Indacenodithiophene and indacenodiselenophene polymers and their use as organic semiconductors

A conjugated polymer of formula IIa

• wherein
• one of A1 and A2 is a single bond and the other is CR1R2,
• one of A3 and A4 is a single bond and the other is CR3R4,
• one of U1 and U2 is —CH═ or ═CH— and the other is —X—,
• one of U3 and U4 is —CH═ or ═CH— and the other is —X—,
• provided that if Ai is a single bond then the corresponding Ui is X (with i being an index from 1-4),
• X is in each occurrence independently selected from —S— and —Se—,
• R1-4 are independently of each other identical or different groups which are straight-chain or branched-chain, C1-C20-alkyl, C1-C20-alkoxy, C2-C20-alkenyl, C2-C20-alkynyl, C1-C20-thioalkyl, C1-C20-silyl, C1-C20-ester, C1-C20-amino, or C1-C20-fluoroalkyl,
• Ar1 and Ar2 are independently of each other
• 2,1,3-benzoselenadiazole-4,7-diyl,
• 2,3-dicyano-1,4-phenylene,
• 2,5-dicyano, 1,4-phenylene,
• 2,3-difluro-1,4-phenylene,
• 2,5-difluoro, 1,4-phenylene, or
• 2,3,5,6-tetrafluoro, 1,4-phenylene, all of which are unsubstituted, mono- or polysubstituted with R1 as defined above
• m1 and m2 are independently of each other 0 or 1, 2, 3 or 4, wherein X in each occurrence is —S—, m1 or m2 is >0,
• n is an integer >1, and
• R5 and R6 independently of each other have one of the meanings of R1 above or denote H halogen, —CH2Cl, —CHO, —CH═CH2, —SiR′R″R′″, —SnR′R″R′″, —BR′R″, —B(OR′)(OR″), —B(OH)2, or P-Sp-, wherein P is a polymerizable group and Sp is a spacer group or a single bond, and R′, R″ and R′″ are independently of each other H or an optionally substituted carbyl or hydrocarbyl group optionally comprising one or more hetero atoms, and R′ and R″ may also form a ring together with the hetero atom to which they are attached.