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Investigation of Free Natural Dye Ru-Complex for Application as a Dye Sensitizer of Solar Cells
Khushboo Sharma, Shyam Sunder Sharma and Nandu B. Chaure

The fabrication and measurement of natural dyes-based Dye sensitized solar cells (DSSCs) have been reported using low-cost solution-processable techniques. Titanium dioxide (TiO₂) nanoparticles have been synthesized by a solvothermal process using Titanium isopropoxide (TIP) as a precursor. Two different natural dyes, Henna (Lawsonia inermis) and Indian blackberry (IBB; Syzgium cumini), and their cocktail were used as natural sensitizers with anatase-based nanostructure of TiO₂ thin film on conducting glass substrate. Scanning electron microscopy (SEM) analysis reveals the uniform distribution of the crystalline anatase phase of TiO₂ upon annealing at 550 ˚C. UV-Vis-NIR spectroscopy and SEM results divulge the absorption capability of dyes and the effect of dye loading on TiO₂ photoanodes, respectively. Electrochemical impedance spectroscopy (EIS) studies were carried to study the charge transport processes and its effect on the performance of DSSCs. These measurements show the least values of R_pt/R_ct and R_pt for D3 dye sensitized DSSC as compare to the other two, which certainly has the longer electron transport lifetime resulting from the synergetic effect of co-sensitization of D1 and D2. Thus, the cocktail dye showed promising photovoltaic performance due to an increase in absorption and better dye loading in the device.

Keywords: DSSCs, Natural sensitizers, TiO₂ nanoparticles, optical spectroscopy, electrochemical impedance spectroscopy.