Room-temperature ionic-liquid-assisted hydrothermal synthesis of Ag-In-Zn-S quantum dots for WLEDs

Abstract

Synthesis of water-soluble I-III-VI type quantum dots (QDs) with high luminescence performance in efficient pathways still remains a tremendous challenge. In this study, water-soluble Ag-In-Zn-S (AIZS) QDs were prepared via the room temperature ionic liquids (RTILs) assisted hydrothermal method. The experimental results showed that the RTIL 1-methylimidazolium tetrafluoroborate ([Mim]BF4) played an important role in the phase structure, morphology, and optical properties of the AIZS QDs due to its high polarity and low surface tension, which was beneficial to the nucleation, growth, and surface modulation of QDs, resulting in the improvement of quantum yield (QY) from 23.2% to 28.9%. Moreover, the AIZS QDs exhibited long fluorescence lifetimes of 472.3 ns, further demonstrating the successful passivation of the trap states of QDs. Furthermore, the emission wavelength of AIZS QDs could be adjusted from 608 to 525 nm by tuning Ag/Zn ratios. Finally, a white light-emitting diode (WLED) based on AIZS QDs and green Lu3Al5O12:Ce3+ phosphor was successfully fabricated, which showed high luminous efficiency of 85.2 lm/W, color rendering index (CRI) of 62.2, and the correlated color temperature (CCT) of 6153 K, indicating the promising prospects of AIZS QDs’ application in photoelectric devices.