Method for the manufacture of a solar cell and the resulting solar cell
In a method for the production of a solar cell, a flat aluminium layer is applied to the back of a solar cell substrate. The aluminium is alloyed into the silicon substrate by the effect of the temperature and forms an aluminium BSF. The remaining aluminium that has not been alloyed into the silicon is subsequently removed. The aluminium BSF is transparent to light.
1. A method for the manufacture of a solar cell with a BSF coating, comprising:
applying a BSF coating to a back surface of a solar cell substrate through application of aluminium or TCO to said substrate and subsequent alloying into said substrate, said BSF coating being transparent for light; and
following said alloying step into said substrate, removing only aluminium from an aluminium coating or pure aluminium, wherein solely said aluminium not alloyed into said substrate is removed.
2. The method according to claim 1 , wherein said aluminium or said TCO is applied to said substrate in punctiform manner or in small areas.
3. The method according to claim 1 , wherein a local production of several said BSF's in punctiform manner or in small areas is provided, said points or small areas being located along straight lines, which have a constant spacing and to which subsequently linear, metallic contacts are applied.
4. The method according to claim 1 , wherein said aluminium or said TCO is applied in linear manner to said substrate.
5. The method according to claim 1 , wherein said aluminium is applied in a spread out manner onto said substrate for a spread out BSF.
6. The method according to claim 1 , wherein said entire area of one side of said substrate is covered.
7. The method according to claim 1 , wherein said aluminium or said TCO is applied to said substrate by a screen printing process.
8. The method according to claim 1 , wherein said aluminium or said TCO is applied in liquid or pasty from.
9. The method according to claim 1 , wherein said aluminium or said TCO is applied by sputtering, vaporizing, CVD process or alloying.
10. The method according to claim 1 , wherein said alloying of said aluminium into said substrate or said substrate silicon material takes place through heating which is separate from said aluminium application.
11. The method according to claim 1 , wherein all said aluminium not alloyed in or not alloyed with said silicon material is removed.
12. The method according to claim 1 , wherein said aluminium is removed by etching.
13. The method according to claim 1 , wherein following said aluminium removal a passivation takes place and then an antireflection coating is applied to said back surface of said substrate.
14. The method according to claim 1 , wherein following aluminium removal a p-n junction is produced by diffusion of phosphorus into said n-silicon of said substrate.
15. The method according to claim 1 , wherein said aluminium is applied by a screen printing process on said substrate into prefabricated structures, said structures being through an antireflection coating down to said substrate, wherein subsequently said aluminium is not removed.