Regulating the Auger Recombination Process in Two-Dimensional Sn-Based Halide Perovskites

Two-dimensional tin iodide perovskite light-emitting diodes (LEDs) suffer from severe efficiency roll-off owing to the strong Auger recombination process. However, there has been controversy about the influence of defects and phonon scattering in regulating the Auger recombination process of Sn-based halide perovskites. In this study, we combine cation engineering, temperature-dependent transient absorption spectroscopy, and defect repair engineering to systematically investigate these effects on the Auger recombination rate of layered A₂SnI₄ (A = C₆H₅CH₂CH₂NH₃⁺ (PEA⁺) and CH₃(CH₂)₃NH₃⁺ (BA⁺)) perovskites. The defect scattering and exciton–phonon scattering can reduce the exciton diffusion rate to influence the Auger recombination rate. Our study further reveals that defect scattering dominates in regulating the Auger recombination rate in two-dimensional Sn-based perovskites and is stronger than the exciton–phonon coupling effect. This work provides further insight into the inherent factors influencing the development of two-dimensional Sn-based halide perovskites in laser and LED technologies.