Metal complex-based electron-transfer mediators in dye-sensitized solar cells
View Patent ↗This present invention provides a metal-ligand complex and methods for using and preparing the same. In particular, the metal-ligand complex of the present invention is of the formula: L a -M-X b where L, M, X, a, and b are those define herein. The metal-ligand complexes of the present invention are useful in a variety of applications including as electron-transfer mediators in dye-sensitized solar cells and related photoelectrochromic devices.
1. A metal-ligand complex of the formula:
L a -M
wherein
a is 2;
M is cobalt; and
L is a ligand of the formula:
wherein each R 1 is independently alkyl, cycloalkyl, haloalkyl, heteroaryl, carboxy, or amide.
2. The metal-ligand complex according to claim 1 , wherein each R 1 is independently alkyl.
3. The metal-ligand complex according to claim 2 , wherein each R 1 is independently selected from the group consisting of ethyl and tert-butyl.
4. The metal-ligand complex according to claim 3 , wherein R 1 is ethyl.
5. The metal-ligand complex according to claim 3 , wherein R 1 is tert-butyl.
6. A dye-sensitized solar cell comprising:
a cathode;
a photoanode comprising a dye-sensitizer; and
an electron-transfer mediator operatively connected to said dye-sensitizer, wherein said electron-transfer mediator is a metal-ligand complex of the formula:
L a -M-X b
wherein
a is an integer from 1 to 6;
b is an integer from 0 to 5,
provided the sum of a and b equal the appropriate total number of ligands present on the metal M;
M is a transition metal;
each X is independently a co-ligand; and
each L is independently a substituted polypyridine ligand, wherein at least one of the substituent of the polypyridine ligand is other than a methyl group.
7. The dye-sensitized solar cell according to claim 6 , wherein M is cobalt.
8. The dye-sensitized solar cell according to claim 6 , wherein b is 0.
9. The dye-sensitized solar cell according to claim 8 , wherein L is selected from the group consisting of a bidentate polypyridine, tridentate polypyridine, and a mixture thereof.
10. The dye-sensitized solar cell according to claim 9 , wherein a is 2 or 3.
11. The dye-sensitized solar cell according to claim 10 , wherein a is 2.
12. The dye-sensitized solar cell according to claim 11 , wherein L is a tridentate polypyridine ligand of the formula:
wherein each R 1 is independently hydrogen, alkyl, cycloalkyl, aryl, haloalkyl, hereroaryl, carboxy, or amide provided at least one R 1 is other than hydrogen or methyl.
13. The dye-sensitized solar cell according to claim 12 , wherein each R 1 is independently hydrogen or alkyl.
14. The dye-sensitized solar cell according to claim 13 , wherein each R 1 is independently selected from the group consisting of ethyl and tert-butyl.
15. The dye-sensitized solar cell according to claim 10 , wherein a is 3.
16. The dye-sensitized solar cell according to claim 15 , wherein L is a bidentate polypyridine ligand of the formula:
wherein each of R 2 and R 3 is independently hydrogen, alkyl, aryl, carboxy, amide, cycloalkyl, haloalkyl, or heteroaryl provided at least one of R 2 or R 3 is other than hydrogen or methyl.
17. The dye-sensitized solar cell according to claim 16 , wherein each of R 2 independently selected from the group consisting of hydrogen, alkyl, aryl, carboxy, and amide.
18. The dye-sensitized solar cell according to claim 17 , wherein each of R 2 is independently selected from the group consisting of hydrogen, alkyl, N,N-dialkyl amide, alkyl carboxy, phenyl, and haloalkyl.
19. The dye-sensitized solar cell according to claim 18 , wherein each of R 2 is independently selected from the group consisting of hydrogen, methyl, tert-butyl, 3-pentyl, nonyl, N,N-dibutyl amide, tert-butyl carboxy, phenyl, and haloalkyl.
20. The dye-sensitized solar cell according to claim 15 , wherein L is a bidentate polypyridine ligand of the formula:
wherein each or R 4 and R 5 is independently hydrogen, alkyl, aryl, carboxy, amide, cycloalkyl, haloalkyl, or heteroaryl provided at least one R 4 or R 5 is other than hydrogen or methyl.
21. The dye-sensitized solar cell according to claim 20 , wherein at least one of R 4 is aryl.
22. The dye-sensitized solar cell according to claim 21 , wherein at least one of R 4 is phenyl.
23. The dye-sensitized solar cell according to claim 22 , wherein R 5 is hydrogen.
24. The dye-sensitized solar cell of claim 6 , wherein the electron-transfer mediator comprises a transition metal-polypyridine ligand complex selected from a moiety of the formula:
and a mixture thereof,
wherein
M is a transition metal;
each R 1 is independently alkyl;
each of R 2 , R 3 , R 4 , and R 5 is independently hydrogen, alkyl, aryl, carboxy, amide, cycloalkyl, heteroaryl, or haloalkyl provided at least one of (R 2 or R 3 ) and (R 4 or R 5 ) are other than hydrogen or methyl.
25. The dye-sensitized solar cell of claim 24 , wherein M is cobalt.
26. The dye-sensitized solar cell of claim 24 further comprising a lithium salt.
27. A battery comprising a solar cell, a photoanode comprising a dye-sensitizer, and an electron-transfer mediator, wherein said electron-transfer mediator is a metal-ligand complex of the formula:
L a -M-X b
wherein
a is an integer from 1 to 6;
b is an integer from 0 to 5,
provided the sum of a and b equal the appropriate total number of ligands present on the metal M;
M is a transition metal;
each X is independently a co-ligand; and
each L is independently a substituted polypyridine ligand, wherein at least one of the substituent of the polypyridine ligand is other than a methyl group.
28. A photoelectrochromic device comprising a dye and an electron-transfer mediator, wherein said electron-transfer mediator is a metal-ligand complex of the formula:
L a -M-X b
wherein
a is an integer from 1 to 6;
b is an integer from 0 to 5,
provided the sum of a and b equal the appropriate total number of ligands present on the metal M;
M is a transition metal;
each X is independently a co-ligand; and
each L is independently a substituted polypyridine ligand, wherein at least one of the substituent of the polypyridine ligand is other than a methyl group.