Improved efficiency of organic light-emitting diodes using CoPc buffer layer

Po Ching Kao; Sheng Yuan Chu; Zong Xian You; S. J. Liou; Chan An Chuang

doi:10.1016/j.tsf.2005.07.120

Improved efficiency of organic light-emitting diodes using CoPc buffer layer

Po Ching Kao, Sheng Yuan Chu, Zong Xian You, S. J. Liou, Chan An Chuang

Research output: Contribution to journal › Conference article › peer-review

33 Citations (Scopus)

Abstract

In this paper, the remarkable improvements in turn-on voltage and luminance have been demonstrated in an organic light-emitting diode (OLED) using cobalt phthalocyanine (CoPc) layer as a hole injection layer (HIL) in a device structure of ITO/CoPc/NPB (60 nm)/Alq₃ (75 nm)/LiF (1 nm)/Al (200 nm). The J-V, L-V and η_p-V characteristics were measured at room temperature with a thickness variation of CoPc layer. The improvement of the luminance intensity by a factor of more than two has been obtained and the turn-on voltage at 1 cd/m² decreased about 1 V with the CoPc layer. We propose that such an improvement is mainly due to the relative energy level of the highest-occupied molecular orbital (HOMO) band between that of the NPB hole transport layer (HTL) and the Fermi level of ITO anode, leading to enhance the hole injection from the ITO to organic layer.

Original language	English
Pages (from-to)	249-253
Number of pages	5
Journal	Thin Solid Films
Volume	498
Issue number	1-2
DOIs	https://doi.org/10.1016/j.tsf.2005.07.120
Publication status	Published - 2006 Mar 1
Event	Proceedings of the Third Asian Conference on Chemical Vapor Deposition (Third Asian-CVD), Third Asian CVD - Duration: 2004 Nov 12 → 2004 Nov 14

All Science Journal Classification (ASJC) codes

Electronic, Optical and Magnetic Materials
Surfaces and Interfaces
Surfaces, Coatings and Films
Metals and Alloys
Materials Chemistry

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10.1016/j.tsf.2005.07.120

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title = "Improved efficiency of organic light-emitting diodes using CoPc buffer layer",

abstract = "In this paper, the remarkable improvements in turn-on voltage and luminance have been demonstrated in an organic light-emitting diode (OLED) using cobalt phthalocyanine (CoPc) layer as a hole injection layer (HIL) in a device structure of ITO/CoPc/NPB (60 nm)/Alq3 (75 nm)/LiF (1 nm)/Al (200 nm). The J-V, L-V and ηp-V characteristics were measured at room temperature with a thickness variation of CoPc layer. The improvement of the luminance intensity by a factor of more than two has been obtained and the turn-on voltage at 1 cd/m2 decreased about 1 V with the CoPc layer. We propose that such an improvement is mainly due to the relative energy level of the highest-occupied molecular orbital (HOMO) band between that of the NPB hole transport layer (HTL) and the Fermi level of ITO anode, leading to enhance the hole injection from the ITO to organic layer.",

author = "Kao, {Po Ching} and Chu, {Sheng Yuan} and You, {Zong Xian} and Liou, {S. J.} and Chuang, {Chan An}",

note = "Funding Information: This work was supported by Ministry of Economic Affairs of the Republic of China (No. 91-EC-17-A-07-S1-0018) and Micro-Nanotechnology Research Center of the NCKU.; Proceedings of the Third Asian Conference on Chemical Vapor Deposition (Third Asian-CVD), Third Asian CVD ; Conference date: 12-11-2004 Through 14-11-2004",

year = "2006",

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doi = "10.1016/j.tsf.2005.07.120",

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AU - Kao, Po Ching

AU - Chu, Sheng Yuan

AU - You, Zong Xian

AU - Liou, S. J.

AU - Chuang, Chan An

N1 - Funding Information: This work was supported by Ministry of Economic Affairs of the Republic of China (No. 91-EC-17-A-07-S1-0018) and Micro-Nanotechnology Research Center of the NCKU.

PY - 2006/3/1

Y1 - 2006/3/1

N2 - In this paper, the remarkable improvements in turn-on voltage and luminance have been demonstrated in an organic light-emitting diode (OLED) using cobalt phthalocyanine (CoPc) layer as a hole injection layer (HIL) in a device structure of ITO/CoPc/NPB (60 nm)/Alq3 (75 nm)/LiF (1 nm)/Al (200 nm). The J-V, L-V and ηp-V characteristics were measured at room temperature with a thickness variation of CoPc layer. The improvement of the luminance intensity by a factor of more than two has been obtained and the turn-on voltage at 1 cd/m2 decreased about 1 V with the CoPc layer. We propose that such an improvement is mainly due to the relative energy level of the highest-occupied molecular orbital (HOMO) band between that of the NPB hole transport layer (HTL) and the Fermi level of ITO anode, leading to enhance the hole injection from the ITO to organic layer.

AB - In this paper, the remarkable improvements in turn-on voltage and luminance have been demonstrated in an organic light-emitting diode (OLED) using cobalt phthalocyanine (CoPc) layer as a hole injection layer (HIL) in a device structure of ITO/CoPc/NPB (60 nm)/Alq3 (75 nm)/LiF (1 nm)/Al (200 nm). The J-V, L-V and ηp-V characteristics were measured at room temperature with a thickness variation of CoPc layer. The improvement of the luminance intensity by a factor of more than two has been obtained and the turn-on voltage at 1 cd/m2 decreased about 1 V with the CoPc layer. We propose that such an improvement is mainly due to the relative energy level of the highest-occupied molecular orbital (HOMO) band between that of the NPB hole transport layer (HTL) and the Fermi level of ITO anode, leading to enhance the hole injection from the ITO to organic layer.

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JO - Thin Solid Films

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T2 - Proceedings of the Third Asian Conference on Chemical Vapor Deposition (Third Asian-CVD), Third Asian CVD

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ER -

Improved efficiency of organic light-emitting diodes using CoPc buffer layer

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