Solar cell equipped with electrode having mesh structure, and process for manufacturing same

Abstract

The embodiment provides a solar cell and a manufacturing process thereof. The solar cell is equipped with an electrode on the light incident surface side; and the electrode has both low resistivity and high transparency, can efficiently utilize solar light for excitation of carriers, and can be made of inexpensive materials. The solar cell comprises a photoelectric conversion layer, a first electrode layer arranged on the light incident surface side, and a second electrode layer arranged opposed to the first electrode layer. The first electrode layer has a thickness in the range of 10 to 200 nm, and has plural penetrating openings. Each of the individual openings occupies an area in the range of 80 nm 2 to 0.8 μm 2 , and the aperture ratio thereof is in the range 10 to 66%. The first electrode layer in the cell can be produced by etching procedure using an etching mask obtained by use of a single particle layer of fine particles, by use of a dot pattern formed by self-assembly of a block copolymer, or by use of a stamper.

1 . A solar cell comprising
 a photoelectric conversion layer containing at least a p-type semiconductor and an n-type semiconductor,   a first electrode layer made of metal and formed on the light incident side surface of said photoelectric conversion layer, and   a second electrode layer formed on the surface opposite to said light incident side surface; wherein   said first electrode layer has a thickness in the range of 10 nm to 200 nm,   said first electrode layer has plural penetrating openings each of which occupies an area in the range of 80 nm 2  to 0.8 μm 2 , and   the aperture ratio, which is a ratio of the total area of said openings based on the total area of said first electrode layer, is in the range of 10% to 66%.   
     
     
         2 . The solar cell according to  claim 1 , wherein said photoelectric conversion layer comprises a depletion layer at least partly positioned within a distance of 1 μm from the interface between said first electrode layer and said photoelectric conversion layer. 
     
     
         3 . The solar cell according to  claim 1 , wherein said openings are so arranged that the average distance between adjacent openings is in the range of 10 nm to 200 nm. 
     
     
         4 . The solar cell according to  claim 1 , wherein said first electrode layer is made of at least one metal selected from the group consisting of aluminum, silver, gold, platinum, nickel, cobalt, chromium, copper and titanium. 
     
     
         5 . A process for manufacturing a solar cell, comprising the steps of
 forming a photoelectric conversion layer,   forming a first electrode layer on the light incident side surface of said photoelectric conversion layer, and   forming a second electrode layer on the side opposite to the light incident side surface of said photoelectric conversion layer; wherein   said step of forming a first electrode layer comprises the sub-steps of   forming a metal thin layer,   coating a resist composition on at least a part of said metal thin layer, to form a resist layer,   forming a single particle layer of fine particles on the surface of said resist layer,   etching said resist layer by use of said single particle layer as an etching mask, to form a resist pattern,   filling openings in said resist pattern with inorganic substance, to form a reverse pattern mask, and   etching said thin metal layer by use of said reverse pattern mask as an etching mask, to form the first electrode layer having fine openings.   
     
     
         6 . The process according to  claim 5 , wherein said fine particles are silica particles. 
     
     
         7 . A process for manufacturing a solar cell, comprising the steps of
 forming a photoelectric conversion layer,   forming a first electrode layer on the light incident side surface of said photoelectric conversion layer, and   forming a second electrode layer on the side opposite to the light incident side surface of said photoelectric conversion layer; wherein   said step of forming a first electrode layer comprises the sub-steps of   forming a thin metal layer,   coating a block copolymer-containing composition on at least a part of said thin metal layer, to form a block copolymer layer,   causing phase separation of said block copolymer, to form microdomains in a dot pattern, and   etching said thin metal layer by use of said dot pattern of microdomains as an etching mask, to form the first electrode layer having fine openings.   
     
     
         8 . The process according to  claim 7 , wherein said block copolymer is a diblock copolymer of polystyrene-polymethyl methacrylate. 
     
     
         9 . A process for manufacturing a solar cell, comprising the steps of
 forming a photoelectric conversion layer,   forming a first electrode layer on the light incident side surface of said photoelectric conversion layer, and   forming a second electrode layer on the side opposite to the light incident side surface of said photoelectric conversion layer; wherein   said step of forming a first electrode layer comprises the sub-steps of   forming a thin metal layer,   preparing a stamper whose surface has a fine relief pattern corresponding to the shape of the first electrode layer intended to be formed,   transferring a resist pattern onto at least a part of said thin metal layer by use of said stamper, and   etching said thin metal layer by use of said resist pattern as an etching mask, to form the first electrode layer having fine openings.   
     
     
         10 . The process according to  claim 9 , wherein said stamper is produced by use of electron beam exposure.