Fabrication of metal-organic framework structure doped tio2 based dye sensitized solar cells (DSSCS) and determination of their photovoltaic parameters

In this thesis, the performance of various photoanode materials used to improve the efficiency of dye-sensitized solar cells (DSSCs) is investigated in terms of optical absorption properties, electron lifetime and recombination resistance. In this study, the efficiencies of DSSCs based on the synthesized MOF structures (MOF-5, ZIF-67, MIL-101, nano-MIL-101), graphene oxide (GO) doped and GO/MOF co-doped photoanodes were investigated. In the first part of the research, photoanode surface modification in DSSC1 set by using MOF solutions, photoanode component DSSC2 set prepared by using powder MOF structure doped paste was studied. The effect of doping on photovoltaic parameters was investigated under three different light sources. In the continuation of the study, GO, MOF doped and GO/MOF co-doped films were coated on glass and FTO substrates by the Doctor Blade method to determine the physical and photovoltaic characteristics. The crystal structures, molecular properties, surface morphology and elemental analysis and optical features of the prepared films were investigated by XRD, FT-IR, FE-SEM-EDX and UV-Vis measurements, respectively. By using XRD, it was recorded that the films have a polycrystalline TiO2 (anatase and rutile phase) structure. The optical band gap of the derived films narrowed with doping. Optical absorbance, dye loading capacity of doped photoanodes were evaluated as critical factors affecting on the efficiency of DSSCs. Current-voltage (I-V) measurements were performed under the solar simulator (100 mW/cm2) to determine the photovoltaic parameters and efficiency (ɳ) of the DSSCs with doped photoanodes, with defined physical properties. Electrical impedance spectroscopy (EIS) measurements were carried to investigate the recombination dynamics of the cells. It has been recorded that electron lifetime and recombination resistance, effective participation of electrons into the current transportation are the factors, affecting the efficiency. The research results showed that the efficiencies of GO, MOF doped and GO/MOF co-doped photoanode based DSSC are higher than the efficiency of the undoped DSSC. Among different doped photoanodes, the nano-MIL-101 doped one has provided the highest efficiency, while other doped photoanodes were found to have some limitations. The reason for this can be explained as the fact that the MOF molecules promotes both the possibility of electronic transition and the surface area for dye loading with their porous structure. These results provide important information on material selection and design to increase the performance of DSSC technology.