Computational analysis and design of the morphology of organic solar cells

Projected increases in energy demand and increasing global concern regarding climate change have focused research attention on renewable, clean energy sources, such as organic solar cells (OSCs). OSCs based on blend of electron donating conjugate polymers and electron accepting fullerene materials have potential to be a disruptive technology within the solar cell market. OSCs have several advantages over their inorganic counterparts. The materials used in most OSCs are flexible, allowing for easier transport and installation of such devices. However, because of OSCs main deficiency of significantly low photocurrent generation, they have not yet seen mass adoption in industry. The problem of low photocurrent generation of OSCs is examined in this thesis. In this thesis we focus on computational study and design of OSCs. We explore various strategies in order to increase photocurrent generation of OSCs through morphology improvement. We perform OSC simulation using both continuum and atomistic models. Our continuum model is based on excitonic drift-diffusion (XDD) equations. First, we develop an efficient and fast framework for simulation of OSC current generation. Second, we apply the morphology aware XDD model to the experimentally retrieved large domain morphology for the first time with an in-house parallel computing framework using the finite element method. Third, we couple, XDD model with CAD and optimization techniques to design new 2D and 3D microstructures whose performance is better than known microstructures (bilayer and bulk heterojunctions). Later we develop an atomistic model in order to investigate effect of different parameters on the performance of the organic solar cell. we utilize a directed graph representation to relate the microscopic properties of polymer systems and the consequent charge transfer