A transparent and stable polypyrrole counter electrode for dye-sensitized solar cell

► A transparent PPy film with electrochemical catalytic activity has been prepared. ► A bifacial DSSC based on this PPy film has been reported for the first time. ► The DSSC based on this PPy counter electrode shows excellent long-term stability. ► The application of this PPy film in DSSC would bring down the production cost.