Design of Ag-Ga-S2-xSex-based eco-friendly core/shell quantum dots for narrow full-width at half-maximum using noble ZnGa2S4 shell material

Abstract

I-III-VI-based quantum dots (QDs) are promising eco-friendly light-emitting materials for next-generation displays. Thus far, I-III-VI-based QDs (i.e., AgIn1-xGaxS2) are still insufficient as light-emitting materials for display fields because of their deteriorated optical properties caused by lattice mismatch between the core/shell materials. We designed a novel passivation process using a shell material (i.e., ZnGa2S4) with crystalline structure identical to that of AgGaS2-xSex core QDs (tetragonal). Green and red light-emitting AgGaS2/ZnGa2S4 core/shell QDs demonstrated superior optical properties owing to the minimum lattice mismatch between the AgGaS2-xSe2 core and ZnGa2S4 shell materials. In particular, a higher quantum yield (QY) and narrow full-width at half-maximum (FWHM) for the green and red light-emitting QDs were achieved, i.e., QYs of 69% and 64% and FWHMs of 26 and 28 nm, respectively. In addition, this remarkable enhancement of optical properties resulted in an increase of similar to 94.4% in the color-space agreement with ITU-R recommendation BT.2020. This means that AgGaS2-xSex-based core/shell QDs have the potential to be used as eco-friendly QDs for light-emitting materials in next-generation displays.