Role of the platinum nanoclusters in the iodide/triiodide redox system of dye solar cells

The publication covers materials and cluster science aspects of the platinum counter electrode (CE) in the "monolithic type" dye sensitized solar cell systems (DSSC). Nanocluster based catalytic platinum layers are utilized for the iodide/triiodide reduction in different electrolytes. Various preparative methods have been applied for the preparation of platinum nanoparticles for the CE. The structure, properties, and performance of the different nanoparticles obtained by thermal decomposition of H2PtCl6, triorganohydroborate reduction of a platinum salt, reductive stabilization of Pt(acac)(2) by trialkylaluminium, the "polyol method", and the reduction of the H2PtCl6 by hydrogen are compared. The oxidation states of the platinum surface- and core-atoms were analyzed by X-Ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Near Edge Structure (XANES) respectively. Size and the crystalline structure of the particles were investigated by Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD). The charge transfer resistance of the different catalytic platinum layers resulted from the above mentioned preparative methods, was compared by electrochemical impedance spectroscopy (EIS).