title: Nickel incorporated carbon nanotube/nanofiber composites as counter electrodes for dye-sensitized solar cells.
abstract: A nickel incorporated carbon nanotube/nanofiber composite (Ni-CNT-CNF) was used as a low cost alternative to Pt as counter electrode (CE) for dye-sensitized solar cells (DSCs). Measurements based on energy dispersive X-rays spectroscopy (EDX) showed that the majority of the composite CE was carbon at 88.49 wt%, while the amount of Ni nanoparticles was about 11.51 wt%. Measurements based on electrochemical impedance spectroscopy (EIS) showed that the charge transfer resistance (R(ct)) of the Ni-CNT-CNF composite electrode was 0.71 Ω cm(2), much lower than that of the Pt electrode (1.81 Ω cm(2)). Such a low value of R(ct) indicated that the Ni-CNT-CNF composite carried a higher catalytic activity than the traditional Pt CE. By mixing with CNTs and Ni nanoparticles, series resistance (R(s)) of the Ni-CNT-CNF electrode was measured as 5.96 Ω cm(2), which was close to the R(s) of 5.77 Ω cm(2) of the Pt electrode, despite the significant difference in their thicknesses: ∼22 μm for Ni-CNT-CNF composite, while ∼40 nm for Pt film. This indicated that use of a thick layer (tens of microns) of Ni-CNT-CNF counter electrode does not add a significant amount of resistance to the total series resistance (R(s-tot)) in DSCs. The DSCs based on the Ni-CNT-CNF composite CEs yielded an efficiency of 7.96% with a short circuit current density (J(sc)) of 15.83 mA cm(-2), open circuit voltage (V(oc)) of 0.80 V, and fill factor (FF) of 0.63, which was comparable to the device based on Pt, that exhibited an efficiency of 8.32% with J(sc) of 15.01 mA cm(-2), V(oc) of 0.83, and FF of 0.67.
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Prakash
authors.initials: P
authors.lastname: Joshi
authors.forename: Zhengping
authors.initials: Z
authors.lastname: Zhou
authors.forename: Prashant
authors.initials: P
authors.lastname: Poudel
authors.forename: Amit
authors.initials: A
authors.lastname: Thapa
authors.forename: Xiang-Fa
authors.initials: XF
authors.lastname: Wu
authors.forename: Qiquan
authors.initials: Q
authors.lastname: Qiao
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D058266:Dielectric Spectroscopy; D004566:Electrodes; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D009532:Nickel / Q000737:chemistry*; D012993:Solar Energy
chemical_list: D004396:Coloring Agents; D037742:Nanotubes, Carbon; D009532:Nickel