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

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 2–10 nm and exhibit optical gaps of 2–3.9 eV. The presence of excess anions on the particle surface enables binding of Lewis acidic, Z-type ligands and results in enhanced photoluminescence. Electronic structure computations 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.