Stacked photovoltaic device

Abstract

A back metal electrode, a bottom cell using microcrystalline silicon for a photoelectric conversion layer, a front cell using amorphous silicon for a photoelectric conversion layer, and a transparent front electrode are formed in this order on a supporting substrate. At least one of the concentration of impurities contained in the front photoelectric conversion layer and the concentration of impurities contained in the bottom photoelectric conversion layer is controlled such that the concentration of impurities in the bottom photoelectric conversion layer is higher than the concentration of impurities in the front photoelectric conversion layer. Impurities do not include a p-type dopant or an n-type dopant but are any one, two, or all of carbon, nitrogen, and oxygen.

1 . A stacked photovoltaic device having a light incidence surface, comprising
 a plurality of photovoltaic cells stacked and each including a photoelectric conversion layer composed of a substantially intrinsic semiconductor,   the photoelectric conversion layer in the one photovoltaic cell closest to the light incidence surface including an amorphous semiconductor, and the photoelectric conversion layer in another photovoltaic cell including a non-single crystalline semiconductor containing crystal grains, and   the concentration of impurities contained in the photoelectric conversion layer in said other photovoltaic cell being higher than the concentration of impurities contained in the photoelectric conversion layer in said one photovoltaic cell.   
     
     
         2 . The photovoltaic device according to  claim 1 , wherein
 said non-single crystalline semiconductor is a microcrystalline semiconductor containing crystal grains having a diameter of not more than 1 μm.   
     
     
         3 . The photovoltaic device according to  claim 1 , wherein
 said impurities include carbon, the concentration of carbon contained in the photoelectric conversion layer in said other photovoltaic cell being higher than the concentration of carbon contained in the photoelectric conversion layer in said one photovoltaic cell.   
     
     
         4 . The photovoltaic device according to  claim 1 , wherein
 said impurities include nitrogen, the concentration of nitrogen contained in the photoelectric conversion layer in said other photovoltaic cell being higher than the concentration of nitrogen contained in the photoelectric conversion layer in said one photovoltaic cell.   
     
     
         5 . The photovoltaic device according to  claim 1 , wherein
 said impurities include oxygen, the concentration of oxygen contained in the photoelectric conversion layer in said other photovoltaic cell being higher than the concentration of oxygen contained in the photoelectric conversion layer in said one photovoltaic cell.   
     
     
         6 . A method of manufacturing a stacked photovoltaic device, comprising the steps of:
 forming a plurality of photovoltaic cells in order, each comprising a photoelectric conversion layer composed of a substantially intrinsic semiconductor,   the photoelectric conversion layer in the one photovoltaic cell closest to a light incidence surface including an amorphous semiconductor, and the photoelectric conversion layer in another photovoltaic cell including a non-single crystalline semiconductor containing crystal grains; and   adjusting at least one of the formation condition of the photoelectric conversion layer in said one photovoltaic cell and the formation condition of the photoelectric conversion layer in said other photovoltaic cell such that the concentration of impurities contained in the photoelectric conversion layer in each of said other photovoltaic cell is higher than the concentration of impurities contained in the photoelectric conversion layer in said one photovoltaic cell.