Fluorinated tin oxide back contact for AZTSSe photovoltaic devices
A photovoltaic device includes a substrate, a back contact comprising a stable low-work function material, a photovoltaic absorber material layer comprising Ag 2 ZnSn(S,Se) 4 (AZTSSe) on a side of the back contact opposite the substrate, wherein the back contact forms an Ohmic contact with the photovoltaic absorber material layer, a buffer layer or Schottky contact layer on a side of the absorber layer opposite the back contact, and a top electrode on a side of the buffer layer opposite the absorber layer.
1. A photovoltaic device, comprising:
a substrate;
a back contact comprising a low-work function material selected from the group consisting of fluorinated tin oxide (SnO 2 :F or FTO), ZnO:Al, ZnO:B, In 2 O 3 :Sn, In 2 O 3 :Zn, TiB 2 , LaB 6 , and TiO 2 :Nb;
a photovoltaic absorber material layer comprising an n-type AZTSSe material on a side of the back contact opposite the substrate, the n-type AZTSSe material comprising Ag, Zn, Sn, S, and Se;
wherein the back contact forms an Ohmic contact with the photovoltaic absorber material layer;
a Schottky contact layer comprising MoO 3 on a side of the absorber layer opposite the back contact; and
a top electrode on a side of the Schottky contact layer opposite the absorber layer.
2. The photovoltaic device of claim 1 wherein the low-work function material comprises fluorinated tin oxide (SnO 2 :F or FTO).
3. The photovoltaic device of claim 1 wherein the photovoltaic absorber material layer is annealed with the back contact.
4. The photovoltaic device of claim 1 wherein the n-type AZTSSe material of the photovoltaic absorber material layer comprises has a Ag/Sn ratio of about 1.6 to about 2.3.
5. The photovoltaic device of claim 1 wherein the n-type AZTSSe material of the photovoltaic absorber material layer has a Zn/Sn ratio of about 0.75 to about 1.45.
6. The photovoltaic device of claim 1 wherein the n-type AZTSSE material of the photovoltaic absorber material layer has a ratio of (Ag+Zn+Sn) to (S+Se) of about 0.8 to about 1.
7. The photovoltaic device of claim 1 wherein the n-type AZTSSE material of the photovoltaic absorber material layer has a ratio of S to Se of about 0.25 to about 1.
8. The photovoltaic device of claim 1 wherein the substrate comprises a glass, plastic, ceramic or a metal foil substrate.
9. The photovoltaic device of claim 1 wherein the top electrode comprises a transparent conductive oxide.
10. The photovoltaic device of claim 1 wherein the substrate is FTO-coated and the photovoltaic device comprises a low-work function material layer between the substrate and the photovoltaic absorber material layer.
11. A method for making a photovoltaic device, the method comprising:
providing a substrate;
forming a back contact comprising a low-work function material on the substrate, the low work function material selected from the group consisting of fluorinated tin oxide (SnO 2 :F or FTO), ZnO:Al, ZnO:B, In 2 O 3 :Sn, In 2 O 3 :Zn, TiB 2 , LaB 6 , and TiO 2 :Nb;
forming a photovoltaic absorber material layer comprising an n-type AZTSSe material on a side of the back contact opposite the substrate wherein an Ohmic contact is formed between the low-work function material and the photovoltaic absorber material layer, the n-type AZTSSE material comprising Ag, Zn, Sn, S, and Se;
forming a Schottky contact layer on a side of the absorber layer opposite the back contact, the Schottky contact layer comprising MoO 3 ; and
forming a top electrode on a side of the Schottky contact layer opposite the absorber layer.
12. The method of claim 11 wherein the low-work function material comprises fluorinated tin oxide (SnO 2 :F or FTO).
13. The method of claim 11 wherein the photovoltaic absorber material layer is annealed with the back contact.
14. The method of claim 11 wherein the n-type AZTSSe material of the photovoltaic absorber material layer has a ratio of Ag to Sn of about 1.6 to about 2.3.
15. The method of claim 11 wherein the n-type AZTSSe material of the photovoltaic absorber material layer has a ratio of Zn to Sn of about 0.75 to about 1.45.
16. The method of claim 11 wherein the n-type AZTSSe material of the photovoltaic absorber material layer has a ratio of (Ag+Zn+Sn) to (S+Se) of about 0.8 to about 1.2.
17. The method of claim 11 wherein the n-type AZTSSe material of the photovoltaic absorber material layer has a ratio of S to Se of about 0.25 to about 1.
18. A photovoltaic device, comprising:
a glass substrate;
a back contact selected from the group consisting of fluorinated tin oxide (SnO 2 :F or FTO), ZnO:Al, ZnO:B, In 2 O 3 :Sn, In 2 O 3 :Zn, TiB 2 , LaB 6 , or TiO 2 :Nb;
a photovoltaic absorber material layer comprising an n-type Ag 2 ZnSn(S,Se) 4 material on a side of the back contact opposite the substrate;
wherein the back contact forms an Ohmic contact with the photovoltaic absorber material layer
a Schottky contact layer comprising MoO 3 on a side of the absorber layer opposite the back contact;
a top electrode on a side of the Schottky contact layer opposite the absorber layer; and
a metal contact grid on a side of the top electrode opposite the Schottky contact layer.