Drift-velocity saturation of holes in anthracene at room temperature

Hole-drift-velocity saturation has been measured along the c' direction in anthracene at room temperature. It is attributed to excitation of the 395-cm^-1 intramolecular vibration through the hot hole. A lower limit of 50 meV for the bandwidth at room temperature and a confinement of the electron-phonon coupling constant to values around 1 is deduced from the experiment. These parameter values are of an intermediate case between conventional band transport and formation of a small polaron.