Electrochromic material with improved lifetime

• US 7,521,005 B2
• Filed: 12/20/2004
• Issued: 04/21/2009
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Park, Jin Young, Choi, Shin Jung, Lim, Young Hee, Jang, Ki Seok, Kim, Sang Ho, Kwon, Won Jong
• Primary Examiner(s): Kugel; Timothy J.
• Application Number:
  US11/015,282
• Publication Number:
  US 20050179012A1
• Time in Patent Office: 1,583 Days
• Field of Search: 252/582, 252/583, 252/586, 255/258
• US Class Current: 252/583
• CPC Class Codes: C09K 2211/1011 Condensed systems
• CPC Class Codes: C09K 2211/1022 bridged by heteroatoms, e.g. N, P, Si or B
• CPC Class Codes: C09K 2211/1029 containing one nitrogen atom as the heteroatom
• CPC Class Codes: C09K 2211/1033 with oxygen
• CPC Class Codes: C09K 2211/1037 with sulfur
• CPC Class Codes: C09K 2211/104 with other heteroatoms
• CPC Class Codes: C09K 2211/1044 containing two nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/1059 containing three nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/187 of the iron group metals, i.e. Fe, Co or Ni
• CPC Class Codes: C09K 9/02 Organic tenebrescent materials
• CPC Class Codes: G02F 1/1503 caused by oxidation-reduction reactions in organic liquid solutions, e.g. viologen solutions

Abstract

Disclosed are viologen derivatives as an electrochromic material having improved stability and lifetime, a metal oxide electrode including the same, and an electrochromic device using the viologen derivative as an electrochromic material. The viologen derivative includes a suitable regulator group capable of increasing ΔE that is a potential difference between E₁ (potential at the first redox reaction) and E₂ (potential at the second redox reaction). When ΔE increases, the mole fraction of viologen molecules present in the second reduction state decreases. Therefore, it is possible to lower the mole fraction of viologen molecules present in an irreversibly reduced state at an applied potential, thereby increasing the lifetime of an electrochromic material and an electrochromic device.

Claims

1. An electrochromic material, which comprises a viologen compound having a cationic regulator group linked to 4,4′

-bipyridinium.

2. The electrochromic material according to claim 1, wherein the regulator group is selected from the group consisting of functional groups represented by the following formulae 2 to 5:

4. The electrochromic material according to Claim 1 or 3, wherein the regulator group is linked directly to 4,4′

-bipyridinium without any linker, or linked to 4,4′

-bipyridinium by means of a linker.

5. The electrochromic material according to claim 4, wherein the linker is represented by any one formula selected from the group consisting of the following formulae 22 to 25:

6. The electrochromic material according to claim 1 or 3, wherein an anchor group capable of being bonded to a metal oxide electrode is further linked to 4,4′

-bipyridinium, the anchor group being linked directly to 4,4′

-bipyridinium without any linker, or linked to 4,4′

-bipyridinium by means of a linker.

7. The electroebromic material according to claim 6, wherein the anchor group is selected from the group consisting of functional groups represented by the following formulae 17 to 21:

8. The electrochromic material according to claim 6, wherein the linker is represented by any one formula selected from the group consisting of the following formulae 22 to 25:

9. The electrochromic material according to claim 1 or 3, wherein the electrochromic material comprises a viologen compound having a regulator group linked to 4,4′

-bipyridinium having three oxidation states, bipm²⁺, bipm⁺ and bipm⁰, as represented by the following scheme, the regulator group being capable of increasing Δ

E that is a potential difference between E₁ and E₂;

10. The electrochromic material according to claim 9, wherein the regulator group is capable of increasing Δ

E by 0 04V or more.

11. The electrochromic material according to claim 1 or 3, wherein the viologen compound further includes a counterion, the counterion being Cl⁻

, Br⁻

, BF₄⁻

, PF₆⁻

, ClO₄⁻

or (CF₃SO₂)₂N⁻

.

13. A metal oxide electrode coated with an electrochromic material as defined in claim 1 or 3

14. An electrochromic device comprising a first electrode disposed on a transparent or translucent substrate, a second electrode and an electrolyte, wherein at least one of the first electrode, second electrode and electrolyte comprises an electrochromic material as defined in claim 1 or 3.

3. An electrochromic material, which comprises a viologen compound having an additional redox-coupled functional regulator group linked to 4,4′

-bipyridinium, the regulator group being capable of forming a redox couple electrically with a bipyridinium ring.

12. The electrochromic material according to claim 3, wherein the regulator group is selected from the group consisting of functional groups represented by the following formulae 7 to 16: