Fluorene-based conjugated polymers containing acetylene linkages for photovoltaics

Conjugated polymers have attracted considerable attention due to their versatile applications in the fields of organic optoelectronic devices. In this study, we describe the synthesis and photovoltaic applications of a series of donor-acceptor (D-A) type conjugated polymers having acetylene-linked fluorene-based donor monomers and benzothiadiazole-based acceptor monomers. The link pattern (carbon-carbon single, triple bond) has a significant influence on the solubility, thermal, optical, and structural properties of these polymers. Compared to C-C single-bond linked polymers PFu-1 and PFu-3, the UV absorption of triple-bond linked PFu-2 and PFu-4 polymers is red-shifted due to higher coplanarity and effective p-p stacking of polymer backbones. The range of the power conversion efficiency of bulk heterojunction solar cells fabricated by the resulting polymer series is 1.02-1.30%.