An oxadiazole dye for use as an organic photosensitizer. The oxadiazole dye comprising donor-π-spacer-acceptor type molecules in which at least one of an oxadiazole group acts as a π-conjugated bridge (spacer), a naphthyl unit acts as an electron-donating unit, a carboxyl group act as an electron acceptor group, and a cyano group acts as an anchor group. An optional thiophene group acts as part of the π-conjugated bridge (spacer). The dye for use as organic photosensitizers in a dye-sensitized solar cell. The dye for use in photodynamic therapies. Computational DFT and time dependent DFT (TD-DFT) modeling techniques showing Light Harvesting Efficiency (LHE), Free Energy for Electron Injection (ΔGinject), Excitation Energies, and Frontier Molecular Orbitals (FMOs) indicate that the series of dye comprise a more negative ΔGinject and a higher LHE value; resulting in a higher incident photon to current efficiency (IPCE).