Band Structure Engineering and Optical Properties of Pristine and Doped Monoclinic Zirconia (m-ZrO₂): Density...

Recently, monoclinic ZrO₂ has received great technological importance because of its remarkable dielectric properties, high chemical stability, and high melting point. Herein, we introduce first-principles calculations using the Hubbard approach (DFT + U) to study the effects of doping with Nb and W on the electronic and optical properties of pristine ZrO₂. The introduction of dopant atoms into the pristine crystal structure led to the displacement of the bandgap edges and reallocation of the Fermi level. The valence band maximum (VBM) shifted upward, resulting in band gap tightening from 5.79 to 0.89 for ZrO₂: Nb and to 1.33 eV for ZrO₂: W. The optical absorption of doped crystals extended into the visible and near-infrared regions. Partial density of states (PDOS) calculations showed valence band dependency on the O 2p orbital energy, with the conduction band predominantly composed of Nb 4d and W 5d. For pristine ZrO₂, the results obtained for the imaginary and real parts of the dielectric function, the refractive index, and the reflectivity show good agreement with the available experimental and theoretical results. For ZrO₂:W, we checked the dopant location effect, and the obtained results showed no significant effect on the calculated values of the band gap with a maximum difference of 0.17 eV. Significant band gap tightening and optical properties of our systems indicate that these systems could be promising candidates for photoelectrochemical energy conversion (PEC) applications.