Influence of Al2O3 nanoparticles embedded-TiO2 nanofibers based photoanodes on photovoltaic performance of a dye sensitized solar cell

Abstract

Different weight percentages (1, 3 and 5 wt%) of the Al₂O₃ nanoparticles (NPs) embedded TiO₂ nanofibers (NFs) were prepared by the electrospinning technique. A mixture of titanium isopropoxide, acetic acid, Al₂O₃ NPs and PVP in ethanol were used. X-ray diffraction studies confirmed the formation of anatase and mixed phase (anatase/rutile) for the pure TiO₂ NFs and Al₂O₃ NPs embedded TiO₂ NFs, respectively. SEM and TEM studies showed the morphologies of Al₂O₃ NPs embedded TiO₂ NFs and their average diameter was found to be ∼83 nm. The chemical composition of TiO₂ NFs was confirmed by EDX analysis. The effects of Al₂O₃ NPs embedded TiO₂ nanofibers on the adsorption of dye and the charge transfer resistances were studied using UV-vis spectroscopy and electrochemical AC-impedance studies. Dye sensitized solar cells were fabricated using different weight percentages of Al₂O₃ NPs embedded TiO₂ NFs as photoanodes and Pt as counter electrode and 0.5 M 1-butyl-3-methylimidazolium iodide, 0.5 M LiI, 0.05 M I₂, 0.5 M 4-tertbutylpyridine in acetonitrile as the electrolyte. Among the three photoanodes tried, the cell fabricated using 3 wt% of Al₂O₃ NPs embedded TiO₂ NFs as photoanode had an improved photocurrent efficiency (PCE) of 36.2% compared to other similar systems in the literature. This might be due to an improvement in dye adsorption by the addition of a basic oxide (Al₂O₃) and also the formation of a rutile phase (15.7%), thereby retarding the charge recombinations inside the DSSC and in turn increasing the V_oc and the J_sc of the cell.