Origin of Efficient and Tunable Dual‐Band Emission From Zinc Chalcogenide Quantum Dots for Sustainable Photonics

Abstract

Impurity‐induced optical modulation in quantum‐confined colloidal nanocrystals has attracted intense interest thanks to the unique fundamental photo‐physics and application prospects. However, the present doping strategy is still facing limitations including spectral tunability and impurity controllability. Herein, a new route toward the tunable and efficient dual‐band emission in chlorine‐doped ZnSe (ZnSe:Cl) eco‐friendly quantum dots (QDs) is provided. Corroborated by the comprehensive spectroscopic characterization and first‐principles calculations, the emerging broadband sub‐gap emission is disclosed to originate from the self‐activating center constituted by a fusion of a Cl‐substituted Se point defect and a nearby Zn vacancy (ClSe‐VZn pair). First‐principles calculations confirm that the optically active center state stems from the distorted electron states of Se atoms surrounding the impurity rather than the Cl electron orbitals, which results in robust sub‐gap emission at ambient conditions. A dynamic model involving the transition between the charge and neutral states of the self‐activated center is established. By virtue of the controllable dual‐emission states, the transparent information encryption and the single‐component white light‐emitting diodes are realized, demonstrating the promising potential in sustainable photonic applications.