Poly(3-hexylthiophene) thin-film transistors are subjected to hydrostatic pressure up to 1 GPa. The charge carrier mobility and threshold voltage are extracted from Id - Vgs curves. These parameters change linearly with pressure and retrace upon gradual pressure release. The mobility increases from 0.001 to 0.004 cm2 V s, and the threshold voltage falls from 36 to 2 V over the full pressure range. As a result, the current rises with increasing pressure up to 600 MPa and then falls as pressure is increased further. The increase in the mobility is attributed to enhanced π -orbital overlap under compression. The change in threshold voltage is interpreted as a modulation of trapped charge density.
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This work was supported primarily by the MRSEC Program of the National Science Foundation under Award No. DMR-0212302.