Beyond the metal-insulator transition in polymer electrolyte gated polymer field-effect transistors

摘要

We have studied the carrier transport in poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) field-effect transistors (FETs) at very high field-induced carrier densities (10¹⁵ cm⁻²) using a polymer electrolyte as gate and gate dielectric. At room temperature, we find high current densities, 2 × 10⁶ A/cm², and high metallic conductivities, 10⁴ S/cm, in the FET channel; at 4.2 K, the current density is sustained at 10⁷ A/cm². Thus, metallic conductivity persists to low temperatures. The carrier mobility in these devices is ≈3.5 cm²·V⁻¹·s⁻¹ at 297 K, comparable with that found in fully crystalline organic devices.