Structural Isomer of Fluorinated Ruddlesden-Popper Perovskites Toward Efficient and Stable 2D/3D Perovskite Solar Cells

Defect passivation using two-dimensional (2D)-layered perovskites with organic spacers on 3D bulk perovskites has been proposed as an effective strategy to improve perovskite solar cell stability and efficiency. Specifically, fluorination of the organic spacers has been employed due to the resulting hydrophobic nature and the defect passivation characteristics. In addition to the type of functional groups attached to the spacer molecules, conformational changes of fluorine isomers on layered perovskites can provide an extended strategy to control a variety of opto-electrical properties related to the interlayer spacing. As a model system for the structural isomer of fluorinated spacers, meta -CF 3 and para -CF 3 groups anchored to phenethylammonium iodide (PEAI) spacer molecules are employed to synthesize 2D perovskites and to investigate their full potential as an interfacial modifier f…