Effect of Zn precursors on the optical properties of Indium Phosphorus quantum dots

Indium phosphide (InP) quantum dots (QDs) are attracting attention in the display industry due to their lack of heavy metals and unique optical properties. In order to use QDs in displays, the narrower the emission peaks of QDs, the better, and a display made with QDs having narrow emission peaks achieves higher color saturation. However, it is still challenging to fabricate InP QDs that are comparable to the optical properties of cadmium-based QDs. In recent years, most of the literature has focused on the study of narrow-peak green InP QDs, and the research on narrow-peak red InP QDs is very rare. To fabricate red-light InP QDs with narrow emission peaks, ZnInP QDs cores were first fabricated with different Zn precursors (Zn(ud), ZnBr₂, ZnCl₂) and varying ratios of Zn to In (Zn/In=0, 1, 2 and 3). The experimental results revealed that when the ratio of Zn to In is 1, the absorption wavelength of the QD core increases with larger particle sizes. Subsequently, the ZnInP QDs were enveloped with double shell materials to create core-shell-shell QDs. Among them, the prepared ZnInP/ZnSeS/ZnS core/shell/shell QDs (CSS-QDs) had an emission wavelength of 603 nm and full width at half maximum (FWHM) of 52 nm. The color gamut of WLEDs obtained by mixing red CSS-QDs with green phosphors (Silicate phosphors, EG2762) are 94 % of NTSC. This result is beneficial to the application of the InP red QDs in the high color gamut display.