Over 18% Efficiency of All‐Polymer Solar Cells with Long‐Term Stability Enabled by Y6 as a Solid Additive
Zhongwei Ge, Jiawei Qiao, Yun Li, Jiali Song, Chen Zhang, Zhen Fu, Min Hun Jee, Xiaotao Hao, Han Young Woo, Yanming Sun
Abstract
Abstract Morphology control greatly influences the power conversion efficiency (PCE) and long‐term stability of all‐polymer solar cells (all‐PSCs); however, it remains challenging owing to their complex crystallization behavior. Herein, a small amount of Y6 (2 wt%) is introduced as a solid additive into a PM6:PY‐DT blend. Y6 remained inside the active layer and interacted with PY‐DT to form a well‐mixed phase. Increased molecular packing, enlarged phase separation size, and decreased trap density are observed for the Y6‐processed PM6:PY‐DT blend. The corresponding devices showed simultaneously improved short‐circuit current and fill factor, achieving a high PCE of over 18% and excellent long‐term stability, with a T 80 lifetime of 1180 h and an extrapolated T 70 lifetime of 9185 h at maximum power point tracking (MPP) conditions under continuous one‐sun illumination. This Y6‐assisted strategy is successfully applied to other all‐polymer blends, demonstrating its universality for all‐PSCs. This work paves a new way for the fabrication of all‐PSCs with high efficiency and superior long‐term stability.