Fuel-influenced nanorod-to-nanosphere transformation of vanadium-doped ZnO and its performance in dye-sensitized solar cells

Vanadium-doped zinc oxide (V-doped ZnO) nanostructures synthesized using a solution combustion method are exploited as efficacious photoanode materials for N719 dye-sensitized solar cells. The effect of fuels, including polyethylene glycol (PEG-400) and urea, on the morphological and structural properties of vanadium-doped ZnO nanostructures is elucidated in detail. Using PEG-400 as fuel, the doping of vanadium on ZnO nanostructures effectively transformed the nanoparticles into nanorods, whilst the conversion of nanorods into nanoparticles was conducted with the aid of urea fuel. Optical measurements and X-ray diffraction showed no major shift in the wavelength and peak position, respectively, indicating that vanadium is present on the surface of ZnO rather than in the interstitial position. The high surface area of the material revealed that mesopores present in the photoanode materials, which was 129 m 2 g −1 for the sample synthesized using PEG-400 as fuel, offered higher power conversion efficiency (PCE) due to higher pore volume (0.317 cm 3 g −1 ) and dye adsorbing capability as revealed through BET analysis. The PCE of the PEG-400 fuel used sample showed 5.4% efficiency, whereas the urea fuel sample exhibited 4.9% efficiency. IPCE measurements displayed a wavelength maximum at 510 nm with 22.14% of the IPCE value, indicating that the PEG-400 fuel sample (ZnO-V5%) shows the highest efficiency among other DSSC devices. PEG-400 fuel-induced morphology transformation of a ZnO-V5% semiconductor nanostructured material achieved 5.4% efficiency using commercial N719 as a dye sensitizer.