Fabrication And Characterization Of Dye Sensitized Solar Cells (Dsscs) Using Natural Dyes Obtained From Leaves Of Xanthosoma Saggitifolum, Mimosa Pudica, Delonyx Regia And Dacryodes Edulis :- Ujoatuonu, Amaka L

ABSTRACT

Different natural dye extracts were prepared and used as sensitizers in the fabrication of dye sensitized solar cells (DSSCs). In this work, prior to the sprayed nanoporous TiO₂ layer on Fluorine doped oxide (FTO) glass, a dense layer of TiO₂ of  ~60nm in thickness as an electron blocking layer was deposited directly onto the FTO using spray pyrolysis technology. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis showed some porosity in the sprayed films for the mesoporous layer, and dense structure demonstrating good blocking characteristics. This suggests the presence of small voids rather than pinholes in the deposited films. Finally, the absorption spectra of these DSSCs sensitized with these dyes have been investigated by UV-Vis spectrophotometry. Photovoltaic parameters such as short circuit current density Jsc, open circuit voltage Voc, fill factor FF, shunt resistance and overall conversion efficiency  for the fabricated cells were determined under 100 mW/cm².  The results showed efficiencies   of 0.01% (ff = 0.460, J_sc = 0.62mA/cm² ,R_sh = 19.11Ω and V_oc = 0.372V) for Dacryodes eduli;,  = 0.05% (ff = 0.343.J_sc = 0.05mA/cm² , R_sh = 8.22Ω and V_oc = 0.258V) for Mimosa pudica;  (ff = 0.586, J_sc = 0.196mA/cm² , Rsh =9.12Ω  and V_oc = 0.483V) for Delonyx regia and  (ff = 0.348, J_sc = 0.084mA/cm² , R_sh =15.37Ω  and V_oc = 0.385V) for Xanthosoma saggittifolium. Also their optical band

gaps were obtained using Tauc relation, result showed approximate value of eV. We have successfully showed that the DSSC using these four dyes as a dye sensitizer are useful for the preparation of environmental friendly and low-cost DSSCs.