Extraction of high charge density of states in electrolyte-gated polymer thin-film transistor with temperature-dependent measurements

Abstract

Using temperature-dependent charge transport measurements, we investigated spectral density of states (DOS) in the bandgap of polythiophene thin-films under high carrier densities (<3.5 × 1020 cm−3) induced by electrochemical doping. The thermally activated charge transport indicates that the electrical currents in the polymer thin-film under high charge density state follow the Meyer-Neldel rule. The spectral DOS extracted from the electrolyte-gated polymer film lie in the range of 8.0 × 1019 cm−3 eV−1–8.0 × 1021 cm−3 eV−1, which are at least two orders of magnitude larger than the DOS extracted from the same polymer film at relatively low induced carrier densities by general oxide dielectrics.