Accelerating\nAdditive-Assisted\nDefect Passivation\nvia the Structural Isomer Effect for Highly Efficient and Stable Perovskite\nSolar Cells

Defects\nin hybrid perovskites have hindered the development\nof\nhighly efficient and stable hybrid perovskite solar cells (PSCs).\nTherefore, researchers have used additives to passivate defects in\nhybrid perovskites; however, detailed studies on multifunctional group\nadditives with structural isomers are limited. In this letter, we\nreport the improved defect passivation ability of additives through\nthe structural isomer effect and enhanced photovoltaic performance\nusing this effect. l-Alanine methyl ester hydrochloride (l-AMECl) and its structural isomer, β-AMECl, were used\nto understand the influence of structural variations in functional\ngroups. The structural isomer β-AMECl effectively reduced the\ntrap density in the hybrid perovskite, thereby enhancing the photovoltaic\nparameters. Consequently, we achieved a power conversion efficiency\nof 24.25% with β-AMECl, which is the best result among PSCs\nusing additives. Additionally, the PSCs with β-AMECl maintained\nan initial efficiency of 94% over 2500 h at 25 °C and 25% relative\nhumidity, showing improved long-term stability.