Photochromic-electrochromic compositions
A composition comprising a diarylethene photochromic anodic species, a cathodic species and an electrolyte that comprises a supporting electrolyte and a solvent. Electrochromic devices such as optical filters are prepared from such compositions.
1. A composition comprising:
(a) a first photochromic anodic species, wherein the first photochromic anodic species is a diarylethene, reversibly convertible between ring-closed and ring-open isomers;
(b) a cathodic species, wherein the cathodic species comprises a viologen, a substituted viologen, a phenazinium, a substituted phenazinium, a ferrocenium or a substituted ferrocenium salt, and wherein the cathodic species has a reduction potential at least 600 mV less anodic than a ring-closed oxidation potential of the first photochromic anodic species; and
(c) an electrolyte, wherein the electrolyte comprises:
(i) a supporting electrolyte; and
(ii) a solvent portion comprising one or more solvents.
2. The composition of claim 1 , wherein the first photochromic anodic species and the cathodic species are present in a ratio of from about 100:1 to about 2:1.
3. The composition of claim 1 , wherein the cathodic species has a reduction potential between −1.0 and +0.6 V referenced to Ag/AgCl.
4. The composition of claim 1 , wherein reduction of the cathodic species is reversible.
5. The composition of claim 1 , wherein the composition is transitionable from a light state to a dark state on exposure to light of less than 475 nm, 450 nm, or 400 nm, and from a dark state to a light state with application of a voltage.
6. The composition of claim 1 , wherein the first photochromic anodic species has an oxidation potential of from about 0.6V to about 1.3V.
7. The composition of claim 1 , comprising a second photochromic anodic species.
8. The composition of claim 7 , wherein ring-closed oxidation potentials of the photochromic anodic species are within 200 mV of one another, within 100 mV of one another, within 50 mV of one another or within 25 mV of one another.
9. The composition of claim 1 , further comprising a polymer, wherein the polymer comprises one or more monomeric units according to Formula VI:
wherein:
each of R 70 , R 71 , R 72 are independently H or a hydrocarbon group C n H 2n+1 ;
R 73 is H, C n H 2n+1 , C n H 2n OH, C n H 2n NCO, or
and
n is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
10. The composition of claim 9 , wherein the polymer comprises a pendant hydroxyl group, a pendant primary alcohol group, a pendant secondary alcohol group, a pendant epoxide group or a pendant isocyanate group.
11. The composition of claim 10 , wherein the polymer is cross-linked through the pendant hydroxyl group, the hydroxyl moiety of the pendant primary alcohol group, the hydroxyl moiety of the pendant secondary alcohol group, the pendant epoxide group or the pendant isocyanate group.
12. The composition of claim 9 , wherein the polymer is cross-linked via a urethane linkage.
13. The composition of claim 1 , wherein the photochromic anodic species are soluble in the electrolyte at a concentration of at least about 50 mM, 75 mM, 100 mM, or 200 mM, or wherein the cathodic species are soluble in the electrolyte at a concentration of at least about 5 mM, 10 mM, 25 mM, 50 mM, 75 mM, 100 mM or 200 mM.
14. An electrochromic device comprising the composition of claim 1 .
15. An optical filter comprising:
(a) a first substantially transparent substrate and a second substantially transparent substrate;
(b) a first electrode and a second electrode disposed on a surface of at least one of said substrates;
(c) a layer comprising the composition according to claim 1 disposed between the first substantially transparent substrate and the second substantially transparent substrate, and in contact with the first electrode and the second electrode.
16. The optical filter according to claim 15 , further comprising a UV light blocker capable of blocking UV light at wavelengths of less than about 365 nm, less than about 375 nm, less than about 385 nm, less than about 400 nm, or less than about 410 nm.
17. A method of preparing an optical filter, the method comprising:
(a) disposing a layer of the composition according to claim 1 between a first substantially transparent substrate and a second substantially transparent substrate wherein a first electrode and a second electrode are disposed on a surface of at least one of the substrates such that the layer is in contact with each electrode; and
(b) providing an electrical connector for connecting the first electrode and the second electrode to a source of electric voltage.
18. An optical filter comprising:
(a) a first substantially transparent substrate and a second substantially transparent substrate;
(b) a first electrode disposed on a surface of the first substantially transparent substrate;
(c) a second electrode disposed on a surface of the second substantially transparent substrate;
(d) a cathodic material disposed on a surface of the first electrode, wherein the cathodic material comprises a viologen, a substituted viologen, a phenazinium, a substituted phenazinium, a ferrocenium or a substituted ferrocenium salt, and wherein the cathodic material has a reduction potential at least 600 mV less anodic than a ring-closed oxidation potential of a first photochromic anodic species; and
(e) a layer of switching material disposed between the first substantially transparent substrate and the second substantially transparent substrate and in contact with the first electrode and the second electrode, the layer of switching material comprising:
(i) at least one photochromic anodic species, wherein the first photochromic anodic species of the at least one photochromic anodic species is a diarylethene, reversibly convertible between ring-closed and ring-open isomers; and
(ii) an electrolyte comprising a supporting electrolyte and a solvent portion comprising one or more solvents; and
wherein the cathodic material is insoluble in the layer of switching material.