Epitaxial Growth of Spherical Monodisperse ZnSe Quantum Dots: Roles of Additives and Precursors

Zinc selenide (ZnSe) quantum dots (QDs) emerge as promising eco-friendly materials for generating pure blue light emission due to their suitable bandgap. However, conventional synthetic methods of ZnSe QDs face persistent challenges in achieving isotropic growth and morphological uniformity. In this study, the roles of additives and precursors in the homogeneous growth of ZnSe QDs via a seed-mediated growth strategy are systematically investigated. Trioctylamine is introduced as the sole amine additive, replacing the traditionally used oleylamine, which effectively eliminates water byproducts and significantly reduces surface oxide defects. Furthermore, the reactivity of the selenium precursor is found to play a decisive role in determining the growth rate and morphology of the ZnSe QDs. By redesigning the growth protocol, spherical monodisperse ZnSe QDs with sizes ranging from 4 to 11 nm are successfully achieved, accompanied by an exceptionally narrow photoluminescence fwhm of merely 9.8 nm. Additionally, this epitaxial growth strategy successfully extends to the epitaxy of ZnSe shells onto CdSe core QDs, resulting in spherical CdSe/ZnSe core/shell structures with a thickness up to 15 monolayers. This work provides new insights into the homogeneous growth of ZnSe QDs and paves the way for developing blue-emitting ZnSe-based QDs and high-quality core-shell QDs with superior isotropy.