Hydrothermal synthesis of highly fluorescent Ag–In–S/ZnS core/shell quantum dots for white light-emitting diodes

Highly fluorescent Ag–In–S/ZnS (AIS/ZnS) core/shell quantum dots (QDs) with good crystallinity were synthesized via hydrothermal method with adding ZnS precursors directly into AIS cores initial solution. The influences of shell growth time and Zn/AgIn ratios on the crystal structure, composition and morphology were analyzed by using X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM), and the fluorescence properties of AIS/ZnS core/shell QDs were systematically investigated by absorption and photoluminescence (PL) spectra. In contrast with AIS cores, the AIS/ZnS core/shell QDs showed significantly improved yellow-orange emission with long PL lifetimes, as well as the maximum quantum yield (QY) increased from 21.6% to 45.7%. Moreover, bright white light was successfully generated from the AIS/ZnS QDs and Lu₃Al₅O₁₂:Ce³⁺ phosphors based white light-emitting diode (WLED). Under the forward bias current of 200 mA, the fabricated WLED exhibited a high luminous efficiency of 77.98 lm/W with the Commission Internationale de I'Eclairage (CIE) color coordinate of (0.32, 0.32), a color rendering index (CRI) of 85 and the correlated color temperature (CCT) of 6215 K, demonstrating the prospective application of obtained QDs in solid-state lighting devices.