Highly enhanced UV absorption and light emission of monolayer WS<sub>2</sub> through hybridization with Ti<sub>2</sub>N MXene quantum dots and g-C<sub>3</sub>N<sub>4</sub> quantum dots

Two-dimensional (2D) transition metal dichalcogenides (TMD) are atomically thin semiconductors with promising optoelectronic applications across the visible spectrum. However, their intrinsically weak light absorption and the low photoluminescence quantum yield (PLQY) restrict their performance and potential use, especially in ultraviolet (UV) wavelength light ranges. Quantum dots (QD) derived from 2D materials (2D/QD) provide efficient light absorption and emission of which energy can be tuned for desirable light wavelength. In this study, we greatly enhanced the photon absorption and PLQY of monolayer (1L) tungsten disulfide (WS2) in the UV range via hybridization with 2D/QD, particularly titanium nitride MXene QD (Ti2N MQD) and graphitic carbon nitride QD (GCNQD). With the hybridization of MQD or GCNQD, 1L-WS2 showed a maximum PL enhancement by 15 times with 300 nm wavelength excitation, while no noticeable enhancement was observed when the excitation photon energy was less than the bandgap of the QD, indicating that UV absorption by the QD played a crucial role in enhancing the light emission of 1L-WS2 in our 0D/2D hybrid system. Our findings present a convenient method for enhancing the photo-response of 1L-WS2 to UV light and offer exciting possibilities for harvesting UV energy using 1L-TMD.