Improving Charge Injection via a Blade-Coating Molybdenum Oxide Layer: Toward High-Performance Large-Area Quantum-Dot Light-Emitting Diodes

Zeng, Qunying; Xu, Zhiai; Zheng, Congxiu; Liu, Yang; Chen, Wei; Guo, Tailiang; Li, Fushan; Xiang, Chaoyu; Yang, Yixing; Cao, Weiran; Xie, Xiangwei; Yan, Xiaolin; Liu, Qian; Holloway, Paul H.

doi:10.1021/acsami.7b19333

Cited by 47 publications

(33 citation statements)

References 29 publications

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“…Various metal oxides have been utilized in the hole‐injection layer (HIL) and/or HTL of QLEDs, including tungsten oxide (WO x ), molybdenum oxide (MoO x ), nickel oxide (NiO), copper oxide (Cu x O), and vanadium oxide (VO x ) . These metal oxides have excellent stability and suitable energy levels for efficient charge injection/transport, and can also prevent the penetration of water or oxygen molecules .…”

Section: Enhancement Of Qled Lifetimementioning

confidence: 99%

Stability of Quantum Dots, Quantum Dot Films, and Quantum Dot Light‐Emitting Diodes for Display Applications

et al. 2019

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Quantum dots (QDs) are being highlighted in display applications for their excellent optical properties, including tunable bandgaps, narrow emission bandwidth, and high efficiency. However, issues with their stability must be overcome to achieve the next level of development. QDs are utilized in display applications for their photoluminescence (PL) and electroluminescence. The PL characteristics of QDs are applied to display or lighting applications in the form of color‐conversion QD films, and the electroluminescence of QDs is utilized in quantum dot light‐emitting diodes (QLEDs). Studies on the stability of QDs and QD devices in display applications are reviewed herein. QDs can be degraded by oxygen, water, thermal heating, and UV exposure. Various approaches have been developed to protect QDs from degradation by controlling the composition of their shells and ligands. Phosphorescent QDs have been protected by bulky ligands, physical incorporation in polymer matrices, and covalent bonding with polymer matrices. The stability of electroluminescent QLEDs can be enhanced by using inorganic charge transport layers and by improving charge balance. As understanding of the degradation mechanisms of QDs increases and more stable QDs and display devices are developed, QDs are expected to play critical roles in advanced display applications.

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Section: Enhancement Of Qled Lifetimementioning

confidence: 99%

Stability of Quantum Dots, Quantum Dot Films, and Quantum Dot Light‐Emitting Diodes for Display Applications

et al. 2019

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“…Then the samples were dried at 100C for 30 min. Thermovacuum deposited MoO3 was as used as the hole injector layer [20,26] and TPBi as an organic semiconductor electron transport layer [21,27]. Ca and Al metal electrodes were disposed onto a precleaned ITO-coated glass surface under a vacuum of 10 -5 Torr.…”

Section: Experiments and Methodsmentioning

confidence: 99%

“…Particularly, in such devices the coating of QD from aqueous solutions onto an inorganic hole transport layer (HTL) like MoO3 [20,21] is accomplished at the initial stages of the QLED formation. The following steps of this formation involve a technique of thermovacuum deposition for organic semiconductive films or spin-coating from organic solutions.…”

Section: Introductionmentioning

confidence: 99%

Multi-channel electroluminescence of CdTe/CdS core-shell quantum dots implemented into a QLED device

et al. 2019

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CdTe/CdS core-shell quantum dots were synthesized and implemented into a light emitting device resulting in multi-channel electroluminescence with a light-green emission colour. The main electroluminescence band at about 530 nm corresponds to the emission by the CdTe core (type I core/shell structure), while the next emission band at 595 nm is assigned to the crossed recombination of electrons from the conduction band of the CdS shell and holes from the valence band of the CdTe core (type II core/shell structure). At the same time, the photoluminescence spectrum of the synthesized CdTe/CdS core-shell quantum dots contains only one emission band distinctive for type II structures. This behavior of CdTe/CdS core-shell quantum dots upon the electroexcitation allows the extension of the electroluminescence spectrum in the optical region in a way that is useful for the lighting-source applications. Such multi-channel electroluminescence can most probably also be reproduced in related core-shell systems accounting for size-confinement between the core size and shell thickness.

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“…Quantum dot light‐emitting diodes (QLEDs) are considered as emerging future display devices because of their high color purity and wide color expression resulted from their narrow full width of half maximum (FWHM), high quantum yields, and potential for low processing cost via all solution process . All‐solution‐processed QLEDs can reduce the processing cost for large‐area displays, as vacuum evaporation processes can be replaced with various printing processes . QLEDs can be fabricated with a conventional‐structure in which holes are injected through indium tin oxide (ITO) electrodes .…”

Section: Key Characteristics Of the All‐solution‐processed Inverted‐smentioning

confidence: 99%

Efficiency Enhancement of All‐Solution‐Processed Inverted‐Structure Green Quantum Dot Light‐Emitting Diodes Via Partial Ligand Exchange with Thiophenol Derivatives Having Negative Dipole Moment

Moon

Chae

2019

Advanced Optical Materials

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Thiophenol derivatives having a negative dipole moment such as thiophenol (TP), 4‐methylthiophenol (4‐MTP), and 4‐(dimethylamino)thiophenol (4‐DMATP) are incorporated into quantum dots (QDs) and the efficiency of all‐solution‐processed inverted‐structure quantum dot light‐emitting diodes (QLEDs) is enhanced. The negative dipole moments of TP, 4‐MTP, and 4‐DMATP are attributed to the enhancement of the efficiency of the QLEDs. The valence band maximum (VBM) of the QDs is upshifted, and the energy gap between the VBM and the highest molecular orbital level of the hole transport layer is reduced to −0.16 from 0.46 eV by the negative dipole moment of thiophenol derivatives. The electron and hole transport of the QDs are accelerated, and charge balance is achieved at 5 V with a reduction of 1.25 V by the thiophenol derivatives. The QLEDs with 4‐DMATP exhibit a maximum luminance of 106 400 cd m−2, a maximum current efficiency of 98.2 cd A−1, and an external quantum efficiency (EQE) of 24.8%. The EQE of 24.8% is the highest value reported thus far for all‐solution‐processed inverted‐structure single‐device QLEDs, to the best of knowledge. Improvement by factors of 2.99, 1.57, and 1.54 are achieved in the maximum luminescence, maximum current efficiency, and EQE respectively, compared with a QLED with OA ligands.

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Improving Charge Injection via a Blade-Coating Molybdenum Oxide Layer: Toward High-Performance Large-Area Quantum-Dot Light-Emitting Diodes

Cited by 47 publications

References 29 publications

Stability of Quantum Dots, Quantum Dot Films, and Quantum Dot Light‐Emitting Diodes for Display Applications

Stability of Quantum Dots, Quantum Dot Films, and Quantum Dot Light‐Emitting Diodes for Display Applications

Multi-channel electroluminescence of CdTe/CdS core-shell quantum dots implemented into a QLED device

Efficiency Enhancement of All‐Solution‐Processed Inverted‐Structure Green Quantum Dot Light‐Emitting Diodes Via Partial Ligand Exchange with Thiophenol Derivatives Having Negative Dipole Moment

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