Crystallization Manipulation of Wide‐bandgap Perovskite by Amino Acid Derivative for High Performance Solar Cells

Abstract Developing high‐quality wide bandgap (WBG) perovskites with ≈ 1.68 eV bandgap is essential for constructing efficient tandem devices. However, WBG perovskite solar cells (PSCs) always suffer from large open‐circuit voltage ( V OC ) loss and unstable power output under operation. These challenges are mainly originated from poor film quality due to uncontrollable fast crystallization of high‐bromide‐content WBG perovskites and numerous defect sites. In this study, D‐arginine iodide (DAI) is synthesized and used it as an additive to improve the quality of WBG perovskite films. It is revealed that the multi‐functional groups in DAI favorably interact with perovskite precursors, fundamentally retarding the crystallization process of perovskite grains. The yielded perovskite film exhibits significantly enlarged grain size and reduced grain boundaries, which lead to the reduction of defects, residual stress, and consequently suppressed non‐radiative recombination, ion migration, and light‐induced halide segregation. Consequently, the DAI‐incorporated PSCs achieve a 23.1% power conversion efficiency (PCE), with a high V OC of 1.266 V (0.414 V V OC loss). Encouragingly, the operational stability of PSCs with DAI incorporation has been substantially enhanced by preserving 91.7% PCE for over 700 h, outperforming the reference with 55.7% PCE retaining after 430 h.