A Binary Solution Strategy Enables High-Efficiency Quasi-2D Perovskite Solar Cells with Excellent Thermal Stability
Tong Yue, Kang Li, Xing Li, Nafees Ahmad, Hui Kang, Qian Cheng, Yingyu Zhang, Yingyu Zhang, Yaochang Yue, Ya‐Nan Jing, Boxin Wang, Shilin Li, Jieyi Chen, Gaosheng Huang, Yanxun Li, Zihao Fu, Tong Wu, Saud Uz Zafar, Li‐Na Zhu, Huiqiong Zhou, Yuan Zhang, Yuan Zhang
Abstract
Quasi-two-dimensional (2D) perovskites are highly promising light-harvesting materials for commercialization of perovskite solar cells (PSCs) owing to the excellent materials stability. However, the coexistence of multiple n -value species in 2D perovskites often causes increased complexities in crystallization that can negatively affect the eventual photovoltaic performance. Herein, we present a binary solution based strategy via introducing nontoxic and widely accessible CH 3 COOH (HAc) as a co-solvent for preparing high-quality 2D perovskite films. Based on a 2D perovskite model system, (AA) 2 MA 4 Pb 5 I 16 ( n = 5), we show that the prenucleation and grain growth kinetics are appreciably modified with HAc, which benefits from the strong electron-donating ability of HAc with the key component of PbI 2, leading to formation of favorable cluster aggregates and resultant modulation of crystal growth. With the HAc-based method, the devices yield a boosted photovoltaic efficiency of 18.55% with an impressive photovoltage of 1.26 V. The champion cells exhibit a supreme thermal stability, showing <3% efficiency degradation under continuous thermal aging for 800 h.