Synthesis of coal pitch-derived carbon dots with yellow emission and improved photoluminescence quantum yield through pre-surface engineering and nitrogen doping

Abstract

Carbon dots (CDs) have unique advantages as the luminorphores of optoelectronic devices. Taking advantage of the carbon-rich nature of coal pitch, converting coal pitch into CDs is an efficient avenue for the noncombustive use of coal pitch in response to the global carbon neutralization demand. However, to achieve coal pitch-derived CDs with long wavelength emission and high photoluminescence quantum yield (PLQY) remains a great challenge. Herein, a strategy to tailor the PL property of coal pitch-derived CDs is developed. It includes introducing nitro groups on the surface of coal pitch (NO2-coal pitch) and followed by sovolthermal treatment of NO2-coal pitch and aspartic acid (ASP), which effectively promote the dehydration and carbonization processes, and favorably increase the content of pyrrolic N in the CDs. As a result, yellow-emissive CDs (y-CDs) with an improved PLQY of 34% are obtained. Transparent y-CDs polymer films with solid-state fluorescence are fabricated and their potential application for light emitting diodes (LEDs) is demonstrated. This current work provides a feasible way to regulate the PL property of coal pitch-derived CDs for wide applications.