Nanostructured platinum films deposited by polyol reduction of a platinum precursor and their application as counter electrode of dye-sensitized solar cells

Abstract

Platinum precursors such as H2PtCl6 can be reduced to platinum (Pt) by polyols at temperatures below 200 °. This method was developed to deposit nanostructured Pt films on various substrates through a solution process. High-quality Pt films with good adhesion to substrate were obtained on substrates like conducting polymer films, indium tin oxide (ITO), and polyimide by dropping a solution of H2PtCl6 in ethylene glycol (EG). Two types of Pt structures, that is, dense and porous Pt structures, were observed for the Pt deposited by EG reduction. The dense Pt structure is the result of Pt growth from the substrate immediately after the reduction. This Pt growth from the substrate can produce a continuous nanostructured Pt film with metallic luster and good adhesion to the substrate. The porous Pt structure is the result of the nucleation of Pt in solution. The Pt nucleation in solution gives rise to Pt particle formation. These Pt particles aggregate and finally precipitate as porous Pt on the dense Pt. The quality of the Pt film was affected by the experimental conditions, such as substrate, concentration, and pH value of H2PtCl6 solution in EG, and temperature during the reduction. Pt deposited by this method could be used as the counter electrode of high-performance dyesensitized solar cells (DSCs). The DSCs exhibited a light-to-electricity conversion efficiency of 8.1%, quite close to that of the DSCs with Pt counter electrode prepared by the conventional pyrolysis. In addition, this low-temperature method enabled the Pt deposition on flexible substrate, which could be used as the flexible counter electrode for DSCs. ©2010 American Chemical Society.