Matt Panzer University of Delaware ; 2002 Honors B.S. Chemical Engineering with Distinction University of Minnesota ; 2007 Ph.D. Chemical Engineering Email: mpanzer@cems.umn.edu

Organic thin-film transistors (OTFTs) have been extensively studied in recent years, since they serve both as an experimental vehicle for studying charge carrier transport in organic semiconductors, and also as a practical device component for applications such as backplane arrays for flexible LCD screens. While there have been vast gains in the mobility (ease with which charge carriers can move across a transistor channel) values obtained in both well-studied and newly-synthesized organic semiconductors, there are now indications that we are close to reaching the upper limit of mobility in organic materials. Consequently, a shift in focus toward improving other parts of the OTFT (including the gate insulator and the source and drain contacts) is currently underway.

In an OTFT, all of the action happens at the interface between the gate insulator and the organic semiconductor layers. Here – just inside the semiconductor, right next to the insulator – is where the conducting channel is formed by the application of a suitable gate voltage. Pentacene, the benchmark organic semiconductor material, packs with an areal density of 4.5 x 10¹⁴ molecules/cm² at this interface when grown on SiO₂. However, the maximum charge carrier density achievable (at breakdown conditions) on SiO₂ is only 2.2 x 10¹³ charges/cm². This means that, at most, only 5% of the pentacene molecules in the first monolayer can participate in charge transport in an OTFT fabricated on SiO₂.

My research explores an alternative gate insulator – a solid polymer electrolyte – as a means to obtaining much higher charge carrier densities (> 10¹⁵ charges/cm²) in OTFTs. At high carrier densities, both intriguing OTFT behaviors and exciting device physics can be observed. Pushing the limits of OTFT performance overall is of great interest to me, and the achievement of very high charge densities in these devices may be one way to accomplish this.

Publications

"Contact Effects in Organic Field Effect Transistors", Panzer, M.J. and Frisbie, C.D., in Organic Field Effect Transistors, ed. Z. Bao and J. Locklin. Vol 128, Optical Science and Engineering Series. CRC Press, 2007.

“Ion gel gated polymer thin-film transistors.” Lee, J.; Panzer, M.J.; He, Y.; Lodge, T.P.; Frisbie, C.D. J. Am. Chem. Soc., 2007, 129, 4532. DOI: 10.1021/ja0707254.

“Polymer Electrolyte-Gated Organic Field-Effect Transistors: Low-Voltage, High-Current Switches for Organic Electronics and Testbeds for Probing Electrical Transport at High Charge Carrier Density.” Panzer, M.J.; Frisbie, C.D. J. Am. Chem. Soc., 2007, 129, 6599. DOI: 10.1021/ja0708767.

"High Charge Carrier Densities and Conductance Maxima in Single-Crystal Organic Field-Effect Transistors with a Polymer Electrolyte Gate Dielectric," Panzer, M. J.; Frisbie, C. D., Appl. Phys. Lett. 2006, 88 203504.

"High Carrier Density and Metallic Conductivity in Poly(3-hexylthiophene) Achieved by Electrostatic Charge Injection," Panzer, M. J.; Frisbie, C. D., Adv. Funct. Mater. 2006, 16 1051-1056.

"High Mobility Top-Gated Pentacene Thin-Film Transistors," Newman, C. R.; Chesterfield, R. J.; Panzer, M. J.; Frisbie, C. D., J. Appl. Phys. 2005, 98 084506.

"Polymer Electrolyte Gate Dielectric Reveals Finite Windows of High Conductivity in Organic Thin Film Transistors at High Charge Carrier Densities," Panzer, M. J.; Frisbie, C. D., J. Am. Chem. Soc. 2005, 127 6960.

"Low-Voltage Operation of a Pentacene Field-Effect Transistor with a Polymer Electrolyte Gate Dielectric," Panzer, M. J.; Newman, C. R.; Frisbie, C. D., Appl. Phys. Lett. 2005, 86 103503.

"Mass Transfer Properties of Monoliths," Hahn, R.; Panzer, M.; Hansen, E.; Mollerup, J.; Jungbauer, A., Sep. Sci. & Tech. 2002, 37 1545.