Regulation of hole transport layer for perovskite quantum dot light-emitting diodes

Ronghong Zheng,Dong Huang,Yu Chen,Chengzhao Luo,Dongyang Shen,L Duan,A.Z Abdullah

doi:10.1051/e3sconf/202124503021

Abstract

Perovskite quantum dots have been widely used in light-emitting diodes (LEDs) because of their adjustable color, high quantum yield and easy solution processing. Furthermore, matching energy levels of device plays a profound role in the resultant LEDs. In this study, a polymeric material, namely poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4’-(N-(pbutylphenyl))diphenylamine)] (TFB), is introduced between the quantum dot emission layer and the hole injection layer PEDOT:PSS, which not only prevents the fluorescence quenching caused by the direct contact between the perovskite layer and the hole injection layer, but also reduces hole injection barrier, both being beneficial to the device performance. The optimal thickness of TFB has been obtained by adjusting the rotational speed and precursor solution concentration during spin coating. The optimized quantum dots LED has a switching on voltage of about 2.2 V, a maximum brightness of 4300 cd/m2, a maximum external quantum efficiency of 0.15%, and a maximum current density of 0.54 cd/A.

Highlights

Peroveskite quantum dots have been widely reported as emissive materials in light-emitting diodes (LEDs) because of their high quantum yield, good monochromaticity (FWHM~20nm), adjustable color and other advantages
LED devices have been developed from simple sandwich structure to a more widely adopted multilayer structure, including anode, hole transport layer (HTL), emitting layer (EML), electron transport layer (ETL) and cathode
If the quantum dots (QDs) were directly combined with the HTL material with large energy level difference and inappropiate thickness, fluorescence quenching and low injection efficiency may be resulted

Summary

Introduction

Owing to their tunable direct bandgap, high optical absorption coefficient, long carrier diffusion length and high defect tolerance, perovskites have been widely attempted in various optoelectronic applications, such as solar cells, light-emitting diodes, lasers and optical detectors.[1,2,3,4,5,6,7] Peroveskite quantum dots have been widely reported as emissive materials in LEDs because of their high quantum yield, good monochromaticity (FWHM~20nm), adjustable color and other advantages. To obtain a high-performance LED, besides the optimization of the emissive perovskite materials, it is of highly importance to improve the device struture, including the selection of materials for each layer, the matching of energy levels, the wettability, film forming ability and carrier mobility of each layer. If the QDs were directly combined with the HTL material with large energy level difference and inappropiate thickness, fluorescence quenching and low injection efficiency may be resulted

Methods

Results

Conclusion