Active materials for electro-optic devices and electro-optic devices
View Patent ↗Tandem electro-optic devices and active materials for electro-optic devices are disclosed. Tandem devices include p-type and n-type layers between the active layers, which are doped to achieve carrier tunneling. Low bandgap conjugated polymers are also disclosed.
1. An inverted tandem polymer photovoltaic device, comprising:
a hole-extracting electrode;
an electron extracting electrode spaced apart from said hole-extracting electrode;
a first bulk hetero-junction polymer semiconductor layer;
a second bulk hetero-junction polymer semiconductor layer spaced apart from said first bulk hetero-junction polymer semiconductor layer; and
between said first and second bulk hetero-junction polymer semiconductor layers, a p-type layer in physical contact with one of the first and second bulk hetero-junction polymer semicondutor layers, and an n-type layer in physical contact with the other of the first and second bulk hetero-junction polymer semiconductor layer;
wherein at least one of the p-type layer and the n-type layer is doped to an extent that charge carriers tunnel through the p-type and/or n-type layer, and wherein one polymer used in either the first or second bulk hetero-junction polymer semiconductor layers has a structure of formula (I)
wherein R 1 , R 2 , and R 3 are independently selected from alkyl groups with up to 18 carbon atoms, aryls and substituted aryls;
X is selected from oxygen, sulfur, selenium and nitrogen atoms; and
Ar 1 and Ar 2 are each, independently, one to five monocyclic arylene, bicyclic arylene, and polycyclic arylene, monocyclic heteroarylene, bicyclic heteroarylene and polycyclic heteroarylene groups, either fused or linked.
2. A tandem polymer photovoltaic device according to claim 1 , wherein said electron-extracting electrode is transparent.
3. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type layer is closer to the electron-extracting electrode than said n-type layer.
4. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type layer is in physical contact with said n-type layer.
5. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type layer is doped to an extent that holes tunnel through the doped p-type layer.
6. The tandem polymer photovoltaic device according to claim 5 , wherein the p-type layer is doped with poly(styrene sulfonic acid), FeCl 3 , I 2 , or H 2 O 2 .
7. A tandem polymer photovoltaic device according to claim 1 , wherein said n-type layer is doped to an extent that electrons tunnel through the doped n-type layer.
8. The tandem polymer photovoltaic device according to claim 7 , whereins said n-type layer is doped with a low work function metal, Na, Li, Al, a low work function fluorides, LiF, CsF, a low work function salts, or Cs 2 CO 3 .
9. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type layer and said n-type layer both are doped to an extent that charge carriers tunnel through both doped layers.
10. A tandem polymer photovoltaic device according to claim 1 , wherein said n-type layer is comprises an n-type metal oxide.
11. A tandem polymer photovoltaic device according to claim 8 , wherein said n-type metal oxide is selected from the group consisting of ZnO, ZnOx, TiO2, TiOx and combinations thereof.
12. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type comprises a p-type metal oxide.
13. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type metal oxide is selected from the group consisting of MoO 3 , MoOx, V 2 O 5 , VOx, WO3, WOx, NiO, NiOx, graphene oxide, and combinations thereof.
14. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type layer is a p-type polymer layer.
15. A tandem polymer photovoltaic device according to claim 1 , wherein said p-type layer is PEDOT doped with poly(styrenesulfonic acid).
16. A tandem polymer photovoltaic device according to claim 1 , wherein said n-type layer is ZnO.
17. The tandem polymer photovoltaic device according to claim 1 further comprising an electron transporting layer between the electron extracting electrode and the first bulk hetero-junction polymer semiconductor layer or second bulk hetero-junction polymer semiconductor layer.
18. The tandem polymer photovoltaic device according to claim 1 further comprising a hole transporting layer between the hole extracting electrode and the first bulk hetero-junction polymer semiconductor layer or second bulk hetero-junction polymer semiconductor layer.
19. The tandem polymer photovoltaic device according to claim 1 , wherein the first bulk hetero-junction polymer semiconductor layer is closer to the electron extracting electrode than the second bulk hetero-junction polymer semiconductor layer.
20. The tandem polymer photovoltaic device according to claim 19 , wherein the polymer used in the first bulk hetero-junction polymer semiconductor layer has a wider bandgap than the polymer used in the second bulk hetero-junction polymer semiconductor layer.
21. The tandem polymer photovoltaic device according to claim 20 , wherein the polymer used in the first bulk hetero-junction polymer semiconductor layer has an absorbance maximum between about 400 nm and about 700 nm and the polymer used in the second bulk hetero-junction polymer semiconductor layer as an absorbance maximum between 700 nm and about 1000 nm.
22. The tandem polymer photovoltaic device according to claim 20 , wherein the absorbance maximum of the polymer used in the first bulk hetero-junction polymer semiconductor layer is more than 20 nm shorter than the absorbance maximum of the polymer used in the second bulk hetero-junction polymer semiconductor layer.
23. The tandem polymer photovoltaic device according to claim 20 , wherein the wavelength of the trailing edge at 60% of the maximum absorbance of the absorbance spectrum between 300 nm and 1000 nm of the polymer used in the first bulk hetero-junction polymer semiconductor layer is shorter than or equal to the wavelength of the leading edge at 60% of the maximum absorbance the absorbance spectrum between 300 nm and 1000 nm of the polymer used in the second bulk hetero-junction polymer semiconductor layer.
24. The tandem polymer photovoltaic device according to claim 20 , wherein the absorbance at the wavelength halfway between the absorbance maximum of the polymer used in the first bulk hetero-junction polymer semiconductor layer and the absorbance maximum of the polymer used in the second bulk hetero-junction polymer semiconductor layer in the sum of the normalized absorbance spectra measured between 300 nm and 1000 nm is greater than 10% and less than 150% of the normalized maximum absorbance of either polymer individually.