Identification of Defect Origin and White-Light Emission Tuning of Chalcogenide Quantum Dots Through Pressure Engineering

Chalcogenide quantum dots (QDs) are established as promising materials for white-light-emitting applications because of their wide surface defect emission. However, the limited understanding of the origin of defect emission poses challenges in attaining efficient white -light emission. Herein, we sought to introduce high pressure to strengthen the interaction between different types of ligands and QDs, as well as enable in situ observation of surface trap passivation that contributes to emission control. Under pressure, both defect emission and band-edge emission in the CdS QDs could be selectively enhanced by more than an order of magnitude through treatment with X -type and Z -type ligands, respectively. Our findings identified that surface hole traps predominantly contributed to defect emission, whereas nonradiative recombination was primarily associated with surface electron traps. Our goal was to service ambient science through high-pressure research. Thus, based on this proposed mechanism, an energy-saving "neutral" white light with a human-eyefriendly color rendering index of 86 was achieved by tuning the defect emission through further elimination of surface Cd sites. This study endowed high pressure as an efficient tool to elucidate the defect origin of chalcogenide QDs under ambient conditions, paving the way for precise control over white -light emission through materials design application in solid -state lighting.