Rapid synthesis of ultra-bright blue and cyan CQDs fluorescent powders based on chemical dispersion and concentration effects

Abstract

It is often impossible to obtain solid carbon quantum dots (CQDs) fluorescent powder by direct drying due to a self-quenching effect, which limits their large-scale application. Here, we first report a general method for rapidly conversing CQDs solution into fluorescent powder via a crosslinking reaction of 3-glycidyloxypropyltrimethoxysilane (KH-560). Initially, N-doped CQDs (N-CQDs) with an ultra-high quantum yield (QY) of 98.45 % and concentration-dependent luminescence behavior were synthesized via a straightforward hydrothermal reaction involving citric acid and ethylenediamine. The N-CQDs solution at low and high concentrations emits blue and cyan fluorescence under ultraviolet light, respectively. By the action of aqueous ammonia, KH-560 quickly forms a gel matrix at room temperature to realize the dispersion and anchor of N-CQDs to prepare N-CQDs fluorescent powder (NK). NK not only inherits the strong luminescence performance (QY = 71.87 %) of N-CQDs but also exhibits excellent fluorescence stability, successfully applied in blue and cyan LED lighting and fluorescent ink.