Facile synthesis of ZnS-AglnS₂ solid solution nanoparticles for a color-adjustable luminophore

Nanoparticles of ZnS-AgInS₂ solid solution (ZAIS) were synthesized by the thermal decomposition of (AgIn)_xZn_2(1-x)(S₂CN(C₂H₅)₂)₄ precursors in a hot oleylamine solution. X-ray powder diffraction analyses revealed that the resulting nanoparticle powders were not a mixture of ZnS and AgInS₂ but a ZnS-AgInS₂ solid solution in which the fraction of ZnS was enlarged with a decrease in the value of x, that is, an increase in the content of Zn²⁺ in the precursors used. The energy gap of ZAIS nanoparticles could be controlled by the composition of solid solution. Intense emission was observed at room temperature, regardless of the kind of the particles, the peak wavelength of PL being blue-shifted from 720 to 540 nm with a decrease in the value of x. The highest quantum yield of ca. 24% was obtained for nanoparticles prepared with x = 0.86, which was much higher than the quantum yields reported for I-III-VI₂-based semiconductor nanoparticles, such as CuInS₂ and ZnS-CuInS₂ solid solution.