Quantifying the relation between the morphology and performance of polymer solar cells using Monte Carlo simulations

Morphology is a crucially important factor determining the efficiency of photocurrent generation in bulk heterojunction polymer solar cells. Morphology, which depends on the characteristics of the polymers as well as on the conditions of phase separation, affects the performance of solar cells by influencing the rate of exciton dissociation and the efficiency of charge carrier transport. Using Monte Carlo simulations, we investigate the effects of annealing time on the morphology of phase separation and charge transfer behavior inside the active layers of polymer solar cells. We find that a suitably defined correlation distance is an effective parameter that quantitatively characterizes different morphologies and can be used to establish a direct link with transmission electron microscopy images of real polymer solar cells. Optimal morphologies have been investigated, showing results that are consistent with experimental data.