Effect of built-in potential on charge carrier mobility evaluated from extraction current transients in poly(3-hexylthiophene) thin film

The charge carrier mobility of a poly(3-hexylthiophene) film was estimated using charge extraction by the linearly increasing voltage (CELIV) method under dark conditions. To estimate the mobility of a thin film with a thickness similar to that of an actual device, the effects of the built-in potential and depletion region at the counter electrode interface were investigated. The application of a forward bias before the voltage scan affected the estimated mobility, and flat-band conditions were required to estimate the mobility precisely. The dark CELIV mobility was compared with the mobility estimated by the space-charge-limited current method using thin films under the same conditions. (C) 2018 The Japan Society of Applied Physics