Metal oxynitride back contact layers for photovoltaic devices
According to the embodiments provided herein, back contacts for photovoltaic devices can include one or more metal oxynitride layers.
1 . A photovoltaic device comprising:
a substrate;
a front contact over the substrate;
an absorber layer over the front contact;
a conducting layer having a surface formed by a layer comprising aluminum; and
a back contact between the absorber layer and the conducting layer, the back contact having a first surface, a second surface, and a thickness defined between the first surface of the back contact and the second surface of the back contact, wherein:
the thickness of the back contact is in a range of about 10 nm to about 150 nm;
the first surface of the back contact is in contact with the absorber layer;
the second surface of the back contact is in contact with the surface of the conducting layer;
the back contact comprises: a first layer comprising zinc and tellurium; a second layer comprising zinc and tellurium; and a layer comprising a metal oxynitride material; wherein:
the metal of the metal oxynitride material is at least one of titanium or tungsten;
the first layer comprises a first dopant; and
the second layer comprises a second dopant.
2 . The photovoltaic device of claim 1 , wherein the metal oxynitride material is composed of about 50% or less oxygen or nitrogen.
3 . The photovoltaic device of claim 1 , wherein:
the first dopant includes a copper dopant, a silver dopant or both; and
the second dopant is a group I dopant.
4 . The photovoltaic device of claim 1 , further comprising a high purity metal layer, wherein:
the high-purity metal layer consists essentially of: titanium, tungsten, tantalum, zirconium, or combinations thereof;
the high-purity metal layer has a thickness between about 1 nm to about 5 nm; and
the high purity metal layer is between the layer comprising the metal oxynitride material and the second layer of the back contact.
5 . The photovoltaic device of claim 4 , wherein the metal oxynitride material includes a thickness in a ratio of at least about 2:1 in comparison to the high purity metal layer.
6 . The photovoltaic device of claim 1 , wherein the absorber layer includes a group I dopant, a group V dopant or a combination thereof.