Abstract We report the synthesis of a transparent plastic material with very high performance ultraviolet (UV)-blocking and blue-light (440 nm) emission. Polyvinyl alcohol (PVA) was employed as a transparent plastic matrix that disperses N-doped carbon dots (N-CDs) prepared via hydrothermal treatment of citric acid, ethylene diamine, and HCl solution. Luminescence of these N-CDs is excitation-independent and the quantum yield (QY) is maximal at an excitation wavelength range of 350–370 nm, in the UV-A radiation segment of the solar spectrum. By encapsulating N-CDs in a polyvinyl alcohol (PVA) matrix, the absolute QY achieves 91%, which is higher than in aqueous solution. As the particle concentration increases in PVA matrix or in solution, UV absorbance increases and QY decreases. On the other hand, UV absorbance of the film is proportional to thickness with no appreciable deterioration in QY, a quality that is beneficial for UV light absorption as well as conversion into blue light. We propose that this N-CD/PVA composite is an ideal transparent plastic for UV-ray shielding, as well as being useful for blue light emission, composed only of eco-friendly nontoxic elements. The high UV absorption and strong luminescence of N-CDs are beneficial also for other applications that include anti-counterfeiting (secret inks) and greenhouse sheathing that simultaneously blocks UV-rays while generating blue light to promote plant growth.

中文翻译：

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含有分散的 N 掺杂碳点的透明聚合物薄膜的双重作用：高效蓝光转换器和紫外线屏幕

摘要 我们报告了一种具有非常高性能的紫外线 (UV) 阻挡和蓝光 (440 nm) 发射的透明塑料材料的合成。采用聚乙烯醇 (PVA) 作为透明塑料基质，分散通过柠檬酸、乙二胺和 HCl 溶液的水热处理制备的 N 掺杂碳点 (N-CD)。这些 N-CD 的发光与激发无关，并且在太阳光谱的 UV-A 辐射段中，激发波长范围为 350-370 nm 时量子产率 (QY) 最大。通过将 N-CD 封装在聚乙烯醇 (PVA) 基质中，绝对 QY 达到 91%，高于水溶液中的 QY。随着 PVA 基质或溶液中颗粒浓度的增加，UV 吸光度增加而 QY 降低。另一方面，薄膜的紫外线吸收率与厚度成正比，QY 没有明显劣化，这种品质有利于紫外线吸收以及转化为蓝光。我们建议这种 N-CD/PVA 复合材料是一种理想的紫外线屏蔽透明塑料，也可用于蓝光发射，仅由环保无毒元素组成。N-CD 的高紫外线吸收和强发光也有利于其他应用，包括防伪（秘密墨水）和温室护套，可同时阻挡紫外线，同时产生蓝光以促进植物生长。我们建议这种 N-CD/PVA 复合材料是一种理想的紫外线屏蔽透明塑料，也可用于蓝光发射，仅由环保无毒元素组成。N-CD 的高紫外线吸收和强发光也有利于其他应用，包括防伪（秘密墨水）和温室护套，可同时阻挡紫外线，同时产生蓝光以促进植物生长。我们建议这种 N-CD/PVA 复合材料是一种理想的紫外线屏蔽透明塑料，也可用于蓝光发射，仅由环保无毒元素组成。N-CD 的高紫外线吸收和强发光也有利于其他应用，包括防伪（秘密墨水）和温室护套，可同时阻挡紫外线，同时产生蓝光以促进植物生长。