<p>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 (<b>5</b>), (E)-5-((4-fluorophenyl)diazenyl)-2-hydroxybenzaldehyde (<b>6</b>), (E)-5-((4-(tert-butyl)phenyl)diazenyl)-2-hydroxybenzaldehyde (<b>7</b>), (E)-2-hydroxy-5-(mesityldiazenyl)benzaldehyde (<b>8</b>) 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 <b>6</b>, while the lowest efficiency was observed with η (%) = 0.32 with ligand <b>5</b>. The chemical structure of the molecules was calculated using the density functional system (DFT) implemented in the Gaussian 16 W program [<CitationRef CitationID="CR1">1</CitationRef>]. HOMO and LUMO energies of ligands <b>5</b>–<b>8</b> 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.</p>