Abstract
In this study, the CuInS2/ZnS core/shell quantum dots (QDs) were prepared via simple and environmentally friendly solvothermal synthesis and were used as phosphors for white light-emitting diodes (WLEDs). The surface defect of the CuInS2 core QDs were passivated by the ZnS shell by forming CuInS2/ZnS core/shell QDs. By adjusting the Cu/In ratio and the nucleation temperature, the photoluminescence (PL) peak of the CuInS2 QDs was tunable in a range of 651–775 nm. After coating the ZnS layer and modifying oleic acid ligands, the PL quantum yield increased to 85.06%. The CuInS2/ZnS QD powder thermal stability results showed that the PL intensity of the QDs remained 91% at 100°C for 10 min. High color rendering index values (CRI, 90) and correlated color temperature of 4360 K for the efficient WLEDs were fabricated using CuInS2/ZnS QDs and (Ba,Sr)2SiO4:Eu2+ as color converters in combination with a blue GaN light-emitting diode chip.
Highlights
Energy shortages and environmental pollution are two major global problems
After the optimization for zinc source and OA ligands with a Cu/In ratio of 1:2, the photoluminescence quantum yield (PLQY) of CIS/ZnS quantum dots (QDs) can be increased to 85.06%
The mixture was further heated to 200◦C and this temperature was kept for 14 h, allowing the ZnS shell to grow
Summary
Energy shortages and environmental pollution are two major global problems. Lighting requires approximately 19% of all global power consumption. Phosphor-converted white light-emitting diodes (WLEDs) are widely used because they are cost-effective and environmentally friendly. Their commercialization is expanding to large-scale utilization, including display and general lighting. Yellow Y3Al5O12:Ce3+(YAG:Ce) or green light-emitting (Ba,Sr)2SiO4:Eu2+ is often used as a converter phosphor to form WLEDs in combination with InGaN or GaN blue chips (Bachmann et al, 2009; Ji et al, 2016; Dong et al, 2019). WLEDs with a low color rendering index (CRI) have some drawbacks, including the use of expensive rare-earth materials and lack of red spectral regions. Developing novel materials for low-cost, high-efficiency, and high-CRI WLEDs has attracted considerable attention
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