The concept of three-dimensional (3D) photovoltaics is explored computationally using a genetic algorithm to optimize the energy production in a day for arbitrarily shaped 3D solar cells confined to a given area footprint and total volume. Our simulations demonstrate that the performance of 3D photovoltaic structures scales linearly with height, leading to volumetric energy conversion, and provides power fairly evenly throughout the day. Furthermore, we show that optimal 3D structures are not simple box-like shapes, and that design attributes such as reflectivity could be optimized using three-dimensionality.
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The sun was assumed to be a source of parallel rays, and cloud-cover and all light-obstructions (except from other triangles in the structure) were neglected. For simplicity, it is assumed that all transmitted radiation counts toward the generated power, and only one reflection step (from solar cell surfaces) is taken into account. The triangles surfaces were assumed flat in the sense that all reflections were taken to be specular ; the opposite extreme, not implemented, would be Lambertian reflection, in which incident radiation scatters isotropically in the hemisphere. The number of ray-traces per cell (i.e., per triangle) was fixed to 100 during most simulations to limit computation time. After optimization, the final reported power values of the structures were evaluated with a larger standard number of ray-traces per cell (10 000), allowing convergence of the calculated energy value to better than 0.01%.
18.
In the present work -polarized light was assumed in the calculations. Extensive studies with unpolarized light are underway and will be discussed separately. Preliminary results suggest that the conclusions are consistent with this study, although unpolarized light leads to increased values of due to the poorer performance of the flat panel.
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We chose a typical for the average index of refraction (1.505) for organic active layers that would give . The efficiency was set to 6% to simulate the best performance of state-of-the-art polymer solar cells Ref. 8.
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2010
American Institute of Physics
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