Carbon black base composite counter electrode materials for dyesensitized solar cells

Platinum (Pt) has been commonly used as a counter electrode material in dye-sensitized solar cells because it has high catalytic activity and electric conductivity as well as chemical inertness with iodide electrolyte. However, Pt is too expensive to be used commercially. Therefore, in the present study, a carbon black counter electrode with Pt and a carbon nanotube (CNT) was investigated. The power conversion efficiency of the carbon black electrode with Pt was lower than that of a pure Pt electrode which was 6.47%. By adding 3 wt% Pt to the carbon black counter electrode, the power conversion efficiency was maximized at 5.88%. By adding 1 wt% CNT to that, the power conversion efficiency (η) increased to 6.21%. The reason for this improvement was examined by comparing the impedance properties using electrochemical impedance spectroscopy (EIS).