Preparation And Properties Of The Fabric Counter Electrode For Dye‐sensitized Solar Cells

Dye-sensitized Solar Cells(DSSCs) have attracted more and more attention due to their simple fabrication procedure, low cost, high conversion efficiency, environment-friendliness and so on. DSSCs mainly composes of working electrode, electrolyte, and a counter electrode(CE). The CE is mainly used for collecting the electrons flowing from the external circuit, accelerating I-/I3- exchange rate between the electrolyte solution and the electrodes. The traditional CEs are mostly based on FTO or ITO coated glass substrate, and then plating a layer of platinum on it as catalytic material. Because of the FTO glass substrate is of heavy quality, easily broken and the preparation methods are complex, and yet the platinum is precious metal, its price is very expensive and its reserveon the earth is relatively low, which would limit the development of the DSSCs. This thesis focused on the development of Pt-free flexible counter electrode. The daily-used cotton fabrics were used as the substrates, which were metalized by the chemically plating method. Then polypyrrole(PPy) was deposited as Pt-free catalyst layer using in situ chemical polymerization or electrochemical polymerization method; nickel sulfide(Ni S) also was synthesized on the metalized fabric by using the electrochemical deposition method. The obtained fabrics were investigated as CEs in DSSCs by using scanning electron microscopy,ultraviolet visible light, infrared spectrum analysis, XRD, cyclic voltammograms, AC impedance and I-Vcurve. The main conclusions are as follows:(1)we have prepared a novel fabric CE for DSSCs using an everyday cotton fabric coated with Ni as substrate and PPy as catalytic material. PPy was prepared in situ chemical polymerization. The fabric CE shows sufficient catalytic activity towards the reduction of I3-. The DSSCs fabricated using the fabric CE exhibits power conversion efficiency of 3.30% under AM 1.5 illumination. Our results demonstrate that the PPy/Ni-coated fabric is a promising candidate as Pt-free CE for DSSC fabrication. Furthermore, the flexibility, low weight and low price of the fabric CE would benefit for lowering the production and transportation cost of DSSCs.(2) In this work, PPy films has been synthesized on Ni-coated fabric substrate by an electrochemical polymerization method and has been employed as the CE in DSSCs. PPy is of porous structure and shows sufficient catalytic activity towards the reduction of I3-. The DSSCs fabricated using the fabric CE exhibits power conversion efficiency of 3.91% under AM 1.5 illumination.(3) The transition metal sulfides are of special performance and structure. Ni S films has been synthesized on Ni-coated fabric substrate by electrochemical deposition method and uses as CE in DSSCs. The DSSCs fabricated using the fabric CE exhibits power conversion efficiency of 1.7% under AM 1.5 illumination. Our work is still going on.