Synthesis and characterization of ZnO@WO₃ core/shell nanoparticles as counter electrode for dye-sensitized solar cell

Dye-sensitized solar cells are an impending new technology for addressing energy and environmental issues. Counter electrodes based on ZnO@WO₃ core/shell nanoparticles are made by drop casting onto ITO glass to address the high cost of the preferred platinum counter electrode. These counter electrodes are employed in dye-sensitized solar cell applications. This work investigates the ZnO@WO₃ core/shell nanoparticles synthesized by using the sol-gel method. In order to better understand the morphological, optical, and structural features of the produced nanoparticles, a variety of characterization methods were used in this work. The prepared sample was subjected to calcination/annealing at 100 °C, 300 °C and 500 °C; and the UV–Vis spectroscopy results revealed that the sample calcinated at 100 °C demonstrates better absorption as compared to others. Two samples of ZnO@WO₃ core/shell nanoparticles i.e., as-synthesized (sample A) and the one annealed at 100 °C (sample B), were investigated as counter electrode in methyl orange-based dye-sensitized solar cell. Moreover, the results were compared to the conventional platinum counter electrode. When sample B of binary nanoparticles-based counter electrode was compared to sample A, it was seen that sample B exhibits much higher electrocatalytic activity toward I₃⁻ reduction. A power conversion efficiency of 5.73% is accomplished by the dye-sensitized solar cell utilizing sample B counter electrode, which is significantly greater than the 4.55% and 4.51% achieved by the sample A and platinum counter electrodes, respectively. The findings suggest that using the drop casting approach to manufacture durable counter electrodes based on ZnO@WO₃ core/shell nanoparticles is a potential option for constructing dye-sensitized solar cells.