Enhancement of semiconducting photovoltaic absorbers by the addition of alkali salts through solution coating techniques

Abstract

In particular embodiments, a method is described for forming photovoltaic devices that includes providing a substrate suitable for use in a photovoltaic device, depositing a conductive contact layer over the substrate, depositing a salt solution over the surface of the conductive contact layer, the solution comprising a volatile solvent and an alkali metal salt solute, and depositing a semiconducting absorber layer over the solute residue left by the evaporated solvent.

What is claimed is: 
     
         1 . An intermediate structure for use in a photovoltaic cell comprising:
 a substrate;   a conductive contact layer deposited over the substrate; and   an alkali metal salt layer deposited over the conductive contact layer.   
     
     
         2 . The structure of  claim 1 , further comprising a semiconducting absorber layer deposited over and immediately adjacent the alkali metal salt layer. 
     
     
         3 . The structure of  claim 2 , further comprising a second alkali metal salt layer over and immediately adjacent the absorber layer. 
     
     
         4 . The structure of  claim 1 , wherein the alkali metal salt solute is comprised of:
 one or more alkali metals including one or more of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and caesium (Cs); and   one or more cations including one or more of fluorine (F), chlorine (Cl), bromine (Br), iodine (I), sulfur (S), selenium (Se), tellurium (Te), and oxygen (O).   
     
     
         5 . The structure of  claim 1 , wherein the absorber layer is comprised of one or more layers each comprised of one or more of copper indium gallium diselenide, copper indium gallium selenide sulfide, and copper indium gallium disulfide, copper-indium-disulfide, or copper-indium-diselenide.