Dye-Sensitized Solar Cells Using ZnO as A Semiconducting Layer

Abstract

Dye-sensitized solar cell (DSSC) was developed by Grätzel in 1991 which was named "Grätzel Cell". DSSC is considered the third generation of photovoltaic devices for the conversion of visible light into electric energy. These new types of solar cells are based on the photosensitization produced by the dyes on wide band-gap semiconductors such as TiO2. This sensitization is produced by the dye absorption of part of the visible light spectrum. One advantage of DSSCs is the low cost of the solar energy conversion into electricity because of inexpensive materials and the relative ease of the fabrication processes. Recent studies have shown that metal oxides such as TiO2, have been successfully used as photo-anode when a dye is absorbed in the interior of the porous layer of the semiconductor. In this work, DSSCs were prepared using Zinc oxide (ZnO) as a semiconducting layer with eight natural and eight chemical dyes. Thin films of nanocrystalline ZnO was spread on transparent conducting FTO coated glass using doctor blade method. The absorption spectra of all dyes were performed. The I-V characteristic curves of the fabricated cells were measured and studied at different light intensity. All photovoltaic parameters of the cells were defined. The results revealed that the extract of safflower and Eosin Y corresponds to the highest efficiency. Optimization of the fabricated cells were conducted concerning the sintering temperature and the thickness of the ZnO layer.