High-Performance Intrinsically-Stretchable Organic Solar Cells Enabled by Electron Acceptors with Flexible Linkers.

Intrinsically stretchable organic solar cells (IS-OSCs) are emerging as promising candidates for powering next-generation wearable electronics. However, developing molecular design strategies to achieve both high efficiency and mechanical robustness in IS-OSCs remains a significant challenge. In this work, we present a novel approach by synthesizing a dimerized electron acceptor (DY-FBrL) that enables rigid OSCs with a high power conversion efficiency (PCE) of 18.75 % and a crack-onset strain (COS) of 18.54 %. The enhanced PCE and stretchability of DY-FBrL-based devices are attributed to its extended π-conjugated backbone and elongated side chains. Furthermore, we introduce an innovative polymerized acceptor (PDY-FL), synthesized via the polymerization of DY-FBrL. While PDY-FL-based devices exhibit a slightly lower PCE of 14.13 %, they achieve a significantly higher COS of 23.45 %, representing one of the highest PCEs reported for polymerized acceptors containing only flexible linkers. Consequently, IS-OSCs fabricated using DY-FBrL and PDY-FL achieve notable PCEs of 14.31 % and 11.61 %, respectively. Additionally, the device stretchability improves progressively from Y6 (strain at PCE80%=11 %), to DY-FBrL (strain at PCE80%=23 %), and PDY-FL (strain at PCE80%=31 %). This study presents a promising molecular design strategy for tailoring electron acceptor structures, offering a new pathway to develop high-performance IS-OSCs with enhanced mechanical properties.