China develops new polymer solar cells with 19.1% efficiency

Researchers from Wuhan University of Technology in China have developed a new polymer solar cell (PSC) that achieves a power conversion efficiency (PCE) of 19.1% while maintaining exceptional operational stability. Published in the journal Matter, the study reveals that by incorporating small-molecule acceptors into polymer matrices, the team improved molecular packing and charge transport, resulting in flexible devices that retain 97% of their initial efficiency after 2,000 hours of exposure to air. This corresponds to an extrapolated device lifetime exceeding 100,000 hours, marking a significant advancement toward the commercial viability of PSCs. The research addresses the longstanding challenges of insufficient performance and stability in polymer solar cells by elucidating the photochemical degradation mechanisms of polymer acceptors. Specifically, the study identifies weak chemical bonds in polymeric acceptors that reduce photostability and demonstrates that blending small molecules mitigates chain entanglement and free volume, enhancing both photochemical and thermal stability. These findings not only improve the efficiency and durability