Modulating electronic properties of pyridinium lead halide perovskites via fluorinated methyl substituents

• Published in: Materials chemistry and physics 2021-11, Vol.273, p.125139, Article 125139
• Main Authors: Kevorkyants, R., Selivanov, N.I., Emeline, A.V.
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Crystal structure; Density functional theory; DFT; Electronic properties; Energy gap; Fluorination; Halides; Lead compounds; Metal halides; One dimensional models; Organometal halide perovskites; Perovskites; Substitutes; Two dimensional models
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.125139

We study the effect of variation in donor/acceptor strength of aromatic ring's substituent on electronic properties of novel low-dimensional 3-(R)pyridinium lead halide perovskites, R = CH(3-n)Fn (n = 0–3). First, the series of hypothetical quasi 1D perovskites having Pbca crystal structure of actual 3-(methyl)pyridinium lead halides is considered. Regardless of halide anion (Br− or I−), Density Functional Theory calculations show monotonic decrease in electronic bandgap with increase in the degree of their methyl group fluorination. In contrast, actual meta-substituted pyridinium lead halides have spatial symmetries other than Pbca. Moreover, two of them form quasi 2D structures as opposed to the 1D model compounds. Therefore, the synthesized meta-substituted pyridinium lead halides do not demonstrate the found theoretical bandgap trend. We conclude that although bandgap modulation of organometal halide perovskites with aromatic cations via ring substitution is feasible theoretical band structure predictions could be severely biased by a hard to predict structure of actual perovskites. •Novel low-dimensional fluoromethyl pyridinium perovskites are synthesized and characterized.•Model Pbca fluoromethyl pyridinium perovskites demonstrate gradual change in electronic bandgap.•Obtained perovskite structures differ from that of the parent Pbca 3-(methyl)pyridinium compounds.•Due to the symmetry difference the synthesized perovskites do not show the trend in model species.