Perovskite-germanium heterostructure with periodical nanoparticles for broadband light harvesting

The optical properties of the methylammonium lead iodide (CH₃NH₃PbI₃) - Germanium (Ge) heterojunction with a layer of periodical nanoparticles was investigated to achieve broadband light harvesting by 3D Finite Element Method (FEM). The constructed heterojunction device showed a broad bandwidth from 300nm to 1600nm. Under the AM(1.5) illumination, the maximal energy absorbed by the heterojunction device was 776.64W/m² after optimizing thickness of perovskite and Ge, as well as radius of metallic or dielectric nanospheres (Au, Ag, Al, Si₃N₄, TiO₂, Ta₂O₅). The improved optical performance was further demonstrated by comparing calculated electric fields and charge carrier generation rates of the optimized heterojunction with periodical nanoparticles layer with that of corresponding flat device.