Effect of natural alizarin sensitizer on the efficiency of TiO2-based dye-sensitized solar cell under different light intensities

One of the major challenges in the commercialization of dye-sensitized solar cells (DSSCs) is the simultaneous non-achievement of long-term device stability and high photoconversion efficiency (PCE). In addition, while natural dyes are often preferred due to the high cost and toxic nature of commonly used synthetic dyes, they typically suffer from photo-instability and low PCE, which limits the overall performance of DSSCs. In this context, we investigated the effect of the natural dye sensitizer alizarin on the efficiency of a TiO2-based DSSC under varying solar light intensities. TiO2 nanoparticles, intended for use as photoanode in DSSC, were synthesized using an environmentally friendly hydrothermal method. A paste prepared from the synthesized TiO2 nanoparticles was applied onto a 0.49 cm2 area of fluorine-doped tin oxide (FTO)-coated glass substrate using the doctor blade method. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses indicated that the TiO2 photoanode was in the anatase phase, with a dense and porous morphology composed of nanoparticles. UV-Vis analysis revealed that the photoanode exhibited a maximum transmittance of 80% in the visible region and a direct bandgap energy of 3.28 eV. A DSSC with the architecture FTO/TiO2/Alizarin/(I⁻/I3⁻)/Pt/FTO was fabricated, and its photovoltaic performance was evaluated under varying light intensities. The measurements revealed that the DSSC exhibited variations in JSC (4.48-9.59 mA/cm²), VOC (0.65-0.76 V), FF (0.55-0.65) and PCE (η) (4.01-9.48%), depending on the light intensity. Our findings indicate that natural alizarin dye is a promising candidate sensitizer for the commercialization of DSSCs.