Charge carrier extraction study of hole mobility and dynamics in poly(3-hexylthiophene) films subjected to photothermal aging

Publication date: Available online 23 October 2016
Source:Thin Solid Films
Author(s): Y.L. Moskvin, N.P. Piven, D.K. Susarova, S.D. Babenko, P.A. Troshin
The evolution of charge carriers mobility μ and their concentration p in the diode devices indium tin oxide (ITO)/poly(3-hexylthiophene) (P3HT)/Al subjected to photothermal aging in argon atmosphere was investigated using Current Extracted by the Linearly Increasing Voltage type (CELIV-type) technique based on measuring charge carrier extraction under applied voltage pulses of arbitrary shape and limited amplitude. The kinetics of accumulation of radicals in the P3HT films was explored by the electron spin resonance (ESR) spectroscopy under similar conditions. A remarkable dynamics of μ and p in the system was observed after applying bias voltage to the photothermally aged P3HT-based diode devices. This process was shown to be fully reversible and the system undergoes relaxation to the original state after removal the bias voltage. The experimental data reflecting the photothermal degradation of P3HT in the presence of trace amounts of oxygen trapped in the films were explained by the proposed kinetic scheme describing the interactions of free charge carriers with the donor-acceptor pairs.