Title： | Thermally Stable All-Polymer Solar Cells with High Tolerance on Blend Ratios |
Authors： | Yannan Zhang, Yalong Xu, Michael J. Ford, Fangchao Li, Jianxia Sun, Xufeng Ling, Yongjie Wang, Jinan Gu, Jianyu Yuan,* and Wanli Ma* |
Institutions： | 1Institute of Functional Nano & Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Joint International Research Laboratory of Carbon-Based Functional Materials and Devices Soochow University 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, P. R. China 2Center of Polymers and Organic Solids Materials Department University of California Santa Barbara, CA 93106, USA |
Abstract： | Tuning the blend composition is an essential step to optimize the power conversion effciency (PCE) of organic bulk heterojunction (BHJ) solar cells. PCEs from devices of unoptimized donor: acceptor (D:A) weight ratio are generally significantly lower than optimized devices. Here, two high-performance organic nonfullerene BHJ blends PBDB-T:ITIC and PBDB-T:N2200 are adopted to investigate the effect of blend ratio on device performance. It is found that the PCEs of polymer-polymer (PBDB-T:N2200) blend are more tolerant to composition changes, relative to polymer-molecule (PBDB-T:ITIC) devices. In both systems, short-circuit current density (Jsc) is tracked closely with PCE, indicating that exciton dissociation and transport strongly influence PCEs. With dilute acceptor concentrations, polymer-polymer blends maintain high electron mobility relative to the polymer-molecule blends, which explains the dramatic difference in PCEs between them as a function of D:A blend ratio. In addition, polymer-polymer solar cells, especially at high D:A blend ratio, are stable (less than 5% relative loss) over 70 d under continuous heating at 80 °C in a glovebox without encapsulation. This work demonstrates that all-polymersolar cells show advantage in operational lifetime under thermal stress and blend-ratio resilience, which indicates their high potential for designing of stable and scalable solar cells. |
IF： | 16.721 |
Link： | https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.201800029 Editor: Danting Xiang |