title: Efficient low-temperature transparent electrocatalytic layers based on graphene oxide nanosheets for dye-sensitized solar cells.
abstract: Electrocatalytic materials with a porous structure have been fabricated on glass substrates, via high-temperature fabrication, for application as alternatives to platinum in dye-sensitized solar cells (DSCs). Efficient, nonporous, nanometer-thick electrocatalytic layers based on graphene oxide (GO) nanosheets were prepared on plastic substrates using electrochemical control at low temperatures of ≤100 °C. Single-layer, oxygen-rich GO nanosheets prepared on indium tin oxide (ITO) substrates were electrochemically deoxygenated in acidic medium within a narrow scan range in order to obtain marginally reduced GO at minimum expense of the oxygen groups. The resulting electrochemically reduced GO (E-RGO) had a high density of residual alcohol groups with high electrocatalytic activity toward the positively charged cobalt-complex redox mediators used in DSCs. The ultrathin, alcohol-rich E-RGO layer on ITO-coated poly(ethylene terephthalate) was successfully applied as a lightweight, low-temperature counter electrode with an extremely high optical transmittance of ∼97.7% at 550 nm. A cobalt(II/III)-mediated DSC employing the highly transparent, alcohol-rich E-RGO electrode exhibited a photovoltaic power conversion efficiency of 5.07%. This is superior to that obtained with conventionally reduced GO using hydrazine (3.94%) and even similar to that obtained with platinum (5.10%). This is the first report of a highly transparent planar electrocatalytic layer based on carbonaceous materials fabricated on ITO plastics for application in DSCs.
authors.affiliation: †Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, Korea.
authors.forename: Seon Hee
authors.initials: SH
authors.lastname: Seo
authors.affiliation: †Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, Korea.|‡Department of Advanced Materials Engineering, College of Engineering, Chosun University, Gwangju 501-759, Korea.
authors.forename: Eun Ji
authors.initials: EJ
authors.lastname: Jeong
authors.affiliation: †Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, Korea.
authors.forename: Joong Tark
authors.initials: JT
authors.lastname: Han
authors.affiliation: ‡Department of Advanced Materials Engineering, College of Engineering, Chosun University, Gwangju 501-759, Korea.
authors.forename: Hyon Chol
authors.initials: HC
authors.lastname: Kang
authors.affiliation: †Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, Korea.
authors.forename: Seung I
authors.initials: SI
authors.lastname: Cha
authors.affiliation: †Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, Korea.
authors.forename: Dong Yoon
authors.initials: DY
authors.lastname: Lee
authors.affiliation: †Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, Korea.
authors.forename: Geon-Woong
authors.initials: GW
authors.lastname: Lee
keywords: dye-sensitized solar cell; electrocatalyst; graphene oxide; low-temperature fabrication; transparent counter electrode