Stoichiometry of the Core Determines the Electronic Structure of Environmentally Friendly Core-Shell III–V/II-VI Nanoparticles

Recently III-V quantum dots (QDs) emerged as an environmentally friendly alternative to CdSe, however, they exhibit broader emission spectra and inferior photoluminescence quantum yield. Here we present a computational study of the opto-electronic properties of In_xP_z and In_xGa_yP_z QDs interfaced with zinc chalcogenide shells[1]. Using density functional theory, we show that fine-tuning the composition of the core is critical to achieving narrow emission lines. We show that core-shell nanoparticles where the core has the same diameter but different stoichiometries may absorb and emit at different wavelengths, leading to broad absorption and emission spectra. The value of the fundamental gap of the core-shell particles depends on the ratio between the number of group III and P atoms in the core and is maximized for 1:1 composition. We also show that the interplay between quantum confinement and strain determines the difference in the electronic properties of III-V QDs interfaced with ZnS or ZnSe shells.

[1]. Mariami Rusishvili, Stefan Wippermann, Dmitri Talapin, Giulia Galli Chemistry of Materials, 2020, DOI: 10.1021/acs.chemmater.0c03939