Ultrafast Charge Carrier Dynamics in Colloidal ZnIn₂S₄ Nanosheets Using Transient Absorption Spectroscopy

Recently, 2D colloidal semiconductors have emerged as a promising candidate for solar-harvesting applications. A comprehensive understanding of the light-harvesting characteristics and dynamics of the photogenerated charge carriers is crucial for enhancing their optoelectronic performance. Here, we have successfully synthesized the ultrathin colloidal ZnIn₂S₄ nanosheets using the hot-injection method and subsequently explored the photophysical properties of this ternary 2D material by means of transient absorption (TA) spectroscopy. The trap-mediated recombination dynamics were observed for the colloidal nanosheets. Energy-dependent TA studies unravelled the presence of the Auger recombination processes. With the help of temperature-dependent TA spectroscopy, we investigate the strong influence of electron-phonon coupling on the carrier dynamics of colloidal nanosheets at cryogenic temperatures. This in-depth study unveils several unexplored transient phenomena for 2D ternary colloidal chalcogenide, which will be beneficial for designing colloidal semiconductor-based next-generation optoelectronic devices.