Polaron Formation in Two-Dimensional Bismuth Oxyhalides BiOX (X = Cl, Br, I)

Abstract

Bismuth oxyhalides BiOX (X = Cl, Br, I) have garnered widespread attention in the field of photocatalysis due to their unique layered structures and excellent optoelectronic properties. Based on first-principles calculations, we investigated the formation of electron-phonon coupled polarons in bismuth oxyhalides BiOX (X = Cl, Br, I) using the EPW code. The results indicate that hole polarons tend to form small polarons, whereas electron polarons develop into large polarons. Furthermore, as the atomic number of the halogen increases, the formation energy gradually rises, and the polarons tend to become more delocalized. Simultaneously, our study provides a detailed enumeration of the phonon and electronic contributions to the polarons. The research provides new insights into the physical properties of polarons in bismuth oxyhalides BiOX (X = Cl, Br, I) and offers guidance for understanding and exploring polarons in related materials.