Facile synthesis of a narrow-bandgap strong-donor-alt-strong-acceptor copolymer of poly(5,6-difluorobenzo-[c][1,2,5]-thiadiazole-alt-5H-dithieno[3,2-b:2′,3′-d]pyran) via direct C-H arylation polymerization

A narrow bandgap D-A conjugated polymer based on 5H-dithieno [3,2-b:2',3'-d]pyran alternating with 5,6-difluoro-2,1,3-benzothiadiazole (denoted as PDFI3T-alt-DTP) was synthesized via direct C-H arylation polymerization (DAP) as an atomically efficient protocol. The optimal reaction condition for the DAP gave the target polymers with moderate number-average molecular weights (M-n) using optimized catalytic condition of Pd2 (dba)3/(o-MeOPh)(3)P/PivOH/K2CO3 in o-xylene. UV-vis-NIR absorption spectra of the obtained polymers show the presence of aggregation and interchain interaction in thin films. H-1-NMR spectroscopic analysis indicates good C-H selectivity corresponding to an alternating strong-donor-alt strong -acceptor conjugated backbone. The hole mobility of the resulting polymers in a magnitude of 10(-4) cm(2)v(-1) S-1 was reached in bottom-gate top-contact field-effect transistors fabricated and tested under ambient conditions. (C) 2017 Elsevier Ltd. All rights reserved.