A composite (Pt/CS) catalyst produced by homogeneously depositing Pt nanoparticles on a carbon spheres (CS) surface is synthesized by a simple method. A large-scale, highly effective, and flexible counter electrode is further fabricated with this composite catalyst on an ITO-PEN substrate for dye-sensitized solar cells (DSCs). As inferred from cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization curves results, this flexible Pt/CS counter electrode exhibits higher catalytic activity toward Co3+/2+ redox couple regeneration than Pt and CS counter electrodes. The supercatalytic behavior of Pt/CS can essentially be attributed to the low apparent activation energy (Ea) of the redox reaction between Co3+ and Co2+. Using the Pt/CS counter electrode, a high power conversion efficiency (PCE) of 9.02% is achieved with a small DSCs (16 mm(2)), and the largescale device (360 mm(2)) generates a PCE of 6.26% under 100 mW cm(-2) of simulated sunlight illumination. (C) 2016 Elsevier Inc. All rights reserved.