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http://dx.doi.org/10.4313/JKEM.2008.21.3.255

Built-in Voltage in Organic Light-emitting Diodes depending on the Alg3 Layer Thickness  

Lee, Eun-Hye (홍익대학교 정보디스플레이공학과)
Yoon, Hee-Myoung (홍익대학교 정보디스플레이공학과)
Kim, Tae-Wan (홍익대학교 정보디스플레이공학과)
Publication Information
Journal of the Korean Institute of Electrical and Electronic Material Engineers / v.21, no.3, 2008 , pp. 255-259 More about this Journal
Abstract
Built-in voltage in ITO/$Alq_3$/ Al organic light-emitting diodes was studied by varying a thickness of $Alq_3$ layer using modulated photocurrent technique at ambient condition. A thickness of the $Alq_3$ layer was varied from 100 to 250 nm. From the bias voltage-dependent photocurrent, built-in voltage of the device was able to be determined. The obtained built-in voltage is about 0.8 V irrespective of the $Alq_3$ layer thickness in the device. This value of built-in voltage confirms that the built-in voltage is generated due to a difference of work function of the anode and cathode. The $Alq_3$ layer thickness independent built-in voltage indicates that the built-in electric field in the device is uniform across the organic layer.
Keywords
Built-in voltage; Organic light-emitting diodes; Modulated photocurrent;
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