An efficient dye-sensitized solar cell with a promising material of Bi4Ti3O12 nanofibers/graphene

In this work, the composites of Bi4Ti3O12/graphere (BTO/Gr) are used as counter electrode (CE) through facile method based on sol-gel and electrospinning techniques to improve the efficiency of dye-sensitized solar cells (DSSCs). The structure and morphology of the composites with different ratios are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The optical bandgap of the composites decreases as Gr content increases. The electrochemical performance of BTO/Gr CE is characterized by cyclic voltammetry curves, electrochemical impedance spectroscopy, Tafel polarization curves and photocurrent density-voltage character curves. Compared with pure BTO CE, BTO/Gr CE has a higher electrocatalytic activity and a lower charge transfer resistance in the electrolyte/electrode interface. The power conversion efficiency of DSSCs with BTO/Gr CE (contained 2.5 wt.% Gr), has reached 9.70% under a simulated solar illumilnation of 100 mW/cm2, which is much larger than that of BTO CE. The power conversion efficiency amounts to 79.6% of the Pt CE and 86.2% of the graphene CE.