Validity of density-functional-theory-based molecular modeling for UV/visible spectroscopy and rationale of panchromatic PbI64-(MeNH3+)4-structured molecular solar cells

Abstract

Density-functional-theory-based molecular modeling verifies that perovskite solar cells (PSC) are composed of semiconducting and panchromatic layers constructed by van der Waals and Coulomb interactions (vdW&Clmb) between PbI64-(MeNH3+)4-derived species. Firstly we validate that DFT-based UV/vis spectral analysis is a useful approach for vdW&Clmb based on assignments of the fine-structured UV/vis spectrum of a benzene solution. The UV/vis spectral analysis of aggregated PbI64-(MeNH3+)4 proves that dimeric aggregates of [PbI64-(MeNH3+)4]2 have a panchromatic UV/vis spectrum of λ max ranging from 417 to 959 nm. Further analysis proves that the strong vdW&Clmb of PbI64-(MeNH3+)4 leads to unidirectional electron transport at the structured components such as the dimer of [PbI64-(MeNH3+)4]2, nc-TiO2/PbI64-(MeNH3+)4, and PbI64-(MeNH3+)4/spiro-OMeTAD. PbI64-(MeNH3+)4-structured solar cells should have a photoelectron diffusion length enhanced by the alignment of the frontier molecular orbitals in the structured PbI64-(MeNH3+)4 components, which supports remarkable short-circuit photocurrent, open-circuit voltage, and fill factor for the molecular-orbital-connected solar cell of HOTi9O18H/[PbI64-(MeNH3+)4] n /spiro-OMeTAD under solar-light irradiance.