Back contact for thin film solar cells
View Patent ↗Disclosed is a novel thin film photovoltaic device and a process of making. The device comprises an interface layer between the absorber layer and the electrode resulting in an improved back contact and improved device efficiency. The interface layer comprises a material comprising a M a -(Group VIA) b compound, where M is a transition metal the Group VIA designates Te, Se and/or S.
1. A photovoltaic device, comprising:
a substrate,
a back electrode layer,
an absorber layer comprising CdTe, and
an interface layer disposed between the back electrode layer and the absorber layer,
wherein
the interface layer comprises a first interface composition comprising Mo x Te y , where 0<x≦3 and 0<y≦4.
2. A photovoltaic device according to claim 1 , wherein:
the interface layer comprises MoTe 2 and/or Mo 3 Te 4 .
3. A photovoltaic device according to claim 2 , wherein:
the interface layer and/or the absorber layer are p-doped.
4. A photovoltaic device according to claim 3 , wherein:
the dopant comprises copper.
5. A photovoltaic device according claim 1 , wherein:
the interface layer comprises a first interface layer and a second interface layer,
wherein said first interface layer is disposed next to the absorber layer and said second interface layer is disposed next to said back electrode, and said first interface layer comprises a mixture comprising CdTe and said first interface composition and said
second interface layer comprises Mo x Te y , where 0<x≦3 and 0<y≦4.
6. A photovoltaic device according to claim 5 , wherein:
the first interface layer and said second interface layer are either the same or different and comprise MoTe 2 and/or Mo 3 Te 4 .
7. A photovoltaic device according to claim 5 , wherein:
the first interface layer, the second interface layer and/or the absorber layer are each independently doped or undoped.
8. A photovoltaic device, comprising:
a substrate,
a back electrode layer,
an absorber layer comprising CIGS and
an interface layer disposed between the back electrode layer and the absorber layer,
wherein
the interface layer comprises a first interface composition comprising Mo x Te y , where 0<x≦3 and 0<y≦4.
9. A photovoltaic device according to claim 8 , wherein:
the interface layer comprises MoTe 2 and/or Mo 3 Te 4 .
10. A photovoltaic device according to claim 9 , wherein:
the interface layer and/or the absorber layer are p-doped.
11. A photovoltaic device according to claim 10 , wherein:
the dopant comprises copper.
12. A photovoltaic device according claim 8 , wherein:
the interface layer comprises a first interface layer and a second interface layer,
wherein said first interface layer is disposed next to the absorber layer and said second interface layer is disposed next to said back electrode, and said first interface layer comprises a mixture of CIGS and said first interface composition, and said second interface layer comprises Mo x Te y , where 0<x≦3 and 0<y≦4.
13. A photovoltaic device according to claim 12 , wherein:
the first interface layer and said second interface layer are either the same or different and comprise MoTe 2 and/or Mo 3 Te 4 .
14. A photovoltaic device according to claim 12 , wherein:
the first interface layer, the second interface layer and/or the absorber layer are each independently doped or undoped.