaced by F, Cl, Br, I or CN, and in which one or more CH2 or CH3 groups are each optionally replaced by a cationic or anionic group, or aryl, heteroaryl, arylalkyl, heteroarylalkyl, aryloxy or heteroaryloxy, wherein each of the aforementioned cyclic groups has 5 to 20 ring atoms, is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups L,
• and the pair of R1 and R2, together with the C or Si atom to which they are attached, may also form a spiro group with 5 to 20 ring atoms which is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups L,
• R5-8 are H, F, Cl, CN, or straight-chain, branched or cyclic alkyl with 1 to 30 C atoms, in which one or more CH2 groups are each optionally replaced by —O—, —S—, —C(═O)—, —C(═S)—, —C(═O)—O—, —O—C(═O)—, —NR0—, —SiR0R00—, —CF2—, —CR0═CR00—, —CY1═CY2— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are each optionally replaced by F, Cl, Br, I or CN, and in which one or more CH2 or CH3 groups are each optionally replaced by a cationic or anionic group, or aryl, heteroaryl, arylalkyl, heteroarylalkyl, aryloxy or heteroaryloxy, wherein each of the aforementioned cyclic groups has 5 to 20 ring atoms, is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups L,
• RW is an electron withdrawing group,
• L is F, Cl, —NO2, —CN, —NC, —NCO, —NCS, —OCN, —SCN, R0, OR0, SR0, —C(═O)X0, —C(═O)R0, —C(═O)—OR0, —O—C(═O)—R0, —NH2, —NHR0, —NR0R00, —C(═O)NHR0, —C(═O)NR0R00, —SO3R0, —SO2R0, —OH, —CF3, —SF5, or optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 30 C atoms that is optionally substituted and optionally comprises one or more hetero atoms,
• R0, R00 are H or straight-chain or branched alkyl with 1 to 20 C atoms that is optionally fluorinated,
• X0 is halogen,
• RT1, RT2 are each independently selected from the group consisting of the following formulae
• Ra, Rb are aryl or heteroaryl, each having from 4 to 30 ring atoms, optionally containing fused rings and being unsubstituted or substituted with one or more groups L, or one of the meanings given for L,
• R*, R**, R*** are alkyl with 1 to 20 C atoms which is straight-chain, branched or cyclic, and is unsubstituted, or substituted with one or more F or Cl atoms or CN groups, or perfluorinated, and in which one or more C atoms are optionally replaced by —O—, —S—, —C(═O)—, —C(═S)—, —SiR0R00—, —NR0R00—, —CHR0═CR00— or —C≡C— such that O- and/or S-atoms are not directly linked to each other,
• L′ is H or one of the meanings of L,
• Y1, Y2 are H, F, Cl or CN,
• r is 0, 1, 2, 3 or 4,
• s is 0, 1, 2, 3, 4 or 5,
• t is 0, 1, 2 or 3,
• u is 0, 1 or 2,
• a, b are 0, 1, 2 or 3,
• c, d are 0, 1, 2 or 3,
• m is 1, 2 or 3,
• k is 1, 2 or 3.