Buffer layer for high performing and low light degraded solar cells

Abstract

Methods for forming a photovoltaic device include forming a buffer layer between a transparent electrode and a p-type layer. The buffer layer includes a doped germanium-free silicon base material. The buffer layer has a work function that falls within barrier energies of the transparent electrode and the p-type layer. An intrinsic layer and an n-type layer are formed on the p-type layer. Devices are also provided.

1 . A method for forming a photovoltaic device, comprising:
 forming a buffer layer between a transparent electrode and a non-crystalline silicon containing p-type layer, the buffer layer including a non-crystalline doped germanium-free silicon base material, wherein the forming of the buffer layer comprises adjusting the deposition power so that a work function of the buffer layer falls within barrier energies of the transparent electrode and the p-type layer; and   forming an intrinsic layer and an n-type layer on the p-type layer.   
     
     
         2 . The method as recited in  claim 1 , wherein forming the buffer layer includes depositing a noncrystalline form of silicon. 
     
     
         3 . The method as recited in  claim 1 , wherein forming the buffer layer includes depositing the silicon base material at a deposition power density of less than about 0.20 Watts per square centimeter. 
     
     
         4 . The method as recited in  claim 3 , wherein the deposition power includes a power density of less than about 0.10 Watts per square centimeter. 
     
     
         5 . The method as recited in  claim 1 , wherein forming the buffer layer includes doping the buffer layer with one or more of the following dopants: H, B, Ga, and In. 
     
     
         6 . The method as recited in  claim 1 , wherein forming a buffer layer includes forming the buffer layer with a plasma enhanced chemical vapor deposition process. 
     
     
         7 . The method as recited in  claim 1 , wherein the p-type layer includes at least one of amorphous silicon, amorphous silicon carbide, hydrogenated amorphous silicon, or hydrogenated amorphous silicon carbide. 
     
     
         8 . The method as recited in  claim 1 , wherein depositing the buffer layer includes providing a deposition rate of between about 1 and 2 Angstroms per second to provide improved long-term efficiency of the photovoltaic device. 
     
     
         9 . A method for forming a photovoltaic device, comprising:
 forming a transparent electrode on a transparent substrate;   depositing a buffer layer on the transparent electrode, the buffer layer being deposited by a plasma enhanced chemical vapor deposition process at a deposition power to provide a doped germanium-free noncrystalline silicon layer with a work function that falls substantially in a middle of a barrier formed between adjacent layers to the buffer layer to provide resistance to light induced degradation and reduce a Schottky barrier;   depositing a p-type layer of a non-crystalline silicon containing material on the buffer layer;   forming an intrinsic layer on the p-type layer;   forming an n-type layer on the intrinsic layer; and   forming a back electrode on the n-type layer.   
     
     
         10 . The method as recited in  claim 9 , wherein depositing the buffer layer includes depositing a hydrogenated amorphous silicon. 
     
     
         11 . The method as recited in  claim 9 , wherein depositing the buffer layer includes doping the buffer layer with one or more of H, B, Ga, and In. 
     
     
         12 . The method as recited in  claim 9 , wherein the deposition power includes a power density of less than about 0.20 Watts per square centimeter. 
     
     
         13 . The method as recited in  claim 12 , wherein the deposition power includes a power density of less than about 0.10 Watts per square centimeter. 
     
     
         14 . The method as recited in  claim 9 , wherein depositing the buffer layer includes providing a deposition rate of between about 1 and 2 Angstroms per second to provide improved long-term efficiency of the photovoltaic device. 
     
     
         15 . The method as recited in  claim 9 , wherein the p-type layer includes at least one of amorphous silicon, amorphous silicon carbide, hydrogenated amorphous silicon, or hydrogenated amorphous silicon carbide. 
     
     
         16 - 25 . (canceled)