Gel Electrolytes For Dye Sensitized Solar Cells

Abstract

Replacing liquid electrolytes with solid or quasi-solid electrolytes facilitates the production of photovoltaic cells using continuous manufacturing processes, such as roll-to-roll or web processes, thus creating inexpensive, lightweight photovoltaic cells using flexible plastic substrates.

What is claimed is: 
     
         1 . An electrolyte composition adapted for use in a solar cell, the electrolyte composition comprising, in solution:
 a gelling compound comprising a metal ion or a compound of the formula MiXj; and   an ionic liquid comprising an imidazolium iodide.   
     
     
         2 . The electrolyte composition of  claim 1 , further comprising an organic compound capable of complexing with the metal ion at a plurality of sites 
     
     
         3 . The electrolyte composition of  claim 1 , wherein the metal ion comprises a lithium ion. 
     
     
         4 . The electrolyte composition of  claim 2 , wherein the organic compound is selected from the group consisting of poly(4-vinyl pyridine), poly(2-vinyl pyridine), polyethylene oxide, polyurethanes, and polyamides. 
     
     
         5 . The electrolyte composition of  claim 1 , wherein the gelling compound is a lithium salt. 
     
     
         6 . The electrolyte composition of  claim 5 , wherein the lithium salt has the formula LiX, wherein X is an iodide, bromide, chloride, perchlorate, thiocyanate, trifluoromethyl sulfonate, or hexafluorophosphate. 
     
     
         7 . The electrolyte composition of  claim 3 , further comprising iodine at a concentration of at least about 0.05 M. 
     
     
         8 . The electrolyte solution of  claim 1  wherein i and j are ≧1, X is an anion, and M is selected from the group consisting of Li, Cu, Ba, Zn, Ni, lanthanides, Co, Ca, Al, and Mg. 
     
     
         9 . The electrolyte solution of  claim 8 , wherein the anion is selected from the group consisting of chloride, perchlorate, thiocyanate, trifluoromethyl sulfonate, and hexafluorophosphate. 
     
     
         10 . A method of gelling an electrolyte solution for use in a dye-sensitized solar cell, the method comprising the steps of:
 providing an electrolyte solution;   adding to the electrolyte solution a material capable of complexing at a plurality of sites; and   adding to the electrolyte solution a metal ion that complexes at the sites thereby forming a gel.   
     
     
         11 . The method of  claim 10 , wherein the steps are performed at a temperature below 50° C. 
     
     
         12 . The method of  claim 10 , wherein the steps are performed at standard pressure. 
     
     
         13 . The method of  claim 10 , wherein the electrolyte solution has a gelling rate controlled by changing a concentration of counter ions in the electrolyte solution. 
     
     
         14 . The method of  claim 10 , wherein the metal ion is a lithium ion. 
     
     
         15 . An electrolyte composition adapted for use in a solar cell, the electrolyte comprising:
 at least about 90 wt % of an ionic liquid comprising an imidazolium iodide;   an amount of water ranging from 0 to 10 wt %;   iodine at a concentration of at least 0.05 M; and   methyl-benzimidazole.   
     
     
         16 . The electrolyte composition of  claim 15 , wherein the ionic liquid is selected from the group consisting of butylmethylimidazolium iodide, propylmethylimidazolium iodide, hexylmethylimidazolium iodide and combinations thereof. 
     
     
         17 . The electrolyte composition of  claim 15 , further comprising LiCl. 
     
     
         18 . The electrolyte composition of  claim 17 , wherein the amount of LiCl is between about 1 wt % LiCl and 6 wt % LiCl. 
     
     
         19 . The electrolyte composition of  claim 17 , wherein the amount of LiCl is at least about 1 wt % LiCl. 
     
     
         20 . The electrolyte composition of  claim 17 , wherein the amount of LiCl is less than about 6 wt % LiCl. 
     
     
         21 . The electrolyte composition of  claim 15 , further comprising LiI. 
     
     
         22 . The electrolyte composition of  claim 21 , wherein the amount of LiI is between about 1 wt % LiI and 6 wt % LiI. 
     
     
         23 . The electrolyte composition of  claim 21 , wherein the amount of Li is at least about 1 wt % LiI. 
     
     
         24 . The electrolyte composition of  claim 21 , wherein the amount of LiI is less than about 6 wt % LiI.