Improved optical performance of CH₃NH₃PbI₃ perovskite-germanium heterostructure photodetectors assisted by a periodic nanosphere array

Abstract

The methylammonium lead iodide (CH3NH3PbI3)-germanium (Ge) heterojunction with a layer of periodic nanospheres was numerically studied to achieve improved performance over broadband from 300 nm to 1600 nm by the 3D finite element method (FEM). Under AM 1.5 g illumination, the total absorbed power increased 14% in heterojunction photodetectors assisted by an Al2O3 antireflection (AR) array, after optimizing the thickness of perovskite and Ge, as well as the radius, period and material type (metal or dielectric permittivity) of nanosphere array by genetic algorithm, with reference to a corresponding device without nanospheres. The enhanced optical properties were further elaborated and demonstrated by comparatively analyzing broadband absorptance, electric field distributions, absorbed power distributions and the optical generation rate of charge carriers in the two photodetector models. The proposed perovskite-Ge heterojunction with spheres shows great promise for optoelectronic devices.