Organic semiconducting compounds

A compound comprising a unit of formula I

• wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings
• one of X1 and X2 is F and the other of X1 and X2 is Cl,
• U is NR, O, S, Se or Te,
• R is H or linear, branched or cyclic alkyl with 1 to 30 C atoms, in which one or more CH2 groups are 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 optionally replaced by F, Cl, Br, I or CN,
• Y1, Y2 are, each independently, H, F, Cl or CN,
• R0, R00 are, each independently, H or linear or branched alkyl with 1 to 20 atoms that is optionally fluorinated,
• with the proviso that the following compounds are excluded
• wherein X1, X2 and U are as defined above, A and B denote H or F, or one of A and B denotes F and the other denotes Cl,
• and,
• the compound which is a small molecule or oligomer of formula S1 or S2
• RT1—(Ar11)a1—[(Ar13)c1—U1-(Ar14)d1—]e1(Ar12)b1—RT2 S1
• RT1—(Ar21)a2—(Ar23)c2-[(core1)f2-(Ar25)e2-(core2)g2]h2-(Ar24)d2—(Ar22)b2—RT2 S2
• wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings
• U1 is a unit of formula I,
• Ar11-14 are, each independently, arylene or heteroarylene that has from 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 R1, or —CY1═CY2— or —C≡C—,
• Ar21-25 are, each independently, arylene or heteroarylene that has from 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 R1, or —CY1═CY2— or —C≡C—,
• wherein at least one of Ar21-25 denotes U1,
• core1, core2 are, each independently, polycyclic, fused arylene or heteroarylene that has from 8 to 30 ring atoms, and is unsubstituted or substituted by one or more identical or different groups R1,
• R1 is 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 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 optionally replaced by F, Cl, Br, I or CN, and in which one or more CH2 or CH3 groups are 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, does optionally contain fused rings, and is unsubstituted or substituted by one or more identical or different groups L,
• L is F, Cl, —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, —NO2, —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, wherein X0 is halogen,
• Y1, Y2 are, each independently, H, F, Cl or CN,
• R0, R00 are, each independently, H or linear or branched alkyl with 1 to 20 C atoms that is optionally fluorinated,
• RT1, RT2 are, each independently, H, F, Cl, Br, —NO2, or a carbyl or hydrocarbyl group with 1 to 30 C atoms that is optionally substituted by one or more groups L and optionally comprises one or more hetero atoms,
• and wherein in formula S2 at least one of RT1 and RT2 is H or an electron withdrawing group,
• a1-d1 are, each independently, 0, 1, 2 or 3, preferably with at least one of a1-d1 being ≥1,
• e1 is 1, 2 or 3,
• a2-e2 are, each independently, 0, 1, 2 or 3, with at least one of a2, b2, c2 and d2 being ≥1,
• f2 is 1, 2 or 3,
• g2 is 0, 1, 2 or 3,
• h2 is 1, 2 or 3,
• and,
• which is selected of formula S2 wherein those of Ar21-25 that are not a unit of formula I are each independently and on each occurrence identically or differently selected from the following formulae and their mirror images:
• wherein X21, X22, X23 and X24 denote H, F, Cl, —CN, R0, OR0 or C(═O)OR0, and R0 is H or straight-chain or branched alkyl with 1 to 20 C atoms that is optionally fluorinated, and wherein in formula AR6 those groups are excluded wherein one of X21 and X22 is F and the other of X21 and X22 is Cl.