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b'Solar cells generate clean electricity from sunlight. However, they remain signi\\ufb01cantly more\\nexpensive than other, less environmentally-friendly, energy generation technologies. Although\\nthe emergence of thin-\\ufb01lm solar cells, low-cost alternatives to the prevailing crystalline silicon\\nsolar cells, has been a signi\\ufb01cant advance in photovoltaic technology, these devices typically\\nsuffer from low absorption. If this absorption could be enhanced, it would enable an increase\\nin power conversion ef\\ufb01ciency and hence a reduction in cost/kW of generating capacity. This\\nis the motivation of the work presented in this doctoral thesis. Metallic nanostructures are used\\nto trap light within the semiconductor \\ufb01lm in organic solar cells. By increasing the optical path\\nlength, the probability that photons are absorbed before exiting the \\ufb01lm is increased. A novel\\nprocess is developed to fabricate nanostructured metallic electrode organic solar cells. These\\ndevices feature a nanovoid array interface between the metallic electrode and the semiconduc-\\ntor \\ufb01lm. Absorption enhancements over conventional, planar architectures as high as 45% are\\ndemonstrated. This light-trapping is found to be largely enabled by localized void plasmons.\\nThe experimental investigations are supported by \\ufb01nite element simulations of absorption in\\nsolar cells, which display very good agreement with experimental results. It is found that light\\ntrapped in organic solar cell architectures is very ef\\ufb01ciently absorbed by the organic \\ufb01lm - in-\\ncreases in the exciton generation rate per unit volume of semiconductor material of up to 17%\\nare observed. The simulation routine is additionally used to compare and contrast common\\nplasmonic architectures in organic solar cells. The role of the metallic nanostructure geometry\\non the dominant light-trapping mechanism is assessed for various size domains and optimum\\narchitectures are identi\\ufb01ed. When implemented according to the \\ufb01ndings of this thesis, light-\\ntrapping will have the potential to vastly increase the ef\\ufb01ciency and hence decrease the price\\nof thin-\\ufb01lm solar cells.'