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
Highlights
Dye-sensitized solar cells (DSC) are an inexpensive alternative to conventional p– n junction solar cells (1–4)
We report the use of Rose Bengal (RB) as the photosensitizer to modify the surface of SnO2 film electrodes to harvest the radiations in the visible spectrum (6)
It can be observed that RB sensitization leads to an improvement in absorbed photon energy ranging from 2 to 3.25 or 3.75 eV respectively for the annealed and asgrown films
Summary
Dye-sensitized solar cells (DSC) are an inexpensive alternative to conventional p– n junction solar cells (1–4). When inorganic dyes are used, the reported maximum conversion efficacy of DSCs is 12% (1). This is much less than the 20–30% efficiency available from. Murali & Remadevi / Indian Journal of Science and Technology 2021;14(25):2097–2105 thin-film solar cells and Si-based solar cells(3). This indicates that further research on photo-anode (working electrode) and related components is still necessary to carry out to improve DSCs to apply them in practice. The important component of the DSC is the working electrode, which is a nanostructured, highly porous metal oxide film, sensitized to the visible light by an adsorbed molecular dye. The photosensitive dyes are responsible for the supply of photoelectrons and the nanostructured semiconductor is transporting the charge carriers(1)
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