Minimally color changing n-type ion storage layers, electrochromic devices made therewith, and related methods
Ion-storage layers for electrochromic devices (ECDs) that are tuned to be minimally color changing (MCC) during operation of the ECDs. In some embodiments, an ion-storage layer is composed of an n-type metal oxide that complements a p-type electrochromic (EC) layer, such as an EC layer made of a p-type EC polymer. In some embodiments, an ion-storage layer may be tuned to be MCC by configuring an ion-storage layer to have a total charge density that is higher than the total charge density of a corresponding EC layer or to have a coloration efficiency lower than the coloration efficiency of the corresponding EC layer, or both. Methods for preparing ion-storage layers are disclosed, including methods for creating highly structured metal oxide having reduced coloration efficiencies. ECD devices incorporating MCC ion-storage layers are also disclosed.
1. An electrochromic device, comprising:
a working electrode that includes an electrochromic layer comprising an electrochromic material of a p-type and having a coloration efficiency and a total charge density; and
a counter electrode that includes an ion-storage layer comprising an n-type metal oxide and having a coloration efficiency and a total charge density;
wherein:
the coloration efficiency of the electrochromic layer is greater than the coloration efficiency of the ion-storage layer; or
the total charge density of the counter electrode is greater than the total charge density of the electrochromic layer; or
the coloration efficiency of the electrochromic layer is greater than the coloration efficiency of the ion storage layer and the total charge density of the counter electrode is greater than the total charge density of the electrochromic layer.
2. The electrochromic device of claim 1 , wherein the coloration efficiency of the ion-storage layer is equal to or less than about 50 cm 2 C −1 .
3. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 100 cm 2 C −1 .
4. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 300 cm 2 C −1 .
5. The electrochromic device of claim 1 , wherein the coloration efficiency of the ion-storage layer is equal to or less than about 40 cm 2 C −1 .
6. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 100 cm 2 C −1 .
7. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 200 cm 2 C −1 .
8. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 300 cm 2 C −1 .
9. The electrochromic device of claim 1 , wherein the coloration efficiency of the ion-storage layer is equal to or less than about 30 cm 2 C −1 .
10. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 100 cm 2 C −1 .
11. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 200 cm 2 C −1 .
12. The electrochromic device of claim 1 , wherein the coloration efficiency of the electrochromic layer is at least about 300 cm 2 C −1 .
13. The electrochromic device of claim 1 , wherein the total charge density of the ion-storage layer is equal to or more than one times the total charge density of the electrochromic layer.
14. The electrochromic device of claim 1 , wherein the total charge density of the ion-storage layer is at least about 2 times the total charge density of the electrochromic layer.
15. The electrochromic device of claim 1 , wherein the n-type metal oxide comprises an amorphous metal oxide.
16. The electrochromic device of claim 1 , wherein the n-type metal oxide comprises Nb 2 O 5 .
17. The electrochromic device of claim 1 , wherein the Nb 2 O 5 is substantially amorphous in the ion-storage layer.
18. The electrochromic device of claim 1 , wherein the p-type electrochromic material comprises an electrochromic polymer.
19. The electrochromic device of claim 18 , wherein the total charge density of the ion-storage layer is equal to or more than the total charge density of the electrochromic layer.
20. The electrochromic device of claim 1 , wherein, when the electrochromic device is operating, the electrochromic layer operates in a full-charge regime while the ion-storage layer operates in an intermediate-charge regime.