High-density electrostatic carrier doping in organic single-crystal transistors with polymer gel electrolyte

High-density carrier accumulation in organic semiconductors is demonstrated in $\mathrm{Au}∕\mathrm{polymer}$ gel electrolyte/rubrene $\mathrm{crystal}∕{\mathrm{SiO}}_2∕\mathrm{doped}$ Si dual-gate transistors, forming electric double layers in the polymer gel. Application of only $1.2\mathrm{V}$ across the polymer gel electrolyte drastically enhances the conductance of the rubrene single crystal with the field-induced carrier density up to $\sim 5\times {10}^{13}{\mathrm{cm}}^{-2}$ . Directly comparing the transfer characteristics of the same device channel in the dual-gate transistors revealed that the achieved doping level is beyond the maximum of the ${\mathrm{SiO}}_2$ -based transistor on the opposite side of the organic crystal.