Synthesis of CuInS2 fluorescent nanocrystals and enhancement of fluorescence by controlling crystal defect

For this study, Cu–In–S nanocrystals were developed as a low toxic fluorescent. The stoichiometric $\mathrm{Cu}\mathrm{In}{\mathrm{S}}_2$ nanocrystals were synthesized facilely by heating a solution of metal complexes and dodecanethiol. The fluorescence would be originated from the crystal defect. We intentionally introduced the crystal defect in nanocrystal with the prospect that the fluorescence intensity would be increased. The defect structure of products was analyzed using Raman spectroscopy and other techniques. The nanocrystals have many defects without phase separation as observed in the bulk material. Consequently, the fluorescence quantum yield achieved $\sim 5\%$ . Moreover, the fluorescence quantum yield was increased up to 15% by the ZnS coating.