Exploring A-site cation variations in Dion-Jacobson two-dimensional halide perovskites for enhanced solar cell applications. A density functional theory study

The exceptional photophysical and electronic properties of 2D hybrid perovskites possess potential applications in the field of solar energy harvesting. The present work focuses on the two systems, exhibiting the Dion-Jacobson phase of 2D perovskite consisting of methylammonium (MA) and formamidinium (FA) cations at A-site and 3-(aminomethyl)pyridinium (3AMPY) as ring-shaped organic spacer. Altering A-site cations creates a distortion of inorganic layers and hydrogen bond interactions. It has been noted that the angles of Pb-I-Pb and I-Pb-I are more symmetric (close to 180°) for (3AMPY)(MA)Pb${}_2$I${}_7$ compared to (3AMPY)(FA)Pb${}_2$I${}_7$ and result in increase of bandgap from 1.51 to 1.58 eV. This further leads to a significant difference in Rashba splitting energy under the influence of spin-orbit coupling effects, where the highest splitting (36 meV) is calculated for conduction band edge of the (3AMPY)(FA)Pb${}_2$I${}_7$, suggesting the promising applications toward spintronics. The calculated absorption spectra cover the range from 300 to 450 nm, indicating significant optical activity of 2D (3AMPY)(MA)Pb${}_2$I${}_7$ and (3AMPY)(FA)Pb${}_2$I${}_7$ in the visible and ultraviolet regions, which bodes well for their application in advanced optoelectronic devices. The bandgap and high absorption coefficients present more than 30% of theoretical power conversion efficiency for both systems, as calculated from the spectroscopic-limited maximum efficiency. (© 2023 The Authors. Advanced Energy and Sustainability Research published by Wiley‐VCH GmbH)