Incorporating Semiflexible Linkers into Double-Cable Conjugated Polymers via Click Reaction

Single-component organic solar cells (SCOSCs) have been recognized as the promising photovoltaic technology due to the excellent stability, but their power conversion efficiencies (PCEs) are far lagging their bulk-heterojunction counterparts. Current strategies have mainly focused on the new polymer backbones and pendent acceptors, while linkers are ignored. Here, we develop a new semiflexible linker consisting of the triazole unit and alkyl chain via Click reaction between alkyne and azide end groups, which is different from the alkyl linkers in previous reports. Two new polymers P1 and P2 with different linker lengths (C6H12-triazole for P1 and C12H24-triazole for P2) were developed. The optical properties, energy levels, photovoltaic performance and morphology of the two polymers were systematically studied and compared with a similar alkyl chain linked polymer JP02 in our previous work. Unfortunately, both the two polymers-based SCOSC devices exhibited low PCEs due to the lower short-circuit current density (Jsc) and fill factors (FF) than JP02 based cells, which may be ascribed to the decreased charge transporting properties originated from the increased π-π stacking distance of the two polymers. Our work will offer a new strategy to design new double-cable polymers for SCOSCs.