Multiscale modelling of the influence of phase separation in the functioning of organic phovoltaic devices

Abstract

Controlling and understanding the influence of the morphology of the active layer made of polymer/low weight molecules blend in organic solar cells (OSC) is, in our days, seen as one of the key issues to increase its efficiency. Most of the research in this area, is made at experimental level focusing not only on the influence of the molecular structure of the materials used, but also on the deposition conditions that changes the nanomorphology and thus the OSC performance. On the other hand, the few theoretical studies published in the literature that concern the influence of the active layer morphology in OSC functioning, simulate a blend morphology far from what is expected from experimental data. In this communication, we present a study of the influence of polymer/low-weight molecule morphology in OSC functioning, using a multiscale model based on quantum molecular dynamic calculations to obtain the molecular properties of the organic materials and a mesoscopic model that considers not only the main physical processes that are behind OSC functioning, but also simulates different possible polymer/low-weight molecule phase separation. Our results shed some light on how the different polymer/low-weight molecule blend morphologies affects exciton diffusion/dissociation and charge transport/collection processes in OSC performance.