Deciphering the Orientation of the Aromatic Spacer Cation in Bilayer Perovskite Solar Cells through Spectroscopic Techniques

Slowing the degradation of perovskite-based solar cells (PSCs) is substantial interest. We engineered surface by introducing a hydrophobic overlayer on three-dimensional (3D) perovskite using fluorinated or nonfluorinated aryl ammonium cation spacers. The placement fluoroarene allows formation bilayer structure, that is, layered/3D perovskites. By doing so, character increases notably virtue perfluorinated benzene moiety. fabricated devices thereof gave higher performance and longevity than control in addition to boosting reliability. fluoro-phenethylammonium iodide (FPEAI)-based showed lower nonradiative carrier recombination. To decipher orientation spacer this we probed polarization-modulated infrared reflection–absorption spectroscopy noted differences due presence fluorine substitution. hypothesize stronger van der Waals interactions electronegativity FPEAI govern enhancement act as barrier moisture decomposition.