Coloring Tetrahedral Semiconductors: Synthesis and Photoluminescence Enhancement of Ternary II-III2-VI4 Colloidal Nanocrystals

Abstract

Ternary tetrahedral II-III₂-VI₄ semiconductors, where II is Zn or Cd, III In or Ga, and VI S, Se, or Te, are of interest in UV radiation detectors in medicine and space physics as well as CO₂ photoreduction under visible light. We synthesize colloidal II-III₂-VI₄ semiconductor nanocrystals from readily available precursors and ascertain their ternary nature by structural and spectroscopic methods, including ⁷⁷Se solid-state NMR spectroscopy. The pyramidally shaped nanocrystals range between 2 and 12 nm and exhibit optical gaps of 2–3.9 eV. In the presence of excess anions on the particle surface, treatment with Lewis acidic, Z-type ligands results in better passivation and enhanced photoluminescence. Electronic structure calculations reveal the most stable, lowest energy polymorphs and coloring patterns. This work will pave the way toward more environmentally friendly, ternary semiconductors for optoelectronics and electrocatalysis.