Three-dimensional networks of ITO/CdS coaxial nanofibers for photovoltaic applications

Abstract

When serving as the electrode of semiconductor sensitized solar cells (SSSCs), conductive transparent nanofibers can enlarge the surface area and accelerate the electron transport, and can thus be expected to enhance the final power conversion efficiency of the device. Here we report the fabrication of three dimensional networks of indium tin oxide (ITO) nanofibers on a conductive glass substrate with a low sheet resistance of 15 Ω sq⁻¹ by using an electrospinning technique. A post-treatment involving polyethylene glycol impregnation and calcination is developed to realize the excellent electrical contact of ITO nanofibers with the substrate, and maintain the fibrous morphology of the nanofibers also. Light-harvesting CdS nanocrystals are electrodeposited onto ITO nanofibers, and then the obtained ITO/CdS coaxial nanofibers are constructed into SSSCs. We find that the performance of this novel SSSC is remarkably improved compared with CdS nanocrystals directly deposited on a flat conductive substrate, and an unprecedented photocurrent density of 9.27 mA cm⁻² is achieved under the illumination of one sun (AM1.5, 100 mW cm⁻²). Our work indicates that the special designation of three-dimensional coaxial nanofibers can pave a new avenue to efficient photovoltaic devices.