Air stable organic-inorganic nanoparticles hybrid solar cells

Abstract

A solar cell includes a low work function cathode, an active layer of an organic-inorganic nanoparticle composite, a ZnO nanoparticle layer situated between and physically contacting the cathode and active layers; and a transparent high work function anode that is a bilayer electrode. The inclusion of the ZnO nanoparticle layer results in a solar cell displaying a conversion efficiency increase and reduces the device degradation rate. Embodiments of the invention are directed to novel ZnO nanoparticles that are advantageous for use as the ZnO nanoparticle layers of the novel solar cells and a method to prepare the ZnO nanoparticles.

We claim: 
     
         1 . A method of preparing ZnO nanoparticles comprising:
 providing a solution of a Zinc salt of a carboxylic acid in a polar aprotic solvent;   providing a solution of a tetraalkylammonium hydroxide in an alcohol;   combining said zinc salt solution with said tetraalkylammonium hydroxide solution, wherein ZnO nanoparticles form; and   isolating said ZnO nanoparticles as ZnO nanospheres and/or as coupled ZnO nanospheres wherein said coupled ZnO nanospheres comprise dimers, trimers, tetramers or pentamers.   
     
     
         2 . The method of  claim 1 , wherein said zinc salt is zinc acetate. 
     
     
         3 . The method of  claim 1 , wherein said tetraalkylammonium hydroxide is tetramethylammonium hydroxide. 
     
     
         4 . The method of  claim 1 , wherein said polar aprotic solvent is dimethylsulfoxide. 
     
     
         5 . The method of  claim 1 , wherein said alcohol is ethanol. 
     
     
         6 . The method of  claim 1 , wherein said combination occurs at room temperature. 
     
     
         7 . The method of  claim 1 , wherein said isolating comprises washing with an alcohol-hydrocarbon mixture. 
     
     
         8 . The method of  claim 7 , wherein said alcohol-hydrocarbon mixture comprises ethanol and heptane. 
     
     
         9 . The method of  claim 7 , wherein said alcohol-hydrocarbon mixture comprises about 1 part alcohol to 4 parts hydrocarbon by volume. 
     
     
         10 . ZnO nanoparticles comprising a plurality of coupled ZnO nanospheres. 
     
     
         11 . The ZnO nanoparticles of  claim 10 , wherein said coupled ZnO nanospheres comprise dimers, trimers, tetramers or pentamers. 
     
     
         12 . The ZnO nanoparticles of  claim 11 , wherein a majority of said coupled ZnO nanospheres are dimers. 
     
     
         13 . The ZnO nanoparticles of  claim 10 , wherein said coupled ZnO nanospheres comprise ZnO nanospheres of 2 to 6 nm in diameter. 
     
     
         14 . The ZnO nanoparticles of  claim 10 , wherein said coupled ZnO nanospheres comprise ZnO nanospheres of 3 to 4 nm in diameter. 
     
     
         15 . The ZnO nanoparticles of  claim 10 , wherein said coupled ZnO nanospheres comprise ZnO nanospheres, wherein each of said ZnO nanospheres is an individual crystal.