You Jingbi and Zhang Xingwang, Sci. Adv.: High-Efficiency Pure-Red Perovskite Light-Emitting Diodes Achieved via Strong Passivation with Ultra-Small Molecules

In recent years, perovskite light-emitting diodes (PeLEDs) have attracted widespread attention. However, halogen-vacancy defects in perovskites severely impede the development of high-efficiency devices. Conventional approaches typically rely on large-sized passivators, but the effectiveness of defect passivation is limited by weak bonding or significant steric hindrance. Based on density-functional theory calculations, Jingbi You and Xingwang Zhang at the Chinese Academy of Sciences, among others, predicted that ultra-small formate (Fa) and acetate (Ac) ligands exhibit more effective passivation due to their stronger binding to the perovskite lattice. By introducing these ultra-small cesium salts (CsFa/CsAc) at the buried interface, they can also diffuse into the bulk, achieving simultaneous passivation of both the buried interface and the bulk. Furthermore, the incorporation of CsFa/CsAc as additives enhances the hydrophilicity of the perovskite, thereby improving its crystallization. Leveraging these advantages, a pure-red PeLED with an external quantum efficiency of 24.2% at 639 nm was achieved.

Ji Jiang et al., Efficient pure-red perovskite light-emitting diodes with strong passivation via ultrasmall-sized molecules. Sci. Adv. 10, eadn5683 (2024). DOI: 10.1126/sciadv.adn5683 https://www.science.org/doi/10.1126/sciadv.adn5683