Pure-colored red, green, and blue quantum dot light-emitting diodes using emitting layers composed of cadmium-free quantum dots and organic electron-transporting materials

Abstract

This study focuses on the use of highly saturated and efficient red, green, and blue (RGB) cadmium (Cd)-free quantum dot light-emitting diodes (QD-LEDs). RGB QD-LEDs were fabricated using emitting layers (EMLs) comprising Cd-free QDs (red and green InP-based QDs and blue Zn–SeTe QDs) and organic electron-transporting materials (ETMs). The green QD-LED with high color purity was realized by adjusting the QD concentration in the EMLs and suppressing the defect-associated emission in the QD-LEDs. Narrow emissions of the full-width at half-maximum of 40, 34, and 23 nm were realized in the RGB QD-LEDs, respectively. Wide-area coverage of 80% of the available color reproduction area specified in Recommendation ITU-R BT.2020 was achieved using the developed RGB QD-LEDs without applying any color filter and cavity structure. Furthermore, the addition of organic ETMs into the EMLs improved the efficiency of all RGB QD-LEDs.