Highly-fluorescent and photo-stable chromophores for wavelength conversion

• US 10,461,201 B2
• Filed: 04/27/2018
• Issued: 10/29/2019
• Est. Priority Date: 01/04/2013
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Rachwal, Mila, Yamamoto, Michiharu
• Primary Examiner(s): Willis, Douglas M
• Application Number:
  US15/965,329
• Publication Number:
  US 20180248053A1
• Time in Patent Office: 550 Days
• Field of Search: 544345
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1011 Condensed systems
• CPC Class Codes: C09K 2211/1014 bridged by heteroatoms, e.g. N, P, Si or B
• 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 2211/1044 containing two nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/1051 with sulfur
• CPC Class Codes: C09K 2211/1059 containing three nitrogen atoms as heteroatoms
• CPC Class Codes: H01L 31/02322 comprising luminescent members, e.g. fluorescent sheets upon the device
• CPC Class Codes: H01L 31/055 where light is absorbed and re-emitted at a different wavelength by the optical element directly associated or integrated with the PV cell, e.g. by using luminescent material, fluorescent concentrators or up-conversion arrangements
• CPC Class Codes: H10K 85/657 Polycyclic condensed heteroaromatic hydrocarbons
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

The invention provides highly fluorescent materials comprising a heterocyclic systems represented by formula (I):

wherein i is 0 and Het is

wherein X is selected from the group consisting of —N(A₀)-. The chromophores are particularly useful for absorption and emission of photons in the visible and near infrared wavelength range. The photo-stable highly luminescent chromophores are useful in various applications, including in wavelength conversion films. Wavelength conversion films have the potential to significantly enhance the solar harvesting efficiency of photovoltaic or solar cell devices.

Claims

1. A chromophore represented by formula (I):

2. The chromophore of claim 1, wherein A₀ is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl and —

(CH₂)₂O(CH₂)₃CH₃.

3. The chromophore of claim 1, wherein A₀ is C_1-8 alkyl.

4. The chromophore of claim 1, wherein:

D₁ and D₂ are each independently selected from the group consisting of;

5. The chromophore of claim 1, wherein:

R_a is selected from the group consisting of;

(1) hydrogen;

(2) C_1-8 alkyl, optionally substituted by;

(a) C_1-6 alkoxy;

or

(b) C_6-10 aryl, optionally substituted by halo or CN; and

(3) C_6-10 aryl, optionally substituted by;

(a) halo;

or

(b) CN; and

R_b is selected from the group consisting of;

(1) hydrogen;

(2) C_1-8 alkyl, optionally substituted by;

(a) C_1-6 alkoxy;

or

(b) C_6-10 aryl, optionally substituted by halo or CN; and

(3) C_6-10 aryl, optionally substituted by;

(a) halo;

or

(b) CN;

or

R_a and R_b, together with the carbon atoms to which they are attached, form a polycyclic ring system.

6. The chromophore of claim 5, wherein:

R_a is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, 2-ethylhexyl, 2-butoxyethyl, benzyl, 4-fluorobenzyl or 2,6-difluorobenzyl, phenyl and 3,4-dicyanophenyl; and

R_b is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, 2-ethylhexyl, 2-butoxyethyl, benzyl, 4-fluorobenzyl or 2,6-difluorobenzyl, phenyl and 3,4-dicyanophenyl.

7. The chromophore of claim 1, wherein:

R_a and R_b, together with the carbon atoms to which they are attached, form a monocyclic ring or polycyclic ring system selected from the group consisting of;

8. The chromophore of claim 1, wherein:

Het is;

9. The chromophore of claim 1, wherein:

Het is;

10. A wavelength conversion luminescent medium comprising an optically transparent polymer matrix and at least one luminescent dye comprising a chromophore of claim 1.

11. The wavelength conversion luminescent medium of claim 10, wherein the optically transparent polymer matrix comprises a substance selected from the group consisting of polyethylene terephthalate, polymethyl methacrylate, polyvinyl butyral, ethylene vinyl acetate, ethylene tetrafluoroethylene, polyimide, amorphous polycarbonate, polystyrene, siloxane sol-gel, polyurethane and polyacrylate, and combinations thereof.

12. The wavelength conversion luminescent medium of claim 10, wherein the refractive index of the optically transparent polymer matrix is in the range of 1.4 to 1.7.

13. The wavelength conversion luminescent medium of claim 10, wherein the at least one luminescent dye is present in the optically transparent polymer matrix in an amount in the range of 0.01 wt. % to 3 wt. %.

14. A photovoltaic module comprising at least one photovoltaic device or solar cell and a wavelength conversion luminescent medium of claim 10.

15. The photovoltaic module of claim 14, wherein the photovoltaic module further comprises a refractive index matching liquid or optical adhesive.

16. The photovoltaic module of claim 14, wherein the photovoltaic device or solar cell comprises at least one device selected from the group consisting of a cadmium sulfide/cadmium telluride solar cell, a copper indium gallium diselenide solar cell, an amorphous silicon solar cell, a microcrystalline silicon solar cell and a crystalline silicon solar cell.

17. The photovoltaic module of claim 14, wherein the wavelength conversion luminescent medium is a film having a thickness in the range of 0.1 μ

m to 1 mm.

18. A method for improving the performance of a photovoltaic device of solar cell, wherein the method comprises:

(a) applying the wavelength conversion luminescent medium of claim 10 directly onto the light incident side of the photovoltaic device or solar cell;

or

(b) encapsulating the wavelength conversion luminescent medium of claim 10 in the photovoltaic device or solar cell.