Electroluminescence enhancement in ultraviolet organic light‐emitting diode with graded hole‐injection and ‐transporting structure |
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| Authors: | Xiaowen Zhang Bingjie Mo Fengjiao You Xiujuan Zhou Liming Liu Honghang Wang Bin Wei |
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| Affiliation: | 1. Guangxi Key Laboratory of Information Materials and School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, P.R. China;2. Guangxi Experiment Center of Information Science, Guilin University of Electronic Technology, Guilin, P.R. China;3. Zhongshan Branch of State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan, P.R. China;4. Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University, Shanghai, P.R. China |
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| Abstract: | Electroluminescent intensity and external quantum efficiency (EQE) in ultraviolet organic light‐emitting diodes (UV OLEDs) have been remarkably enhanced by using a graded hole‐injection and ‐transporting (HIT) structure of MoO3/N,N ′‐bis(naphthalen‐1‐yl)‐N,N ′‐bis(phenyl)‐benzidine/MoO3/4,4′‐bis(carbazol‐9‐yl)biphenyl (CBP). The graded‐HIT based UV OLED shows superior short‐wavelength emis‐ sion with spectral peak of ～410 nm, maximum electroluminescent intensity of 2.2 mW/cm2 at 215 mA/cm2 and an EQE of 0.72% at 5.5 mA/cm2. Impedance spectroscopy is employed to clarify the enhanced hole‐injection and ‐transporting capacity of the graded‐HIT structure. Our results provide a simple and effective approach for constructing efficient UV OLEDs. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) |
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| Keywords: | organic light‐emitting diodes hole injection electronic transport impedance spectroscopy electroluminescence |
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