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Efficient and stable emission of warm-white light from lead-free halide double perovskites
摘要： Lighting accounts for one-fifth of global electricity consumption1. Single materials with efficient and stable white-light emission are ideal for lighting applications, but photon emission covering the entire visible spectrum is difficult to achieve using a single material. Metal halide perovskites have outstanding emission properties2,3; however, the best-performing materials of this type contain lead and have unsatisfactory stability. Here we report a lead-free double perovskite that exhibits efficient and stable white-light emission via self-trapped excitons that originate from the Jahn–Teller distortion of the AgCl6 octahedron in the excited state. By alloying sodium cations into Cs2AgInCl6, we break the dark transition (the inversion-symmetry-induced parity-forbidden transition) by manipulating the parity of the wavefunction of the self-trapped exciton and reduce the electronic dimensionality of the semiconductor4. This leads to an increase in photoluminescence efficiency by three orders of magnitude compared to pure Cs2AgInCl6. The optimally alloyed Cs2(Ag0.60Na0.40)InCl6 with 0.04 per cent bismuth doping emits warm-white light with 86 ± 5 per cent quantum efficiency and works for over 1,000 hours. We anticipate that these results will stimulate research on single-emitter-based white-light-emitting phosphors and diodes for next-generation lighting and display technologies.
关键词： lead-free halide double perovskites,self-trapped excitons,white-light emission,photoluminescence efficiency,Jahn–Teller distortion
更新于2025-09-23 15:21:21
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Unique ion diffusion properties in lead-free halide double perovskites: A first-principles study
摘要： Pb-free halide double perovskites (HDPs) are proposed as potential candidates for various optoelectronic applications to replace the mainstream hybrid organic-inorganic halide perovskites, e.g., CH3NH3PbI3. While it is known that ion di?usion is a critical problem to a?ect the structural and electronic stability of CH3NH3PbI3, the mechanism of ion di?usions in HDPs is still unclear and highly desired to be revealed. In this study, taking Cs2AgInX6 (X = Cl, Br) HDPs as prototypes, for the ?rst time we suggest that the fast ion di?usion of the dominant defects may play an important role in the performance stability of HDPs. Importantly, we ?nd that the Agi+ di?usion in a multi-ion concerted fashion has a much faster di?usion rate, compared to the VAg? and VX? di?usion in a single-ion fashion. It is revealed that HDPs exhibit quite di?erent di?usion properties from CH3NH3PbI3. Furthermore, we demonstrate that the di?usion rate of Agi+ in HDPs can be e?ectively suppressed by applying an epitaxial strain, which opens a promising way to enhance the performance stability of perovskite materials for various device applications.
关键词： Lead-free halide double perovskites,Ion di?usion,Performance stability,ab initio calculations,Solar cells
更新于2025-09-04 15:30:14