Nonthermalized Multiple Localized States Enable Efficient and Stable White-Light-Emitting Quantum Dots

Here we show that photogenerated holes in a AgIn_<i>x</i>Ga_1–<i>x</i>S₂/ZnS core/shell QD can be controllably partitioned into two parallel, kinetically isolated, and nonthermalized localized states, each of which then radiatively recombines with the delocalized electron with distinct formation and recombination kinetics.

The high-energy and low-energy photoluminescence (PL) peaks are related to a small-polaron-like state in the core and a manifold of trap states near the core–shell boundary, respectively. The nonequilibrated dual-state architecture yields composition-tunable and ultrabroad emission with a PL full width at half maximum (fwhm) of 120–130 nm, near-unity quantum yield (QY), negligible Urbach tail, and robust operation under thermal and optical stress.