Efficient Red Sn-Based Perovskite Light Emitting Diodes by a Competitive Antioxidation Strategy

Tin (Sn)-based perovskite light-emitting diodes (PeLEDs) have emerged as a promising candidate for next-generation displays because of their eco-friendliness, exceptional optoelectronic properties, and cost-effective solution processability. However, their electroluminescence performance still lags behind their lead (Pb) counterparts, primarily due to the undesired Sn²⁺ oxidation to Sn4+ and the rapid crystallization of Sn-based perovskite, resulting in high defect density as well as poor film quality. Herein, we reported a competitive antioxidation strategy by utilizing a phosphorus ylide, namely (triphenylphosphoranilidene) acetaldehyde (TPPA), to suppress the oxidation of Sn²⁺ and regulate the growth kinetics, simultaneously. The TPPA with highly active polar phosphorus-carbon bonds can be oxidized prior to Sn²⁺, and their large steric hindrance can slow down the crystallization process of tin-based perovskite. Moreover, the main product from the oxidation reaction, namely triphenylphosphine oxide (TPPO), can further passivate defects by coordinating with SnI₆ octahedra. The resulting Sn-based perovskite film exhibits enhanced optical properties and uniform, dense morphology. Leveraging these improvements, the optimized PeLED delivers pure-red light emission with Commission Internationale de L’Eclairage (CIE) color coordinates of (0.69, 0.30), an external quantum efficiency (EQE) of 8.1% and maximum luminance of 672 cd m^-2. This work provides a facile route to enhance the overall performance of Sn-based PeLEDs.