Tailoring the band gap of solar cells made of liquid silane by adding germanium
AssigneeEvonik Degussa GmbH
InventorsBernhard Stuetzel, Wolfgang Fahrner
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Abstract
The present invention relates to a method for decreasing or increasing the band gap shift in the production of photovoltaic devices by means of coating a substrate with a formulation containing a silicon compound, e.g., in the production of a solar cell comprising a step in which a substrate is coated with a liquid-silane formulation, the invention being characterized in that the formulation also contains at least one germanium compound. The invention further relates to the method for producing such a photovoltaic device.
Claims22
A process for reducing or eliminating the band gap shift in the production of a photovoltaic system, said production process comprising:
- oligomerizing or polymerizing a mixture comprising a silane and a germanium compound to form a formulation comprising the silane, the germanium compound and a co-oligomerized product consisting of units of the silane and the germanium compound;
- coating a flat surface of a substrate with the formulation, wherein during the coating the formulation is in liquid form, to obtain a coated substrate,
- irradiating, thermally treating, or both irradiating and thermally treating the coated substrate to obtain an at least partially polymorphic layer comprising silicon and germanium on the flat surface of the substrate;
- wherein the germanium compound is of formula GenH2n+2 or GenH2n where n is an integer from 4 to 8 and is present in the mixture with an oligomeric germanium compound of formula GenR2n+2 or GenR2n and having weight-average molecular weight of 500 to 10,000 g/mol, wherein n is an integer from 4 to 8, R is independently H, halogen, or organyl, and at least one R is an organyl,
- wherein the silane is of formula (i) SinH2n+2 where n is an integer from 3 to 10, (ii) SinH2n where n is an integer from 4 to 8, (iii) SinR2n+2 where n is an integer from 8 to 100 and R is H or an organyl with at least one R being an organyl, or (iv) SinR2 where n is an integer from 8 to 100 and R is H or an organyl with at least one R being an organyl.
A process for producing a photovoltaic system comprising at least one layer consisting essentially of silicon-germanium, said production process comprising:
- oligomerizing or polymerizing a mixture comprising a silane and a germanium compound to form a formulation comprising the silane, the germanium compound and a co-oligomerized product consisting of units of the silane and the germanium compound;
- coating a flat surface of a substrate with the formulation, wherein during the coating the formulation is in liquid form, to obtain a coated substrate,
- irradiating, thermally treating, or both irradiating and thermally treating the coated substrate to obtain an at least partially polymorphic layer comprising silicon and germanium on the flat surface of the substrate;
- wherein the germanium compound is of formula GenH2n+2 or GenH2n where n is an integer from 4 to 8 and is present in the mixture with an oligomeric germanium compound of formula GenR2n+2 or GenR2n and having weight-average molecular weight of 500 to 10,000 g/mol, wherein n is an integer from 4 to 8, R is independently H, halogen, or organyl, and at least one R is an organyl,
- wherein the silane is of formula (i) SinH2n+2 where n is an integer from 3 to 10, (ii) SinH2n where n is an integer from 4 to 8, (iii) SinR2n+2 where n is an integer from 8 to 100 and R is H or an organyl with at least one R being organyl, or (iv) SinR2 where n is an integer from 8 to 100 and R is H or an organyl with at least one R being an organyl.
Dependencies are inferred from the claim text.