Four types of graphene nanosheets (GNs) with different graphene layer number were employed to fabricate counter electrode for dyesensitized solar cells (DSCs), with emphasis on understanding the influence of graphene layer number on the properties of the counter electrode and the device. The results show that with the graphene layer number of the GNs increases from 3 to 8, both efficiency and fill factor of the GNs based DSCs firstly climb and reach a peak at 6 of graphene layer number, and then decline with further increasing. Electrochemical impedance spectroscopy (EIS) reveals that when the graphene layer number of the GNs increases from 3 to 6, the decreased sheet resistance of the electrode and the strengthened capability of electrolyte diffusion in the electrode result in the improvement of the photovoltaic performances of the DSCs. However, when the graphene layer number further ascends to 8, the weakened capabilities of both catalytic activity of the electrode for the reduction and electrolyte diffusion in the electrode lead to the poor photovoltaic performances of the device.
Expanded Phase Distribution in Low Average Layer‐Number 2D Perovskite Films: Toward Efficient Semitransparent Solar Cells
