Study of Light Harvesting Properties of Different Classes of Metal-Free Organic Dyes in TiO2Based Dye-Sensitized Solar Cells

In dye-sensitized solar cells, the photosensitization of TiO2thin film semiconductor was accomplished by using different classes of metal-free (fluorone, triarymethane, azo and thiazine based) organic dyes as photosensitizer. The broad electronic absorption spectra of these dyes have been obtained in the visible region due to the presence of chromophoric groups in these dyes. The contribution of these dyes as light harvesting species is seen from the photocurrent action spectrum of the cell. Here, we report the sensitization activity of these dyes in terms of current-potential curve, open-circuit potential, fill factor, IPCE, and overall solar energy conversion efficiency which have been evaluated under 100 mW/cm2light intensity. The results suggest that dyes based on fluorone and azo groups are promising candidates for high performance, dye-sensitized solar cells because of better anchoring groups (–COOH, –OH, and –SO3-) present in these dyes. Better anchorage of dyes to the surface of TiO2semiconductor helps in charge transfer phenomenon.