Indoleacetic acid-mediated suppression of oxidation and crystallization in tin perovskite LEDs

Abstract

Two-dimensional organic–inorganic hybrid tin-based halide perovskite materials are highly promising candidates for next-generation light-emitting diodes (LEDs), owing to their high color purity and compatibility with solution-based fabrication. However, the intrinsic oxidative properties of Sn²⁺ and the rapid crystallization kinetics of tin-based systems cause poor stability and high defect density of tin-based perovskites, limiting the further development of these perovskites. Here, we report 2-methyl-3-indoleacetic acid (MIAA) as an effective molecular additive for the PEA₂SnI₄ system. We demonstrate that MIAA can not only suppress the oxidation of Sn²⁺, but also effectively retard the crystallization rate of PEA₂SnI₄. Both of these regulatory effects significantly enhance the crystalline quality of the PEA₂SnI₄ perovskite film. Consequently, the resulting devices exhibit substantially enhanced performance, achieving an EQE of 1.5% for pure red emission at 621 nm, with a maximum luminance of 1412 cd m⁻². These results underscore that the MIAA-mediated additive strategy effectively improves the performance of tin-based perovskite LEDs by suppressing Sn²⁺ oxidation and rapid crystallization, providing a viable strategy for advancing lead-free perovskite optoelectronics.