Synthesis of SiO2-coated CdSe/ZnS quantum dots using various dispersants in the photoresist for color-conversion micro-LED displays

Abstract

Quantum dots (QDs) are a promising technology for next-generation display screens owing to their well-defined and tunable emission wavelengths. However, QDs can chemically react with external environment, decreasing their photoluminescence efficiency and reliability. In addition, further work is needed on lithography techniques to make QDs compatible with semiconductor manufacturing processes. In this study, silicon dioxide (SiO2)-coated cadmium selenide/zinc sulfide QDs are synthesized using tetraethoxysilane. The ratio of cadmium oxide to zinc acetate was tuned before coating the SiO2 passivation layer to adjust the emission wavelength of the QDs between 520 and 625 nm. The SiO2 passivation layer not only enhanced the photoluminescence intensity (PLI) by 69% but also effectively decelerated the fluorescence decay rate (<1% PLI decay after 100 h). In addition, the hydrophilicity of the SiO2-coated QDs enabled them to integrate with appropriate dispersants and photoresist for creating a 50-μm × 50-μm pixel on the color-conversion layer of a blue microlight emitting diode (micro-LED) display. Finally, a structure of a distributed Bragg reflector (DBR) was designed using TFCalc software. Subsequently, a DBR layer was deposited on the red–green QDs’ color-conversion layer to fabricate a full-color micro-LED display.