Mobility and Recombination Coefficient of Charge Carriers in Disordered Pentacene

Both transient and stationary photoconduction of pentacene layers prepared by vapor deposition at 180 K and annealing at 295 K is studied in a surface electrode arrangement. Except at low light intensities photocurrents are recombination controlled. A ratio γ/μ = 1.8 × 10 −7 V cm is obtained. The sum of electron and hole mobility monitored in a time interval 5 × 10 −5 to 5 × 10 −4 s after carrier generation is 10 −2 cm 2 /Vs. It agrees with a value determined previously employing the initial photocurrent pulse method thus proving the reliability of that method to monitor transport properties of disordered solids on a short time scale.