Multiscale modeling and simulation for optimizing polymer bulk heterojunction solar cells

Optimizing polymer bulk heterojunction solar cells requires a fine tune over the thickness, weight ratio, and the morphology because of the strong coupling among light absorption, exciton dissociation, and charge carrier transport within bulk heterojunctions. Without guidance from modeling and simulation, it will be a daunting challenge to optimize the device performance. In this paper, we present a multiscale modeling and simulation approach by integrating the Monte Carlo simulation, the optical absorption calculation, and the macroscopic device simulation. Such integration accounts for multiscale aspects of the bulk heterojunctions in polymer solar cells, which is not possible by any individual method alone. For the first time, we are able to predict the best device performance by simultaneously optimizing the thickness of the active layer, the nanoscale morphology of the bulk heterojunctions, and the donor/acceptor weight ratio through the multiscale simulation.