  The electronic, structural, optical, and thermoelectric properties of the
Cs2O cubic structure have been investigated using density functional theory
(DFT). The calculations utilize a full relativistic version of the
full-potential augmented plane-wave plus local orbitals method, which is based
on density functional theory, employing both the GGA and LDA approximations.
Additionally, we employed the GGA proposed by Trans-Blaha (GGA-mBJ) for band
structure computations, revealing the indirect band gap nature of Cs2O. The
optical properties are also addressed by computing the refractive index,
extinction coefficient, and complex dielectric tensor. The electrical
conductivity, Seebeck coefficient, and thermal conductivity exhibit
temperature-dependent variations, indicating the formation of a thermoelectric
material. Our findings indicate that the compound under investigation is
categorized as a p-type semiconductor, with the majority of charge carriers
responsible for conduction being holes rather than electrons.
