Benzothiadiazole-Based Double-Cable Conjugated Polymers for Single-Component Organic Solar Cells with Efficiency over 4%

Abstract

Double-cable conjugated polymers have been successfully applied into single-component organic solar cells (SCOSCs) in recent years. The chemical structures of conjugated backbones and aromatic cable units, and the rational tuning of nanophase separation between them, are clue factors for double-cable polymers to further enhance the photovoltaic performance. In this work, we introduced a benzothiadiazole (BT) unit into the backbone of double-cable polymers, where BT was conjugated with two linkers, thiophene and thienothiophene, which were used to control the aggregation behavior. The studies reveal that, although thiophene-containing polymer backbones show less aggregation tendency, the corresponding perylene bisimide (PBI) side units form better stacking. Therefore, thiophene-based double-cable polymers had high hole/electron mobilities and hence a high efficiency of 4.35%, while thienothiophene-containing polymer exhibited a low efficiency of 2.35%. These results demonstrate that BT-polymers display a promising application for high performance double-cable conjugated polymers for SCOSCs.