Lifetime elongation of quantum-dot light-emitting diodes by inhibiting the degradation of hole transport layer
Journal
RSC Advances
Journal Volume
11
Journal Issue
34
Pages
20884-20891
Date Issued
2021
Author(s)
Abstract
Developing a colloidal quantum-dot light-emitting device (QDLED) with high efficiency and good reliability is necessarily preliminary for the next-generation high-quality display application. Most QDLED reports are focused on efficiency improvement, but the device operational lifetime issue is less addressed and also the relevant degradation mechanisms. This study achieved a 1.72 times elongation in the operational lifetime and a 9 times improvement in the efficiency of QDLED by inserting a hole-transporting/electron-blocking poly(9-vinylcarbazole) (PVK) layer, which prevented operational degradation on poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-secbutylphenyl))-diphenylamine)] (TFB) hole-transporting layer and also confined the electron in the QD-emitting layer. Although the TFB/PVK HTL structure is a well-known pair to enhance the device performance, its detailed mechanisms were rarely mentioned, especially for relative operational lifetime issues. Herein, a new insight behind operational lifetime elongation of QDLED is disclosed through various fundamental experiments including steady-state photoluminescence, transient electroluminescence and single-carrier only devices. Evidently, other than QD degradation, this study found that the other crucial factor that decreased the device lifetime was TFB-HTL degradation using steady-state photoluminescence and transient electroluminescence analyses. The PVK electron-only device exhibited a stable voltage value when it was driven by fixed current, which also affirmed that PVK has excellent electron-stability characteristics. ? The Royal Society of Chemistry 2021.
Subjects
Degradation
Display devices
Efficiency
Electroluminescence
Elongation
Light
Nanocrystals
Photoluminescence
Quantum chemistry
Semiconductor quantum dots
Colloidal quantum dots
Efficiency improvement
Fundamental experiments
Hole transporting layers
Light emitting devices
Poly(9-vinylcarbazole)
Quantum-dot light emitting diodes
Transient electroluminescence
Organic light emitting diodes (OLED)
Type
journal article