Modeling Fill Factor Losses in Organic Solar Cells




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Determining how certain electronic devices can outperform other devices is of immense interest in the modern world. Many advance experimental characterization techniques have been applied such as X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to aid in the understanding of device performance. However, simulations often offer a more effective complementary to experiments in discovering the physics governing new materials. First principles or ab initio simulations offer a big advantage since they require no experimental information at all. Empirical methods, on the other hand, need previously determined experimental values to match the experiment. In this thesis, I explain how I further simplify the present understanding of emerging materials from a theoretical perspective. I first discussed why experiments observed fill factor losses in dilute-donor organic solar cells by performing kinetic Monte Carlo simulations. From my kinetic Monte Carlo simulations, I discovered a linear relation between the fill factor and the fraction of donors touching the anode and concluded that fill factor losses are due to donors not touching the anode. In addition to studying the fill factor losses, I studied solvent effects on the highest occupied molecular orbital energy of solute molecules by implementing a first solvation shell method. A first solvation shell is a mix between implicit solvent methods and explicit solvent methods. I found that present implicit solvent methods are not sensitive to solvent choice because those methods cannot discern how solvents and ambient temperature perturb the solute geometries. Finally, I also studied how the bandgap of Tellurium becomes more suitable as a channel material when scaled to extremely small sizes (~1-3 nm).



Physics, Molecular, Physics, Condensed Matter, Physics, Electricity and Magnetism