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 In³⁺ content. Femtosecond transient absorption spectroscopy demonstrates that both the hot carrier cooling time and Auger lifetime prolong with higher In³⁺ content. Furthermore, the influence of In³⁺ 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.