Molecular Intercalation Regulation of Solid-State Reaction Enables Thermally Evaporated FASnI3 Light-Emitting Diodes
Junhao Liu, Xueli Li, Qingxun Guo, Yajing Li, Haoyu Zheng, Xiaorong Shi, Yuxuan Wei, Yutian Xu, Na Meng, Boya Hu, Mengxun Kong, Huili Ma, Xue Min, Kui Xu, Yonghua ChenAbstract
Tin-based perovskite light-emitting diodes (PeLEDs), particularly FASnI3-based devices, are promising for lead-free near-infrared optoelectronics. However, thermally evaporated FASnI3-PeLEDs remain unexplored because of the difficulty in controlling solid-state precursor diffusion, reaction, and crystallization. Here, we develop a molecular intercalation strategy to regulate the solid-state reaction and crystallization of layer-by-layer evaporated FASnI3. A tryptophan (Trp) interlayer modulates interfacial reaction kinetics and precursor interdiffusion, enabling controlled crystallization and improved structural quality. Meanwhile, Trp interacts strongly with the Sn-based perovskite lattice, suppressing defect formation and Sn2+ oxidation and thereby reducing nonradiative recombination. The resulting fully thermally evaporated FASnI3-PeLEDs achieve a peak radiance exceeding 100 W sr–1 m–2. Large-area devices up to 2500 mm2 and patterned devices with uniform emission are also demonstrated, highlighting the potential of molecularly regulated solid-state crystallization for scalable vacuum-processed perovskite optoelectronics.