Three-Dimensional to Layered Halide Perovskites: A Parameter-Free Hybrid Functional Method for Predicting Electronic Band Gaps

TL;DR

This paper introduces a parameter-free hybrid functional method based on dielectric properties for accurately predicting electronic band gaps in 3D and layered halide perovskites, improving computational efficiency and prediction accuracy.

Contribution

The study develops a dielectric-dependent hybrid functional approach tailored for layered halide perovskites, enhancing band gap predictions without adjustable parameters.

Findings

The DSH functional accurately predicts band gaps when structural disorder is considered.

Using the dielectric constant of 3D perovskites improves layered perovskite predictions.

HSE underestimates band gaps; PBE0 aligns well with experiments for layered iodides.

Abstract

Accurate prediction of electronic band gaps in halide perovskites using density functional theory is crucial for optoelectronic applications. Standard hybrid functionals like HSE and PBE0 are becoming computationally accessible, yet can fail at predicting the band gaps for three-dimensional (3D) and/or layered halide perovskite. This study evaluates the doubly screened dielectric-dependent hybrid (DSH) functional for predicting band gaps of Pb- and Sn-based inorganic and hybrid 3D halide perovskites, as well as layered hybrid perovskites. The DSH functional employs material-dependent mixing parameters derived from macroscopic dielectric constants, and accurately predicts band gaps for 3D perovskites only if structural local disorder is taken into account. For layered hybrid perovskites, the DSH functional based on average dielectric constants tends to overestimate the band gaps. To improve predictions, we propose using the calculated dielectric constant of the respective 3D perovskites to define the DSH screening. This method is then applied to Pb- and Sn-based layered halide perovskites with various organic spacers and multilayered structures, such as $BA_2MA_{n-1}Pb_{n}I_{3n-1}$ with n =1, 2, 3, resulting in improved precision. The HSE functional systematically underestimates band gaps in layered perovskites due to the missing non-local long-range dielectric screening. On the other hand, the PBE0 is in good agreement with the experimental values, in particular for the layered iodide perovskites. The computational framework introduced here provides an efficient parameter-free \textit{ab initio} methodology suitable for predicting the electronic properties of 3D, layered halide perovskites and their heterostructures, towards modelling materials for advanced optoelectronic devices