Thermal treatment optimization of ZnO nanoparticles-photoelectrodes for high photovoltaic performance of dye-sensitized solar cells

Annealing temperature has pronounced effect on DSSC performance. ZnO nanoparticles photoelectrodes were prepared on FTO glass and annealed at different temperatures in the range 200–500 °C. The thermal properties of the paste were studied using DTA/TG technique which revealed that no changes are expected at temperatures higher than 350 °C. Electrical properties of the DSSCs using ZnO nanoparticles photoelectrodes annealed at different temperatures were studied using I–V characteristic and electrochemical impedance spectroscopy (EIS). The surface area and dye loading increased as the annealing temperature increased up to 350 °C. The electrical properties are found to be dependent on the photoelectrode annealing temperature. Annealing temperatures higher than 400 °C resulted in a decrease in current density. The highest value of current density Isc (15.6 mA/cm2), open circuit potential Voc (0.55 V) and efficiency (3.01%) is achieved at annealing temperature of 400 °C.