Carbon Fibers Coated with Ternary Ni–Co–Se Alloy Particles as a Low-Cost Counter Electrode for Flexible Dye Sensitized Solar Cells

Compared to flat devices based on rigid substrates, cable-shaped dye-sensitized solar cells hold advantages of smaller size, light weight, facile fabrication, flexibility, and low cost, thus a promising direction for applications such as wearable electronic devices. However, most reported fiber-shaped dye-sensitized solar cells use Pt wires as counter electrodes, which are high in cost. Herein, a flexible Pt-free counter electrode is fabricated via depositing ternary nickel cobalt selenide (Ni–Co–Se) particles on the surface of carbon fibers. Scanning electron microscopy and X-ray diffraction are used to characterize the counter electrode and alloy material. Results from bare and modified carbon fiber counter electrodes reveal that Ni–Co–Se alloy particles greatly enhance electrocatalytic activity, leading to significant improvement in power conversion efficiency, which is comparable with devices using carbon fiber coated with Pt as the counter electrode. The performance increase may be attributed to the improved catalytic property of CoSe2 due to its higher composition ratio and larger crystallite size. Bending and multiple irradiation cycling tests are also performed to show the superior flexibility and durability of the novel device.