Stepwise Bi-layer hole-transport interlayers with deep highest occupied molecular orbital level for efficient green quantum dot light-emitting diodes

Xiaojun Wang; Piaoyang Shen; Fan Cao; Sheng Wang; Haoran Wang; Qianqian Wu; Jianhua Zhang; Xuyong Yang

doi:10.1109/LED.2019.2916584

Stepwise Bi-layer hole-transport interlayers with deep highest occupied molecular orbital level for efficient green quantum dot light-emitting diodes

Xiaojun Wang, Piaoyang Shen, Fan Cao, Sheng Wang, Haoran Wang, Qianqian Wu, Jianhua Zhang, Xuyong Yang

Biochemistry, Chemistry & Physics

Shanghai University

Research output: Contribution to journal › Article › peer-review

14 Scopus citations

Abstract

The imbalanced charge transport/injection in quantum dot (QD) light-emitting diodes (QLEDs) due to the existing excess electrons has greatly restricted the device performance. Here, we designed a stepwise bi-layer structured hole-transport layer (HTL) containing 4, 4′-bis-(carbazole-9-yl)biphenyl (CBP)/1,3-bis(9H-pyrido[2,3-b]indol-9-yl) benzene (mCaP) with deep highest occupied molecular orbital (HOMO) level to realize more efficient hole injection into QD emissive layer for balancing charge in the QLED devices. The resulting green QLEDs show a maximum current efficiency (CE) of 41.2 cd A^-1 corresponding to an external quantum efficiency (EQE) of 12.6%, which is a significant efficiency enhancement compared with the devices with only single-layer HTL. In addition, the device turn-on voltage is also reduced from 5 to 3 V, and meanwhile the operational lifetime is increased by more than twofold.

Original language	English
Article number	8714044
Pages (from-to)	1139-1142
Number of pages	4
Journal	IEEE Electron Device Letters
Volume	40
Issue number	7
DOIs	https://doi.org/10.1109/LED.2019.2916584
State	Published - Jul 2019

Scopus Subject Areas

Electronic, Optical and Magnetic Materials
Electrical and Electronic Engineering

Keywords

QLEDs
Quantum dots
charge balance
deep HOMO level
light-emitting diodes

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10.1109/LED.2019.2916584

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title = "Stepwise Bi-layer hole-transport interlayers with deep highest occupied molecular orbital level for efficient green quantum dot light-emitting diodes",

abstract = "The imbalanced charge transport/injection in quantum dot (QD) light-emitting diodes (QLEDs) due to the existing excess electrons has greatly restricted the device performance. Here, we designed a stepwise bi-layer structured hole-transport layer (HTL) containing 4, 4′-bis-(carbazole-9-yl)biphenyl (CBP)/1,3-bis(9H-pyrido[2,3-b]indol-9-yl) benzene (mCaP) with deep highest occupied molecular orbital (HOMO) level to realize more efficient hole injection into QD emissive layer for balancing charge in the QLED devices. The resulting green QLEDs show a maximum current efficiency (CE) of 41.2 cd A-1 corresponding to an external quantum efficiency (EQE) of 12.6%, which is a significant efficiency enhancement compared with the devices with only single-layer HTL. In addition, the device turn-on voltage is also reduced from 5 to 3 V, and meanwhile the operational lifetime is increased by more than twofold.",

keywords = "QLEDs, Quantum dots, charge balance, deep HOMO level, light-emitting diodes",

author = "Xiaojun Wang and Piaoyang Shen and Fan Cao and Sheng Wang and Haoran Wang and Qianqian Wu and Jianhua Zhang and Xuyong Yang",

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year = "2019",

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AU - Wang, Xiaojun

AU - Shen, Piaoyang

AU - Cao, Fan

AU - Wang, Sheng

AU - Wang, Haoran

AU - Wu, Qianqian

AU - Zhang, Jianhua

AU - Yang, Xuyong

PY - 2019/7

Y1 - 2019/7

N2 - The imbalanced charge transport/injection in quantum dot (QD) light-emitting diodes (QLEDs) due to the existing excess electrons has greatly restricted the device performance. Here, we designed a stepwise bi-layer structured hole-transport layer (HTL) containing 4, 4′-bis-(carbazole-9-yl)biphenyl (CBP)/1,3-bis(9H-pyrido[2,3-b]indol-9-yl) benzene (mCaP) with deep highest occupied molecular orbital (HOMO) level to realize more efficient hole injection into QD emissive layer for balancing charge in the QLED devices. The resulting green QLEDs show a maximum current efficiency (CE) of 41.2 cd A-1 corresponding to an external quantum efficiency (EQE) of 12.6%, which is a significant efficiency enhancement compared with the devices with only single-layer HTL. In addition, the device turn-on voltage is also reduced from 5 to 3 V, and meanwhile the operational lifetime is increased by more than twofold.

AB - The imbalanced charge transport/injection in quantum dot (QD) light-emitting diodes (QLEDs) due to the existing excess electrons has greatly restricted the device performance. Here, we designed a stepwise bi-layer structured hole-transport layer (HTL) containing 4, 4′-bis-(carbazole-9-yl)biphenyl (CBP)/1,3-bis(9H-pyrido[2,3-b]indol-9-yl) benzene (mCaP) with deep highest occupied molecular orbital (HOMO) level to realize more efficient hole injection into QD emissive layer for balancing charge in the QLED devices. The resulting green QLEDs show a maximum current efficiency (CE) of 41.2 cd A-1 corresponding to an external quantum efficiency (EQE) of 12.6%, which is a significant efficiency enhancement compared with the devices with only single-layer HTL. In addition, the device turn-on voltage is also reduced from 5 to 3 V, and meanwhile the operational lifetime is increased by more than twofold.

KW - QLEDs

KW - Quantum dots

KW - charge balance

KW - deep HOMO level

KW - light-emitting diodes

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Stepwise Bi-layer hole-transport interlayers with deep highest occupied molecular orbital level for efficient green quantum dot light-emitting diodes

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Keywords

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