Solution-Processed Graphene Composite Films as Freestanding Platinum-Free Counter Electrodes for Bendable Dye Sensitized Solar Cells

Sulfuric acid-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/less-defective reduced graphene oxide (ST-PEDOT:PSS/L-rGO) composite films were prepared via a solution-processing route and used as the counter electrodes of dye sensitized solar cells (DSSCs). These platinum (Pt)- and transparent conductive oxide (TCO)-free counter electrodes exhibited strong catalytic activity and excellent flexibility, showing no obvious change in their sheet resistances after 10000 cycles of bending. The integrated quasi-solid-state DSSC device with a TiO2 nanotube/Ti mesh photoanode and a ST-PEDOT:PSS/L-rGO counter electrode exhibited an energy conversion efficiency () of about 1.8%. It also displayed an excellent mechanical stability and durability after bending for 1000 cycles at a small curvature radius of 10 mm. The high flexibility, low cost and efficient catalytic activity make ST-PEDOT:PSS/L-rGO composite films promising counter electrodes for flexible DSSCs.