Herein, dye-sensitized solar cells (DSSCs) have been sensitized with natural red dye (extracted from red spinach) and yellow dye (extracted from turmeric) and five different combinations of red and yellow dyes (at different volume ratios) to determine the optimum combination of red and yellow dyes for the maximum cell efficiency. In addition, the effect of post-TiCl 4 treatment in improving cell efficiency has been studied. From UV-vis absorption spectrum, higher absorbance and cumulative absorption properties over the entire visible region show that the combination of red and yellow dyes absorbs light better than the individual red or yellow dyes. DSSCs sensitized with red and yellow dyes have a photoconversion efficiency of 0.416% and 0.921%, respectively. DSSCs sensitized with the combination of red and yellow dyes showed higher cell parameters than the DSSCs sensitized with the individual yellow or red dye. The photoelectrical parameters of DSSCs cosensitized with the optimum combination of dyes (40% red þ 60% yellow) were as follows: short-circuit current (I sc ) ¼ 5.343 mA, open-circuit voltage (V oc ) ¼ 0.493 V, fill factor (FF) ¼ 0.481, and overall photoconversion efficiency ¼ 1.267%. However, after the treatment of FTO (fluorine doped tin oxide) / TiO 2 with TiCl 4 , a significant amount of improvement in the I sc , V oc , and FF was observed. DSSCs fabricated with TiCl 4 -treated FTO/ TiO 2 and sensitized with the optimum combination of red and yellow dyes showed the following cell parameters: I sc ¼ 5.829 mA, V oc ¼ 0.498 V, and F$F ¼ 0.541. Hence, the efficiency obtained was 1.572%, which is almost 1.24 times higher than that of the DSSCs fabricated without TiCl 4 treatment. Finally, the possible effect of water content in the combination of dyes has been observed with a fixed amount of red dye in the combination.

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