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Undoped polythiophene FETs with field-effect mobility of 1 cm^2 V^-1 s^-1



Behrang Hamadani, Iain McCulloch, Martin Heeney, David J. Gundlach


We report on charge transport in organic field-effect transistors based on (2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) as the active polymer layer with saturation field-effect mobilities as large as 1 cm2 V-1 s-1. The dependence of mobility on transistor channel length is investigated for devices with Au or Pt as the source and drain electrodes. We find that Pt makes a lower contact resistance to the polymer compared with Au, and the device mobility increases as a function of decreasing channel length, consistent with a Poole-Frenkel model of charge transport within the channel. A much less pronounced behavior is observed in the case of Au/polymer devices with relatively high contact to channel resistance ratios for channel lengths shorter than 10 ?m. Our results demonstrate the importance of making good contacts to organic semiconducting materials, therefore, allowing for intrinsic properties of the material to be dominant in the device, including mobilities of 1 cm^2 V^-1 s^-1 or more at channel lengths of order a few microns.
Applied Physics Letters


contact effects, organic field-effect transistors


Hamadani, B. , McCulloch, I. , Heeney, M. and Gundlach, D. (2007), Undoped polythiophene FETs with field-effect mobility of 1 cm^2 V^-1 s^-1, Applied Physics Letters (Accessed June 19, 2024)


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Created December 28, 2007, Updated October 12, 2021