Hydrothermal Synthesis and the Study of Fluorescence Properties of Quaternary Ag-In-Zn-S Quantum Dots

Ag-In-Zn-S quantum dots (AIZS QDs) were prepared by hydrothermal method using inorganic metal salts as raw materials, Glutathione (GSH) and Sodium Citrate (SC) as ligands. The effects of pH values, Ag/In and Ag/Zn ratios on phase, morphology, and fluorescence properties were systematically investigated, and the phase, morphology and fluorescence properties of AIZS QDs were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, Ultraviolet and visible absorption spectra, photoluminescence spectra, respectively. The results showed that the AIZS QDs with excellent fluorescence properties could be prepared via g reen and facile hydrothermal method. The surface defects of AIZS QDs could be effectively passivated by ligands with the increase of pH values (pH = 7 similar to 9 ), resulting in the enhanced emission intensity. Moreover, the emission wavelength of AIZS QDs located the range of 632.1 nm similar to 588.9 nm with the Ag/In ratios of 1 : 1 similar to 1 : 11, and their Quantum Yields (QYs) could reach up to 27. 3Yo with the A g /In ratio of 1 : 7. Furthermore, the emission peak showed a systematic blue-shift from 604.1 nm to 581.5 nm by varying the Ag/Zn ratio from 1 : 0.5 to 1 : 3.0 due to the increased alloying effect. AIZS QDs exhibited the strong est emission and the maximum QYs of could be further increased to 35.3% with the Ag/Zn ratio of 1 : 1.5, indicating that the incorporation of Zn-2 could effectively improve the fluorescence properties of AIZS QDs by stabilizing the lattice and suppressing the non-radiative recombination. Under the forward bias current of 200 mA, the AIZS QDs-based white light-emitting diode (WLED) exhibited a high Color Rendering Index (CRI) of 80. 1, Luminous Efficiency ( LE) of 60.8 lm/W with the Commission Internationale de I'Eclairage (CIE) color coordinate of (0.29, 0.35), demonstrating the prospective application of obtained QDs in solid-state lighting devices.