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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 Rpt/Rct and Rpt 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.