Latent fingerprint (LFP) detection is an important tool in criminal offense detection. Nowadays, ultraviolet (UV) excited visible emission phosphors are widely used in LFP detection, however due to the shortcomings of UV excited (λex < 270 nm) with low power, high price, and visible light susceptible to the influence of natural light, the application in LFP detection is restrained. Here, a new idea is proposed: the use of blue light-excited near-infrared (NIR) emitting phosphors as a tool for fingerprint detection visualization. To this end, in this work, a series of blue-excited (λex = 467 nm) NIR phosphors Ca(1-x)SrxO:Eu2+ (x = 0-0.2) were designed based on CaO:Eu2+ by using the crystal field engineering strategy. When x = 0.2, the luminescence center is red-shifted from 733 nm to 783 nm, and the full width at half maximum (FWHM) is broadened from 100 nm to 156 nm, and the red-shifted and broadening of the spectrum greatly improves the accuracy of fingerprint detection. Finally, Ca0.8Sr0.2O:0.1%Eu2+ gives high-quality visualized fingerprints in LFP detection, which is a good solution to the problems faced by UV-excited visible-emitting phosphors in LFP detection. Not only that, a NIR phosphor-converted light-emitting diode (NIR pc-LED) was prepared by combining Ca0.8Sr0.2O:0.1%Eu2+ with a blue LED chip, which was verified to have the potential for applications in biological tissue penetration and night vision illumination. This work introduces a new idea for the detection of LFP and demonstrates that rationalizing the local structure around Eu2+ is an effective strategy for exploring Eu2+-doped NIR luminescent phosphors.

中文翻译：

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离子调制实现Eu2+掺杂近红外荧光粉及其多功能应用


潜在指纹（LFP）检测是刑事犯罪检测的重要工具。目前，紫外（UV）激发可见光发射荧光粉广泛应用于LFP检测，但由于紫外激发（λex < 270 nm）功率低、价格昂贵、可见光易受自然光影响等缺点，在LFP检测中的应用受到限制。在这里，提出了一个新想法：使用蓝光激发的近红外（NIR）发射磷光体作为指纹检测可视化的工具。为此，本工作基于CaO:Eu2+，利用晶体场设计了一系列蓝色激发（λex = 467 nm）近红外荧光粉Ca(1-x)SrxO:Eu2+ (x = 0-0.2)工程策略。当x=0.2时，发光中心从733 nm红移到783 nm，半峰全宽（FWHM）从100 nm展宽到156 nm，光谱的红移和展宽程度大大提高指纹检测的准确性。最后，Ca0.8Sr0.2O:0.1%Eu2+在LFP检测中给出了高质量的可视化指纹，很好地解决了紫外激发可见光荧光粉在LFP检测中面临的问题。不仅如此，通过Ca0.8Sr0.2O:0.1%Eu2+与蓝色LED芯片结合制备了近红外荧光粉转换发光二极管（NIR pc-LED），并被验证具有在生物组织中应用的潜力穿透力和夜视照明。这项工作提出了一种检测LFP的新思路，并证明合理化Eu2+周围的局域结构是探索Eu2+掺杂近红外发光荧光粉的有效策略。