Bifunctional Precursor-Assisted Shell Growth and Exciton Dynamics of Highly Luminescent CuInS₂/ZnS Quantum Dots

CuInS₂ (CIS) quantum dots (QDs) are promising emissive materials due to their eco-friendly compositions and broadly tunable emission. However, achieving high photoluminescence (PL) performance and elucidating the unusual photophysical properties remain challenging. Herein, we develop a shell-epitaxy strategy using bifunctional precursors obtained by directly dissolving ZnI₂ in 1-dodecanethiol to synthesize CIS/ZnS core/shell QDs, which simultaneously supply monomers for shell growth and generate HI in situ to eliminate surface oxides. The resulting QDs exhibit exceptional optical properties, including a PL quantum yield of ∼90%, monoexponential decay dynamics, and suppressed blinking at the single-dot level. Combined with emission-wavelength-dependent excited-state dynamics revealed by spectroscopic analysis and energy levels measured by electrochemical studies, we propose a dual-governed exciton recombination model highlighting the synergistic interplay between band-edge states and Cu-related intragap states in CIS-based QDs. This work sheds new light on the synthesis and exciton dynamics of CIS-based QDs, pushing ahead toward the development of optoelectronic applications.