Effects of annealing temperature optimization on the efficiency of ZnO nanoparticles photoanode based dye sensitized solar cells

In the present work, the effect of annealing temperatures (300–500 °C) optimization on the performance of ZnO nanoparticles based dye-sensitized solar cells (DSSCs) was investigated in detail. We have synthesized ZnO nanoparticles by simple and cost-effective aqueous chemical method. Crystallography, phase determination and morphology were observed by X-ray diffraction (XRD), micro raman and field emission scanning electron microscopy (FESEM). The present article describes the photocurrent density–voltage (J–V) characteristic of the DSSCs using ZnO nanoparticles photoelectrodes annealed at various temperatures. At low annealing temperature (300 °C) minimum photocurrent density of 5.70 mA/cm2 was obtained, which gradually increased up to a value 8.82 mA/cm2 at 400 °C attributed to a better charge collection. The electrical properties were found to be dependent on the annealing temperature of photoelectrode for DSSC. Furthermore, by increasing the annealing temperature up to 500 °C a reduction in photocurrent density (8.61 mA/cm2) was found. The IPCE and impedance analyses reveal adequate improvements. The impedance study shows a decrease in the charge transport resistance and an increment in the chemical capacitance of the solar cell. On the basis of our results, we could conclude that ZnO photoanode annealed at 400 °C temperature are better suited for fabricating DSSC with improved efficiency (3.35 %), photo-current density (8.82 mA/cm2), and fill factor (57.78 %).