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Dielectric properties depending on frequency in organic light-emitting diodes |
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| Authors: | Joon Ho Ahn Dae-Shik Seo Won-Jae Lee |
| Affiliation: | a Science & Technology Institute, Hongik University, Seoul 121-791, South Korea b Department of Hospital Biomedical Engineering, Dongshin University, Naju 520-714, South Korea c School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, South Korea d Department of Electrical Engineering, Kyungwon University, Sungnam 461-702, South Korea e Department of Electronic and Communication Engineering, Kyungwon University, Sungnam, 461-702, South Korea f Department of Physics, Hongik University, Seoul 121-791, South Korea |
| Abstract: | Dielectric properties of organic light-emitting diodes were investigated using ITO/Alq3/Al device. In spite of various advantages in organic light-emitting diodes, a fundamental study on physical properties is not yet sufficient. Dielectric properties are used for studying fundamental physical properties of materials through a frequency-dependent response. We have investigated magnitude and phase of impedance, electrical conductivity, and the dielectric loss depending on a bias-voltage variation using ITO/Alq3(60 nm)/Al device. The device shows a frequency-dependent response such that a major contribution is resistive below time constant and capacitive above time constant. Also, the device shows a voltage-dependent electrical conductivity in low-frequency region. A bulk resistance rapidly decreases as the frequency increases above 1 MHz. The dielectric loss shows that there appears an interfacial polarization in low-frequency region, and an orientational polarization in high-frequency region. |
| Keywords: | Organic light-emitting diodes Permittivity Dielectric loss |
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