关键词: 苯乙胺溴化铅, 二维钙钛矿单晶, 光致发光, 荧光防伪, 织物标贴, 纺织品防伪

Abstract: The development and application of fabric security labels with identification function ensure the safety of textiles. Ultraviolet photoluminescent textiles refer to the fact that the fabric emits a specific color of light after being excited from a colorless state when it is irradiated by ultraviolet light, so as to achieve the purpose of anti-counterfeiting. Previous studies have shown that the (PEA)2PbBr4 single crystal with ultraviolet photoluminescence performance has excellent characteristics such as high color purity and high crystallinity, and can be prepared by simple process, mild conditions and mass production.
To prepare efficient and lightweight fluorescent anti-counterfeiting fabric labels, phenethylammonium bromide was prepared by β-phenethylamine and hydrobromic acid, and it was dissolved with lead bromide at a molar ratio of 2:1 to N, N-dimethylformamide to configure a precursor solution. By adjusting the solvent ratio of o-dichlorobenzene to N, N-dimethylformamide, two-dimensional layered (PEA)2PbBr4 single crystals of different sizes and densities were grown by anti-solvent gas-assisted crystallization. The single crystal with the best distribution and luminescence performance was selected, and the single crystal solution under this condition was spin-coated and encapsulated in a 0.1 mm thick PVC film to prepare a single crystal/PVC composite film, and a fabric label with photoluminescence anti-counterfeiting function was obtained by hot rolling with the fabric. The crystallization properties, distribution, morphological structure and luminescence characteristics of single crystals and composite films and fabric labels were studied by fluorescence microscopy, laser particle size analyzer, XRD, SEM, ultraviolet-visible photometer and transient fluorescence spectrometer, and their application effects in textiles were discussed through washable wearable and wear-resistant tests.
The results show that (PEA)2PbBr4 single crystals have a series of periodically repeated, uniformly spaced and well-defined strong diffraction peaks belonging to the two-dimensional layered perovskite structure, with excellent crystallinity and high preference orientation. And the morphology is regular, the edges are sharp, and the elements forming single crystals in the energy dispersive spectrum are evenly distributed; single crystals with a size of 5-10 μm are about 200 nm thick; the absorption and emission peaks are located at 394 nm and 412 nm, respectively. The larger the solvent ratio of o-dichlorobenzene to N, N-dimethylformamide, the smaller the single crystal size is; when the single crystal size is about 5 μm, its distribution state, crystallinity and luminescence performance are the best. The absorption peaks and emission peaks of the single crystal/PVC composite film are located at 391 nm and 414 nm, respectively, and the spectra shows that the single crystal inside the PVC film still has high quality and high color purity. The composite film used as the fabric security label uses ultra-small amounts of single crystals to emit a strong and uniform blue-violet light under the excitation of 365 nm ultraviolet light, realizing effective anti-counterfeiting function. It is tested and applied to fabric security labels to meet washable and wear-resistant standards.

Key words: phenylethylamine lead bromine, two-dimensional perovskite single crystal, PL photoluminescence, fluorescent anti-counterfeiting, fabric labeling, textile anti-counterfeiting