Proc. SPIE. 9898, Photonics for Solar Energy Systems VI
KEYWORDS: Modeling, Thin films, Photovoltaics, Optical properties, Solar cells, Crystals, Silicon, Reflectivity, 3D modeling, Thin film solar cells, Thin film devices, Multijunction solar cells, Absorption, Perovskite
Barium di-silicide (BaSi<sub>2</sub>) is an abundant and inexpensive semiconductor with appealing opto-electrical properties. In this work we show that a 2-μm thick BaSi<sub>2</sub>-based thin-film solar cell can exhibit an implied photo-current density equal to 41.1 mA/cm<sup>2</sup>, which is higher than that of a state-of-the-art wafer-based c-Si hetero-junction solar cell. This performance makes BaSi<sub>2</sub> an attractive absorber for high-performing thin-film and multi-junction solar cells. In particular, to assess the potential of barium di-silicide, we propose a thin-film double-junction solar cell based on organometallic halide perovskite (CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>) as top absorber and BaSi<sub>2</sub> as bottom absorber. The resulting modelled ultra-thin double-junction CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> / BaSi<sub>2</sub> (< 2 μm) exhibits an implied total photo-current density equal to 38.65 mA/cm<sup>2</sup> (19.84 mA/cm<sup>2</sup> top cell, 18.81 mA/cm<sup>2</sup> bottom cell) and conversion efficiencies up to 28%.
Thin-film solar cells contain nano-textured interfaces that scatter the incident light, leading to increased absorption and hence increased current densities in the solar cell. In this manuscript we systematically study optimized random nano-textured morphologies for three different cases: amorphous hydrogenated silicon solar cells (a-Si:H, bandgap 1.7 eV), nano-crystalline silicon solar cells (nc-Si:H, bandgap 1.1 eV) and tandem solar cells consisting of an a-Si:H and a nc-Si:H junction. For the optimization we use the Perlin texture algorithm, the scalar scattering theory, and a semi-coherent optical device simulator.