High-Performance Green and Blue Light-Emitting Diodes Enabled by CdZnSe/ZnS Core/Shell Colloidal Quantum Wells

TL;DR

This paper reports the development of high-efficiency green and blue colloidal quantum well LEDs using tailored CdZnSe/ZnS core/shell structures, achieving record brightness and quantum efficiency for solution-processed devices.

Contribution

It introduces a novel synthesis method combining cation exchange and hot-injection shell growth to produce high-performance CQWs for LEDs, surpassing previous efficiencies.

Findings

Peak external quantum efficiency of 20.4% for green LEDs

Maximum brightness of 347,683 cd/m^2 for green LEDs

Enhanced optoelectronic properties of synthesized CQWs

Abstract

The unique anisotropic properties of colloidal quantum wells (CQWs) make them highly promising as components in nanocrystal-based devices. However, the limited performance of green and blue light-emitting diodes (LEDs) based on CQWs has impeded their practical applications. In this study, we tailored alloy CdZnSe core CQWs with precise compositions via direct cation exchange (CE) from CdSe CQWs with specific size, shape, and crystal structure and utilized hot-injection shell (HIS) growth to synthesize CdZnSe/ZnS core/shell CQWs exhibiting exceptional optoelectronic characteristics. This approach enabled us to successfully fabricate green and blue LEDs manifesting superior performance compared to previously reported solution-processed CQW-LEDs. Our devices demonstrated a remarkable peak external quantum efficiency (20.4% for green and 10.6% for blue), accompanied by a maximum brightness 347,683 cd m-2 for green and 38,063 cd m-2 for blue. The high-performance represents a significant advancement for nanocrystal-based light-emitting diodes (Nc-LEDs) incorporating anisotropic nanocrystals. This work provides a comprehensive synthesis strategy for enhancing the efficiency of Nc-LEDs utilizing anisotropic nanocrystals.