Bifunctional Spacer Cation Enables High-Efficiency Chiral Red Quasi-2D Perovskite Light-Emitting Diodes via Defect Passivation and Chirality Enhancement
Jialin Yin, Danyang Zhao, Yifei Qiao, Jie Zhao, Rui Jiang, Pengfei Tian, Wanlu Zhang, Bingzhe Wang, Guichuan Xing, Ruiqian Guo, Shiliang Mei
Abstract
Quasi-two-dimensional (quasi-2D) perovskites are promising candidates for circularly polarized luminescence (CPL) materials and spin light-emitting diodes (LEDs), owing to their strong spin–orbit coupling, tunable chiral-inducing structures, and device compatibility. However, achieving high dissymmetry factors and efficient spin-LED performance remains challenging due to the limited chirality transfer and poor optical properties of existing chiral quasi-2D perovskites. In this work, we introduce a bifunctional achiral organic spacer, 2-phenoxyethanamine (POEA + ) into quasi-2D perovskites, resulting in mixed chiral and achiral spacer cations. The incorporation of POEA + not only passivates defects and improves the optical properties of the perovskite films but also enhances the chirality-induced spin selectivity (CISS) by facilitating efficient chirality transfer within the mixed spacer cation system and promoting a more effective energy transfer process. Additionally, the presence of POEA + promotes the formation of intermediate phases, which act as energy transfer channels, thereby enabling more efficient energy funneling and a stronger CISS effect. As a result, the mixed spacer cation perovskite film exhibits a significantly enhanced CPL signal at ∼701 nm, with a maximum photoluminescence dissymmetry factor of 5.4 × 10 –3 at room temperature. Furthermore, LEDs based on the optimized film demonstrate a high external quantum efficiency of 4.22%. This work proposes an effective strategy to simultaneously enhance the chiroptical properties of quasi-2D perovskites and improve the quality of the films, which shows great potential for future applications in chiroptoelectronics and spintronics.