A simple and convenient preparation of multicolor carbon dot (CD) solutions was proposed using neutral red as the carbon and nitrogen sources by a layering and extraction procedure. After poly(vinylpyrrolidone) (PVP) as the cross-linking agent was doped into as-prepared solutions, red-, orange-, and yellow-emitting CD powders were finally fabricated with solid-state fluorescence quantum (QY) yields of 6.33, 16.5, and 43.6%, respectively. Through studies of surface functional groups and photoluminescence (PL) property compared with solution and powder states of CDs, the cross-linking effect emission (CEE) brought by PVP was confirmed in charge of the high solid-state QY of CD powders. In addition, the conjugate structure of neutral red and increasing hydrophobicity are believed to be responsible for the long-wavelength emission of CD powders. Notably, multicolor imaging of latent fingerprints (LFPs) was successfully achieved on complex background surfaces under 365 nm UV illumination. As a result, these carbon-based phosphors are promising in forensic investigation, bioimaging, and sensing fields.

中文翻译：

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具有基于交联的长波长发射的碳点粉末用于潜在指纹的多色成像

提出了一种简单方便的多色碳点 (CD) 溶液的制备方法，该溶液使用中性红作为碳源和氮源，通过分层和提取程序。将聚（乙烯基吡咯烷酮）（PVP）作为交联剂掺杂到所制备的溶液中后，最终制备出发射红色、橙色和黄色的 CD 粉末，其固态荧光量子（QY）产率为 6.33，分别为 16.5% 和 43.6%。通过对CDs的表面官能团和光致发光（PL）性质的研究，与溶液和粉末状态相比，PVP带来的交联效应发射（CEE）被证实负责CD粉末的高固态QY。此外，中性红的共轭结构和增加的疏水性被认为是造成 CD 粉末长波长发射的原因。值得注意的是，在 365 nm 紫外线照射下，在复杂背景表面上成功实现了潜在指纹 (LFP) 的多色成像。因此，这些碳基荧光粉在法医调查、生物成像和传感领域很有前景。