Synthesis of nanosized TiO2 using different molecular weight polyethylene glycol (PEG) as capping agent and their performance as photoanode in dye-sensitized solar cells

In this study, synthesis of nanosized TiO2 in which hydrolysis and polycondensation of precursor, Ti(OC4H9)4, has been performed in presence of different molecular weight polyethylene glycol (PEG) polymer as a capping agent is reported. Three different capped materials (TN-P400, TN-P4000, and TN-P8000) were synthesized along with un-capped TiO2 (TiO2 synthesized without using PEG, TN) for the sake of comparison. The structure and morphology of the synthesized TiO2 were characterized by XRD, FTIR, SEM, and DLS analyses. The X-ray diffraction spectrums show the presence of anatase phase TiO2. The as-synthesized PEG-capped TiO2 were used as photoanode material for dye-sensitized solar cells (DSSC) after coating with sensitizer dye N719, and photoelectric conversion efficiency (PCE) of 2.52%, under the illumination of 100 mW cm−2, has been achieved with TN-P8000, which was much improved compared with DSSC performance with un-capped TiO2 (PCE = 1.02%). EIS analyses revealed that TN-P8000 photoanode–based cell exhibited facile charge transfer, enhanced electron lifetime, and greater charge collection efficiency that contributed better photovoltaic performance. The results demonstrated that using PEG as a capping agent is a potential approach for improving the efficiency of DSSC and current conversion efficiency was increased as the molecular weight of PEG was increased.