Structures and Optical Absorption of Bi2OS2 and LaOBiS2

TL;DR

This study investigates the electronic structures and optical properties of Bi2OS2 and LaOBiS2, revealing their potential as non-toxic, near-infrared optoelectronic semiconductors with direct band gaps around 1 eV.

Contribution

It provides combined experimental and computational analysis of the band gaps and electronic structures of Bi2OS2 and LaOBiS2, highlighting their suitability for optoelectronic applications.

Findings

Both compounds are semiconductors with direct band gaps of 0.8-1.0 eV.

Optical and computational band gaps are in close agreement.

They are potential candidates for non-toxic near-infrared optoelectronic devices.

Abstract

The band gaps of isostructural Bi2OS2 and LaOBiS2 were examined using optical absorption and discussed with the band structures calculated based on the crystal structures determined using synchrotron X-ray diffraction. The Bi 6p and S 3p orbitals in the Bi-S plane were computationally predicted to constitute the bands near the Fermi level. The optical reflectance spectra of Bi2OS2 and LaOBiS2 showed optical band gaps of ca. 1.0 eV, which were close to the computationally calculated direct band gaps of ca. 0.8 eV. Our results show that Bi2OS2 and LaOBiS2 are semiconductors containing direct band gaps of 0.8-1.0 eV, and they are suggested to be candidates for optoelectronic materials in the near-infrared region without highly toxic elements.