Abstract
Charge carrier diffusion and recombination in an absorber blend of poly (3-hexylthiophene) (P3HT) and [6,6]1-phenyl C-70-butyric acid methyl ester (PCBM) with indium tin oxide (ITO) and aluminum contacts have been analyzed by means of impedance spectroscopy. The capacitance exhibits Mott-Schottky behavior indicating the formation of a Schottky junction (band bending) at the P3HT:PCBM/Al interface. Built-in potential of 0.88 V and acceptor impurities concentrations of 9.3 x 10(15) cm(3) was calculated through capacitance measurements. Impedance measurement shows, at high frequency, an. inclined straight line indicates the inhomogeneous nature of the electrode-organic interface. On the other hand, the arc localized at low-frequency is attributed to recombination in the photoactive blend. Global mobility is in the range of 1.1-1.4 x 10(-3) cm(2) V-1 s(-1), which is slightly higher as compared to the literature. (C) 2014 Elsevier Ltd. All rights reserved.