Efficient counter electrode for copper (I)(II)-mediated dye-sensitized solar cells based on polyvinyl alcohol capped platinum nanoclusters

•Counter electrodes are prepared by one-step dipping of FTO in PVA-Pt nanoclusters suspension.•Catalytic activity of platinum-based counter electrode toward copper(II/I)-mediator can be enable by controlling size of platinum nanoparticles.•PVA-Pt-based DSSC exhibits power conversion efficiency of 8.26 %, which is 10 % higher than those employs PEDOT electrode with efficiency of 7.95 %.