High charge carrier densities have been realized in organic field-effect transistors based on single crystals of the organic semiconductors rubrene and tetracene using a high capacitance polymer electrolyte gate dielectric. The source-drain current was modulated by five orders of magnitude in a rubrene single-crystal organic field-effect transistor (SC-OFET) with gate voltages ranging from 0 to -3 V. A peak in the field-effect conductance was also observed in SC-OFETs at induced carrier densities of ∼ 1015 charges cm2. Key to successful device fabrication was the introduction of a thin, insulating spacer layer between the organic single crystal (OSC) and the polymer electrolyte gate dielectric. Further improvement of the device fabrication procedure may eliminate suspected solvent-related degradation effects and raise mobility values in these SC-OFETs, opening the door to a wide spectrum of experiments on OSCs at high charge carrier densities.
Bibliographical noteFunding Information:
The authors would like to thank C. R. Newman for crystal growth and B. T. Holmes for providing DPTP. This work was supported in part by the IGERT Program of the National Science Foundation under Award No. DGE-0114372. This work was also partially supported by the NSF Materials Research Science and Engineering Center Program (DMR-0212302).