Lead-free double perovskites with near-unity photoluminescence quantum yield for flexible anti-counterfeiting fibers and optoelectronic devices

All-inorganic lead-free double perovskites have great application potential due to their unique crystal structure and low toxicity. Among them, the shortcomings of indirect band gap and inhibiting transition in some lead-free double perovskites reduce their optical performance. In this study, the facile method at low temperature and atmospheric pressure was used to prepare a high-efficiency green-emitting Sc 3+ -doped Cs 2 NaTbCl 6 . The synthesized Cs 2 NaTbCl 6 and Sc 3+ -doped Cs 2 NaTbCl 6 perovskite crystals had similar crystal structures. Interestingly, Sc 3+ -doped Cs 2 NaTbCl 6 could improve the luminescence performance of Cs 2 NaTbCl 6 while maintaining the excitation-emission characteristics of Cs 2 NaTbCl 6 . After doping with Sc 3+ at a concentration of 0.05 mmol, the band gap of Cs 2 NaTbCl 6 became wider. When the doping amount of Sc 3+ reached 0.05 m mol, the photoluminescence emission intensity was increased by 31.33 % compared with Cs 2 NaTbCl 6 . The fluorescence lifetime became longer and the photoluminescence quantum yield reached 96.07 %. In this work, we further prepared light-emitting diodes and white light-emitting diodes with excellent performance using Sc 3+ -doped Cs 2 NaTbCl 6 . In addition, Sc 3+ -doped Cs 2 NaTbCl 6 and aramid chopped fibers/polyphenylene sulfide were combined to prepare the composite paper. The functional composite fiber paper had excellent photostability in a variety of extreme environments. The potential application value of Sc 3+ -doped Cs 2 NaTbCl 6 double perovskite in daily lighting, color display, fluorescent anti-counterfeiting, functional fibers, and optoelectronic devices was demonstrated.