Sensitization of copper oxide nanoparticles by Victoria Blue R for dye-sensitized solar cells: A DFT study

The model structures of the copper oxide (CuO) nanoparticles and the Victoria blue R (VBR) dye were drawn and optimized using density functional theory (DFT) methods. The orbital energy diagrams of CuO, VBR, and the VBR-sensitized CuO were calculated by means of DFT/B3LYP/6-31G^* method. The study revealed the energy of the highest occupied molecular orbital (E_HOMO), the lowest unoccupied molecular orbital (E_LUMO), and the band gap (ΔE_HOMO-LUMO) of the VBR molecule as -3.85, -2.77, and 1.08 eV, respectively. Same calculations on the model structure of CuO nanoparticles represented the band gap of 2.78 eV, which was decreased into 0.80 eV for the VBR-sensitized CuO. The ultraviolet-visible (UV-Vis), infrared (IR), and nuclear magnetic resonance (NMR) spectrums, as well as the effect of solvation on the molecular orbitals of the VBR molecule, were also calculated. The UV-Visible spectra of the dye display two broad absorption peaks in the visible region. In addition, the electrostatic potential and the local ionization potential maps of the modeled VBR-sensitized CuO photoanode were illustrated and discussed. This study successfully describes the potential of VBR-sensitized CuO to be used as a photoanode in dye-sensitized solar cells (DSCs).