Transflective coatings for transparencies
An electro-optic element includes a first substantially transparent substrate defining a first surface and a second surface. A second substantially transparent substrate defines a third surface and a fourth surface. A primary seal is disposed between the first and second substrates. The seal and the first and second substrates define a cavity. An electro-optic material is positioned within the cavity. A transflective coating having a transmittance of between about 15% and about 60% in a visible wavelength band is positioned on at least one of the second and third surfaces. The transflective coating includes a first layer including an absorbing material, a second layer, a third layer including a low index metal and a fourth layer. The second and fourth layers include at least one of a dielectric material and a transparent conducting oxide.
1. An electro-optic element, comprising:
a first substantially transparent substrate defining a first surface and a second surface L wherein the first surface faces an interior;
a second substantially transparent substrate defining a third surface and a fourth surface, wherein the fourth surface faces an exterior;
a primary seal disposed between the first and second substrates, the seal and the first and second substrates defining a cavity therebetween;
an electro-optic material positioned within the cavity;
a transflective coating having a transmittance of between about 15% and about 60% in a visible wavelength band positioned on at least one of the second and third surfaces, comprising:
a first layer comprising an absorbing material;
a second layer;
a third layer comprising a low index metal; and
a fourth layer, wherein the second and fourth layers comprise at least one of a dielectric material and a transparent conducting oxide, wherein the first layer is closer to the first surface than the fourth layer; and
wherein an interior visible-band reflectance as measured proximate the first surface is less than or equal to about 20%.
2. The electro-optic element of claim 1 , wherein the transflective coating has a greater reflectance of visible light as measured from the fourth surface than the first surface.
3. The electro-optic element of claim 1 , wherein the transflective coating has a reflectance in the near-infrared spectrum of greater than about 50%.
4. The electro-optic element of claim 3 , wherein the transflective coating has a reflectance in the near-infrared spectrum of greater than about 70%.
5. The electro-optic element of claim 1 , wherein a reflection of a visible band of light as measured proximate the fourth surface is between about 15% and about 50%.
6. The electro-optic element of claim 5 , wherein a reflection of a visible band of light as measured proximate the fourth surface is between about 20% and about 40%.
7. The electro-optic element of claim 1 , wherein an absorption of at least one of a visible, near-infrared and total solar band of light as measured from the first surface is greater than an absorption of the band of light as measured proximate the fourth surface by greater than or equal to about 1.25 times.
8. The electro-optic element of claim 1 , wherein a color value is less than about 15 C* for at least one of transmittance, reflectance measured from the first surface and reflectance measured proximate the fourth surface.
9. The electro-optic element of claim 8 , wherein a color value is less than about 5 C* for at least one of transmittance, reflectance measured from the first surface and reflectance measured proximate the fourth surface.
10. The electro-optic element of claim 1 , wherein the electro-optic material is an electrochromic material and wherein at least one of the first and fourth layers is electrically conductive.
11. The electro-optic element of claim 1 , wherein the first layer has a thickness of between about 0.5 nm and about 10 nm.
12. The electro-optic element of claim 1 , wherein the second layer has a thickness of between about 40 nm and about 500 nm.
13. The electro-optic element of claim 1 , wherein a sheet resistance of the transflective coating is less than or equal to about 10 ohms/sq.
14. The electro-optic element of claim 13 , wherein a sheet resistance of the transflective coating is less than or equal to about 6 ohms/sq.
15. The electro-optic element of claim 14 , wherein a sheet resistance of the transflective coating is less than or equal to about 3 ohms/sq.
16. A transparency, comprising:
a substrate defining a first surface and a second surface, wherein the first surface faces
an interior; and
a transflective coating having a transmittance of between about 15% and about 60% positioned on at least one of the first and second surfaces, comprising:
a first layer comprising an absorbing material;
a second layer;
a third layer comprising a low index metal; and
a fourth layer, wherein the second and fourth layers comprise at least one of a dielectric material and a transparent conducting oxide,
further wherein the transflective coating has a greater reflectance of visible light as measured from the second surface than the first surface and an interior visible-band reflectance as measured proximate the first surface is less than or equal to about 20%.
17. The transparency of claim 16 , wherein the transflective coating has a reflectance in the near-infrared spectrum of greater than about 25%.
18. The transparency of claim 16 , wherein the transflective coating has a reflectance in the near-infrared spectrum of greater than about 70%.
19. The transparency of claim 16 , wherein the transflective coating has a delta C* of less than or equal to about 15 with angle shift of less than about 60 degrees.
20. The transparency of claim 19 , wherein the transflective coating has a delta C* of less than or equal to about 6 with angle shift up to about 45 degrees.