Fe3O4–carbon black nanocomposite as a highly efficient counter electrode material for dye-sensitized solar cell

Iron oxide–carbon black (Fe3O4–CB) nanocomposite has been proposed as a cost–effective alternative counter electrode (CE) to the conventional Pt in a dye sensitized solar cell (DSSC). The Fe3O4–CB nanocomposite at three different weight ratio (1:1, 1:2 and 2:1) was prepared by a simple solution mixing process and the material was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopy techniques. The performance of the three Fe3O4–CB nanocomposite CEs was assessed with respect to Fe3O4, CB and Pt in a conventional DSSC consisting of N719 dye sensitized TiO2 (P25) photoanode in contact with an electrolyte containing the I−/I3− redox couple. The electrocatalytic activities of the various CEs towards triiodide (I3−) reduction were analyzed by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization analysis. The photocurrent voltage (J–V) characteristics of the DSSCs assembled with various counter electrodes were assessed at a light intensity of 80 mW cm−2. The DSSC assembled with Fe3O4–CB nanocomposite (1:2) CE showed the best photovoltaic performance in terms of a high power conversion efficiency of 6.1% which is superior to that of sputtered Pt (4.1%). The simple preparation, excellent electrocatalytic activity and low-cost nature allow the Fe3O4–CB nanocomposite to be a promising alternative CE to Pt for use in DSSCs.