TiO2/polyisothianaphthene—A novel hybrid nanocomposite as highly efficient photoanode in dye sensitized solar cell

• The work describes a new strategy to improve the efficiency of DSSC.
• A new nanocomposite TiO2-polyisothianaphthene is evaluated as photoanode.
• The nanocomposite is characterized by TGA, XRD, SEM, TEM and AFM techniques.
• The presence of PITN significantly enhances the dye adsorption enabling efficient light harvesting.
• Electrochemical impedance data indicate substantially reduced back electron transfer.

A new strategy for improving the adsorption of acidic dyes like N719 on the TiO2 photoanode layer is presented. For the first time, we demonstrate that polyisothianaphthene (PITN) modified TiO2 photoanode plays a dual role in dye sensitized solar cells (DSSCs) i.e. to greatly enhance the dye adsorption and to aid in effective suppression of charge recombination. The hybrid nanocomposites were prepared by simple blending of TiO2 with small quantities of PITN (<0.9 wt%) in the presence of PEG20000, acetylacetone, Triton X-100 and characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, atomic force microscopy and transmission electron microscopy techniques. PITN is a highly electron rich system and it is proposed that its addition to TiO2 improves the basicity of TiO2 which in turn leads to an enhanced dye adsorption and this is confirmed by UV–vis spectroscopy measurements. Also PITN has the higher conduction band edge than TiO2 resulting in reduced back electron transfer. The PITN content in the nanocomposite is taken as the variable to optimize the performance of the DSSC. Electrochemical impedance and photovoltaic data indicate that the optimum performance can be achieved with just 0.5 wt% of PITN in the TiO2 layer. The DSSC with TiO2/(PITN)0.5 photoanode shows a significantly improved (∼54%) photovoltaic performance (η = 6.88%) than the pristine TiO2 cells (η = 4.48%).

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