Bright and Uniform Green Light Emitting InP/ZnSe/ZnS Quantum Dots and Their Photophysical Properties

Abstract: There is an urgent demand to improve the efficiency and color purity of environment-friendly quantum dots (QDs), which could be used in wide color gamut (WCG) displays. In this study, we optimized the reaction conditions of the InP core synthesis and the ZnSe/ZnS multi-shell growth during the preparation of InP-based QDs. As a result, remarkable improvements were observed in the photoluminescence quantum yield (PL QY, 95％) and the full width at half-maximum (FWHM, 36 nm), with perfectly matched wavelength (528 nm) for the green color in WCG displays. Injection of the phosphorous precursor at a mild temperature during the InP core synthesis reduced the size distribution of core QDs to 12％, and the shell growth carried out at a high temperature significantly enhanced the crystallinity to grow a thick passivating layer. We also investigated the photophysical properties, particularly the energy trap distributions and trap state emissions of InP-based QDs with different shell structures. The time-resolved and temperature-dependent PL spectra clearly indicated that the well-passivated InP/ZnSe/ZnS QDs showed nearly trap-free emissions over a wide temperature range (77？297 K). The on- and off-time probability on single QD blinking and Auger ionization efficiencies also showed that these QDs are hardly affected by the surface traps.