Studies on pristine and tin-doped zinc oxide nanorod-based photoanodes with graphene oxide coated counter electrodes for photovoltaic applications

Pristine and Tin-doped zinc oxide nanorods were synthesized using the hydrothermal method, employing various Sn concentrations (0, 0.5, 1, and 1.5 wt%). The influence of Sn incorporation along with graphene oxide-coated counter electrodes on the optical, structural, and photovoltaic characteristics of ZnO nanorods was investigated. X-ray diffraction patterns indicated that the nanorods predominantly grow along the (002) plane, exhibiting a hexagonal wurtzite crystal structure. The field-emission scanning electron microscopy investigation revealed that the nanorods aligned perpendicularly on the fluorine-doped tin oxide substrates. Observations from the FE-SEM images indicated that an increase in the concentration of Sn led to nanorods with greater length and diameter. UV–Vis spectroscopy results indicated that the absorbance increased and the band gap values decreased with increasing Sn concentration. Subsequently, these nanorod films were employed as working electrodes in dye-sensitized solar cells. The enhanced performance is achieved at an optimal Sn doping concentration of 1.5 wt%, where improved crystallinity, increased nanorod dimensions, enhanced light absorption, and reduced charge recombination collectively contribute to a higher photocurrent density of 4.62% and overall power conversion efficiency of nearly 76% higher than its counterparts.