Origin of photoluminescence of water-soluble CuInS(2) quantum dots prepared via a hydrothermal method

This study was performed to investigate the origin of the photoluminescence (PL) properties of hydrothermally-synthesized water-soluble CuInS(2) (CIS) quantum dots (QDs). The corresponding PL decay profiles, time-resolved PL spectra, and excitation intensity dependence of the PL spectra were evaluated. The decay profiles exhibited a strong dependence on the detection energy, and the peak of the time-resolved PL spectra shifted to lower energies with increasing time. With increasing excitation light intensity, the PL peak shifted to the high-energy side. These experimental results were consistent with the characteristics of donor–acceptor pair emission. The PL properties of Cu-doped and non-doped CdSe QDs, which show Cu-related and defect-related PL emission, respectively, were compared. Based on these results, it was concluded that donor–acceptor pair emission is the underlying mechanism of the PL of the hydrothermally-synthesized water-soluble CIS QDs.