REDUCTION OF LIGHT INDUCED DEGRADATION IN THIN FILM SILICON SOLAR CELLS
A device and method for reducing degradation in a photovoltaic device includes adjusting a band offset of the device during one or more of forming an electrode, forming a first doped layer or forming an intrinsic layer. The adjusting reduces a band offset between one or more of the electrode, the first doped layer and the intrinsic layer to reduce light-induced degradation of the device. A second doped layer is formed on the intrinsic layer.
1 . A device having resistance to light-induced degradation, comprising:
a p-i-n stack having a p-type layer, an intrinsic layer and an n-type layer; and
a bi-layer transparent electrode in contact with the p-type layer and having a doping gradient which increases with distance from an interface between the p-type layer and the bi-layer transparent electrode, the bi-layer transparent electrode providing an interface having a reduced barrier offset to provide resistance to light-induced degradation.
2 . The device as recited in claim 1 , wherein the bi-layer electrode includes at least two dopant regions.
3 . The device as recited in claim 2 , wherein the at least two dopant regions include a highly doped region and a lighter region, the lighter doped region being in contact with the first doped layer.
4 . The device as recited in claim 3 , wherein the lighter doped region includes a concentration that provides approximately zero band offset between the lighter doped region and the p-type layer.
5 . The device as recited in claim 3 , wherein the highly doped region includes a concentration of about 1.0×10 21 or less.
6 . The device as recited in claim 1 , wherein the intrinsic layer is formed from amorphous silicon and includes Ge content to adjust the band offset.
7 . The device as recited in claim 1 , wherein the p-type layer is formed from amorphous silicon and includes C content to adjust the band offset.
8 . The device as recited in claim 1 , wherein the bi-layer transparent electrode includes one of zinc oxide and indium tin oxide.
9 . The device as recited in claim 1 , wherein doping gradient includes a stepped dopant concentration.