Computational exploration of two-dimensional silicon diarsenide and germanium arsenide for photovoltaic applications.

Sri Kasi Matta,Yalong Jiao,Aijun Du,Anthony O'Mullane,Chunmei Zhang

doi:10.3762/bjnano.9.116

Abstract

The properties of bulk compounds required to be suitable for photovoltaic applications, such as excellent visible light absorption, favorable exciton formation, and charge separation are equally essential for two-dimensional (2D) materials. Here, we systematically study 2D group IV–V compounds such as SiAs2 and GeAs2 with regard to their structural, electronic and optical properties using density functional theory (DFT), hybrid functional and Bethe–Salpeter equation (BSE) approaches. We find that the exfoliation of single-layer SiAs2 and GeAs2 is highly feasible and in principle could be carried out experimentally by mechanical cleavage due to the dynamic stability of the compounds, which is inferred by analyzing their vibrational normal mode. SiAs2 and GeAs2 monolayers possess a bandgap of 1.91 and 1.64 eV, respectively, which is excellent for sunlight harvesting, while the exciton binding energy is found to be 0.25 and 0.14 eV, respectively. Furthermore, band-gap tuning is also possible by application of tensile strain. Our results highlight a new family of 2D materials with great potential for solar cell applications.

Highlights

The potential applications of two-dimensional (2D) materials are one of the key research areas for many researchers since graphene was isolated and characterized in 2004 [1]
Single elemental 2D materials from groups IV and V, such as like phosphorene and stanine, have been studied in detail [2,3], we focus our study on the less well-known combination of IV–V compound semiconductor materials at the two-dimensional scale for their possible electronic applications
In 1963, Hulliger et al [8] predicted that the group IV–V compounds SiAs, GeAs and GeAs2 would show semiconductor be

Summary

Introduction

The potential applications of two-dimensional (2D) materials are one of the key research areas for many researchers since graphene was isolated and characterized in 2004 [1]. In order to further study GeAs2 and to compare it with a similar material from the same IV–V group combination, we focus our study on two-dimensional SiAs2 and GeAs2 and compare them with their bulk counter parts with regard to electronic band structure, phononvibration frequencies, optical properties, band gap modulation behavior and predict their potential applications. Where, E2D and E3D are the energies of the monolayer and the bulk material, respectively.

Results

Conclusion