Electro-optical element including IMI coatings

• US 8,368,992 B2
• Filed: 11/08/2010
• Issued: 02/05/2013
• Est. Priority Date: 03/03/2006
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Neuman, George A., Luten, Henry A., Anderson, John S., Forgette, Jeffrey A., VanderZwaag, Scott W.
• Primary Examiner(s): Lester, Evelyn A.
• Application Number:
  US12/941,724
• Publication Number:
  US 20110080629A1
• Time in Patent Office: 820 Days
• Field of Search: 359265-275
• US Class Current: 359/267
• CPC Class Codes: G02F 1/155 Electrodes
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 1/161 Gaskets; Spacers; Sealing of cells; Filling or closing of cells

Abstract

An electrochromic element comprises a first substrate having a first surface and a second surface opposite the first surface, a second substrate in spaced-apart relationship to the first substrate and having a third surface facing the second surface and a fourth surface opposite the third surface, and an electrochromic medium located between the first and second substrates, wherein the electrochromic medium has a light transmittance that is variable upon application of an electric field thereto. The electrochromic element further comprises a transparent electrode layer covering at least a portion of at least a select one of the first surface, the second surface, the third surface, and the fourth surface, wherein the transparent electrode layer comprises an insulator/metal/insulator stack. The materials utilized to construct the insulator/metal/insulator stack are selected to optimize optical and physical properties of the electrochromic element such as reflectivity, color, electrical switch stability, and environmental durability.

Claims

1. An electrochromic (EC) element comprising:

a first base including a first substrate having a first surface and a second surface opposite the first surface, the second surface carrying a transparent electrode layer that comprises a first optical thin-film structure including a first metal layer sandwiched between first and second dielectric layers, the first and second dielectric layers comprising materials having corresponding refractive indices greater than 1.7;

a second base having third and fourth surfaces, the first and second bases disposed in a parallel and spaced-apart relationship so as to define a gap therebetween, the second and third surfaces opposing each other; and

an electrochromic medium located in the gap;

wherein transmittance of the first base measured in light generated by a standard D65 illuminant exceeds 50 percent.

2. An EC element according to claim 1, wherein the transmittance of the first base exceeds 60 percent.

3. An EC element according to claim 1, wherein the first and second dielectric layers comprise materials having corresponding extinction coefficients smaller than 0.2.

4. An EC element according to claim 1, wherein the at least one metal layer includes silver configured to have thickness less than 300 Angstroms whereby the transmittance of the first base exceeds 70 percent.

5. An EC element according to claim 3, wherein at least one of the first and second dielectric layers comprises materials having corresponding refractive indices greater than 2.0 whereby the transmittance of the first base exceeds 80 percent.

6. An EC element according to claim 5, wherein the first and second dielectric layers comprise materials having corresponding extinction coefficients smaller than 0.04.

7. An EC element according to claim 1, wherein the transmittance of the first base exceeds 80 percent and sheet resistance of the optical thin-film stack is between 5 and 9 Ohms per square.

8. An EC element according to claim 7, wherein the sheet resistance of the optical thin-film stack is between 6 and 7 Ohms per square.

9. An EC element according to claim 1, wherein the at least one metal layer includes silver configured to have thickness less than 200 Angstrom whereby the transmittance of the first base exceeds 90 percent.

10. An EC element according to claim 1, wherein at least one of the first and second dielectric layers comprises materials having corresponding refractive indices greater than 2.5.

11. An EC element according to claim 1 characterized by a color rendering index of greater than or equal to 90.

12. An EC-element according to claim 1, further comprising a second optical thin-film structure including a second metal layer sandwiched between third and fourth dielectric layers, wherein the transmittance of the first base exceeds 80 percent.

13. An EC-element according to claim 12, wherein sheet resistance of the transparent electrode is below 2 Ohms per square.

14. An EC-element according to claim 12, further comprising an second electrode layer on the third surface, the transparent and second electrode layers being structured equivalently, the EC-element characterized by transmittance of more than 70 percent measured in light generated by a standard D65 illuminant.

15. An EC element according to claim 1 configured within a vehicular rearview assembly comprising at least one of an illumination assembly, a display, a voice activated system, a compass system, a telephone system, a highway toll booth interface, a telemetry system, a headlight controller, a rain sensor, a tire pressure monitoring system, a navigation system, a lane departure warning system, and an adaptive cruise control system.

16. An EC-element according to claim 1, configured as part of a window having a solar gain hear coefficient less than 0.5.

17. An EC element according to claim 1, wherein a relationship between a value T of transmittance of said transparent electrode layer, measured in percent in light generated by a standard D65 illuminant, and a value of sheet resistance R_sh of said first optical thin-film structure is described by an expression (28/R_SH+T+2)>

100.

18. An EC-element according to claim 17, wherein the value of R_SH is less than 6 Ohms/square and a value of (28/R_SH +T+2), normalized by a value of thickness of said transparent electrode, is greater than 0.3.

19. An EC element according to claim 1, wherein the first optical thin-film structure is configured to ensure that a color characteristic of light reflected by the EC element in a dark state is less than 20 C* units.

20. An EC element according to claim 1, wherein the first optical thin-film structure is configured to ensure that a color characteristic of light reflected by the EC element in a dark state is less than 10 C* units.

21. An EC element according to claim 1, wherein a difference between first and second color characteristic values of the EC element, measured in reflection of light generated by the standard D65 illuminant and incident onto the first base thereof, does not exceed 20 C* units, wherein the first color characteristic value corresponds to light incident onto the EC element along a normal to a surface of the EC element and the second color characteristic value corresponds to light incident onto the EC element at about 45 degrees with respect to such normal.

22. An EC element according to claim 1, configured as part of a window having a solar heat gain coefficient of less than 0.3.

23. An EC element according to claim 1 , configured as part of a window having a solar heat gain coefficient of less than 0.15.

24. An EC element according to claim 1, wherein a surface peak-to-valley roughness of a layer underlying the first metal layer is less than 15 angstroms.

25. An EC element according to claim 1, wherein the first metal layer of the first optical thin-film structure includes silver, and wherein said optical thin-film structure is deposited such as to ensure that a material of the first metal layer is characterized by at least one of (i) a corresponding bulk electrical resistivity value of less than 8 microOhm-centimeter and (ii) a real part of the refractive index of less than 0.12 in at least one portion of a spectral region between 380 and 780 nm.

26. An EC element according to claim 1, wherein a value of non-specular reflectance, measured in light generated by a standard D65 illuminant incident on and reflected by said first optical thin-film structure on the first substrate does not exceed 0.175.

27. An electrochromic (EC) element comprising:

a first base including a first substrate having a first surface and a second surface opposite the first surface, the second surface carrying a first transparent electrode layer that comprises a periodic optical thin-film structure having at least two periods, each of the periods including a metal layer sandwiched between first and second dielectric layers;

a second base having third and fourth surfaces, the first and second bases disposed in a parallel and spaced-apart relationship so as to define a gap therebetween, the second and third surfaces opposing each other; and

an electrochromic medium located in the gap;

wherein transmittance of the EC-element measured in light generated by a standard D65 illuminant exceeds 60 percent.

28. An EC-element according to claim 27, wherein the second base has a second transparent electrode layer on the third surface, the second transparent electrode layer having a structure equivalent to that of the first transparent electrode layer.

29. An EC-element according to claim 27, wherein sheet resistance of the first transparent electrode is below 2 Ohms per square.

30. An EC-element according to claim 27, wherein the metal layer includes silver, and first and second dielectric layers include at least one of indium zinc oxide and aluminum zinc oxide.

31. An EC-element according to claim 27, wherein thickness of the metal layer does not exceed 225 Angstroms.

32. An EC element according to claim 27 configured within a vehicular rearview assembly comprising at least one of an illumination assembly, a display, a voice activated system, a compass system, a telephone system, a highway toll booth interface, a telemetry system, a headlight controller, a rain sensor, a tire pressure monitoring system, a navigation system, a lane departure warning system, and an adaptive cruise control system.

33. An EC-element according to claim 27, configured as part of a window having a solar heat gain coefficient of less than 0.5.

34. An EC element according to claim 27, wherein the optical thin-film structure further contains a barrier material adjoining a boundary formed by the first metallic layer and an immediately adjacent layer, said barrier material including at least one of Ni alloy, a noble metal, a sulfur containing material, selenium, and zinc oxide.

35. An EC element according to claim 27, wherein a relationship between a value T of transmittance of said first transparent electrode layer, measured in percent in light generated by a standard D65 illuminant, and a value of sheet resistance R_sh of said periodic optical thin-film structure is described by an expression 28/R_SH+T+2>

100.

36. An EC-element according to claim 35, wherein the value of R_SH is less than 6 Ohms/square and a value of 28/R_SH+T+2>

100, normalized by a value of thickness of said first transparent electrode, is greater than 0.3.

37. An EC element according to claim 27, wherein the periodic optical thin-film structure is configured to ensure that a color characteristic of light reflected by the EC element in a dark state is less than 20 C* units.

38. An EC element according to claim 27, wherein the periodic optical thin-film structure is configured to ensure that a color characteristic of light reflected by the EC element in a dark state is less than 10 C* units.

39. An EC element according to claim 27, wherein a difference between first and second color characteristic values of the EC element, as measured in reflection of light generated by the standard D65 illuminant and incident onto the first base thereof, does not exceed 20 C* units, wherein the first color characteristic value corresponds to light incident onto the EC element along a normal to a surface of the EC element and the second color characteristic value corresponds to light incident onto the EC element at about 45 degrees with respect to such normal.

40. An EC element according to claim 27, configured as part of a window having a solar heat gain coefficient of less than 0.3.

41. An EC element according to claim 27 , configured as part of a window having a solar heat gain coefficient of less than 0.15.

42. An electrochromic (EC) element comprising:

a first base including a first substrate having a first surface and a second surface opposite the first surface, the second surface carrying a first electrode layer;

a second base having third and fourth surfaces, the first and second bases disposed in a parallel and spaced-apart relationship so as to define a gap therebetween, the second and third surfaces opposing each other; and

an electrochromic medium located in the gap;

wherein the first electrode layer comprises a first optical thin-film stack including a first metal layer sandwiched between first and second dielectric layers, the first electrode layer configured such that transmittance of the EC element measured in ultraviolet (UV) light does not exceed 50 percent.

43. An EC element according to claim 42, wherein at least one of the first and second dielectric layers comprises at least a select one of indium zinc oxide, indium tin oxide, aluminum zinc oxide, titanium oxide, zinc oxide, electrically conductive TiO2, CeOx, tin dioxide, silicon nitride, silicon dioxide, ZnS, chromium oxide, niobium oxide, ZrOx, WO₃, nickel oxide, IrO₂, whereby the transmittance of the EC element measured in ultraviolet (UV) light does not exceed 25 percent.

44. An EC element according to claim 42, wherein sheet resistance of the transparent electrode layer is between 5 and 9 Ohms per square.

45. An EC element according to claim 42 characterized by a color rendering index of greater than or equal to 90.

46. An EC element according to claim 42, wherein the first electrode layer comprises a second optical thin-films stack that includes a second metal layer sandwiched between third and fourth dielectric layers and that is adjoining the first optical thin-film stack, and wherein sheet resistance of the first electrode layer does not exceed 2 Ohms per square.

47. An EC element according to claim 42, further comprising a second electrode layer disposed on the third surface, the first and second electrode layers having equivalent structures.

48. An EC element according to claim 42, wherein the first electrode layer is configured to ensure that transmittance of the EC element, measured in ultraviolet (UV) light between about 300 nm and about 400 nm and expressed as a non-weighted average, does not exceed 25 percent.

49. An EC element according to claim 42, wherein the first electrode layer is configured to ensure that transmittance of the EC element, measured in ultraviolet (UV) light between about 300 nm and about 400 nm and expressed as a non-weighted average, does not exceed 15 percent.

50. An electrochromic (EC) element comprising:

a first substrate having a first surface and a second surface opposite the first surface;

a second substrate having third and fourth surfaces, the first and second substrates disposed in a parallel and spaced apart relationship so as to define a gap therebetween, the second and third surfaces opposing each other;

an electrochromic medium located in the gap, the electrochromic medium having a light transmittance that is variable upon the application of an electric field thereto; and

a transparent electrode layer covering at least a portion of at least a select one of the second surface and the third surface, wherein the transparent electrode layer comprises a stack including a first insulator layer, a metal layer, and a second insulator layer,

wherein any of the first and second insulator layers has an absolute stress of less than 3 GPa.

51. An EC element according to claim 50, wherein the absolute stress of any of the first and second insulator layers is less than 1.5 GPa.

52. An EC element according to claim 50, wherein the absolute stress of any of the first and second insulator layers is less than 0.5 GPa.