Back contact for thin film solar cells

1. A photovoltaic device having a substrate configuration, comprising:

a substrate,

said substrate being transparent or opaque,

a metal electrode layer,

a transparent conductor layer,

an absorber layer,

said absorber layer comprises a Group II-VI semiconductor compound,

a window layer, and

an interface layer, wherein

the interface layer comprises nanoparticles and/or nanoparticles that are sintered and is disposed between the metal electrode layer and the absorber layer such that an ohmic contact is created between the metal electrode layer and the absorber layer.

2. A photovoltaic device according claim 1 , wherein:

said absorber layer comprises a CdTe semiconductor.

3. A photovoltaic device according claim 2 , wherein:

said window layer comprises a CdS semiconductor.

4. A photovoltaic device as claimed in claim 1 , wherein:

the interface layer comprises a plurality of layers, wherein:

said plurality of layers comprises a layer comprising a thin film, and

said thin film comprises a material selected from the group consisting of Group II-VI compounds, Group IV-VI compounds, Group IV compounds, Group III-V compounds and Group I-III-VI compounds.

5. A photovoltaic device as claimed in claim 1 , wherein:

the nanoparticles and/or nanoparticles that are sintered each independently comprise a material selected from the group consisting of

Group II-VI compounds, Group IV-VI compounds, Group IV compounds, Group III-V compounds and Group I-III-VI compounds.

6. A photovoltaic device as claimed in claim 5 , wherein:

the nanoparticles and/or nanoparticles that are sintered independently comprise a material selected from the group consisting of Cu x Te where 1≦x≦2, ZnTe, p doped ZnTe, Cd x Te y where x≠y, Cu doped CdTe, CdZnTe, Sb 2 Te 3 , Bi 2 Te 3 and Te metal.

7. A photovoltaic device as claimed in claim 6 , wherein:

the nanoparticles and/or nanoparticles that are sintered independently comprise a material selected from the group consisting of Cd x Te y where y>x and Cu doped ZnTe.

8. A photovoltaic device as claimed in claim 1 , wherein:

the interface layer comprises a plurality of layers.

9. A photovoltaic device as claimed in claim 1 , wherein:

the interface layer comprises a plurality of layers,

said plurality of layers comprising a first layer comprising p-doped ZnTe nanoparticles,

and a second layer comprising ZnTe nanoparticles.

10. A photovoltaic device as claimed in claim 9 , wherein:

the interface layer further comprises a third layer comprising Te metal nanoparticles disposed between the second layer comprising ZnTe nanoparticles and the absorber layer.

11. A photovoltaic device as claimed in claim 1 , wherein:

said interface layer comprises a plurality of layers,

said plurality of layers comprises a first layer comprising Cu x Te where 1≦x≦2 nanoparticles,

and a second layer comprising ZnTe nanoparticles.

12. A photovoltaic device as claimed in claim 11 , wherein:

the interface layer further comprises a third layer disposed between the second layer and the absorber layer,

said third layer comprising a material selected from the group consisting of Te metal nanoparticles, Cd x Te y where x≠y nanoparticles and CdZnTe nanoparticles.

13. A photovoltaic device as claimed in claim 1 , wherein:

the interface layer comprises at least three layers, wherein

a first interface layer comprises Cd 1-x Zn x Te nanoparticles that are sintered where x=0,

a second interface layer comprises Cd 1-x Zn x Te nanoparticles that are sintered where x≠0, and

a third interface layer in between the first and second interface layer said layer comprising Cd 1-x Zn x Te nanoparticles that are sintered where 0≦x≦1.

14. A photovoltaic device as claimed in claim 1 , wherein:

the interface layer comprises a plurality of layers,

said plurality of layers comprises a first layer comprising p-doped ZnTe nanoparticles that are sintered,

and a second layer comprising ZnTe nanoparticles that are sintered.

15. A photovoltaic device as claimed in claim 14 , wherein:

the interface layer further comprises a third layer comprising Te metal nanoparticles that are sintered disposed between the second layer comprising ZnTe nanoparticles that are sintered and the absorber layer.

16. A photovoltaic device as claimed in claim 1 , wherein:

said interface layer comprises a plurality of layers,

said plurality of layers comprises a first layer comprising Cu x Te where 1≦x≦2 nanoparticles that are sintered, and

a second layer comprising ZnTe nanoparticles that are sintered.

17. A photovoltaic device as claimed in claim 16 , wherein:

the interface layer further comprises a third layer disposed between the second layer and the absorber layer,

said third layer comprises a material selected from the group consisting of Te metal nanoparticles that are sintered, Cd x Te y where x≠y nanoparticles that are sintered and CdZnTe nanoparticles that are sintered.

18. A photovoltaic device as claimed in claim 1 , wherein:

the interface layer comprises at least three layers, wherein

a first interface layer comprises Cd 1-x Zn x Te nanoparticles that are sintered where x=0,

a second interface layer comprises Cd 1-x Zn x Te nanoparticles that are sintered where x≠0, and

a third interface layer in between the first and second interface layer said layer comprising Cd 1-x Zn x Te nanoparticles that are sintered where 0≦x≦1.

19. A photovoltaic device as claimed in claim 4 , wherein:

said thin film comprises a material selected from the group consisting of Cu x Te where 1≦x≦2, ZnTe, p doped ZnTe, Cd x Te y where x≠y, Cu doped CdTe, CdZnTe, Sb 2 Te 3 , Bi 2 Te 3 and Te metal.

20. A photovoltaic device as claimed in claim 19 , wherein:

the interface layer comprises a Te metal thin film.