DocumentCode :
618971
Title :
Tunneling effect on enhanced OLED performance using Al2O3 buffer layer
Author :
Zhou, Liang ; Su, W.M. ; Cui, Zhigao
Author_Institution :
Printable Electron. Res. Center, Suzhou Inst. of Nano-Technol. & Nano-Bionics, Suzhou, China
fYear :
2013
fDate :
7-10 April 2013
Firstpage :
407
Lastpage :
411
Abstract :
It has been found that introduction of buffer layers between organic holes transport layer and anode layer plays an important role in improving device stability and hole injection efficiency of organic light-emitting diodes (OLED). As for the mechanism of the improvement due to the buffer layer, it is still controversial. To understand the mechanism behind the enhanced performance of OLED by the buffer layer, a new model is therefore proposed which combines classical model and quantum tunneling model to explain the OLED performance improvement. A thin Al2O3 insulating buffer layer deposited on indium tin oxide (ITO) anode by atomic layer deposition has been investigated for OLED. The observed power efficiency and current efficiency improvement at the optimal thickness of 1.4 nm are well explained by the model. A series of Al2O3 films of different thicknesses were deposited on ITO anode and characterized. Their roughness, sheet resistance, surface potential, and resulted OLED current density were investigated. It is believed that the blocking of hole inject by the Al2O3 buffer layer makes more balanced carrier density in emission layer, thus enhances the current efficiency. Though less number of holes are injected in OLED due to the insertion of Al2O3 layer, quantum tunneling through the ultra-thin buffer layer play an important role to contribute to the hole injection, which avoids crossing the interface barrier, resulting in less energy consumed and power efficiency enhanced.
Keywords :
aluminium compounds; atomic layer deposition; buffer layers; carrier density; current density; indium compounds; insulating thin films; organic compounds; organic light emitting diodes; surface potential; surface resistance; surface roughness; tin compounds; tunnelling; Al2O3-ITO; ITO anode; anode layer; atomic layer deposition; classical model; current density; current efficiency; device stability; emission layer; energy consuption; enhanced OLED performance; film thicknesses; hole injection efficiency; indium tin oxide anode; optimal thickness; organic hole transport layer; organic light-emitting diodes; power efficiency; quantum tunneling model; sheet resistance; surface potential; surface roughness; thin insulating buffer layer; ultrathin buffer layer; Aluminum oxide; Anodes; Buffer layers; Indium tin oxide; Organic light emitting diodes; Surface treatment; Tunneling; both current and power efficiency improvement; hole injection mechanism; new model; quantum tunneling; thermionic emission;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Nano/Micro Engineered and Molecular Systems (NEMS), 2013 8th IEEE International Conference on
Conference_Location :
Suzhou
Electronic_ISBN :
978-1-4673-6351-8
Type :
conf
DOI :
10.1109/NEMS.2013.6559760
Filename :
6559760
Link To Document :
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