Investigation of nanocomposite electrodes for dye-sensitized solar cells
The fabrication of efficient a and low-cost electrodes is a highlighted topic for the development of advanced dye-sensitized solar cells (DSSCs). In the first part of this thesis, water-dispersible polyaniline/graphene oxide (PANI-GO)-based CEs was developed. This CE was straightforwardly prepared by deposition of the nanocomposite dispersion onto FTO substrate. The aqueous dispersions of PANI-GO nanocomposites were prepared by two different routes: simple physical mixture of PANI and GO, and in-situ polymerization of aniline in GO aqueous dispersion. DSSC assembled with emeraldine salt polyaniline (PANI-ES)-based CE generated current density (Jsc) of 12.34 mA/cm² and power conversion efficiency (PCE) of 5.18%, which is comparable to the device prepared with Pt-based CE (PCE of 5.24%). The addition of GO is found to increase the Jsc to 13.04 mA/cm² and the fill factor to 68% in CE containing 0.45 wt% of GO (in respect to aniline during synthesis) where the PCE is boosted to 6.21%, which is about 20% higher than Pt-based CE. The investigation of both morphological features and spectroscopic properties showed that PANI-GO nanocomposites prepared by in-situ route have dissimilar protonation and oxidation states when compared with those prepared by physical mixture route. These results give insights into the role of GO in tuning PANI chemical and physical properties in addition to provide a simpler and more efficient methodology for the synthesis of new CEs for DSSCs. In the second part of the Thesis, a simple and scalable methodology was carried out to prepare photoanode by the addition of Ti3C2Tx MXenes into the TiO2 nanoparticulate paste. The incorporation of only 0.075 wt% of the MXene 2D compound (with respect to the TiO2) resulted in an increase of Jsc from 10.25 mA/cm² (bare photoanode) to 12.66 mA/cm² and boosted the PCE from 5.22% to 6.17% (an improvement of about 18% of DSSC PCE). These results indicate that MXene nanostructures work as an efficient pathway for photogenerated electrons from the dye through the mesoporous structured photoanode.