Charge transport and Hall effect in rubrene single-crystal transistors under high pressure

Abstract

Four-terminal conductivity and Hall coefficient are measured in high-mobility rubrene single-crystal field-effect transistors as functions of gate electric field and external hydrostatic pressure up to 900 MPa. Estimating charge density directly from the measured Hall coefficient regardless of contraction in the gate dielectric layer, genuine pressure dependence of the mobility is extracted. It turned out that enhanced intermolecular charge transfer causes an increase in the mobility of the bandlike charge carriers by 20% GPa up to 600 MPa, which is typically one order of magnitude larger than that in inorganic semiconductors. We also found negative pressure coefficient for the mobility above 600 MPa, suggesting that the external hydrostatic force causes additional molecular displacement due to a specific molecular shape.