A new highly stable multifunctional two-dimensional Si2BN monolayer quantum material with a direct bandgap predicted by density functional theory

Abstract

In this work, we present a novel two-dimensional (2D) Si₂BN structure (2D δ-Si₂BN) predicted using density functional theory (DFT). The proposed structure exhibits a unique double quasi-planar layer interconnected by covalent bonds, demonstrating lower energy compared to the previously reported planar Si₂BN nanosheet. Our calculations, conducted at the HSE06 level of theory, reveal its semiconductor nature with a direct band gap of 1.24 eV at the gamma point. The 2D material exhibits exceptional light absorption in the visible region, prompting an exploration of its potential in photovoltaic applications. Remarkably, our findings indicate a maximum theoretical efficiency of 27.6%, underscoring its promise for renewable energy technologies. Furthermore, employing modern polarization theory, we unveil the ferroelectric properties of the Si₂BN monolayer. Notably, a large out-of-plane polarization is observed. It was found that the unstrained 2D δ-Si₂BN monolayer demonstrates an impressive out-of-plane spontaneous electric polarization of 28.98 × 10⁻¹⁰ C m⁻¹, a value six times greater than previously referenced Janus materials. This remarkable enhancement in ferroelectric capabilities positions the Si₂BN monolayer as a promising candidate for applications in next generation novel information storage, nano-electronic, and optoelectronic devices. These findings not only contribute to the understanding of the structural and electronic properties of the 2D δ-Si₂BN monolayer but also highlight its potential for various technological applications, marking a significant advancement in the field of nanomaterials.