Pb–S coordination-assisted <i>in situ</i> ligand engineering of CsPbBr ₃ nanocrystals using (3-mercaptopropyl)methyldimethoxysilane for enhanced robustness and optoelectronic properties

The surface chemistry of perovskite nanocrystals (NCs) is a key determinant of their quantum yield (QY), stability, and defect passivation. However, the rapid growth kinetics and pronounced sensitivity of CsPbBr₃ to moisture and thermal stress result in structural and optical degradation, hindering its practical applications. To address these limitations, we developed a ligand exchange-assisted strategy using (3-mercaptopropyl)methyldimethoxysilane (MPMDMS), a short-chain silane ligand bearing thiol groups. The thiol groups form strong Pb-S bonds with undercoordinated Pb²⁺ ions, effectively passivating surface defects. Treatment with the MPMDMS additive enhanced the photoluminescence intensity, carrier lifetime, and QY, while providing exceptional stability under ambient air, water exposure, and elevated temperatures. Electron-only device measurements revealed up to a threefold increase in electron mobility and more than a twofold reduction in trap density compared with untreated controls. These findings establish MPMDMS as a versatile additive that improves optical and electronic properties while ensuring environmental robustness, laying the foundation for high-performance perovskite-based optoelectronic devices.