Terahertz study of hole transport in pentacene thin films

Abstract

Terahertz electromodulation spectroscopy is a novel tool for studying charge carrier transport in polycrys­talline thin films. The technique selectively probes the high-frequency response of mobile carriers and is insensitive to scattering at grain boundaries as well as to trapping processes. In thin films of pentacene we find a hole mobility of 21 cm² /Vs, which exceeds the largest previously reported values obtained in poly­ crystalline pentacene. Additionally, the data provide an upper limit of the hole conductivity effective mass of m_h ≈ 0.8 m_e.