A low-cost, vein graphite / tin oxide nanoparticles based composite counter electrode for efficient dye-sensitized solar cells

Abstract

Performance of dye-sensitized solar cells made with a novel, low-cost graphite/SnO2 composite counter electrode is demonstrated. The best performance is exhibited by the composite made with 3.0 ml colloidal SnO2 solution and 0.05 g of graphite powder, sintered at 450 °C. The solar cell efficiency was increased from 6.02% for pure vein graphite to 7.95% for optimized composite graphite/SnO2 electrode, which is 86% of the efficiency of 9.25% obtained for the Pt electrode. This impressive 32% increase in efficiency can be associated with the highly porous nanostructure of the graphite/SnO2 composite providing more reaction sites for triiodide ion reduction as confirmed by Scanning Electron Microscopy, X-ray diffraction, and Raman Spectroscopy. Excellent electrocatalytic activity exhibited by the new counter electrode is confirmed by Electrochemical Impedance Spectroscopy and Cyclic Voltammetry, further supported by Tafel plot analysis. This result provides a cost-effective method to fabricate efficient counter electrodes for dye-sensitized solar cells.