Synthesis, Properties and Performance of Platinum and Platinum/Carbon Nanotube Films as Cathode Materials for Dye-Sensitized Solar Cells

Comparative investigation of platinum (Pt) and platinum/carbon nanotube (Pt/CNT) films used as cathodes in dye-sensitized solar cells (DSCs) has been carried out. Nanostructured Pt films on a conductive glass substrate were prepared by polyol reduction (PR-Pt), electrodeposition (ED-Pt) and thermal decomposition (TD-Pt). DSCs with TD-Pt counter electrode show the best performance with stable photovoltaic characteristics. The energy conversion efficiency (η) of DSCs used synthesized cathode materials decreased in the order TD-Pt > ED-Pt > PR-Pt. Energy conversion efficiency (η) of 5% and more can be obtained for DSCs with ED-Pt and TD-Pt counter electrodes, while the DSCs based on PR-Pt attained efficiency less than 3%. Analysis of cyclic voltammograms and electrochemical impedance spectra reveal the high catalytic activity of TD-Pt and ED-Pt films to triiodide/iodide (I3−/I−) redox reaction. The reduction of I3− ions on the TD-Pt electrode is characterized with the lowest overpotential and lowest charge transfer resistance, compared with ED-Pt and PR-Pt electrodes. The synthesized Pt/CNT film showed comparatively high catalytic performance for I3−/I− redox reaction. The efficiency of DSC with the composite Pt/CNT counter electrode increased 70%, compared to DSC built on pure Pt electrode, prepared by the same polyol reduction method.