Light-emitting Ti2N (MXene) quantum dots: synthesis, characterization and theoretical calculations

Abstract

© The Royal Society of Chemistry 2022. MXene-based quantum dots (MQDs), which are obtained by fragmenting MXenes into a nanometer scale, can display photoluminescence (PL), suggesting light-emitting applications for bandgap-less MXenes. However, despite the diverse possible formations of MXene components, only carbide MXene-based MQDs have been reported to emit light. In this study, we synthesized water-soluble MQDs with an average diameter of 3.14 nm using the titanium nitride (Ti2N) MXene. Ti2N MQDs exhibited efficient PL, with a maximum quantum yield of 7.5%, upon light absorption over the deep UV wavelength range of 400-230 nm. The density functional theory calculations and PL excitation measurements identified a bandgap of 3.8 eV and the existence of an unfulfilled band (E-1) between the occupied low-energy (E-0) and unoccupied high-energy (E-2) bands, which induces strong absorption in deep UV energy originating from the E-0-E-2 transition. Light-emitting nitride MQDs expand and facilitate the UV optoelectronic applications of MQDs.