Stepwise Tailoring of Perovskite Nucleation Dynamics and Defect Formation Using a Supersaturation‐Suppression Layer for Developing Efficient and Stable Perovskite Solar Cells

Abstract

Tailoring crystal growth and defects in perovskites, a viable strategy for suppressing non‐radiative recombination, is widely employed for developing efficient and stable perovskite solar cells (PSCs). However, simultaneous tailoring of crystal growth and defects in PSCs is challenging owing to several limitations; for example, excessive interactions between additives and perovskite precursors impede crystallization, and additive‐induced impurity phases can substantially increase the defect density in perovskite films. In this study, we introduced a metal‐induced supersaturation‐suppression layer (SSL) as a pseudo‐additive interfacial layer to tailor the crystallization dynamics and defect formation in perovskite crystals in steps. The proposed perovskite modification process involves an SSL‐induced metal–halide ion reaction, which modulates the crystallization kinetics for grain growth and enables the formation of metal–halide complex anion adducts that can reduce crystalline defects and suppress non‐radiative recombination while facilitating preferential perovskite crystal growth by alleviating residual strains. Because of these stepwise synergistic effects, the SSL‐based PSCs exhibited significantly improved device performances (23.4%), low hysteresis losses, and enhanced atmospheric operational stability.