Photo-characterization of Organic Dye-Sensitized Tin Oxide Films

Abstract

Objectives: To develop organic dye sensitized film electrodes from highly porous tin oxide (SnO2) thin films prepared at room temperature using the SILAR technique. Methods/Analysis: SnO2 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 SnO2 films possess higher porosity and lower refractive index than that of the annealed films. SnO2 films have a resistivity in the range of 10-2-10-3 ΩcmΩcm. The dye adsorbed SnO2 film electrodes have much higher absorbance and cover a broad visible region compared to the bare SnO2 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 SnO2 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 SnO2 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 SnO2 electrodes by the photo-sensitizer RB. Keywords Photo­characterization, rose bengal, sensitization, thin films, tin oxide electrodes