High stability and spectral tunability of versatile manganese/europium/tellurium-doped double perovskite crystals toward flexible functional fabric and semiconductor devices

All-inorganic metal halide perovskites exhibit excellent optoelectronic properties, and cesium lead halide perovskites have been the most extensively studied perovskites. Despite their excellent performance, the toxicity of CsPbX3 (X = halide) perovskites is a significant hurdle in the path of their widespread commercialization, posing challenges for large-scale applications. The lead-free characteristic and inherent air stability of Cs2NaBiX6 render them promising alternatives to CsPbX3 perovskites. Herein, we report the lead-free double perovskite crystals (PCs) derived from Cs2NaBiCl6 incorporating doping with three distinct elements. This doping strategy effectively regulates the emission wavelength of Cs2NaBiCl6, with particular emphasis on Eu-doped and Te-doped Cs2NaBiCl6, which have been scarcely reported in previous studies. Light-emitting diodes (LEDs) have been fabricated by these perovskite crystals. The white LED was prepared by Mn-doped Cs2NaBiCl6 with a high color rendering index (CRI) of 95.5. In addition, fiber paper, composed of aramid chopped fibers (ACFs) and polyphenylene sulfide (PPS), exhibits sustained fluorescence characteristics in different environments under an ultraviolet lamp when post-processed with perovskite. The photoluminescence quantum yield (PLQY) of flexible luminescent fibers prepared from Cs2(NaBi)0.95Mn0.10Cl6 PCs and ACFs/PPS fibers can reach 18.27 %. This fluorescent fiber paper holds potential applications in fields such as fluorescent anti-counterfeiting and intelligent wearable devices. By irradiating with a specific wavelength of the laser, the damaged area of fiber textiles can be quickly detected based on changes in fluorescence intensity. The integration of luminescent crystals and fibers into functional fabrics opens avenues for utilization in high-performance textile testing and other domains.