Synthesis of In2.77S4 nanoflakes/graphene composites and their application as counter electrode in dye-sensitized solar cells

Highlights: • Counter electrode materials of dye-sensitized solar cells are studied and selected. • A novel In_2.77S₄ nanoflakes/graphene composite is prepared for the first time. • Different counter electrode materials are made a full comparison. • The prepared composite possesses commendable electrochemical properties. There are lots of semiconductor-graphene nanocomposites as promising electrode materials using in photovoltaic devices, because of their high conductivity and excellent eletrocatalytic activities. In this work, we have explored a facile one-step hydrothermal method to synthesize a novel composite which is assembled by In_2.77S₄ nanoflakes and graphene. This unique composite belongs to mesoporous materials and inherits many advantages from Indium sulfide and graphene. According to the results of cyclic voltammetry, electrochemical impedance spectra and Tafel polarization tests, the as-prepared In_2.77S₄ nanoflakes/graphene composites possess the commendable electro catalytic activity, charge transfer capability and electrochemical stability. In addition, when the obtained composites are used as counter electrode (CE) materials in dye-sensitized solar cells (DSSCs), the corresponding energy conversion efficiency is as high as 7.32%. This research provides a viable candidate for CEs of DSSCs and will contribute to developing other CE materials.