Alternative low‐cost photon sensitizer for dye‐sensitized solar cells using less explored natural fabric dyes

An attempt is made to develop dye-sensitized solar cell (DSSCs) with TiO2 hollow spheres for photoanode and natural dyes such as Tagetes, Acacia catechu, Punica granatum, Rubia tinctorum, Terminalia chebula and more importantly Biancaea sappan, the cotton dyeing extracts. Hydrothermally treated carbon spheres are used as the template for making the hollow spheres. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) positions of these dyes are analyzed using cyclic voltammogram, and spectroscopic techniques and then the fabrication of the solar cells with TiO2 hollow spheres were done accordingly. It is found that Punica granatum sensitized cell delivers a higher Power Conversion Efficiency (PCE) of 0.26% with the VOC of 0.53 V as expected. It is also found that though the dye from Acacia catechu exhibits low PCE, it possesses the highest fill factor of 85% and open-circuit voltage (VOC) of 0.58 V. Also, these are found to have lower charge transfer resistance (Rct) and better temperature stability compared to the others.