Dye-sensitized solar cell based on electrospun ultra-fine titanium dioxide fibers and fabrication method thereof

Abstract

A dye-sensitized solar cell comprising a semiconductor electrode comprising electrospun ultra-fine titanium dioxide fibers and fabrication method thereof are disclosed. The dye-sensitized solar cell comprises a semiconductor electrode comprising an electrospun ultra-fine fibrous titanium dioxide layer, a counter electrode and electrolyte interposed therebetween. A non-liquid electrolyte such as polymer gel electrolyte or the like having low fluidity, as well as the liquid electrolyte, can be easily infiltrated thereinto. In addition, electrons can be effectively transferred since titanium dioxide crystals are one-dimensionally arranged.

1 . A dye-sensitized solar cell comprising: 
 a semiconductor electrode comprising an electrospun ultra-fine fibrous titanium dioxide layer;    a counter electrode; and    an electrolyte interposed between the semiconductor electrode and the counter electrode.    
     
     
         2 . The cell according to  claim 1 , wherein the semiconductor electrode comprises a glass substrate, a ITO or FTO transparent conductive layer and the electrospun ultra-fine fibrous titanium dioxide layer onto which dye molecules are adsorbed.  
     
     
         3 . The cell according to  claim 1 , wherein the electrospun ultra-fine fibrous titanium dioxide layer has a thickness of 5-20 μm.  
     
     
         4 . The cell according to  claim 1 , wherein the counter comprises a glass substrate, an ITO or FTO transparent conductive layer and a platinum layer.  
     
     
         5 . The cell according to  claim 1 , wherein the electrolyte is a liquid electrolyte containing iodine.  
     
     
         6 . The cell according to  claim 5 , wherein the liquid electrolyte is an electrolyte in which 0.1M lithium iodide, 0.05M iodine, 0.6M 1,2-dimethyl-3-propyl-imidazolium iodide and 0.5M tert-butyl pyridine are dissolved in acetonitrile.  
     
     
         7 . The cell according to  claim 1 , wherein the electrolyte is a polymer gel electrolyte containing one or more polymers selected from the group consisting of poly(vinylidenefluoride)-co-poly(hexafluoropropylene), poly(acrylonitrile), poly-(ethyleneoxide) and poly(alkylacrylate).  
     
     
         8 . The cell according to  claim 7 , wherein the polymer gel electrolyte contains one or more polymers in an amount of 5-20% by weight of a solvent mixture of propylene carbonate and ethylene carbonate.  
     
     
         9 . A method for fabricating a dye-sensitized solar cell, comprising the steps of: 
 adding titanium isopropoxide into a polymer solution, followed by adding acetic acid as a catalyst thereinto, and then stirring the resulting mixture at room temperature, to obtain a solution for electrospinning;    electrospinning the solution to form a film made of ultra-fine titanium dioxide fibers onto an ITO or FTO-coated transparent conductive glass substrate;    pre-treating the substrate having the film of the ultra-fine titanium dioxide fibers formed thereon with acetone or dimethyl formamide;    thermally treating the pre-treated substrate to form a layer of the ultra-fine fibrous titanium dioxide onto the substrate;    impregnating the thermally treated substrate in a solution of dye molecules in ethyl alcohol to obtain a semiconductor electrode on which the dye molecules are adsorbed into the electrospun ultra-fine titanium dioxide fibers;    coating a platinum layer onto an ITO or FTO-coated transparent conductive glass substrate, to obtain a counter electrode;    performing a heating/pressing process on the semiconductor electrode and the counter electrode with a spacer having a thickness of 20 μm therebetween, so as to attach the semiconductor electrode and the counter electrode to each other; and    injecting electrolyte into empty space between the semiconductor electrode and the counter electrode.    
     
     
         10 . The method according to  claim 9 , wherein the polymer solution is a solution in which a polymer selected from the group consisting of polyvinylacetate, polyvinylpyrrolidone, polyvinylalcohol and polyethyleneoxide is dissolved in dimethyl formamide, acetone, tetrahydrofuran, toluene or a mixture thereof in an amount of 5-20 wt %.  
     
     
         11 . The method according to  claim 9 , wherein the electrospinning is performed so as to make the ultra-fine titanium dioxide fibers have a thickness of 50-1000 nm.  
     
     
         12 . The method according to  claim 9 , wherein the layer of the ultra-fine fibrous titanium dioxide is formed at a thickness of 5-20 μm after the thermal treatment.  
     
     
         13 . The method according to  claim 9 , wherein the pre-treatment is performed by a method i) the substrate is treated with vapor of acetone or dimethyl formamide for 1-3 hours in a closed container, ii) the substrate is immersed in acetone or dimethyl formamide solvent for 1 hour or iii) that methods i) and ii) are combined.  
     
     
         14 . The method according to  claim 9 , wherein the electrolyte is a liquid electrolyte or polymer gel electrolyte.