He Siwei, Qin Lanxin, Liu Zhengzheng, Kang Jae-Wook, Luo Jiajun, Du Juan
School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, People's Republic of China.
Wuhan National Laboratory for Optoelectronics (WNLO) and School of Optical and Electronic Information, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan, 430074, People's Republic of China.
Nanomicro Lett. 2025 May 22;17(1):270. doi: 10.1007/s40820-025-01776-3.
α-phase formamidinium lead triiodide (FAPbI) has demonstrated extraordinary properties for near-infrared perovskite light-emitting diodes (NIR-PeLEDs). The vacuum processing technique has recently received increasing attention from industry and academia due to its solvent-free feature and compatibility with large-scale production. Nevertheless, vacuum-deposited NIR-PeLEDs have been less studied, and their efficiencies lag far behind those of solution-based PeLEDs as it is still challenging to prepare pure α-FAPbI by the thermal evaporation. Herein, we report a Cs-containing triple-source co-evaporation approach to develop the perovskite films. The addition of thermally stable Cs cation fills in the perovskite crystal lattice and eliminates the formation of metallic Pb caused by the degradation of FA cation during the evaporation process. The tri-source co-evaporation strategy significantly promotes the phase transition from yellow δ-phase FAPbI to black α-phase FACsPbI, fostering smooth, uniform, and pinhole-free perovskite films with higher crystallinity and fewer defects. On this basis, the resulting NIR-PeLED based on FACsPbI yields a maximum EQE of 10.25%, which is around sixfold higher than that of FAPbI-based PeLEDs. Our work demonstrates a reliable and effective strategy to achieve α-FAPbI via thermal evaporation and paves the pathway toward highly efficient perovskite optoelectronic devices for future commercialization.
α相甲脒铅三碘化物（FAPbI）在近红外钙钛矿发光二极管（NIR-PeLED）中展现出非凡的性能。真空处理技术因其无溶剂特性以及与大规模生产的兼容性，近来受到了工业界和学术界越来越多的关注。然而，真空沉积的NIR-PeLED研究较少，其效率远远落后于基于溶液法的PeLED，因为通过热蒸发制备纯α-FAPbI仍然具有挑战性。在此，我们报道一种含铯的三源共蒸发方法来制备钙钛矿薄膜。热稳定的铯阳离子的加入填充了钙钛矿晶格，并消除了蒸发过程中FA阳离子降解导致的金属铅的形成。三源共蒸发策略显著促进了从黄色δ相FAPbI到黑色α相FACsPbI的相变，培育出具有更高结晶度和更少缺陷的光滑、均匀且无针孔的钙钛矿薄膜。在此基础上，基于FACsPbI制备的NIR-PeLED产生了10.25%的最大外量子效率（EQE），这比基于FAPbI的PeLED高出约六倍。我们的工作展示了一种通过热蒸发实现α-FAPbI的可靠且有效的策略，并为未来商业化的高效钙钛矿光电器件铺平了道路。
