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

Abstract

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 (E₁) between the occupied low-energy (E₀) and unoccupied high-energy (E₂) bands, which induces strong absorption in deep UV energy originating from the E₀–E₂ transition. Light-emitting nitride MQDs expand and facilitate the UV optoelectronic applications of MQDs.