Flexible‐Linked Oligomeric Acceptors: Precise Synthesis and Enhanced Photovoltaic/Mechanical Properties for Stretchable Devices

Abstract

Abstract Intrinsically stretchable organic solar cells (IS‐OSCs) are among the most promising technologies for wearable power applications. However, the development of electron acceptors that simultaneously meet the demands for high performance and mechanical stretchability remains a significant challenge. In this study, we creatively synthesized three oligomeric acceptors with flexible linkers (2YF‐Br, 4YF‐T, and 6YF‐BT) and achieved both high efficiency and mechanical robustness in IS‐OSCs. Benefiting from an improved fibrous morphology and excellent charge dynamics, rigid OSCs based on 4YF‐T demonstrated a superior power conversion efficiency (PCE) of 18.76%, outperforming devices based on 2YF‐Br and 6YF‐BT. Additionally, the thermal stability of rigid OSCs progressively improved with increasing molecular weight, from 2YF‐Br to 6YF‐BT. Furthermore, the enlarged molecular weight of the acceptors significantly enhanced mechanical stretchability, with crack‐onset strain (COS) values of 16.11%, 20.62%, and 25.92% for 2YF‐Br, 4YF‐T, and 6YF‐BT, respectively. Importantly, as molecular weight increased, the mechanical robustness of IS‐OSCs also improved, with 6YF‐BT‐based devices achieving remarkable stretchability (strain at PCE 80%  = 35%). This study introduces a new class of high‐molecular‐weight acceptors with well‐defined structures, paving the way for the advancement and practical application of IS‐OSCs in wearable electronics.