Electrochromic or photoelectrochromic device

• US 20020181068A1
• Filed: 06/07/2002
• Published: 12/05/2002
• Est. Priority Date: 03/15/1996
• Status: Active Grant

• Current Assignee: Lorenz Walder, Michael Gratzel, Pierre Bonhote
• Original Assignee: Lorenz Walder, Michael Gratzel, Pierre Bonhote
• Inventors: Gratzel, Michael, Bonhote, Pierre, Walder, Lorenz
• Granted Patent: US 6,734,305 B2
• Time in Patent Office: Days
• US Class Current: 359/265
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02F 1/155 Electrodes
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials

Abstract

An electrochromic or photoelectrochromic device possessing the property of changing color under the effect of an electric voltage and/or of a variation in the intensity of a light radiation, this device comprising at least one cathode and one anode, at least one of these electrodes being constituted at least in part of a transparent or translucent substrate bearing an electrically conductive coating, and an electrolyte arranged between these electrodes, and an electric circuit connecting said cathode and anode, characterized in that at least one of these electrodes carries a coating constituted of at least one nanocrystalline layer of at least one semiconductive material, having a roughness factor equal to at least 20, and a monolayer of electrically active molecules or of an electrically active polymer, said monolayer being absorbed on the surface of this coating, and in that the device contains at least one auxiliary electrically active compound, possibly dissolved in the electrolyte, having the property of being capable of being oxidized or reduced in a reversible manner.

Claims

1. An electrochromic or photoelectrochromic device possessing the property of changing colour under the effect of an electric voltage and/or of a variation in the intensity of a light radiation, this device comprising at least one cathode and one anode, at least one of these electrodes being constituted at least in part of a transparent or translucent substrate bearing an electrically conductive coating, and an electrolyte arranged between these electrodes, and an electric circuit connecting said cathode and anode, characterised in that at least one of these electrodes carries a coating constituted of at least one nanocrystalline layer of at least one semiconductive material, having a roughness factor equal to at least 20, and a monolayer of electrically active molecules or of an electrically active polymer, said monolayer being adsorbed on the surface of this coating, and in that the device contains at least one auxiliary electrically active compound, possibly dissolved in the electrolyte, having the property of being capable of being oxidised or reduced in a reversible manner.

2. A device according to claim 1, characterised in that the said semiconductor is a titanium-, zirconium-, hafnium-, vanadium-, niobium-, tantalum-, molybdenum-, tungsten-, zinc-, strontium-, iron-, nickel-, silver- oxide or a perovskite of the said metals.

3. A device according to claim 1, characterised in that the electrical circuit comprises a current-voltage source.

4. A photoelectrochromic device according to claim 1, characterised in that its coloration adapts automatically to the light intensity.

5. An elelectrochromic device according to claims 1 to 3, characterised in that the cathode carries an adsorbed monolayer of at least one type of electrochromophoric molecules, which molecules comprise at least one adsorbable attachment group, possibly a polymerisable or condensible group, and at least one type n electrochromophoric group of which the property is to be colourless in the oxidised state and coloured in the reduced state, in that the auxiliary electroactive compound is fixed at the anode in the form of an electroactive coating, and in that the said electrolytic solution between the electrodes contains at least one electrochemically inert salt in solution in a solvent.

6. An elelectrochromic device according to claim 5, characterised in that the said electrochromophoric molecules comprise, as the electrochromophoric group, a group selected from among N,N′

-dialkylbipyridinium or the diimide of naphthalene-1,4,5,8-tetracarboxylic acid.

7. An elelectrochromic device according to claim 5, characterised in that the said electrochromophoric molecules comprise, as the attachment group, carboxylate, salicylate, catecholate or phosphonate group, and, if applicable, as the polymerisable group, vinyl or pyrrole group, or, as the condensible group, alcohol or amine group.

8. An elelectrochromic device according to claim 5, characterised in that the cathode and anode are transparent.

9. An elelectrochromic device according to claim 5, characterised in that a reflective screen is placed behind the cathode and the system is therefore opaque.

10. An elelectrochromic device according to claim 9, characterised in that the reflective screen is constituted of a microcrystalline semiconductor layer, said semiconductor layer being according to claim 1, deposited on the cathode face located inside the system.

11. An elelectrochromic device according to claim 10, characterised in that the anode is a metal plate.

12. An elelectrochromic device according to claim 11, characterised in that the said metal is zinc.

13. An elelectrochromic device according to claim 5, characterised in that the said electroactive coating is constituted of a dense electrochemically deposited layer.

14. An elelectrochromic device according to claim 13, characterised in that this dense layer is reduced Prussian blue (“

Prussian white”

, poly-ferrocyanide iron(II)).

15. An elelectrochromic device according to claim 13, characterised in that the said dense layer is an electroactive organic polymer.

16. An elelectrochromic device according to claim 13, characterised in that the said dense layer is constituted of a composite material comprising an electroactive material.

17. An elelectrochromic device according to claim 5, characterised in that the electroactive coating is constituted of a nanocrystalline semiconductor layer, of which the roughness factor is greater than 20, on the surface of which is adsorbed a monolayer of electroactive molecules or an electroactive polymer.

18. An elelectrochromic device according to claim 17, characterised in that the electroactive molecules are electrochromophoric molecule comprising an adsorbable attachment group, possibly a polymerisable or condensible group, and a type p electrochromophoric group of which the property is to be colourless in the reduced state and coloured in the oxidised state.

19. An elelectrochromic device according to claim 11, characterised in that the electrolytic solution likewise contains a metal salt of which metal the anode is constituted.

20. An elelectrochromic device according to claim 5, characterised in that the said solvent is an electrochemically inert liquid salt.

21. An elelectrochromic device according to claim 20, characterised in that the said liquid salt is of 1-ethyl-3-methyl-imidazolium- or 1-propyl-2,3-dimethyl-imidazolium trifluoromethanesulfonate or -bis(trifluoromethylsulfonyl)amide.

22. An elelectrochromic device according to claim 5, characterised in that the said solvent is chosen from among acetonitrile, butyronitrile, glutaronitrile, methoxy-propionitrile, dimethlysulfoxide, sulfolane, dimethylformamide, dimethylacetamide, N-methyl oxazolidinone, dimethyl-tetrahydropyrimidinone (DMPU).

23. An elelectrochromic device according to claim 5, characterised in that the said electrochemically inert salt or salts are selected from among tetraalkyl-ammonium-, 1,3-dialkylimidazolium- or lithium hexafluorophosphate, -trifluoro-methanesulfonate, -bis(trifluoromethylsulfonyl)amide, or -perchlorate.

24. A photoelelectrochromic device according to claim 4, characterised in that the anode carries a nanocrystalline semiconductor layer of which the roughness factor is greater than 20, on the surface of which semiconductor a monolayer of a sensitising agent is adsorbed, said sensitising agent comprising a chromophoric group, an adsorbable attachment group, and possibly a polymerisable or condensible group.

25. A photoelelectrochromic device according to claim 4, characterised in that the anode carries a nanocrystalline semiconductor layer of which the roughness factor is greater than 20, on the surface of which semiconductor a monolayer of electrochromophoric molecules is adsorbed, said molecules comprising an adsorbable attachment group, an type p electrochromophoric group of which the property is to be colourless in the reduced state and coloured in the oxidised state, and possibly a polymerisable or condensible group.

26. A photoelelectrochromic device according to claim 4, characterised in that the anode bears a nanocrystalline semiconductor layer of which the roughness factor is greater than 20, lacking in adsorbed molecules.

27. A photoelelectrochromic device according to claim 24, characterised in that the said sensitising agent comprises a type p electrochromophoric group linked to the chromophore of which the property is to be colourless in the reduced state and coloured in the oxidised state.

28. A photoelelectrochromic device according to claim 24, characterised in that the said sensitising agent and the said electrochromophoric molecules are co-adsorbed on the anode, in the proportions of 1 to 1, of 1 to 2, or of 1 to 5 or more.

29. A photoelelectrochromic device according to claim 4, characterised in that the cathode carries a nanocrystalline semiconductor layer of which the roughness factor is greater than 20, on the surface of which semiconductor is adsorbed a monolayer of at least one type of electrochromophoric molecules, which comprise at least one adsorbable attachment group, at least one type n electrochromophoric group of which the property is to be colourless in the oxidised state and coloured in the reduced state, and possibly a polymerisable or condensible group.

30. A photoelelectrochromic device according to claim 4, characterised in that the said electroactive auxiliary compound is an electrochemically active salt, capable of transporting electrons between cathode and anode, dissolved in the said solution.

31. A photoelelectrochromic device according to claim 4, characterised in that the said electroactive auxiliary compound is a type p electrochromophoric group linked to the chromophore, and in that the said solution only contains electrochemically inactive salts.

32. A photoelelectrochromic device according to claim 30, characterised in that the said electrochemically active salt is an type p or type n electrochromophore in solution.

33. A photoelelectrochromic device, for reversible data storage, according to claim 4, characterised in that a reflective screen is placed behind the anode.

34. A photoelelectrochromic device according to claim 33, characterised in that the reflective screen is constituted of a layer of microcristalline semiconductor, deposited on the face of anode in the inside of the device.

35. A photoelelectrochromic device, for reversible data storage, according to claim 4, characterised in that the cathode is made of a dense layer of electroactive material, capable to be reversibly reduced, said dense layer being deposited on a layer of conductive plastic or glass.

36. A photoelelectrochromic device, for reversible data storage, according to claim 35, characterised in that this dense layer is an electroactive organic polymer or a composite material comprising an electroactive material.

37. A electrochromic or photoelectrochromic device according to claim 1, characterised in that it comprises an auxiliary electrode in addition to the anode and cathode.

39. A type n electrochromophoric compound according to claim 38, characterised in that it further comprises a pyrrole, thiophene, vinyl, alcohol, or amine group.

38. A type n electrochromophoric compound, characterised in that it is formed of one or more viologen groups (4,4′

-dialkyl-bipyridinium) linked by one or more alkyl chains which may include one or more phenylene groups and terminated by a phosphonate, salicylate, or catecholate group.

40. A type n electrochromophoric compound, characterised in that it is formed of one or more diimide of naphthalene-1,4,5,8-tetracarboxylic acid groups linked by one or more alkyl chains which may include one or more phenylene groups and terminated by a phosphonate, salicylate, or catecholate group.

41. A type n electrochromophoric compound according to claim 40, characterised in that it further comprises a pyrrole, thiophene, vinyl, alcohol, or amine group.

42. A type p electrochromophoric compound, characterised in that it is formed of one or more triarylamine groups linked by one or more alkyl chains which may include one or more phenylene groups and terminated by a phosphonate, salicylate, or catecholate group.

43. A type p electrochromophoric compound according to claim 42, characterised in that it further comprises a pyrrole, thiophene, vinyl, alcohol, or amine group.

44. A sensitising agent compound to which are linked one or more type p electrochromophoric groups, characterised in that the sensitising agent is a ruthenium complex comprising polypyridine ligands of which at least one possesses one or more phosphonate, carboxylate, salicylate, or catecholate groups and at least one or more triarylamine groups.

45. A sensitising agent compound according to claim 44, characterised in that it further comprises a pyrrole, thiophene, vinyl, alcohol, or amine group.