# Band gap evolution in Ruddlesden-Popper phases

## TL;DR

This study explores how the band gap in Ruddlesden-Popper phases varies with structure and composition, revealing different behaviors in chalcogenides compared to oxides and halides, influenced by octahedral rotations and quantum confinement.

## Contribution

It provides a detailed analysis of band gap evolution in RP phases, highlighting the roles of octahedral rotations and quantum confinement, aiding rational design of layered perovskites.

## Key findings

- Chalcogenides show different band gap evolution compared to oxides and halides.
- Octahedral rotations and quantum confinement influence band gap changes.
- Insights enable targeted design of layered perovskite materials.

## Abstract

We investigate the variation of the band gap across the Ruddlesden-Popper (RP) series (An+1BnX3n+1) in model chalcogenide, oxide, and halide materials to understand the factors influencing band gap evolution. In contrast to the oxides and halides, we find the band gap of the chalcogenides evolve differently with the thickness of the perovskite blocks in these natural superlattices. We show that octahedral rotations (i.e. deviation of the B-X-B bond angles from 180) and quantum confinement effects compete to decide the band gap evolution of RP phases. The insights gained here will allow us to rationally design layered perovskite phases for electronics and optoelectronics.