Carbon-nanofiber counter electrodes for quasi-solid state dye-sensitized solar cells

Carbon-nanofibers (CNFs) with antler and herringbone structures are studied as a tri-iodide (I3−) reduction electrocatalyst in combination with the liquid electrolyte or an alternative stable quasi-solid state electrolyte. The catalytic properties of the counter electrode (CE) are characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The doctor bladed low temperature CNFs-CE has faster I3− reduction rate and low charge transfer resistance (RCT) of ∼0.5 Ω cm2 than platinum (Pt) (∼2.3 Ω cm2) due to the nanofiber stacking morphology. Its herringbone and antler structures with graphitic layers lead to defect rich edge planes and larger diameter of CNFs facilitate the electron transfer kinetics. The cells with CNF counter electrodes are showing promising energy conversion efficiency greater than 7.0% for the glass based devices and 5.0% for the flexible cells filled with the quasi-solid state electrolyte, which is similar to Pt performance. Application of CNFs-CE in flexible and quasi-solid state electrolyte increases the possibility of roll to roll process, low cost and stable dye-sensitized solar cells (DSCs).

Figure optionsDownload as PowerPoint slideHighlights
► Carbon-nanofibers (CNFs) with antler and herringbone structures were studied as a tri-iodide reduction catalyst in DSCs.
► Terminated graphitic layers and defected edge planes in the surface of CNFs facilitate efficient catalytic property.
► Low temperature optimization of CNFs electrodes pave for flexible counter electrode DSCs.
► Quasi-solid state electrolyte with flexible CNFs counter electrode shows comparable photo conversion efficiency with the Platinum counter electrode.
► Successful application of low temperature counter electrode and Quasi-solid state electrolyte increases the possibility of large scale application by decreasing the cost and stability issues in DSCs.