Enhanced Photoluminescence in CdxZn1–xS Solid Solution by Suppressing Non-Radiative Recombination for White Light-Emitting Diodes

The inevitable defects in conventional II–VI semiconductors, introducing pathways for the non-radiative recombination, substantially lower the photoluminescence (PL) quantum yield. Although considerable progress has been made toward eliminating the defect-induced PL quenching, the low stability that remained after surface passivation or only a small proportion of defects that could be modified via other strategies dramatically limits the whole PL quantum yield of solid-state luminescent materials. In this work, we propose a “defect activation” strategy to improve the luminescent performance of CdxZn1–xS solid solution. A remarkable PL enhancement is realized up to orders of magnitude compared to those of non-activated defect sites. Combining experimental investigations and density functional theory calculations, the PL enhancement mechanism clarified that the sulfur vacancies are activated by electron anti-doping from adsorbed oxygen to effectively suppress the defect-induced non-radiative recombination. The unique “defect activation” engineering will open up a perspective for the positive role of defects and inspire more explorations for achieving optimized optoelectronic materials with excellent optical characteristics and high stability for white light-emitting diodes.