Effect of Flower Extracts on the Optoelectronic Properties of Cd and Sn Doped TiO2 Nanopowder

Studies on the optoelectronic properties of cadmium and tin doped TiO2 nanopowder (P25, commercial powder, 25 nm in diameter and spherical shape) with and without extracts of various flowers viz. Calendula Orange (CO), Calendula Yellow (CY), Dahlia Yellow (DY), Sweet Poppy (SP), and their Mixed Extract (ME) are presented here. Cd and tin were doped with TiO2 using hydrothermal method. Samples were analyzed by using UV-Vis, FTIR, FESEM, XRD, and Raman spectroscopy for elemental, structural and morphological observations. Thick films of these powder were printed using conventional screen printing method on fluorine doped tin oxide (FTO) substrate with organic binders and dried at 45 degrees C. The photoconduction properties are investigated as a function of wavelength from ultra-violet (UV) to infra-red (IR) region at constant illumination intensity. Irradiation from UV to IR region results in gradual reduction in photocurrent. Doping with tin resulted in improved photoconductance than cadmium, which is related to the changes in band gap. Addition of colour pigments (flower extracts) further improved the photoconductance over larger spectrum. Highest photoconductance is observed in case of DY flower extracts. Anthocyanins are known for their antioxidative properties and hence can contribute in the photoconduction via reduction of surface adsorbed oxygen in visible and IR regions. This investigation suggests the potential use of flower extract for dye sensitized solar cell (DSSC) based on composite metal oxides.