Density Functional Theory calculations of optical properties of Hybrid Halide Perovskite Bio-Solar Cells

The photovoltaic performance of hybrid halide perovskite is related to the atomic and electronic structure at the interface between the carrier generating perovskite layer and the electron transport layer (ETL). Based on ab-initio density functional theory (DFT) calculations, we studied the interfacing of the ETL layer, bacteriorhodopsin (bR) protein with Methylammonium lead triiodide CH₃NH₃PbI₃ based organic-inorganic hybrid perovskite to fabricate Perovskite Biosolar Cells, which demonstrated a high ambient stability and an optical bandgap extending into the visible range. The dielectric spectrum of the Perovskite thin films is evaluated and validated with spectroscopic ellipsometry data. We further model the dielectric function according to the established Drude model with coupled harmonic oscillators. Our results agree well with reported data of the optical absorption coefficient and consistent with Kramers−Kronig transformations thus demonstrating band alignment between the protein and the perovskite. Hence, we comment on the structural, electronic, and transport properties at the bR/perovskite/ETL interface.