Hole injection of quantum dot light-emitting diodes facilitated by multilayered hole transport layer

Hwang, Jeong Ha; Kim, Junmo; Kim, Byong Jae; Park, Myeongjin; Kwon, Yong Woo; An, Myungchan; Shin, Dong Yeol; Jeon, Jae Min; Kim, Jun Young; Lee, Wonho; Lim, Jaehoon; Lee, Donggu

doi:10.1016/j.apsusc.2021.149944

Cited by 10 publications

(5 citation statements)

References 27 publications

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“…Typically to increase the conductivity of the organic charge-transport layer, doped charge-transport layers are used with transition metal oxides, − such as MoO 3 and WO 3 , or organic molecules that have high electron affinity, , such as hexaazatriphenylene hexacarbonitrile and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane. In addition, delta doping, which involves inserting a thin nanometer-thick dopant region into the host material − for precisely controlling the doping profile in an organic LED, has been investigated. However, this method was mainly studied based on the vacuum deposition process because of the difficulty due to the dissolution of the underlayer.…”

Section: Introductionmentioning

confidence: 99%

Solution-Processed Thick Hole-Transport Layer for Reliable Quantum-Dot Light-Emitting Diodes Based on an Alternatingly Doped Structure

Kim,

Hwang,

Seo

et al. 2024

ACS Appl. Mater. Interfaces

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The operating lifetime of quantum-dot light-emitting diodes (QLED) is a bottleneck for commercial display applications. To enhance the operational stability of QLEDs, we developed a robust solution-processed highly conductive hole-transportlayer (HTL) structure, which enables a thick HTL structure to mitigate the electric field. An alternating doping strategy, which involves multiple alternating stacks of N4,N4′-di(naphthalen-1-yl)-N4,N4′-bis(4-vinylphenyl)biphenyl-4,4′-diamine and phosphomolybdic acid layers, could provide significantly improved conductivity; more specifically, the 90 nm-thick alternatingly doped HTL exhibited higher conductivity than the 45 nm-thick undoped HTL. Therefore, when applied to a QLED, the increase in the thickness of the alternatingly doped HTL increased device reliability. As a result, the lifetime of the QLED with a thick, alternatingly doped HTL was 48-fold higher than that of the QLED with a thin undoped HTL. This alternating doping strategy provides a new paradigm for increasing the stability of solution-based optoelectronic devices in addition to QLEDs.

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Section: Introductionmentioning

confidence: 99%

Solution-Processed Thick Hole-Transport Layer for Reliable Quantum-Dot Light-Emitting Diodes Based on an Alternatingly Doped Structure

Kim,

Hwang,

Seo

et al. 2024

ACS Appl. Mater. Interfaces

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“…These approaches have successfully demonstrated their effectiveness; however, controlling the injection rate of a single type of charge carrier (i.e., electron) can increase the operational stress within devices and, in certain cases, may not achieve desired charge injection balance. Therefore, sophisticated control of the injection rate of another type of charge carrier (i.e., a hole) should be considered . However, only a limited number of studies have simultaneously engineered the injection rates of both types of charge carriers.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, sophisticated control of the injection rate of another type of charge carrier (i.e., a hole) should be considered. 27 However, only a limited number of studies have simultaneously engineered the injection rates of both types of charge carriers.…”

Section: ■ Introductionmentioning

confidence: 99%

Versatile Use of 1,12-Diaminododecane as an Efficient Charge Balancer for High-Performance Quantum-Dot Light-Emitting Diodes

et al. 2023

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Balancing the charge injection rates in the emissive layer (EML) is a key factor in achieving high-performance quantumdot light-emitting diodes (QD-LEDs). This has mostly been pursued by controlling the injection rate of one type of charge carrier (typically electrons). Simultaneous engineering of both types of charge carriers, however, would be more efficient in achieving the desired charge balance within a device. Herein, the versatile use of 1,12diaminododecane (DAD) ligands is proposed to achieve balanced charge injection rates into the QD EML, thereby enhancing QD-LED performance. By utilizing the dipole moment and short chain lengths, DAD ligands function as efficient electron retarders and hole boosters. Specifically, DAD treatment on the surface of zinc oxide generates an electronic barrier to QDs. Meanwhile, DAD treatment on the surface of the QDs reduces the potential difference between the organic hole transport layers and QDs. Consequently, the QD-LEDs with the adoption of DAD at the two different positions exhibit balanced charge injection rates into the QDs, enhancing device efficiency and operational stability. The present study proposes a simple yet efficient chemical method that controls both electron and hole injection properties to achieve highperformance QD-LEDs.

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“…In addition, due to the nature of organic materials, the PEDOT:PSS has a lower thermal stability than inorganic materials. Transition metal oxides such as molybdenum oxide (MoO 3 ) [ 26 , 27 , 28 ], nickel oxide (NiO) [ 29 , 30 , 31 ], tungsten oxide (WO 3 ) [ 32 , 33 , 34 ], and vanadium oxide (V 2 O 5 ) [ 35 , 36 , 37 ] have successfully been employed in QLEDs as promising alternatives to replace the organic PEDOT:PSS HIL due to their compatibility with a high work function, good stability, and good carrier mobility. Consequently, transition metal oxides have applications in various devices, including photovoltaics, batteries, and light-emitting diodes.…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient All-Solution-Processed Quantum Dot Light-Emitting Diodes Using MoOx Nanoparticle Hole Injection Layer

et al. 2023

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This paper presents a study that aims to enhance the performance of quantum dot light-emitting didoes (QLEDs) by employing a solution-processed molybdenum oxide (MoOx) nanoparticle (NP) as a hole injection layer (HIL). The study investigates the impact of varying the concentrations of the MoOx NP layer on device characteristics and delves into the underlying mechanisms that contribute to the observed enhancements. Experimental techniques such as an X-ray diffraction and field-emission transmission electron microscopy were employed to confirm the formation of MoOx NPs during the synthesis process. Ultraviolet photoelectron spectroscopy was employed to analyze the electron structure of the QLEDs. Remarkable enhancements in device performance were achieved for the QLED by employing an 8 mg/mL concentration of MoOx nanoparticles. This configuration attains a maximum luminance of 69,240.7 cd/cm2, a maximum current efficiency of 56.0 cd/A, and a maximum external quantum efficiency (EQE) of 13.2%. The obtained results signify notable progress in comparison to those for QLED without HIL, and studies that utilize the widely used poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) HIL. They exhibit a remarkable enhancements of 59.5% and 26.4% in maximum current efficiency, respectively, as well as significant improvements of 42.7% and 20.0% in maximum EQE, respectively. This study opens up new possibilities for the selection of HIL and the fabrication of solution-processed QLEDs, contributing to the potential commercialization of these devices in the future.

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Hole injection of quantum dot light-emitting diodes facilitated by multilayered hole transport layer

Cited by 10 publications

References 27 publications

Solution-Processed Thick Hole-Transport Layer for Reliable Quantum-Dot Light-Emitting Diodes Based on an Alternatingly Doped Structure

Solution-Processed Thick Hole-Transport Layer for Reliable Quantum-Dot Light-Emitting Diodes Based on an Alternatingly Doped Structure

Versatile Use of 1,12-Diaminododecane as an Efficient Charge Balancer for High-Performance Quantum-Dot Light-Emitting Diodes

Highly Efficient All-Solution-Processed Quantum Dot Light-Emitting Diodes Using MoOx Nanoparticle Hole Injection Layer

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