Simulation Studies of Organic Solar Cell Structure and Morphology on the Device Efficiency

Solar cells based on organic materials offer several advantages over the traditional solar cells made with inorganic materials. These include a lower impact on nature, smaller weight, the avoidance of cleanrooms for their production, their flexibility which makes it possible to wrap or coat them on objects with varying shapes and geometries, and most significantly their ability to produce electricity in diffuse'd light which is a distinct advantage over conventional solar cells. Organic solar cells have their own disadvantage of very low efficiencies as compared to inorganic solar cells. The morphology and structure of the organic solar cells plays a key role in impacting the overall energy conversion efficiency. In this thesis, we examine and compare three types of structures and their effect on the efficiencies of the respective solar cells. Dynamic Monte Carlo Simulations are used to create an organic solar cell (OSC) that mimics a fabricated structure and morphology. Next, generation of the photo generated excitons, their internal dissociation, and subsequent transport is simulated for quantitative predictions of the efficiencies of the different structures and to provide a relative comparison. The response behavior, with special attention to the conversion efficiency is tracked using Monte Carlo simulations. Internal Quantum Efficiency of the organic solar cells is of primary concern in comparing different models and structures of solar cells. The dependence of efficiency of the size of the organic solar cells is also examined for all structures. This thesis focusses on the poly 3-hexylthiophene (P3HT) and phenyl-C61 butyric acid methyl ester (PCBM) organic materials (P3HT:PCBM) for solar cell performance evaluation.