Pt-free, low-cost and efficient counter electrode with carbon wrapped VO2(M) nanofiber for dye-sensitized solar cells

Subashini Gnanasekar; Pratap Kollu; Soon Kwan Jeong; Andrews Nirmala Grace

doi:10.1038/s41598-019-41693-1

Pt-free, low-cost and efficient counter electrode with carbon wrapped VO₂(M) nanofiber for dye-sensitized solar cells

Sci Rep. 2019 Mar 26;9(1):5177. doi: 10.1038/s41598-019-41693-1.

Authors

Subashini Gnanasekar¹, Pratap Kollu^{2

3}, Soon Kwan Jeong⁴, Andrews Nirmala Grace⁵

Affiliations

¹ Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India.
² CASEST, School of Physics, University of Hyderabad, Gachibowli, Hyderabad, 500046, India.
³ Newton Alumnus Researcher- the Royal Society London, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK.
⁴ Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon, 305-343, South Korea. jeongsk@kier.re.kr.
⁵ Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India. anirmalagladys@gmail.com.

Abstract

The present study reports the use of one-dimensional carbon wrapped VO₂(M) nanofiber (VO₂(M)/C) as a cost-effective counter electrode for dye-sensitized solar cells (DSSCs); where M denotes monoclinic crystal system. Uniform short length nanofiber was synthesised by a sol-gel based simple and versatile electrospinning and post carbonization technique. The investigation of nanostructure and morphological analysis were performed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscope (TEM) with EDAX. The electrochemical response was comprehensively characterized by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization. The electrochemical analysis of the VO₂(M)/C nanofiber counter electrode exhibits significant electrocatalytic activity towards the reduction of triiodide and low charge transfer resistance at the electrode-electrolyte interface. The DSSCs fabricated with carbon-wrapped VO₂(M) nanofiber CE showed high power conversion efficiency of 6.53% under standard test condition of simulated 1SUN illumination at AM1.5 G, which was comparable to the 7.39% observed for conventional thermally decomposed Pt CE based DSSC under same test conditions. This result encourages the next step of modification and use of low-cost VO₂(M) as an alternate counter electrode for DSSCs to achieve a substantial efficiency for future energy demand.