DFT Investigation of the Structural, Electronic, and Optical Properties of AsTi (B)-Phase ZnO under Pressure for Optoelectronic Applications.

Pressure-induced phases of ZnO have attracted considerable attention owing to their excellent electronic and optical properties. This study provides a vital insight into the electronic structure, optical characteristics, and structural properties of the AsTi (B) phase of ZnO under high pressure via the DFT-based first-principles approach. The phase transformation from BN(B) to the B phase of ZnO is estimated at 16.1 GPa using local density approximation, whereas the properties are explored precisely by the hybrid functional B3LYP. The electronic structure exploration confirms that the B phase is an insulator with a wider direct bandgap, which expands by increasing pressure. The dielectric function evidenced that the B phase behaves as a dielectric in the visible region and a metallic material at 18 eV. Optical features such as the refractive index and loss function revealed the transparent nature of the B phase in the UV range. Moreover, the considered B phase is found to possess a high absorption coefficient in the ultraviolet region. This research provides strong theoretical support for the development of B-phase ZnO-based optoelectronic and photovoltaic devices.