Direct Arylation Polycondensation toward Water/Alcohol-Soluble Conjugated Polymers: Influence of Side Chain Functional Groups.

Direct arylation of 2,7-dibromofluorene with n -octyl, 6-diethoxylphosphorylhexyl, 6-( N , N -diethylamino)hexyl or 6-bromohexyl side chains and 1,2,4,5-tetrafluorobenzene (TFB) were conducted to investigate the effect of side chain functional groups on the coupling, and the resulting TFB-substituted fluorene derivatives were used as C-H monomers for the synthesis of water/alcohol soluble conjugated polymers (WSCPs) by direct arylation polycondensation (DArP). The direct arylation and DArP of the monomers carrying phosphonate and amino groups went on smoothly in typical DArP conditions, that is, Pd(OAc) 2 /P t Bu 2 Me-HBF 4 /base/DMAc and Pd 2 (dba) 3 ·CHCl 3 /P( o -MeOPh) 3 /pivalic acid/base/THF, and high molecular weight polymers with these groups were successfully synthesized. However, for fluorene-monomers with bromohexyl side chains, the target products could not be obtained from the above conditions but could be prepared in the absence of carboxylic acid additives in low polar solvents. With the above DArP-made polymers as cathode interfacial layers, high performance organic solar cells (OSCs) were successfully fabricated.