Surface Reconstruction for Efficient and Stable Monolithic Perovskite/Silicon Tandem Solar Cells with Greatly Suppressed Residual Strain
Xin Li, Zhiqin Ying, Jingming Zheng, Xinlong Wang, Ying Chen, Ming Wu, Chuanxiao Xiao, Jingsong Sun, Chunhui Shou, Zhenhai Yang, Yuheng Zeng, Xi Yang, Jichun Ye
Abstract
Abstract Despite the swift rise in power conversion efficiency (PCE) to more than 32%, the instability of perovskite/silicon tandem solar cells is still one of the key obstacles to practical application and is closely related to the residual strain of perovskite films. Herein, a simple surface reconstruction strategy is developed to achieve a global incorporation of butylammonium cations at both surface and bulk grain boundaries by post‐treating perovskite films with a mixture of N,N ‐dimethylformamide and n ‐butylammonium iodide in isopropanol solvent, enabling strain‐free perovskite films with simultaneously reduced defect density, suppressed ion migration, and improved energy level alignment. As a result, the corresponding single‐junction perovskite solar cells yield a champion PCE of 21.8%, while maintaining 100% and 81% of their initial PCEs without encapsulation after storage for over 2500 h in N 2 and 1800 h in air, respectively. Remarkably, a certified stabilized PCE of 29.0% for the monolithic perovskite/silicon tandems based on tunnel oxide passivated contacts is further demonstrated. The unencapsulated tandem device retains 86.6% of its initial performance after 306 h at maximum power point (MPP) tracking under continuous xenon‐lamp illumination without filtering ultraviolet light (in air, 20–35 °C, 25–75%RH, most often ≈60%RH).