Synthesis and Electrochemical Properties of Platinum-based Films Used as Cathode Materials in Dye - Sensitized Solar Cells

摘要

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). The morphology, crystal structure and electrochemical behavior of the synthesized films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). DSCs using the synthesized Pt-based cathodes were characterized by Ⅰ-Ⅴ curve measurement. 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%. The highest catalytic activity for triiodide/iodide (I_3~-/I~-) redox reaction was observed for the ED-Pt film, that exhibits highest peak current densities and lowest charge transfer resistance. Meanwhile the reduction of I_3~- ions may occur on the TD-Pt film with the lowest overpotential and less irreversible, compared with ED-Pt and PR-Pt electrode. The synthesized Pt/CNT film showed comparatively high catalytic performance for I_3~-/I~- redox reaction; however its adhesion to the glass substrate is poor for the DSCs fabrication.