First-principles calculations of the electronic and optical properties of penta-graphene monolayer: study of many-body effects

In the present work, first-principles calculations based on the density functional theory (DFT), GW approximation and Bethe-Salpeter equation (BSE) are performed to study the electronic and optical properties of penta-graphene (PG) monolayer. The results indicated that PG is a semiconductor with an indirect band gap of approximately 2.32 eV at the DFT- GGA level. We found that the utilization of the GW approximation based on many-body perturbation theory led to an increase in the band gap, resulting in a quasi-direct gap of 5.35 eV. Additionally, we employed the G0W0 - RP A and G0W0 - BSE approximations to calculate the optical spectra in the absence and in the presence of electron-hole interaction, respectively. The results demonstrated that the inclusion of electron-hole interaction caused a red-shift of the absorption spectrum towards lower energies compared to the spectrum obtained from the G0W0 - RP A approximation. With the electron-hole interaction, it is found that the optical absorption spectra are dominated by the first bound exciton with a significant binding energy 3.07 eV. The study concluded that the PG monolayer, with a wider band gap and enhanced excitonic effects, holds promise as a suitable candidate for the design and fabrication of optoelectronic components.