Unveiling excitons in two-dimensional $\beta$-pnictogens

In this paper, we investigate the optical, electronic, vibrational, and excitonic properties of four two‑
dimensional β‑pnictogen materials—nitrogenene, phosphorene, arsenene, and antimonene—via
density functional theory calculations and the Bethe–Salpeter equation. These materials possess
indirect gaps with significant exciton binding energies, demonstrating isotropic behavior under
circular light polarization and anisotropic behavior under linear polarization by absorbing light within
the visible solar spectrum (except for nitrogenene). Furthermore, we observed that Raman frequencies
red‑shift in heavier pnictogen atoms aligning with experimental observations; simultaneously, quasi‑
particle effects notably influence the linear optical response intensively. These monolayers’ excitonic
effects lead to optical band gaps optimized for solar energy harvesting, positioning them as promising
candidates for advanced optoelectronic device applications.