Constructing a Double-Cable Polymer Acceptor for Efficient All- Polymer Solar Cells with a Non-Radiative Recombination Energy Loss of 0.16 eV

While vigorous progress with all-polymer solar cells (all-PSCs) has been achieved, the power conversion efficiency (PCE) of all-PSCs is significantly suppressed by polymer acceptors (PAs) that are short on broad light harvesting, high electron mobility, and low energy loss. Here, we demonstrate a promising design strategy to synthesize a graft-structural double-cable polythiophene-based conjugated PA PT-YTz based on a fused-ring benzotriazole-based small-molecule acceptor framework as a pendant side unit. PT-YTz possesses an intensified and extended absorption spectrum, enhanced electron mobility, and favorable active layer morphology when blended with PM6. The optimized PM6/PT-YTz all-PSCs exhibit a high PCE of 16.15% with an energy loss of 0.49 eV and a remarkably low non-radiative voltage loss of only 0.16 eV. This work enables new design directions and strategies to construct narrow band gap PAs toward successful applications in high-performance all-PSCs.

Automated summary

This study demonstrates a promising design strategy to synthesize a polymer acceptor PT-YTz with intensified and extended absorption spectrum and enhanced electron mobility. The PM6/PT-YTz all-PSCs showed favorable active layer morphology and high efficiency.