Preparation of Luminescent AgInS2−AgGaS2 Solid Solution Nanoparticles and Their Optical Properties

Luminescent AgInS 2 −AgGaS 2 solid solution nanoparticles were synthesized by thermal decomposition of a single-source precursor, AgIn y Ga 1− y (S 2 CN(C 2 H 5 ) 2 ) 4 in oleylamine. Transmission electron microscopy showed formation of nanoparticles of good crystallinity with their size ranging from 4 to 5 nm. X-ray powder diffraction spectra showed peaks which were attributable to the chalcopyrite structure, and their peaks were continuously shifted to higher angle as the Ga to In ratio increased. Photoluminescence and absorption spectra were also blue-shifted as the ratio of Ga increased due to the larger band gap of AgGaS 2 compared with that of AgInS 2 . The quantum yield was almost maintained in the composition range of 0.4 < y < 1.0, below which it decreased largely. The mechanism of such behavior was investigated using time-resolved photoluminescence spectra.