Large-scale high-efficiency dye-sensitized solar cells based on a Pt/carbon spheres composite catalyst as a flexible counter electrode

•A composite of Pt nanoparticles deposited on carbon spheres (Pt/CSs) was synthesized.•A large-scale flexible counter electrode was prepared using Pt/CSs for DSCs.•An efficiency of 9.02% was achieved for the DSCs using Pt/CS counter electrodes.

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 mm2), and the largescale device (360 mm2) generates a PCE of 6.26% under 100 mW cm−2 of simulated sunlight illumination.

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