C. Daniel Frisbie Group
Chemical Engineering & Materials Science
University of Minnesota - Twin Cities 		Films & Interfaces,
Molecular Crystals,
Molecular Electronics,
Organic Semiconductors,
Scanning Probe Microscopy

Jiyoul Lee Jiyoul Lee
Yonsei University, Korea; 2001
B.S. Metallurgical Engineering
Yonsei University, Korea; 2006
Ph.D. Applied Physics
Email: leex3106@umn.edu

Ion Gel Gated Polymer Transistors for Plastic Electronics

A major goal of plastic electronics is the development of compatible materials sets, including conductors, semiconductors and insulators, that enable the fabrication of electronic circuitry on flexible substrates at low cost. In this regard, there has been significant interest in developing new kinds of solution processible organic dielectric materials that can serve as gate insulators in organic thin film transistors (OTFTs). An important figure of merit for prospective gate dielectrics is the specific capacitance, which determines how much charge can be induced in the semiconductor channel of an OTFT for a given applied gate voltage; higher capacitance translates into higher induced charge densities and therefore both higher ON currents and lower switching voltages.

My research is focused on the use of a gel electrolyte (so-called “ion gel”) as the gate insulator in polymer TFTs. The ion gel is composed of an ionic liquid and a triblock copolymer. The ion gel provides a very large specific capacitance (up to ~ 40mF/cm2), which allows both low voltage operation and high transconductance. Additionally, the ion gel gated TFTs can be switched at a rate of 10 kHz, suitable for some applications.

The goal of my research is to improve the performance of ion gel gated polymer TFTs in terms of operating frequency, mobility, and stability and finally to realize the plastic electronics with the ion gel gated PTFTs.

Publications

"High Capacitance Ion Gel Gate Dielectrics with Faster Polarization Response Times for Organic Thin Film Transistors", Cho, Jeong Ho; Lee, Jiyoul; He, Yiyong; Kim, B.-S.; Lodge, Timothy P.; Frisbie, C. Daniel; Adv. Mat. (Accepted)

"Ion Gel Gated Polymer Thin-Film Transistors," Lee, Jiyoul; Panzer, Matthew J.; He, Yiyong; Kim, B.-S.; Lodge, Timothy P.; Frisbie, C. Daniel; J. Am. Chem. Soc.; (Comm.) 2007, 129 4532.

"Studies on PMMA Dielectric Layer for Field Effect Transistor: Influence of Polymer Tacticity," Park, J. H.; Hwang, D. K.; Lee, J.; Im, S.; Kim, E., Thin Solid Films 2007, 515 4041.

"A Comparative Study of the Photoresponse from Tetracene-based and Pentacene-based Thin-film Transistors," Choi, J. M.; Lee, J.; Hwang, D. K.; Kim, J. H.; Im, S.; Kim, E., Appl. Phys. Lett. 2006, 88 043508 .

"Improving Resistance to Gate Bias Stress in Pentacene Thin-film Transistors with Optimally-cured Polymer Dielectric Layers," Hwang, D. K.; Park, J. H.; Lee, J.; Choi, J. M.; Kim, J. H.; Kim, E.; Im, S., J. Electrochem. Soc. 2006, 153 G23.

"Enhancing the Ambient-enduring Performance of Pentacene Thin-film Transistors by SnO2-encapsulation," Kim, W. J.; Koo, W. H.; Jo, S. J.; Kim, C. S.; Baik, H. K.; Lee, J.; Im, S., Electrochemical and Solid State Letters 2005, 8 G341.

"Flexible Semitransparent Pentacene Thin-film Transistors with Polymer Dielectric Layers and NiOx Electrodes," Lee, J.; Hwang, D. K.; Choi, J. M.; Lee, K.; Kim, J. H.; Im, S.; Park, J. H.; Kim, E., Appl. Phys. Lett. 2005, 87 023504.

"Pentacene-based TFTs with Polymer Gate Dielectric and NiOx Electrodes," Hwang, D. K.; Park, J. H.; Lee, J.; Choi, J. M.; Kim, J. H.; Kim, E.; Im, S., Electrochemical and Solid State Letters 2005, 8 G140.

"Threshold Voltage Change due to Organic-inorganic Interface in Pentacene Thin-film Transistors," Lee, J.; Kim, J. H.; Im, S.; Jung, D. Y., J. Appl. Phys. 2004, 96 2301.

"Effects of Substrate Temperature on the Device Properties of Pentacene-based Thin-film Transistors using Al2O3+x Gate Dielectric," Lee, J.; Kim, J. H.; Im, S., J. Appl. Phys. 2004, 95 3733.

"Correlation Between Photoelectric and Optical Absorption Spectra of Thermally Evaporated Pentacene Films," Lee, J.; Kim, S. S.; Kim, K.; Kim, J. H.; Im, S., Appl. Phys. Lett. 2004, 84 1701.

"Pentacene-based Photodiode with Schottky Junction," Lee, J.; Hwang, D. K.; Park, C. H.; Kim, S. S.; Im, S., Thin Solid Films 2003, 451-452 12.

"Pentacene Thin-film Transistors with Al2O3+x Gate Dielectric Films Deposited on Indium-tin-oxide Glass," Lee, J.; Kim, J. H.; Im, S., Appl. Phys. Lett. 2003, 83 2689.

"Optimum Channel Thickness in Pentacene-based Thin-film Transistors," Lee, J.; Kim, K.; Kim, J. H.; Im, S.; Jung, D. Y., Appl. Phys. Lett. 2003, 82 4169.

"Electrical Properties of Aluminum Oxide Films Deposited on Indium-tin-oxide Glasses," Lee, J.; Kim, S. S.; Im, S., J. Vac. Sci. and Tech. B 2003, 21 953.

Frisbie Home Page