(A) study on highly efficient and vivid R/G/B patterned light emitting diodes using high quality perovskite quantum dots

Abstract

Displays are crucial devices in the modern era, visualizing and presenting information. Currently, displays are becoming increasingly diverse, extending beyond the past televisions and monitors to include virtual reality displays, wearable devices, and automotive displays. As a result, the demands for next-generation displays are growing even higher, with an increasing need for high-performance displays. In response to this demand, perovskite quantum dots (PeQDs) have been receiving attention as next-generation luminescent materials. In this dissertation, we propose a fabrication process for light emitting diodes (LEDs) that utilize high-quality PeQD materials, achieving high external quantum efficiency and color purity, along with the ability to pattern the LEDs by changing the emitting light color. Particularly, we developed a process that prevents the precipitation of cesium precursor and enhances injection speed of the precursor during the synthesis of cesium lead bromide (CsPbBr$_3$) PeQDs, enabling synthesis of high-quality PeQDs having monodispersity. Based on these synthesized PeQDs, we also developed a process that allows the simultaneous exchange of ligands and halide anions in the thin film state of the PeQDs, leading to improved performance and enabling fabrication of PeQD LEDs with various patterns. Moreover, in this process, we controlled the solvent polarity and the composition of the ligands used, resulting in LEDs with even higher efficiency compared to conventional processes. Consequently, we expect that these material synthesis and process technologies can be widely applied to semiconductor devices targeting various bandgaps.