Initial transient photocurrent as a result of polarization of geminate pairs in organics with donor-acceptor bulk heterojunction

The effect of geminate recombination on the photocurrent kinetics is modeled by Monte-Carlo numerical simulation in organic bulk heterojunction. Non-correlated Gaussian distribution of hopping centers is considered. Non-stationary polarization of geminate pairs by external electric field has a considerable influence on transient photocurrent at the time scale of the order of 0.1 µs after generation pulse, and even inversion of the photocurrent sign is possible. Increase of an energetic barrier at donor-acceptor interface weakens this effect and increases a characteristic time.