Selected Organic Dyes Sensitized Metal Doped Ti02 Based Photoactive Nanostructured Materials Synthesis, Characterization and Application in Dye Sensitized Solar Cells

Abstract

In this research work three schemes have been successfully completed. First of all cadmiumlbarium doped Ti02 nanoparticles and their respective heterostructured nanomaterials (Ti02/ZnO) were synthesized through simple sol-gel and reflux methods respectively. Optical, morphological and structural analysis of as synthesized material were done by using UV-Visible spectroscopy, X-Ray diffraction analysis (XRD) , Scanning electron microscopy (SEM), Energy dispersive X-Ray analysis (EDX), and Fourier Transform infrared spectroscopy (FTIR). The band gap values were calculated from the optical absorption spectra of nanomaterials. The band gap of Ti02 NPs (3.10 e V) was effectively tuned up to 2.82 eV by doping it with different concentrations of cadmium and barium followed by coupling with ZnO nanoparticles. The crystalline nature and phase purity of the materials were confirmed through XRD. Morphological analysis and elemental composition studies were performed with the help of SEM and EDX. Functional groups were detected through FTIR analysis. The nanostructured materials were used in combination with P3HT (as a hole conducting polymer) to fabricate photoactive blend for dye sensitized solar cells. The photovoltaic performances of fabricated device were investigated by using current voltage (I-V) measurements. The results showed that metal doped Ti02 and their respective nanostructures (Ti02/ZnO) showed better conversion efficiencies than undoped Ti02. The maximum conversion efficiency (rD was observed for Pyrocatechol violet sensitized Cd-Ti02/ZnO heterostructured nanomaterial which is 1.84%. The corresponding short circuit current density was found to be 13.11 mAlcm2 . In second scheme, a photoactive nanohybrid material consisting of pyrocatechol violet, carminic acid and dithizone dyes functionalized silver and neodymium-doped Ti02/ZnO nanostructured materials is reported for solid-state dye sensitized solar cells. First of all synthesis metals (silver, neodymium) doped (Ti02) Titanium oxide nanoparticles and their nanocomposites (Ti02/ZnO, M-Ti02/ZnO) was done by using the sol gel and reflux techniques, respectively. The band gap of Ti02 was considerably tuned to 2.47 eV after incorporating metals (Ag and Nd) doping as well as synthesizing respective nanocomposites. Under simulated solar irradiation, the DSSC based on pyrocatechol violet sensitized neodymium doped Ti02/ZnO nanohybrid materials exhibited the best PCE (power conversion efficiency) of 2.38 % and significantly improved Jsc (short circuit current density) of 15.68 mAlcm2 as compared to carminic acid and dithizone in photovoltaic measurements. The improved power conversion efficiency of this device could be due to the proper particle size, increased dye adsorption, increased surface area and thus improved short circuit current density (Jsc). In Third scheme, a sol-gel and hydrothermal techniques were used for the synthesis of metal (holmium, barium & cadmium) doped Ti02/CdS nanocomposites. The energy gap of Ti02 was efficiently reduced to 2.16 eV by doping and coupling it with CdS. In dye sensitized solar cells, the nanomaterials were employed as photoanode and carminic acid, pyrocatechol violet and dithizone dyes were utilized as photo-sensitizers. The highest efficiency attained was 2.68 % for Cd-Ti02/CdS nanocomposites photosensitized with Pyrocatechol violet dye as compared to reference devices (0.82%). For the same devices other characteristic properties, such as open circuit voltage (Voc) and short circuit current density (Jsc), were found to be 16.97 rnA cm2 , 0.41 V respectively.