Improvement of highly efficient organic light-emitting diodes using Mg-doped ZnO buffer layers

Hsin Hsuan Huang; Sheng Yuan Chu; Po Ching Kao; Yung Chen Chen

doi:10.1016/j.tsf.2007.07.081

Improvement of highly efficient organic light-emitting diodes using Mg-doped ZnO buffer layers

Hsin Hsuan Huang, Sheng Yuan Chu, Po Ching Kao, Yung Chen Chen

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

27 Citations (Scopus)

Abstract

In this paper, we report on the improvement of the anode buffer layer of Mg-doped ZnO (MZO) on the electrical and optical properties of organic light-emitting diodes (OLEDs). The MZO layers with different thickness were prepared by thermal-evaporating the MZO powders and then treated by ultraviolet (UV) ozone exposure. The turn-on voltage of OLEDs decreased from 4 V (4.2 cd/m²) to 3 V (4.7 cd/m²), the maximum luminance value increased from 16780 cd/m² to 35400 cd/m² and the power efficiency increased from 2.74 lm/W to 5.77 lm/W as the 1-nm-thick MZO layer was inserted between indium tin oxide (ITO) anodes and α-naphthylphenylbiphenyl diamine (NPB) hole-transporting layers. The surface of the MZO/ITO became smoother with the UV-ozone treatment. X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) studies were performed to show that the formation of the MZO layer and the work function increased as the MZO/ITO layer was treated by UV-ozone for 20 min. Thus, the hole-injection energy barrier was lowered by inserting MZO buffer layer, consequently resulting in the decrease of the turn-on voltage and the increase of the power efficiency in OLEDs.

Original language	English
Pages (from-to)	5664-5668
Number of pages	5
Journal	Thin Solid Films
Volume	516
Issue number	16
DOIs	https://doi.org/10.1016/j.tsf.2007.07.081
Publication status	Published - 2008 Jun 30

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.2007.07.081

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title = "Improvement of highly efficient organic light-emitting diodes using Mg-doped ZnO buffer layers",

abstract = "In this paper, we report on the improvement of the anode buffer layer of Mg-doped ZnO (MZO) on the electrical and optical properties of organic light-emitting diodes (OLEDs). The MZO layers with different thickness were prepared by thermal-evaporating the MZO powders and then treated by ultraviolet (UV) ozone exposure. The turn-on voltage of OLEDs decreased from 4 V (4.2 cd/m2) to 3 V (4.7 cd/m2), the maximum luminance value increased from 16780 cd/m2 to 35400 cd/m2 and the power efficiency increased from 2.74 lm/W to 5.77 lm/W as the 1-nm-thick MZO layer was inserted between indium tin oxide (ITO) anodes and α-naphthylphenylbiphenyl diamine (NPB) hole-transporting layers. The surface of the MZO/ITO became smoother with the UV-ozone treatment. X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) studies were performed to show that the formation of the MZO layer and the work function increased as the MZO/ITO layer was treated by UV-ozone for 20 min. Thus, the hole-injection energy barrier was lowered by inserting MZO buffer layer, consequently resulting in the decrease of the turn-on voltage and the increase of the power efficiency in OLEDs.",

author = "Huang, {Hsin Hsuan} and Chu, {Sheng Yuan} and Kao, {Po Ching} and Chen, {Yung Chen}",

note = "Funding Information: The financial support provided by the Ministry of Economic Affairs (Taiwan, ROC) through Project No. 91-EC-17-A-07-S1-0018 is greatly appreciated. We also thank the Center for Micro-NanoTechnology, National Cheng-Kung University for providing Single-Side Mask Aligner (OAI, J500). ",

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doi = "10.1016/j.tsf.2007.07.081",

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T1 - Improvement of highly efficient organic light-emitting diodes using Mg-doped ZnO buffer layers

AU - Huang, Hsin Hsuan

AU - Chu, Sheng Yuan

AU - Kao, Po Ching

AU - Chen, Yung Chen

N1 - Funding Information: The financial support provided by the Ministry of Economic Affairs (Taiwan, ROC) through Project No. 91-EC-17-A-07-S1-0018 is greatly appreciated. We also thank the Center for Micro-NanoTechnology, National Cheng-Kung University for providing Single-Side Mask Aligner (OAI, J500).

PY - 2008/6/30

Y1 - 2008/6/30

N2 - In this paper, we report on the improvement of the anode buffer layer of Mg-doped ZnO (MZO) on the electrical and optical properties of organic light-emitting diodes (OLEDs). The MZO layers with different thickness were prepared by thermal-evaporating the MZO powders and then treated by ultraviolet (UV) ozone exposure. The turn-on voltage of OLEDs decreased from 4 V (4.2 cd/m2) to 3 V (4.7 cd/m2), the maximum luminance value increased from 16780 cd/m2 to 35400 cd/m2 and the power efficiency increased from 2.74 lm/W to 5.77 lm/W as the 1-nm-thick MZO layer was inserted between indium tin oxide (ITO) anodes and α-naphthylphenylbiphenyl diamine (NPB) hole-transporting layers. The surface of the MZO/ITO became smoother with the UV-ozone treatment. X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) studies were performed to show that the formation of the MZO layer and the work function increased as the MZO/ITO layer was treated by UV-ozone for 20 min. Thus, the hole-injection energy barrier was lowered by inserting MZO buffer layer, consequently resulting in the decrease of the turn-on voltage and the increase of the power efficiency in OLEDs.

AB - In this paper, we report on the improvement of the anode buffer layer of Mg-doped ZnO (MZO) on the electrical and optical properties of organic light-emitting diodes (OLEDs). The MZO layers with different thickness were prepared by thermal-evaporating the MZO powders and then treated by ultraviolet (UV) ozone exposure. The turn-on voltage of OLEDs decreased from 4 V (4.2 cd/m2) to 3 V (4.7 cd/m2), the maximum luminance value increased from 16780 cd/m2 to 35400 cd/m2 and the power efficiency increased from 2.74 lm/W to 5.77 lm/W as the 1-nm-thick MZO layer was inserted between indium tin oxide (ITO) anodes and α-naphthylphenylbiphenyl diamine (NPB) hole-transporting layers. The surface of the MZO/ITO became smoother with the UV-ozone treatment. X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) studies were performed to show that the formation of the MZO layer and the work function increased as the MZO/ITO layer was treated by UV-ozone for 20 min. Thus, the hole-injection energy barrier was lowered by inserting MZO buffer layer, consequently resulting in the decrease of the turn-on voltage and the increase of the power efficiency in OLEDs.

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JO - Thin Solid Films

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ER -

Improvement of highly efficient organic light-emitting diodes using Mg-doped ZnO buffer layers

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