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Effects of Interfacial Charge Depletion in Organic Thin-Film Transistors with Polymeric Dielectrics on Electrical Stability
School of Electrical Engineering, Seoul National University, Seoul 151-600, Korea
School of Electronic and Electrical Engineering, Hongik University, Seoul 121-791, Korea
* Author to whom correspondence should be addressed.
Received: 30 April 2010; Accepted: 8 June 2010 / Published: 9 June 2010
Abstract: We investigated the electrical stabilities of two types of pentacene-based organic thin-film transistors (OTFTs) with two different polymeric dielectrics: polystyrene (PS) and poly(4-vinyl phenol) (PVP), in terms of the interfacial charge depletion. Under a short-term bias stress condition, the OTFT with the PVP layer showed a substantial increase in the drain current and a positive shift of the threshold voltage, while the PS layer case exhibited no change. Furthermore, a significant increase in the off-state current was observed in the OTFT with the PVP layer which has a hydroxyl group. In the presence of the interfacial hydroxyl group in PVP, the holes are not fully depleted during repetitive operation of the OTFT with the PVP layer and a large positive gate voltage in the off-state regime is needed to effectively refresh the electrical characteristics. It is suggested that the depletion-limited holes at the interface, i.e., interfacial charge depletion, between the PVP layer and the pentacene layer play a critical role on the electrical stability during operation of the OTFT.
Keywords: organic thin-film transistors; stability; polymer; dielectrics; hydroxyl group
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Park, J.; Bae, J.-H.; Kim, W.-H.; Kim, M.-H.; Keum, C.-M.; Lee, S.-D.; Choi, J.S. Effects of Interfacial Charge Depletion in Organic Thin-Film Transistors with Polymeric Dielectrics on Electrical Stability. Materials 2010, 3, 3614-3624.
Park J, Bae J-H, Kim W-H, Kim M-H, Keum C-M, Lee S-D, Choi JS. Effects of Interfacial Charge Depletion in Organic Thin-Film Transistors with Polymeric Dielectrics on Electrical Stability. Materials. 2010; 3(6):3614-3624.
Park, Jaehoon; Bae, Jin-Hyuk; Kim, Won-Ho; Kim, Min-Hoi; Keum, Chang-Min; Lee, Sin-Doo; Choi, Jong Sun. 2010. "Effects of Interfacial Charge Depletion in Organic Thin-Film Transistors with Polymeric Dielectrics on Electrical Stability." Materials 3, no. 6: 3614-3624.