| This thesis is focused on the technology of plasmonic thin-film solar cells. Solar energy as one of the most abundant resources, has not been well exploited up to now. Plasmonic thin-film solar cell is a new type of solar cell technology with the rise of nanotechnology. Due to its lower cost, enhanced absorption, efficient utilization, and many other advantages, this technology will be a prominent way for the development of solar energy industry and future energy. This dissertation focuses on the plasmonic thin film cell as follows:1)It is investigated that the influence of surface roughness on the absorption efficiency of plasmonic photovoltaic cell. The pseudo-random function is used to generate a rough surface structure of the dielectric medium, and the case of different period of plasmonic cell, different thickness of surface roughness, and different correlation lengths are analyzed.2)A new structure is proposed to enhance the optical absorption in thin-film by applying mode splitting theory. The Ag strip pairs and Si slab with period slit could excite the localized plasmonic and surface waveguide modes respectively, which interact with each other to split the absorption spectra into wider wavelength range, and greatly increase the absorption efficiency. The proposed structure with the thickness 120nm can increase the absorption efficiency by nearly 53% at least comparing with the bare Si slab structure.3) Another structure is proposed to enhance the optical absorption in thin film by introducing symmetry-breaking. Based on the existing structure, the symmetry-breaking introduced in our proposed structure could excite a new dark mode, which is hidden in the symmetrical structure, to couple with the existed modes, and the coupling could further enhance the absorption of full solar spectrum. The proposed structure can increase the absorption efficiency by nearly 90% comparing with the bare Si slab structure. |
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