Highly Efficient, Bright and Stable Colloidal Quantum Dot Short-Wave Infrared Light Emitting Diodes

TL;DR

This paper introduces a novel charge regulation method in colloidal quantum dot LEDs that significantly enhances efficiency and stability in the short-wave infrared range, enabling practical high-radiance applications.

Contribution

The authors develop an energetic potential landscape engineering technique to improve charge balance in CQD LEDs, achieving record-high efficiency and stability at high radiance levels.

Findings

External quantum efficiency exceeds 8% at 5 Wsr-1m-2 radiance.

Operational stability with a radiance half-life of over 26,000 hours.

Achieved high efficiency in the short-wave infrared range at practical radiance levels.

Abstract

Unbalanced charge injection is deleterious for the performance of colloidal quantum dot (CQD) light emitting diodes (LEDs) as it deteriorates the quantum efficiency (QE), brightness and operational lifetime. CQD LEDs emitting in the infrared have previously achieved high quantum efficiencies but only when driven to emit in the low radiance regime. At higher radiance levels, required for practical applications, the efficiency decreased dramatically in view of the notorious efficiency droop. Here we report a novel methodology to regulate charge supply in multinary bandgap CQD composites that facilitates improved charge balance. Our approach is based on engineering the energetic potential landscape at the supra-nanocrystalline level that has allowed us to report short-wave infrared (SWIR) PbS CQD LEDs with record-high external QE in excess of 8%, most importantly, at a radiance level of ~ 5 WSr-1m2, an order of magnitude higher than prior reports. Furthermore, the balanced charge injection and Auger recombination reduction has led to unprecedentedly high operational stability with radiance half-life of 26068 hours at a radiance of 1Wsr-1m-2.