Preparation of Fluoride-Doped Tin Oxide Films on Soda–Lime Glass Substrates by Atomized Spray Pyrolysis Technique and Their Subsequent Use in Dye-Sensitized Solar Cells

Abstract

The development of a novel method for the fabrication of low-cost, transparent, conducting glass (F–-doped SnO2 layer on soda–lime glass, FTO) by a specially developed atomized spray pyrolysis technique using cheap soda–lime glass in place of commercially used expensive glass at a comparatively lower temperature of 450 °C is presented. The use of these FTO plates in dye-sensitized solar cells (DSCs) will also be described. The optimum temperature of 450 °C for the FTO layer on soda–lime glass is obtained by carrying out atomized spray pyrolysis of the precursor solution onto the soda–lime glass substrate at several different temperatures and by characterizing the materials obtained at each temperature by X-ray diffraction analysis. The FTO layers formed at 450 °C have also been characterized by scanning electron microscopy (SEM) for morphology, grain size, and film thickness and by UV–visible transmittance spectroscopy for the optical transmission in the visible range. The electrical properties of the FTO film prepared at 450 °C are estimated by the van der Pour method and Hall measurements. The FTO films have a uniform texture with smaller grains (≥50 nm) embedded in cages formed by larger particles (≤450 nm). The presence of large grains is important for transparent conducting glass applications. The average film thickness, estimated from the SEM images, is 560 nm. The material possesses superior electrical properties such as electronic conductivity, electron mobility, and carrier density of 1.71 × 103 S cm–1, 10.89 cm2 V–1 s–1, and 9.797 × 1020 cm–3, respectively, at room temperature. This low-cost technique, which uses cheap soda–lime glass for the fabrication of FTO, is better suited for commercialization. The DSCs fabricated using these FTO plates, with the cell configuration of FTO on soda–lime glass/interconnected TiO2 nanocrystalline layer/N719 dye/I–, I3– electrolyte/mirror-type chromium-coated and lightly platinized FTO electrode, give a maximum light-to-electricity efficiency of 10.4% under AM 1.5 (100 mW cm–2) illumination for a cell active area of 0.25 cm2.