Photovoltaic Performance of Azo-Benzaldehyde Sensitizers in DSSCs: A DFT-Experimental Correlation

This study comprehensively investigates the photovoltaic performance and quantum chemical properties of newly synthesized azo dye-sensitized solar cells. A series of azo-aldehyde ligands, (E)-2-hydroxy-5-(p-tolydiazenyl)benzaldehyde (5), (E)-5-((4-fluorophenyl)diazenyl)-2-hydroxybenzaldehyde (6), (E)-5-((4-(tert-butyl)phenyl)diazenyl)-2-hydroxybenzaldehyde (7), (E)-2-hydroxy-5-(mesityldiazenyl)benzaldehyde (8) and their solar cells were fabricated. The ligand structures were elucidated by ¹³C-NMR, ¹H-NMR, FTIR, UV-Visible spectroscopy. In organic dye sensitized solar cells, these azo dyes were used as sensitizers. TiO₂ film deposited on FTO conductive glass by doctor blade method was characterized by UV-Vis, FT-IR, FE-SEM and EDX analysis. Current-voltage (I-V) properties of solar cells were measured by a solar simulator. DSSCs used in our study were simple and inexpensive to produce. In the presence of an electron-withdrawing group such as 4-fluoroaniline, the highest efficiency was obtained with η (%) = 0.42 with Ligand 6, while the lowest efficiency was observed with η (%) = 0.32 with ligand 5. The chemical structure of the molecules was calculated using the density functional system (DFT) implemented in the Gaussian 16 W program [1]. HOMO and LUMO energies of ligands 5-8 were calculated at the theoretical level studied in the gas phase. Dipole moments were found to be in the range of 1,95081-5,861112 μ.