Graphene-based layers deposited onto flexible substrates: Used in dye-sensitized solar cells as counter electrodes

Highlights: • Graphene-based layers have been successfully deposited on the flexible PET/ITO substrate. • DSSCs with graphene-based CEs demonstrate a power conversion efficiency of up to 3.95%. • It was found that the graphene is an excellent candidate for replacing Pt in DSSCs. - Abstract: In this paper, new cost-effective platinum-free and flexible counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) were reported. The ITO/PET CEs were produced using graphene films synthesized by CVD method and graphene flakes with addition PEDOT: PSS or PEDOT: PSS/PVP. The influence of mechanical stress arising from the bending of a flexible substrate on morphology, resistance of CEs as well as electrical properties of DSSCs was analyzed. The testing of these electrodes in DSSCs have demonstrated a power conversion efficiency of up to 3.95% to compare with the power conversion efficiency of 4.39% for DSSC with a standard Pt-based CE. After 100 bending cycles the electrodes demonstrated power conversion efficiency in range the 2.37–3.23% to compare with the power conversion efficiency of 2.08% for DSSC with a standard Pt-based CE. HRTEM investigation confirms the crystallographic structure of graphene. The obtained results demonstrate the possibility of replacing expensive platinum in DSCC by using graphene-based counter electrode.