Photo-characterization of Organic Dye-Sensitized Tin Oxide Films

Abstract

Objectives: To develop organic dye sensitized film electrodes from highly porous tin oxide (SnO 2 ) thin films prepared at room temperature using the SILAR technique. Methods/Analysis: SnO 2 films were fabricated by the successive ionic layer adsorption and reaction (SILAR) technique at room temperature and its sensitization was done using the organic dye Rose Bengal (RB). The effect of sensitization on the as-grown and annealed film electrodes was investigated. Findings: Crystalline films with cauliflower-like morphology exhibit a large inherent adsorptive surface area and exhibit steady transmittance of 60-80% in the visible region. As-grown SnO 2 films possess higher porosity and lower refractive index than that of the annealed films. SnO 2 films have a resistivity in the range of 10 -2 -10 -3 Ωcm. The dye adsorbed SnO 2 film electrodes have much higher absorbance and cover a broad visible region compared to the bare SnO 2 film electrodes. RB sensitization leads to an accelerated improvement in absorbed photon energy through the visible region of the spectrum extending from 2 to 3.75 eV. Novelty: Contrary to the sophisticated methods of preparation in the reported literature, highly porous crystalline SnO 2 thin films were prepared at room temperature, using glacial acetic acid and hydrogen peroxide by a cost-effective simple wet chemical method. Work demonstrates that SnO 2 films sensitized with RB act as an excellent dye-sensitized electrode, which can absorb almost half the visible spectrum (400-600 nm) of solar radiations. We believe that this is the unique report of surface modification of wet chemically prepared SnO 2 electrodes by the photo-sensitizer RB.