▎ 摘　　要

Optically transparent counter electrodes outperforming the conventional Pt counter electrodes in dye sensitized solar cells (DSSCs) are seldom reported. In this work, a highly transparent (similar to 88% at 550 nm) and catalytic (charge transfer resistance <1 Omega cm(2)) counter electrode based on a novel Pt polyelectrolyte functionalized graphene composite is demonstrated. Graphene sheets (HEG) are synthesized by hydrogen induced simultaneous exfoliation-reduction of graphite oxide. HEG is functionalized by a cationic polyelectrolyte, poly-diallyl-diammonium chloride (PDDA) which causes minimum damage to graphene and assists in uniform tethering of nanoparticles. Pt nanoparticles are decorated on PDDA-HEG by a simple microwave assisted polyol reduction method. Electrochemical impedance measurements and cylic voltammetry measurements show that the higher catalytic activity of Pt/PDDA-HEG is due to the presence of positive charges and nanostructured Pt. As a consequence, the DSSCs fabricated with Pt/PDDA-HEG counter electrode exhibits an enhanced power conversion efficiency of similar to 5.7% as compared to 4.5% for reference cells with Pt counter electrode. (C) 2012 Elsevier Ltd. All rights reserved.