| As solar cells can convert sunlight into electrical energy by photovoltaic effect, it has been a great way to solve the energy problem. However, the cost of solar electrical power generation has remained higher than fossil fuel. Amorphous silicon thin film solar cells offer the potential for a considerable cost reduction which benefits from the reduced material volume and the low cost of material. But the reduced active layer thickness of a-si solar cells leads to poor light absorption capability. Therefore, improving the absorption efficiency of solar cells by using advanced light trapping structures has attracted more and more attention. Among these structures, the metal surface plasmons nanostructures are found to perform an excellent light concentration and broadband absorption enhancement and demonstrate significant value in the design of thin film solar cells.In our work, we study the principle of surface plasmons light trapping techniques and analyze the influence of shape and size to the absorption performance, which provide theoretical support and reference design for our design of new thin film solar cells with high absorption efficiency based on surface plasmons.Then we propose an ultra-thin film solar cell structure combining front semicircular dielectric grooves and back trapezoidal metal reflector. The back trapezoidal metal structure traps light by the excitation of plasmonic modes to enhance the absorption at long wavelengths. The front groove structure boosts absorption at short wavelengths by the mechanisms of Fabry-Perot resonance, scattering and the interaction with back plasmonic structure. The total absorption efficiency over the entire spectrum is increased by30%under normal incident light and the structure can maintain a high absorption efficiency as the angle of incidence ranges from-60°to60°. Broadband absorption, efficiency enhancement and insensitivity to the angle indicate the dual interface nanostructure to be a practical reference. |
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