Synthesis, physicochemical characterization, and application of a water-soluble oxovanadium(V) Schiff-base complex in dye-sensitized solar cells with aloe latex-assisted photoconversion enhancement

Photosensitizers play a pivotal role as photoanode materials in dye-sensitized solar cells (DSSCs). However, systems that offer superior water-solubility and provide good optical absorption while allowing facile synthesis are highly sought-after. Here, a water-soluble dinuclear oxovanadium(V) Schiff-base complex (V-SBC) is synthesized, and its physicochemical properties and its photoconversion performance as a DSSC photosensitizer are examined using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, photoluminescence measurements, scanning electron microscopy, and electrical measurements. We show that the V-SBC exhibits a major V5+ oxidation state of coordinated vanadium ions and chemical bonds of the dinuclear structure, as resolved using crystallographic diffraction. The onset of optical absorption at about 2.43 eV and a 3.62 ns photoelectron lifetime is determined, while the defect-laden nature of V-SBC is evidenced by additional near-band edge and broad donor–acceptor or deep-level emissions of respective energies at about 2.36 and 2.20 eV. Photoconversion performances of DSSCs sensitized with the V-SBC and DSSCs co-sensitized with the V-SBC and aloe latex solid (ALS) are evaluated. Without specific optimization, the electrical characteristics of FTO/TiO2/V-SBC/Electrolyte/Pt/FTO DSSCs yield an open-circuit voltage (VOC) of 0.204 V, a short-circuit current density (JSC) of 0.328 mA.cm–2, and a fill factor (FF) of 47.1%. When co-sensitizing the V-SBC DSSC with ALS, a power conversion efficiency (PCE) enhancement of more than 7 times is achieved, suggesting promising opportunities for accessible low-cost DSSCs with facile fabrication.