The formation process of five-component Cu–In–Zn–Se–S nanocrystals from ternary Cu–In–S and quaternary Cu–In–Se–S nanocrystals via gradually induced synthesis

Multinary Cu-based chalcogenide nanocrystals (NCs) are excellent candidates for optoelectronic applications, but their growth mechanism and its impacts on the NCs’ optical properties remain controversial. Herein, we employed a simple colloidal chemistry method for the growth of multinary Cu-based NCs including ternary Cu–In–S NCs, quaternary Cu–In–Se–S NCs, and five-component Cu–In–Zn–Se–S NCs, to explore their growth mechanism and investigate their optical properties. It is found that the ternary Cu–In–S NCs contain a large number of copper vacancies, which affect the major acceptor level for the exciton recombination. With the high reaction activity of Se, the quaternary Cu–In–Se–S NCs form at low reaction temperature and have a red-shift of the photoluminescence (PL) maximum due to the recombination from the conduction band to the acceptor level. The formation process of five-component Cu–In–Zn–Se–S NCs highly depends on the Zn amount, which shows a competitive relationship between the NCs’ growth and diffusion of Zn, leading to the red- and blue-shift of PL maximum, respectively. Our study provides a clear map for the growth of multinary Cu-based NCs and shows their impacts on optical properties.