Using all dielectric and plasmonic cross grating metasurface for enhancing efficiency of CZTS solar cells

CZTS (Cu2ZnSnS4) based solar cell has many advantages as its materials are earth abundant and low cost. However, its efficiency is low compared with other thin film solar cells. Enhancing efficiency of CZTS solar cell could be achieved using nanostructures for controlling light propagation using nanophotonics techniques. Recently, metamaterial has been used widely for guiding and confining electromagnetic waves over entire wavelength range. Cross grating metasurface would be possible for reducing light reflection and increasing generated photocurrent inside CZTS solar cells. Herein, we studied theoretically effect of using different plasmonic cross grating metasurface above or below CZTS active layer. Then, we replaced plasmonic material with all dielectric metasurface to compare how light losses inside metasurface would reduce and light coupled to CZTS active layer increase. Moreover, we studied how using dielectric coating for metasurface would increase or decrease active layer light absorption. Our findings indicate that, light absorption enhancement in CZTS active layer is largely depend on material, coated material, dimension and pitch of proposed cross grating wires. Our results suggest certain nanostructure to be used for getting better photocurrent and efficiency. All proposed nanostructures done in this study made in three-dimensional using finite element method simulation tool, and use measured solar spectrum as input power. Using proposed cross grating metasurface with suggested material coating, would enhance overall efficiency of CZTS solar cells.