A modeling method to enhance the conversion efficiency by optimizing light trapping structure in thin-film solar cells

Nano-scaled dielectric and metallic structures are popular light tapping structures in thin-film solar cells. However, a large parasitic absorption in those structures is unavoidable. Most schemes based on such structures also involve the textured active layers that may bring undesirable degradation of the material quality. Here we propose a novel light trapping structure based on the prism structured SiO2 for thin-film solar cells, and a flat active layer is introduced purposefully. Such a light trapping structure is imposed by the geometrical shape optimization to gain the best optical benefit. A self-consistent simulation method including the solutions of Maxwell, drift-diffusion and Poisson equations is adopted for modeling the optical and electrical performance of the solar cell. By examining our scheme, it is disclosed that the conversion efficiency of the flat a-Si:H thin-film solar cell (8.1%) can be promoted to an impressive value (10.74%) that is higher than previous reports. As the method proposed in this work is also applicable to design the thin-film solar cell systems with other materials, this proposal would provide useful guides for developing high-performance thin-film solar cells.