Towards efficient and stable multi-color carbon nanoparticle phosphors: synergy between inner polar groups and outer silica matrix

Nanocarbon as an eco-friendly and abundant material has strong multi-color fluorescence, which makes it a promising candidate for healthy lighting and display. However, the low fluorescence efficiency and poor stability of multi-color carbon nanoparticle (CNP) phosphors are main hurdles that hinder their applications. This work demonstrated efficient and stable multi-color CNP phosphors through synergy between inner polar groups and outer silica matrix. The polar groups in polyethylene glycol (PEG) 6,000 are favor of high fluorescence of the CNP phosphors, and the low melting point (64°C) of PEG 6,000 helps to improve the thermal stability of the phosphors, while the silica matrix provides protection to the phosphors. Based on this design, blue, green, yellow and red CNP phosphors with photoluminescence quantum yield of 53.1%, 47.4%, 43.8% and 42.3% have been achieved, all of which are the best values in ever reported multi-color CNP phosphors. Furthermore, the fluorescence of the CNP phosphors keeps almost unchanged at 100°C and degrades little in one month, indicating their good thermal tolerance and temporal stability. In addition, multicolor devices including white light-emitting devices (LEDs) have been realized by coating the CNP phosphors onto UV chips. The luminous efficiency, correlated color temperature, Commission Internationale de L’Eclairage and color rendering index of the white LED can reach 12 lm W−1, 6,107 K, (0.32, 0.33) and 89, respectively, indicating the potential applications of the CNP phosphors in lighting and display. 纳米碳作为一种资源丰富的环境友好型材料, 会产生明亮的多色荧光, 成为一种在健康照明与显示领域有前景的材料. 然而多色碳 纳米粒子荧光粉的荧光效率和稳定性仍然低于预期, 这极大地限制了碳纳米粒子的应用. 本工作通过内层极性官能团与外层二氧化硅的 协同作用, 制备了高效稳定的多色碳纳米颗粒荧光粉. 聚乙二醇6000中的官能团有利于碳纳米粒子的发光, 其较低的熔点(64°C)提升了碳 纳米粒子的热稳定性, 而外层的二氧化硅对荧光粉提供了保护作用. 基于这个设计, 制备出了量子效率为53.1%, 47.4%, 43.8%以及42.3%的 蓝光、绿光、黄光和红光碳纳米粒子荧光粉, 量子效率均为已报道的多色碳纳米粒子荧光粉的最高值. 所制备的碳纳米粒子荧光粉展现 了良好的热稳定性和时间稳定性, 其荧光在100°C和一个月后仍能保持不变. 将所制备的碳纳米粒子荧光粉涂覆到紫外芯片上, 实现了包 括白光在内的多色发光器件. 其中, 白光器件的流明效率为12 lm W−1, 色温, 色坐标和显色指数分别为6107 K, (0.32,0.33)和89, 表明碳纳米 粒子荧光粉在照明与显示领域有潜在的应用前景.