Chalcogen back surface field layer
Kesterite photovoltaic devices having a back surface field layer are provided. In one aspect, a method of forming a photovoltaic device includes: forming a complete photovoltaic device having a substrate, an electrically conductive layer on the substrate, an absorber layer on the electrically conductive layer, a buffer layer on the absorber layer, and a transparent front contact on the buffer layer; removing the substrate and the electrically conductive layer from the complete photovoltaic device to expose a backside surface of the absorber layer; forming a passivating layer on the backside surface of the absorber layer; and forming a high work function back contact on the passivating layer. A photovoltaic device having a passivating layer is also provided.
1. A method of forming a photovoltaic device, the method comprising:
forming a complete photovoltaic device having a substrate, an electrically conductive layer on the substrate, an absorber layer on the electrically conductive layer, a buffer layer on the absorber layer, and a transparent front contact on the buffer layer;
removing the substrate and the electrically conductive layer from the complete photovoltaic device to expose a backside surface of the absorber layer;
forming a passivating layer on the backside surface of the absorber layer, wherein the passivating layer comprises a material selected from the group consisting of: pure selenium, pure sulfur, and pure tellurium; and
forming a high work function back contact on the passivating layer.
2. The method of claim 1 , wherein the substrate is selected from the group consisting of: a glass substrate, a ceramic substrate, a metal foil substrate, and a plastic substrate.
3. The method of claim 1 , wherein the electrically conductive layer comprises a material selected from the group consisting of: molybdenum, molybdenum trioxide, gold, nickel, tantalum, tungsten, aluminum, platinum, titanium nitride, silicon nitride, and combinations thereof.
4. The method of claim 1 , wherein the absorber layer comprises a kesterite material.
5. The method of claim 4 , wherein the absorber layer comprises copper, zinc, tin, and at least one of sulfur and selenium.
6. The method of claim 1 , wherein the absorber layer has a thickness of from about 0.5 micrometers to about 2 micrometers, and ranges therebetween.
7. The method of claim 1 , wherein the buffer layer comprises a material selected from the group consisting of: cadmium sulfide, cadmium-zinc-sulfur, indium sulfide, zinc oxide, zinc oxysulfide, aluminum oxide, and combinations thereof.
8. The method of claim 1 , wherein the transparent front contact comprises a transparent conductive oxide selected from the group consisting of: indium-tin-oxide, aluminum-doped zinc oxide, and combinations thereof.
9. The method of claim 1 , wherein the substrate and the electrically conductive layer are removed from the complete photovoltaic device using exfoliation.
10. The method of claim 1 , wherein the high work function back contact comprises a material selected from the group consisting of: molybdenum, molybdenum trioxide, gold, nickel, tantalum, tungsten, aluminum, platinum, titanium nitride, silicon nitride, and combinations thereof.
11. The method of claim 1 , wherein the high work function back contact comprises molybdenum trioxide and gold.
12. The method of claim 1 , wherein the forming of the complete photovoltaic device further comprises:
forming a metal grid on the transparent front contact.
13. The method of claim 1 , wherein the metal grid comprises a material selected from the group consisting of: nickel, aluminum, and combinations thereof.
14. The method of claim 1 , wherein the forming of the complete photovoltaic device comprises:
forming the electrically conductive layer on the substrate;
forming the absorber layer on the electrically conductive layer;
annealing the absorber layer;
forming the buffer layer on the absorber layer; and
forming the transparent front contact on the buffer layer.
15. The method of claim 14 , wherein the absorber layer is annealed at a temperature of from about 400° C. to about 800° C., and ranges therebetween.