Natural pigment sensitized solar cells based on ZnO-TiO2-Fe2O3 nanocomposite in quasi-solid state electrolyte system

Abstract

Nanocomposites of Zn-Ti-Fe oxide using zinc as a host with different ratios of precursor salts were prepared by co-precipitation method to use as semiconductors for dye sensitized solar cell (DSSC). The as-synthesized nanocomposites were characterized using XRD, SEM-EDX, TEM and UV-Vis spectrophotometer. DSSCs based on the new semiconductors and di-tetrabutylammoniumcis-bis(isothiocyanato)bis(2,2’-bipyridyl-4,4’-dicarboxylato)-ruthenium(II) (N719) dye has been constructed and characterized. Stability towards dissolution of deposited films of semiconductors in the acidic dye and conversion efficiency was obtained in the order of: ZnO(100%) <ZnO(70%)-TiO₂(30%) <ZnO(70%)-Fe₂O₃(30%) <ZnO(60%)-TiO₂(20%)-Fe₂O₃(20%). Natural pigments were also extracted using ethanol and water as solvents from flowers of Guizotia scabra and Salvia leucantha plants. From UV-Vis spectra analysis all ethanol extracts of natural sensitizers absorb in the visible region. DSSCs were constructed using the natural pigments as sensitizers. The following best device parameter was achieved by the ethanol extract of Salvia leucantha and ZnO-TiO₂-Fe₂O₃ nanocomposite semiconductor. When the potential is scanned: a V_oc of 280 mV, J_sc of 0.01761 mAcm^-2 at light intensity of 100 mWcm^-2 were obtained; the maximum IPCE % was 1.7 and 25.7 for the N719 dye and Salvia luecantha, respectively.

KEY WORDS: Nanocomposite, Co-precipitation method, Semiconductor, Dye sensitized solar cell, Natural pigments, Conversion efficiency

Bull. Chem. Soc. Ethiop. 2017, 31(2), 263-279.   

DOI: http://dx.doi.org/10.4314/bcse.v31i2.8