Enhanced Excitons Delocalization Toward High-Quality Emission Harvesting Unlocked by Pressure and Ligand Engineering

Quantum dots (QDs) are promising candidates for applications in electronics, optoelectronics, and bioelectronics. Currently, the development of precise surface modifications to regulate defect density and type is a research hotspot. Here, we report on high-quality green defect emission from CdS QDs with a considerable photoluminescence quantum yield of 34.9% generated through pressure and ligand engineering. Upon an increase in the external pressure applied on CdS QDs, a remarkable piezochromism phenomenon from orange to cyan was observed. Note that after complete release of pressure, an unconventional bright green emission can be stabilized. The permanent modulation of the interaction between CdS QDs and the ligand through pressure treatment intensified the passivation effect and facilitated exciton delocalization to the QD surface, ultimately leading to high-quality emission harvesting. This work contributes to the precise construction of ligand engineering for future QD-based technologies.