Tunable luminescence properties of AgInS2-ZnS and AgInS2-ZnS@ZnS particles

Luminescent nanocrystals of AgInS2-ZnS (ZAIS) and core-shell AgInS2-ZnS@ZnS (ZAIS@ZnS) nanostructures were synthesized with different compositions of the core AgInS2-ZnS solid solution. With this method, luminophores displaying a broad emission spectrum and a maximum emission tunable between 555 nm and 825 nm could be obtained. Their optical absorption and luminescence properties were studied in order to understand the evolution of their optical band gap, their photoluminescence quantum yield (PLQY) and the amount of defects. Ageing tests of the colloidal solutions of these nanocrystals under blue light excitation were also performed. We show that the high PLQY of ZAIS nanocrystals is correlated to the amount of defects they contain which explains the effect of both the composition and the synthesis method on the PLQY. We also show that ZnS coated nanocrystals exhibit high photostability under blue light excitation compared to their non-coated counterparts. These results emphasize the potential of ZAIS nanocrystals as highly luminescent and stable luminophores for white-LED applications.