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

摘要

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.