Simple synthesis of AgInS2/ZnS core/shell quantum dots with wide tunable emission wavelength for white light-emitting diodes

Abstract

Phosphor with efficient and broad range emission is necessary for lighting applications. I-III-VI group quantum dots (QDs) have the advantages of non-toxic composition and large adjustable spectrum range, and have potential applications in the field of lighting. However, the efficient luminescence of these QDs at shorter wavelengths still needs further study, which is crucial for the development of high color rendering index white light LED devices (WLEDs). In this work, wide visible range emitting AgInS₂/ZnS QDs with broad band and high luminous efficiency were obtained by altering the Ag/In ratios and Zn²⁺ inter-diffusion with cation of AgInS₂. Photo-luminescent (PL) wavelength range of the obtained core-shell structured AgInS₂/ZnS extended from 703 nm to 524 nm with high PL quantum yield (QY) and stability. The champion device based on the optimized AgInS₂/ZnS QDs exhibits warm white light (correlated color temperature = 3652 K) characteristics with high color rendering index (CRI Ra) of 92.85 while maintaining excellent color stability under different driving currents. These properties are far superior to those of WLEDs with YAG phosphor.