Spectroscopic Properties of Ag-In-Ga-Zn-S Quantum Dots.

I-III-VI group colloidal quantum dots (QDs) have attracted significant scientific interest due to their low toxicity and easily tunable emission wavelengths. However, the fundamental optical properties of I-III-VI QDs remain insufficiently explored, which considerably hinders the development of their related device applications. In this work, a series of Ag-In-Ga-Zn-S (AIGZS) QDs are synthesized by varying the In/Ga ratio. Temperature-dependent photoluminescence spectroscopy reveals that the bandgap becomes less sensitive to temperature variations and the carrier-phonon coupling strength gradually weakens with increasing In content. Femtosecond transient absorption spectroscopy demonstrates that both the hot carrier cooling time and Auger lifetime prolong with higher In content. Furthermore, the influence of In content on the multiphoton absorption cross sections of AIGZS QDs is investigated. These findings provide crucial insights for a comprehensive understanding of the fundamental optical properties of AIGZS QDs.