Paradoxical hole injection enhancement by contamination on the indium tin oxide surface

Hyunbok Lee, Junkyeong Jeong, Jiyeon Lee, Hyunchan Lee, Gyeongho Hyun, Yeonjin Yi, Sang Wan Cho

Research output: Contribution to journalArticle

Abstract

In organic electronics, contact formation at the interface between an electrode and an organic layer has a substantial influence on device performance. Clean substrates are therefore considered prerequisite to obtain high charge injection efficiency. In this study, however, we found that contamination caused by decomposition of a plastic cover film on indium tin oxide (ITO) improved hole injection. Ultraviolet and X-ray photoelectron spectroscopy measurements showed that a contamination layer formed on ITO that had been stored for several months in plastic wrapping, which reduced its work function. As a result, the hole injection barrier between the Fermi level of ITO and the highest occupied molecular orbital level of poly(9-vinylcarbazole) (PVK) was higher than that at the interface between PVK and cleaned ITO. However, in hole-only devices, the contaminated ITO exhibited a higher current density value than the cleaned ITO in the high bias regime. This paradoxical improvement in hole injection could be explained by an insulating buffer model. In this model, the contamination layer functions as an insulating anode buffer layer on the ITO surface. As high bias is applied, the contamination layer results in formation of an energy barrier with a triangular shape. Thus, holes can be injected efficiently from ITO to PVK through tunneling.

Original languageEnglish
Article number021004
JournalJapanese Journal of Applied Physics
Volume58
Issue number2
DOIs
Publication statusPublished - 2019 Jan 1

Fingerprint

Tin oxides
indium oxides
Indium
tin oxides
contamination
Contamination
injection
augmentation
plastics
buffers
Plastics
Charge injection
Energy barriers
Molecular orbitals
Buffer layers
Fermi level
high current
molecular orbitals
Anodes
anodes

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Lee, Hyunbok ; Jeong, Junkyeong ; Lee, Jiyeon ; Lee, Hyunchan ; Hyun, Gyeongho ; Yi, Yeonjin ; Cho, Sang Wan. / Paradoxical hole injection enhancement by contamination on the indium tin oxide surface. In: Japanese Journal of Applied Physics. 2019 ; Vol. 58, No. 2.
@article{2422050c32ac43d5bf2a36fdb7177c5e,
title = "Paradoxical hole injection enhancement by contamination on the indium tin oxide surface",
abstract = "In organic electronics, contact formation at the interface between an electrode and an organic layer has a substantial influence on device performance. Clean substrates are therefore considered prerequisite to obtain high charge injection efficiency. In this study, however, we found that contamination caused by decomposition of a plastic cover film on indium tin oxide (ITO) improved hole injection. Ultraviolet and X-ray photoelectron spectroscopy measurements showed that a contamination layer formed on ITO that had been stored for several months in plastic wrapping, which reduced its work function. As a result, the hole injection barrier between the Fermi level of ITO and the highest occupied molecular orbital level of poly(9-vinylcarbazole) (PVK) was higher than that at the interface between PVK and cleaned ITO. However, in hole-only devices, the contaminated ITO exhibited a higher current density value than the cleaned ITO in the high bias regime. This paradoxical improvement in hole injection could be explained by an insulating buffer model. In this model, the contamination layer functions as an insulating anode buffer layer on the ITO surface. As high bias is applied, the contamination layer results in formation of an energy barrier with a triangular shape. Thus, holes can be injected efficiently from ITO to PVK through tunneling.",
author = "Hyunbok Lee and Junkyeong Jeong and Jiyeon Lee and Hyunchan Lee and Gyeongho Hyun and Yeonjin Yi and Cho, {Sang Wan}",
year = "2019",
month = "1",
day = "1",
doi = "10.7567/1347-4065/aafa6c",
language = "English",
volume = "58",
journal = "Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes",
issn = "0021-4922",
publisher = "Japan Society of Applied Physics",
number = "2",

}

Paradoxical hole injection enhancement by contamination on the indium tin oxide surface. / Lee, Hyunbok; Jeong, Junkyeong; Lee, Jiyeon; Lee, Hyunchan; Hyun, Gyeongho; Yi, Yeonjin; Cho, Sang Wan.

In: Japanese Journal of Applied Physics, Vol. 58, No. 2, 021004, 01.01.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Paradoxical hole injection enhancement by contamination on the indium tin oxide surface

AU - Lee, Hyunbok

AU - Jeong, Junkyeong

AU - Lee, Jiyeon

AU - Lee, Hyunchan

AU - Hyun, Gyeongho

AU - Yi, Yeonjin

AU - Cho, Sang Wan

PY - 2019/1/1

Y1 - 2019/1/1

N2 - In organic electronics, contact formation at the interface between an electrode and an organic layer has a substantial influence on device performance. Clean substrates are therefore considered prerequisite to obtain high charge injection efficiency. In this study, however, we found that contamination caused by decomposition of a plastic cover film on indium tin oxide (ITO) improved hole injection. Ultraviolet and X-ray photoelectron spectroscopy measurements showed that a contamination layer formed on ITO that had been stored for several months in plastic wrapping, which reduced its work function. As a result, the hole injection barrier between the Fermi level of ITO and the highest occupied molecular orbital level of poly(9-vinylcarbazole) (PVK) was higher than that at the interface between PVK and cleaned ITO. However, in hole-only devices, the contaminated ITO exhibited a higher current density value than the cleaned ITO in the high bias regime. This paradoxical improvement in hole injection could be explained by an insulating buffer model. In this model, the contamination layer functions as an insulating anode buffer layer on the ITO surface. As high bias is applied, the contamination layer results in formation of an energy barrier with a triangular shape. Thus, holes can be injected efficiently from ITO to PVK through tunneling.

AB - In organic electronics, contact formation at the interface between an electrode and an organic layer has a substantial influence on device performance. Clean substrates are therefore considered prerequisite to obtain high charge injection efficiency. In this study, however, we found that contamination caused by decomposition of a plastic cover film on indium tin oxide (ITO) improved hole injection. Ultraviolet and X-ray photoelectron spectroscopy measurements showed that a contamination layer formed on ITO that had been stored for several months in plastic wrapping, which reduced its work function. As a result, the hole injection barrier between the Fermi level of ITO and the highest occupied molecular orbital level of poly(9-vinylcarbazole) (PVK) was higher than that at the interface between PVK and cleaned ITO. However, in hole-only devices, the contaminated ITO exhibited a higher current density value than the cleaned ITO in the high bias regime. This paradoxical improvement in hole injection could be explained by an insulating buffer model. In this model, the contamination layer functions as an insulating anode buffer layer on the ITO surface. As high bias is applied, the contamination layer results in formation of an energy barrier with a triangular shape. Thus, holes can be injected efficiently from ITO to PVK through tunneling.

UR - http://www.scopus.com/inward/record.url?scp=85065156855&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85065156855&partnerID=8YFLogxK

U2 - 10.7567/1347-4065/aafa6c

DO - 10.7567/1347-4065/aafa6c

M3 - Article

AN - SCOPUS:85065156855

VL - 58

JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes

JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes

SN - 0021-4922

IS - 2

M1 - 021004

ER -