Excitonic and fluorination effects on optoelectronic response of GeC hybrid

Using GW approximation + Bethe-Salpeter equation, we study optical and electronic responses of three fluorinated structures of GeC namely, F-GeC-F, F-GeC and GeC-F and compare our results with other fluorinated 2D materials. The absence of soft modes demonstrates stability of the three structures. The band gaps were determined in presence and absence of quasiparticle correction. The results show that fluorination tunes the gap but its nature remains the same. Effect of polarization direction and local field on imaginary part of macroscopic dielectric function were also reported. Optical properties investigated through analysing absorption spectra reveals a weak electron-hole interaction for GeC-F where Bohr radius of exciton is 8.64 Å. However, a strong electron-hole interaction in the two others fluorinated structures leads to the appearance of small radius of excitons with spatially separated electron and hole, which are localized out of plane and in plane, respectively. The presence of such bounded excitons in the studied structures makes them good candidates for optoelectronic applications and quantum information technologies.