(The) effect of the crystallinity of solid-state light-emitting carbon dots on self-quenching

Abstract

Fluorescent carbon nanomaterials or carbon dots (CDs) have emerged as a promising phosphor because of their low toxicity, abundant precursors, simple preparing routes, chemical resistance, and low photo-bleaching. With these merits, CDs have been actively studied in various field such as LED, display, fluorescence inks, bio-imaging, and energy conversion. However, the application of CDs has been limited partially due to the luminescence-quenching of CDs in solid-state. In this work, we studied the origin of luminescence quenching of CDs in aggregated state and how CDs should be engineered to realize solid-state luminescent CDs. From the structural and spectral analysis, we discovered that the amount of $sp^2$ domains influences their absorption characteristics and occurrence of fluorescence-resonance electron-transfer (FRET) between CD particles. By changing the mass ratios of precursors and the carbonization time, we regulated the degree of crystallinity and successfully realized solid-state luminescence of CDs.