Photovoltaic devices and method of manufacturing
A photovoltaic device includes a substrate structure and at least one Se-containing layer, such as a CdSeTe layer. A process for manufacturing the photovoltaic device includes forming the CdSeTe layer over a substrate by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process, and vapor transport deposition process. The process can also include controlling a thickness range of the Se-containing layer.
1. A photovoltaic device comprising:
a transparent conductive oxide (TCO) layer,
a back contact; and
an absorber layer formed between the TCO layer and the back contact, wherein:
the absorber layer is composed of a CdSe x Te 1-x compound,
x is from about 0.01 to about 0.40,
a ratio of Se atoms to a sum of the Se atoms and Te atoms throughout the CdSe x Te 1-x compound is between 1 to 100 and 4 to 10,
Se is throughout the absorber layer,
the absorber layer has a concentration gradient of Se formed therein, and
a concentration of Se adjacent the TCO layer is higher than a concentration of Se adjacent the back contact.
2. The photovoltaic device of claim 1 , wherein the back contact is formed from one of ZnTe, CdZnTe, ZnTe:Cu, and a bi-layer including a layer of ZnTe and a layer of CdZnTe.
3. The photovoltaic device of claim 1 , further comprising a back metal electrode formed on the back contact.
4. The photovoltaic device of claim 3 , wherein the back metal electrode includes a layer of MoN x .
5. The photovoltaic device of claim 4 , wherein the back metal electrode further includes a layer of aluminum formed between a layer of chromium and the layer of MoN x .
6. The photovoltaic device of claim 3 , further comprising an interfacial layer formed from copper formed between the back metal electrode and the back contact.
7. The photovoltaic device of claim 1 , wherein x is from about 0.01 to about 0.25.
8. The photovoltaic device of claim 1 , wherein the TCO layer is formed from SnO x .
9. The photovoltaic device of claim 1 , wherein the TCO layer is formed from a layer of SnO x adjacent the substrate, a layer of SiO 2 formed on the SnO x layer, a layer of SnO 2 :F formed on the SiO 2 layer, and a layer of SnO 2 formed between the SnO 2 :F layer and the Se containing absorber layer.
10. The photovoltaic device of claim 1 , wherein the absorber layer is doped with copper.
11. The photovoltaic device of claim 1 , wherein the TCO layer comprises indium tin oxide.
12. The photovoltaic device of claim 1 , wherein the TCO layer comprises cadmium stannate.
13. A photovoltaic device comprising:
a transparent conductive oxide (TCO) layer,
a back contact layer;
a p-type absorber between the TCO layer and the back contact layer, wherein:
the p-type absorber comprises a surface adjacent the TCO layer and a surface adjacent the back contact,
the p-type absorber is composed of a CdSe x Te 1-x compound, wherein a ratio of Se atoms to a sum of the Se atoms and Te atoms in the CdSe x Te 1-x compound is between 1 to 100 and 4 to 10,
the p-type absorber has a concentration gradient of Se formed therein, and
a peak concentration of Se of the concentration gradient of Se is located within the p-type absorber and between the surface adjacent the TCO layer and the surface adjacent the back contact.
14. The photovoltaic device of claim 13 , further comprising a buffer layer between the TCO layer and the p-type absorber.
15. The photovoltaic device of claim 14 , wherein the photovoltaic device does not include a window layer.
16. The photovoltaic device of claim 14 , wherein the buffer layer comprises zinc magnesium oxide.
17. The photovoltaic device of claim 13 , wherein the TCO layer comprises indium tin oxide.
18. The photovoltaic device of claim 13 , wherein the TCO layer comprises cadmium stannate.
19. The photovoltaic device of claim 13 , wherein the back contact is formed from a bi-layer including a layer of ZnTe and a layer of CdZnTe.