Polymer Acceptor with Hydrogen-Bonding Functionality for Efficient and Mechanically Robust Ternary Organic Solar Cells
Qingpei Wan, Hyerin Jeon, Soodeok Seo, Eun Sung Oh, Jin‐Woo Lee, Cheng Wang, Taek‐Soo Kim, Bumjoon J. Kim, Barry C. Thompson
Abstract
Organic solar cells (OSCs) with a high power conversion efficiency (PCE) and excellent stretchability are required for applications in wearable devices. However, the use of rigid and highly crystalline small-molecule acceptors (SMAs) limits the mechanical robustness of OSCs. To overcome this limitation, a stretchable and conjugated polymer acceptor (P A, N2200-ThyDap) was synthesized and introduced as the third component to the benchmark polymer donor (P D ):SMA system PM6:Y6-BO. N2200-ThyDap was designed to incorporate hydrogen bonding into the N2200 P A backbone using thymine (Thy) and diaminopyrazine (Dap) units, and the neat film shows excellent stretchability (crack onset strain (COS) = 28.2%) compared to the P A of similar molecular weight without hydrogen bonding (N2200, COS = 1.5%). The N2200-ThyDap-incorporated ternary system (PM6:Y6-BO:N2200-ThyDap) exhibits a higher PCE (16.4%) than the reference binary (PM6:Y6-BO, PCE = 15.4%) and N2200-incorporated control ternary system (PCE = 14.7%). The PM6:Y6-BO:N2200-ThyDap ternary blend film achieves a higher stretchability (COS = 4.8%) than the PM6:Y6-BO binary (COS = 2.1%) and PM6:Y6-BO:N2200 ternary (COS = 2.4%) films. It is likely that a stronger intermolecular interaction enabled by N2200-ThyDap leads to higher photovoltaic performance and improved stretchability.