Direct Arylation Polycondensation of 2,5-Dithienylsilole with a Series of Difluorobenzodiimine-Based Electron Acceptors

Abstract

This paper describes the use of direct arylation polymerization (DArP) reaction to synthesize three new 2,5-dithienylsilole polymers with a series of difluorobenzodiimine-based electron acceptors: 5,6-difluoro[2,1,3]benzothiadiazole (DFBT), 5,6-difluoro[2,1,3]benzoselenadiazole (DFBSe), and 5,6-difluoro[2,1,3]benzotriazole (DFBTA). The Stille cross-coupling polycondensation reaction was performed to confirm the structural quality of the polymers; however, only low molecular weight oligomers were obtained. This result demonstrates the power of the DArP method to prepare polymers containing strong electron-deficient monomers. During our investigation, it was found that Fagnou’s condition did not produce polymers, whereas the condition reported by Ozawa and co-workers gave polymers with moderate molecular weights. This is the first known example of the synthesis of 2,5-dithienylsilole-containing polymers by the DArP. Our polymers have reduced band gaps (<2.0 eV), and P1 provided hole mobility values in the r...