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

Abstract

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.