7% efficiency. The fill factors were strongly dependent on the loading of the MS-275 in vitro carbon black powder and found to be around 68%. Interfacial charge transfer and mass transport were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. This technique of synthesizing nanostructures for high surface area along with optimum carbon black loading afforded an effective and simple way to replace the Pt-based counter electrode for DSSC. Overall, the
TiO2/carbon black-based DSSC showed excellent cell efficiency that rivals cells with a Pt-based CE and exhibited remarkable electrocatalytic activity. This work provides an intriguing way of structurally designing a low-cost, Pt-free, high-performance CE material for DSSCs. Acknowledgements This work was financially supported by the MEST and KETEP JSH-23 manufacturer PRN1371 (MKE) grants (2012 K001288,
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