High-efficiency photovoltaic back-contact solar cell structures and manufacturing methods

Abstract

Back contact back junction solar cell and methods for manufacturing are provided. The back contact back junction solar cell comprises a substrate having a light capturing frontside surface with a passivation layer, a doped base region, and a doped backside emitter region with a polarity opposite the doped base region. A backside passivation layer and patterned reflective layer on the emitter form a light trapping backside mirror. An interdigitated metallization pattern is positioned on the backside of the solar cell and a permanent reinforcement provides support to the cell.

What is claimed is: 
     
         1 . A back contact back junction solar cell, comprising:
 a semiconductor layer, comprising:
 a light capturing frontside surface with a passivation layer, 
 a doped base region, and 
 a doped backside emitter region with a polarity opposite said doped base region; 
   a backside passivation dielectric layer on said backside emitter region,   backside emitter metallization contacting said backside emitter region and backside base metallization contacting said doped base region, wherein said backside passivation dielectric layer and said backside emitter metallization and said backside base metallization form a light trapping backside mirror; and,   a backside reinforcement on the backside of said back contact back junction solar cell, said backside reinforcement having access openings providing access to said backside emitter metallization and said backside base metallization.   
     
     
         2 . The back contact back junction solar cell of  claim 1 , wherein said semiconductor layer is an epitaxial silicon layer with a thickness in the range of 15 to 50 microns. 
     
     
         3 . The back contact back junction solar cell of  claim 1 , wherein said semiconductor layer is a planar epitaxial silicon layer. 
     
     
         4 . The back contact back junction solar cell of  claim 1 , wherein said light capturing frontside surface with a passivation layer serves as an anti-reflection coating. 
     
     
         5 . The back contact back junction solar cell of  claim 1 , wherein said light capturing frontside surface with a passivation layer provides field assisted passivation. 
     
     
         6 . The back contact back junction solar cell of  claim 1 , wherein said doped backside emitter region is an in-situ doped epitaxial emitter region with an emitter junction thickness of less than 3 microns. 
     
     
         7 . The back contact back junction solar cell of  claim 1 , wherein said backside emitter metallization and said backside base metallization is an interdigitated metallization pattern of a distributed array of interdigitated fingers and busbars. 
     
     
         8 . The back contact back junction solar cell of  claim 1 , wherein higher concentration base doping regions under said backside base metallization are separated from emitter regions, thereby forming separated junctions. 
     
     
         9 . The back contact back junction solar cell of  claim 1 , wherein higher concentration base doping under said backside base metallization abut emitter regions, thereby forming abutted junctions. 
     
     
         10 . The back contact back junction solar cell of  claim 1 , wherein said mirror is a lambertian mirror. 
     
     
         11 . The back contact back junction solar cell of  claim 1 , wherein the localized doping concentrations under said backside emitter metallization is higher than said doped backside emitter region, thereby forming selective emitter contacts. 
     
     
         12 . The back contact back junction solar cell of  claim 1 , wherein said backside reinforcement is a permanent support reinforcement plate and said access openings are through-hole openings. 
     
     
         13 . The back contact back junction solar cell of  claim 1 , wherein said backside passivation dielectric layer is aluminum oxide. 
     
     
         14 . The back contact back junction solar cell of  claim 1 , wherein said backside reinforcement is a permanent support reinforcement plate and said access openings are through-hole openings. 
     
     
         15 . The back contact back junction solar cell of  claim 1 , wherein said backside reinforcement is a backside grid-shaped support reinforcement. 
     
     
         16 . The back contact back junction solar cell of  claim 1 , wherein said dopes backside emitter region is a doped backside epitaxial region.