PHOTOVOLTAIC DEVICES AND METHOD OF MAKING

1 . A photovoltaic device, comprising:

a buffer layer disposed on a transparent conductive oxide layer;

a window layer disposed on the buffer layer; and

an interlayer comprising a metal species interposed between the transparent conductive oxide layer and the window layer, wherein the metal species comprises gadolinium, beryllium, calcium, barium, strontium, scandium, yttrium, hafnium, cerium, lutetium, lanthanum, or combinations thereof.

2 . The photovoltaic device of claim 1 , wherein at least a portion of the metal species is present in the interlayer in the form of an elemental metal, a metal alloy, a metal compound, or combinations thereof.

3 . The photovoltaic device of claim 1 , wherein the interlayer further comprises tin, sulfur, oxygen, fluorine, zinc, cadmium, or combinations thereof.

4 . The photovoltaic device of claim 1 , wherein the interlayer comprises a metal compound comprising the metal species, tin, and oxygen.

5 . The photovoltaic device of claim 1 , wherein the interlayer comprises a metal compound comprising the metal species and fluorine.

6 . The photovoltaic device of claim 1 , wherein the interlayer is interposed between the transparent conductive oxide layer and the buffer layer.

7 . The photovoltaic device of claim 1 , wherein the interlayer is interposed between the buffer layer and the window layer.

8 . The photovoltaic device of claim 1 , wherein the transparent conductive oxide layer comprises cadmium tin oxide, zinc tin oxide, indium tin oxide, fluorine-doped tin oxide, indium-doped cadmium-oxide, doped zinc oxide, or combinations thereof.

9 . The photovoltaic device of claim 1 , wherein the buffer layer comprises tin dioxide, zinc oxide, indium oxide, zinc tin oxide, or combinations thereof.

10 . The photovoltaic device of claim 1 , wherein the window layer comprises cadmium sulfide, oxygenated cadmium sulfide, zinc sulfide, cadmium zinc sulfide, cadmium selenide, indium selenide, indium sulfide, or combinations thereof.

11 . The photovoltaic device of claim 1 , further comprising an absorber layer disposed on the window layer.

12 . The photovoltaic device of claim 11 , wherein the absorber layer comprises cadmium telluride, cadmium zinc telluride, cadmium sulfur telluride, cadmium selenium telluride, cadmium manganese telluride, cadmium magnesium telluride, copper indium sulfide, copper indium gallium selenide, copper indium gallium sulfide, or combinations thereof.

13 . The photovoltaic device of claim 11 , further comprising a secondary interlayer interposed between the window layer and the absorber layer, wherein the secondary interlayer comprises magnesium, aluminum, zinc, nickel, gadolinium, or combinations thereof.

14 . The photovoltaic device of claim 1 , wherein the interlayer has a thickness in a range from about 0.2 nanometers to about 200 nanometers.

15 . A photovoltaic device, comprising:

a transparent conductive oxide layer;

a window layer; and

an interlayer comprising a metal species interposed between the transparent conductive oxide layer and the window layer, wherein the metal species comprises gadolinium, beryllium, scandium, yttrium, hafnium, cerium, lutetium, lanthanum, or combinations thereof.

16 . The photovoltaic device of claim 15 , wherein at least a portion of the metal species is present in the interlayer in the form of an elemental metal, a metal alloy, a metal compound, or combinations thereof.

17 . The photovoltaic device of claim 15 , wherein the interlayer further comprises tin, sulfur, oxygen, fluorine, zinc, cadmium, or combinations thereof.

18 . The photovoltaic device of claim 15 , wherein the interlayer comprises a metal compound comprising the metal species, tin, and oxygen.

19 . The photovoltaic device of claim 15 , wherein the interlayer comprises a metal compound comprising the metal species and fluorine.

20 . The photovoltaic device of claim 15 , wherein the interlayer is disposed directly in contact with the transparent conductive oxide layer.

21 . The photovoltaic device of claim 15 , wherein the window layer comprises cadmium sulfide, oxygenated cadmium sulfide, zinc sulfide, cadmium zinc sulfide, cadmium selenide, indium selenide, indium sulfide, or combinations thereof.

22 . A method of making a photovoltaic device, comprising:

disposing a buffer layer between a transparent conductive oxide layer and a window layer; and

disposing an interlayer comprising a metal species between the transparent conductive oxide layer and the window layer, wherein the metal species comprises gadolinium, beryllium, scandium, yttrium, hafnium, cerium, lutetium, lanthanum, calcium, barium, strontium, or combinations thereof.

23 . The photovoltaic device of claim 22 , wherein at least a portion of the metal species is present in the interlayer in the form of an elemental metal, a metal alloy, a metal compound, or combinations thereof.

24 . The method of claim 22 , wherein the interlayer further comprises tin, sulfur, oxygen, fluorine, zinc, cadmium, or combinations thereof.

25 . The method of claim 22 , wherein the window layer comprises cadmium sulfide, oxygenated cadmium sulfide, zinc sulfide, cadmium zinc sulfide, cadmium selenide, indium selenide, indium sulfide, or combinations thereof.

26 . The method of claim 22 , further comprising disposing an absorber layer on the window layer.

27 . The method of claim 26 , wherein the absorber layer comprises cadmium telluride, cadmium zinc telluride, cadmium sulfur telluride, cadmium selenium telluride, cadmium manganese telluride, cadmium magnesium telluride, copper indium sulfide, copper indium gallium selenide, copper indium gallium sulfide, or combinations thereof.

28 . The method of claim 26 , further comprising interposing a secondary interlayer between the window layer and the absorber layer, wherein the secondary interlayer comprises magnesium, aluminum, zinc, nickel, gadolinium, or combinations thereof.