Electrical characterization of gap states in a highly doped conducting oligomer

The electrical characteristics of organic semiconducting devices are strongly influenced by the presence of interface states, midgap states and trap states in the band gap of the semiconductor. Therefore, knowledge of the density of states (DOS) in the band gap of the organic semiconductor is important to characterize and improve future organic devices. In this paper we explore a method that is based on frequency-dependent capacitance-voltage measurements on a highly doped In-thiophene Schottky diode. The obtained DOS of the highly doped thiophene clearly contains structure, with a peak around 0.52 ± 0.06 eV above the valence band.