Push-Pull Effect Enables Large-Area Lead-Free Perovskite Light-Emitting Diodes via Electron Directional Transfer

Tin (Sn) perovskites have emerged as viable candidates for high-performance, lead-free perovskite light-emitting diodes (PeLEDs). However, the limited availability of efficient and stable Sn perovskites, and the development of large-area Sn PeLEDs encourage further research. Here, FPEA 2 SnI 4 (FPEAI, 4-fluoro-phenethylammonium iodide) perovskite is reported as a potential emitter for PeLEDs. To overcome the anisotropic carrier transport in layered FPEA 2 SnI 4 perovskites, an electronic push-pull effect strategy is introduced by incorporating 6-amino-4-hydroxy-2-naphthalenesulfonic acid (γ acid) molecule in FPEA 2 SnI 4 perovskites. The unique electronically push-pull configuration of γ acid establishes a cross-layer electron transfer channel, which mitigates electron aggregation within the organic layers, enhances electron injection and directional transfer, and effectively promotes radiative recombination. Furthermore, multifunctional γ acid provides multiple interaction sites for Sn perovskites, reducing defect state density and stabilizing FPEA 2 SnI 4 perovskites. Leveraging the enhanced robustness of FPEA 2 SnI 4 films with γ acid, a large-area Sn PeLED with an active area of 2.25 cm 2 , achieves a maximum luminance ( L max ) of 371 cd m −2 , a peak external quantum efficiency (EQE) of 15.49%, and an operational half-lifetime of 71.6 h at 100 cd m −2 . These findings underscore the application potential of Sn PeLEDs in the realms of solid-state lighting and planar display.