Fabrication of dye-sensitized solar cells from thin films of zinc oxide nanocrystalline particles and organic dye
Photovoltaic solar modules, which are mostly made of silicon based solar cells, are still expensive to the common people of Nepal. The high cost is, mainly, due to the processing difficulties to get pure crystalline silicon. Here, we present results on devising efficient and low-cost dye sensitized solar cells (DSSCs). The solar cells were fabricated from transparent thin film of zinc oxide (ZnO), as a semiconductor, on top of which a thin layer of synthetic organic dye was deposited for efficient light harvesting. In order to achieve the films with optimum conditions for solar cell fabrication, we prepared transparent thin films of ZnO of various thicknesses and characterized by measuring their light transmittance by UV-Visible spectrophotometry. The results clearly show variation in transmittance curves with variation in film’s thickness.
Also for finding appropriate sensitizer for ZnO nanoparticles, we extensively investigated the light absorbance of synthetic organic dyes. Among the dye species investigated, Green-VS, Patent-Blue, and Black-ADLI show strong absorbance over the wide range in the visible spectrum, demonstrating prospect of utilizing for DSSCs. Then prototype solar cells from ZnO film with various thicknesses were constructed and were sensitized with the mixture of Green-VS and Black-ADLI dyes (with 1:1 ratio). The measured photo-voltage and photo-current from solar cell, from our modest ZnO film, after irradiation with 200 W commercial bulb (calibrated with Pyranometer) as a light source, were about 20 mV and 1 μA, respectively. Also, with increment of the power of radiation both the measured photo-current and photo-voltage increase. Performance of the cell in real sun condition has also been made. With the solar radiation power of 930 W, the observed photo-voltage and photo-current were ca. 230 mV and 50 μA, respectively.
BIBECHANA 11(1) (2014) 53-59