Spatial electron tunneling leads to space-charge-limited current in organic hole transport materials

doi:10.1088/1674-1056/adcb1d

中国物理B ›› 2025, Vol. 34 ›› Issue (7): 78101-078101.doi: 10.1088/1674-1056/adcb1d

Spatial electron tunneling leads to space-charge-limited current in organic hole transport materials

Shaofeng Chen(陈绍枫)^1,2,†, Yanfei Lu(鲁燕飞)^1,2,†, Dongcheng Chen(陈东成)^1,2,‡, and Shi-Jian Su(苏仕健)^1,2

1 State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China;
2 Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640, China

收稿日期:2025-01-14 修回日期:2025-03-31 接受日期:2025-04-10 出版日期:2025-06-18 发布日期:2025-07-10
通讯作者: Dongcheng Chen E-mail:mschendc@scut.edu.cn
基金资助:
Project supported by the National Key Research and Development Program of China (Grant No. 2020YFB0408000), Guangdong Provincial Department of Science and Technology (Grant No. 2019TQ05C778), and Guangdong Basic and Applied Basic Research Foundation (Grant No. 2019A1515011639).

Spatial electron tunneling leads to space-charge-limited current in organic hole transport materials

Shaofeng Chen(陈绍枫)^1,2,†, Yanfei Lu(鲁燕飞)^1,2,†, Dongcheng Chen(陈东成)^1,2,‡, and Shi-Jian Su(苏仕健)^1,2

1 State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China;
2 Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640, China

Received:2025-01-14 Revised:2025-03-31 Accepted:2025-04-10 Online:2025-06-18 Published:2025-07-10
Contact: Dongcheng Chen E-mail:mschendc@scut.edu.cn
Supported by:
Project supported by the National Key Research and Development Program of China (Grant No. 2020YFB0408000), Guangdong Provincial Department of Science and Technology (Grant No. 2019TQ05C778), and Guangdong Basic and Applied Basic Research Foundation (Grant No. 2019A1515011639).

1. 2025-078101-SI.pdf(2608KB)

摘要/Abstract

摘要： The injection of electrical charge from an electrode into organic semiconductors directly influences the performance of organic optoelectronic devices. However, our understanding of the mechanisms behind charge injection remains incomplete. In this study, we explored the hole injection from an indium tin oxide (ITO) electrode into a hole transport layer (HTL) by employing various organic interlayers (ILs) with different ionization potentials (IPs). It was demonstrated that using O$_{2}$ plasma treatment onto an ITO surface and incorporating an interlayer (IL) with a higher IP between the ITO electrode and the HTL can substantially increase the hole current density. This improvement leads to the achievement of barrier-free injection and the establishment of space-charge-limited current. We propose two synergistic mechanisms of spatial electron tunneling that govern the injection characteristics: electron tunneling from the HTL across the IL to the electrode that establishes an electrostatic equilibrium with a zero-injection barrier and an electric-field-induced spatial tunneling effect that occurs during device operation with applying bias. This research offers a strategy to achieve space-charge-limited hole current and provides an explanatory framework for understanding the underlying physics of charge injection.

关键词: organic semiconductor, spatial electron tunneling, hole injection, indium tin oxide, work function

Abstract: The injection of electrical charge from an electrode into organic semiconductors directly influences the performance of organic optoelectronic devices. However, our understanding of the mechanisms behind charge injection remains incomplete. In this study, we explored the hole injection from an indium tin oxide (ITO) electrode into a hole transport layer (HTL) by employing various organic interlayers (ILs) with different ionization potentials (IPs). It was demonstrated that using O$_{2}$ plasma treatment onto an ITO surface and incorporating an interlayer (IL) with a higher IP between the ITO electrode and the HTL can substantially increase the hole current density. This improvement leads to the achievement of barrier-free injection and the establishment of space-charge-limited current. We propose two synergistic mechanisms of spatial electron tunneling that govern the injection characteristics: electron tunneling from the HTL across the IL to the electrode that establishes an electrostatic equilibrium with a zero-injection barrier and an electric-field-induced spatial tunneling effect that occurs during device operation with applying bias. This research offers a strategy to achieve space-charge-limited hole current and provides an explanatory framework for understanding the underlying physics of charge injection.

Key words: organic semiconductor, spatial electron tunneling, hole injection, indium tin oxide, work function

中图分类号: (Polymers and organics)

42.70.Jk

73.43.Jn (Tunneling) 81.05.Fb (Organic semiconductors)

Shaofeng Chen(陈绍枫), Yanfei Lu(鲁燕飞), Dongcheng Chen(陈东成), and Shi-Jian Su(苏仕健). Spatial electron tunneling leads to space-charge-limited current in organic hole transport materials[J]. 中国物理B, 2025, 34(7): 78101-078101.

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Spatial electron tunneling leads to space-charge-limited current in organic hole transport materials

Spatial electron tunneling leads to space-charge-limited current in organic hole transport materials

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