Dye-sensitized solar cells using nanomaterial/PEDOT–PSS composite counter electrodes: Effect of the electronic and structural properties of nanomaterials

Nanomaterials with different electronic and structural properties are employed to construct nanomaterial/PEDOT–PSS composite counter electrodes (CEs) for dye-sensitized solar cells (DSCs). It is found that the photovoltaic performance of the DSC is strongly affected by the addition of nanomaterials. The increase in the fill factor with the incorporation of nanomaterial with PEDOT–PSS is due to the reduced charge transfer resistance (RCT) at electrolyte/CE interface and porous diffusion impedance (Zdiff) of redox couple in porous CE, as evidenced by electrochemical impedance spectrum and Tafel polarization measurements. RCT and Zdiff are determined by the structural property of the nanomaterial, and are low in condition of nanomaterials with large specific surface area. The variations in open circuit voltage (VOC) and short circuit current density (JSC) depend on the electronic property of the nanomaterial, i.e., higher VOC and JSC are achieved in the condition of n-type nanomaterial. This work provides a new perspective for the design of nanomaterial/PEDOT–PSS composite CE.