Molecular Engineering of Pure 2D Lead‐Iodide Perovskite Solar Absorbers Displaying Reduced Band Gaps and Dielectric Confinement

Pure 2D lead-iodide perovskites typically demonstrate poor charge transport and compromised visible light absorption, relative to their 3D congeners. This hinders their potential use as solar absorbers. Herein, we report systematic tuning of pyridinium-based templating cations to introduce intermolecular interactions that provide access to a series of new 2D lead-iodide perovskites with reduced inter-octahedral distortions (largest Pb-( mu -I)-Pb bond angles of 170 - 179 degrees ) and very short inorganic interlayer separations (shortest I...I contacts