High performance top-emitting quantum dot light-emitting diodes with interfacial modification

Shihao Ding,Bing Xu,Weigao Wang,Kai Wang,Shuming Chen,Xiao Wei Sun,Xiangtian Xiao,Zhenghui Wu,Xiangwei Qu

doi:10.1063/5.0005657

Abstract

In this paper, we report high performance top-emitting quantum dot light-emitting diodes (TE-QLEDs) with an interfacial modification layer. The specular metal bottom electrode was modified by an interfacial layer to improve the wettability of the aqueous solution on a metal electrode. By doing so, the potential barrier between the metal electrode and hole injection layer is decreased and the hole injection is enhanced. The capacitance analysis was used to understand the charge transfer process of the TE-QLEDs. The result showed that the indium tin oxide (ITO) interface layer is the best among NiOx, MoO3, and ITO. As a consequence, the red TE-QLEDs with an ITO interfacial modification layer show a maximum luminance and maximum external quantum efficiency of 18 880 cd/m2 and 11.8%, respectively. Our works indicate that the interfacial modification with metal oxides is an effective approach for high performance TE-QLEDs.

Highlights

Colloidal quantum dot light-emitting diodes (QLEDs) have emerged as a strong candidate for the generation displays and lighting, as the quantum dot (QD) enjoys good color purity, tunable emission wavelength, high brightness and solution processability, enabling the fabrication of QLEDs with a large color gamut, and low cost.1–5 At present, considerable research efforts of QLEDs have been devoted to the bottom-emitting structure.6–10 this structure is not suitable for applications using active-matrix QLEDs because it would adversely reduce the aperture ratio
In order to make high efficiency TE-QLEDs, it is important to improve the interface between the metal electrode and hole injection layer (HIL)
When using a 10 nm MoO3 film as the interfacial modification layer, the external quantum efficiency (EQE) of the green light TE-QLEDs can be as high as 7.4%

Summary

Introduction

Colloidal quantum dot light-emitting diodes (QLEDs) have emerged as a strong candidate for the generation displays and lighting, as the quantum dot (QD) enjoys good color purity, tunable emission wavelength, high brightness and solution processability, enabling the fabrication of QLEDs with a large color gamut, and low cost.1–5 At present, considerable research efforts of QLEDs have been devoted to the bottom-emitting structure.6–10 this structure is not suitable for applications using active-matrix QLEDs because it would adversely reduce the aperture ratio. In order to spin-coat a uniform PEDOT: PSS film, 10 nm NiOx by sputtering or 5 nm MoO3 by evaporation or 15 nm ITO by sputtering was deposited on Al electrodes as an interfacial modification layer.

Results

Conclusion