| dc.description.abstract | For optimal functionality of photovoltaic devices, it is imperative to utilize efficient compounds characterized
by outstanding optoelectronic properties. The potentiality of compounds such as ZnO is not yet exhaustively exploited. In
The present investigation, we execute the ab initio studies based on density functional theory (DFT) to explore the structural,
elastic, mechanical, electronic, dynamical, transport and optical properties of three phases of ZnO. Ground state properties
were determined in two distinct scenarios, that is, by application of standard DFT and use of the Green functional (GW)
approximation. The calculated lattice constants of 4.388 Å for C-ZnO, 3.289 Å for Wurtzite (W)-ZnO and 3.276 Å for
monolayer (M)-ZnO are in agreement with other DFT findings and experimental results obtained from literature. The
investigated compounds were found to be mechanically and dynamically stable at ground state, ductile and anisotropic. The
optical absorption coefficient curves prove that ZnO is transparent to many solar radiations as expected in photoanode of dye
sensitized solar cells (DSSCs). All structures tested displayed direct band gap at gamma point of symmetry. The optical band
gap was found to increase on average by 2.33 eV when GW approximation was taken into account. Basically, the inclusion of
the Green’s function (G) and the screened Coulomb interaction (W) in DFT enhances the predictions of the energy band gap
and optical properties. The O-2s, Zn-3d and O-2p orbitals were found to dominate the valence band while 0-2p and Zn-4s
orbitals dominated the conduction band. Generally, ZnO was found to have low absorption ability and high transmittance in
the visible spectrum and therefore making it suitable candidate for DSSCs application. The monolayer ZnO demonstrated the
highest electrical conductivity as desired in DSSC’s. | en_US |
