Copper Indium Disulfide Quantum Dot Light Emitting Diodes for Display and Lighting Technologies

Abstract

While significant advances in the development of quantum dot light emitting diodes (QLEDs) have been reported, these devices are primarily based on cadmium chalcogenide quantum dot (QD) materials. Both environmental and health concerns arise due to the toxicity of cadmium and consequently, alternative less toxic QDs must be developed for large scale QLED applications such as display and solid state lighting technologies. In this work, copper indium disulfide (CIS) was investigated as an alternative QD material for QLED applications. Through experimentation with material synthesis and device fabrication, this project aimed to develop high performing CIS QLEDs. Several synthetic approaches were experimented with and it was determined that the injection of shorter chain 1-octanethoil as sulfur precursor with extensive shell reaction time resulted in highly luminescent QDs. Single color QLEDs were fabricated based on typical device structure, using highly luminescent synthesized CIS QDs as the emissive layer in multilayer devices. Varying the shell reaction time of QDs in order to vary shell thickness resulted in significant differences in device performance. Using thicker shell QDs, high performing devices were obtained with the best performing QLEDs displaying a high peak current efficiency of 14.7 cd/A and high external quantum efficiency of 5.2%.