Thin‐Film Morphology Improvement and Density Functional Theory‐Driven Findings for the Photovoltaic Perovskite MAPI/MAPSI

Abstract

Herein, mixed CH3NH3PbI3/(CH3NH3)2PbI2(SCN)2 (MAPI/MAPSI) thin films are synthesized. Arising from X‐ray diffraction measurements, the composite material is found to be consisting of two crystalline domains, one for each MAPI and MAPSI constitutent materials. Optical analysis from diffuse reflectance spectroscopy shows optical onsets for both the MAPI and MAPSI domains, making the fabricated material an interesting one for multi‐bandgap absorber composite for solar cell devices. Scanning electron microscopy studies yield a noticeable morphology enhancement for the MAPI/MAPSI films when treated with a toluene dripping technique, and then show films with uniform, compact grains in contrast to an initial porous, dendritic growth morphology for the untreated films. A question about the actual geometry for the thiocyanate anions in MAPSI is answered as being of axial configuration around the Pb cation, enlightened by the results of state‐of‐the‐art density functional theory computational modelling within the framework of the Quantum Espresso software package suite, also in‐depth studying of the MAPSI structure through bond indicators such as crystal orbital Hamilton population, non‐covalent interactions analysis, and electron localization function.