Red-enhanced white LCD displays comprising sol-gel-based color conversion films

• US 10,519,314 B2
• Filed: 11/16/2016
• Issued: 12/31/2019
• Est. Priority Date: 11/16/2015
• Status: Active Grant

• Current Assignee: Moleculed Ltd.
• Original Assignee: StoreDot Ltd.
• Inventors: Szwarcman, Daniel, Cohen, Elad, Armon, Mor Shmuel, Kuks, Evgenia Leil (Jeny), Schwarz, Rony, Eisurovich, Elena, Aronov, Daniel, Sella, Eran
• Primary Examiner(s): Mauro, John M
• Application Number:
  US15/353,294
• Publication Number:
  US 20170137627A1
• Time in Patent Office: 1,140 Days
• CPC Class Codes: C08F 120/14 Methyl esters , e.g. methyl (meth)acrylate
• CPC Class Codes: C08F 2810/20 leading to a crosslinking, either explicitly or inherently
• CPC Class Codes: C08K 5/3437 condensed with carbocyclic rings
• CPC Class Codes: C08K 5/5477 containing nitrogen in a heterocyclic ring
• CPC Class Codes: C09B 11/24 Phthaleins containing amino groups ; Phthalanes; Fluoranes; Phthalides; Rhodamine dyes; Phthaleins having heterocyclic aryl rings; Lactone or lactame forms of triarylmethane dyes
• CPC Class Codes: C09B 69/008 Dyes containing a substituent, which contains a silicium atom
• CPC Class Codes: C09B 69/103 containing a diaryl- or triarylmethane dye
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1007 Non-condensed systems
• CPC Class Codes: C09K 2211/1048 with oxygen
• CPC Class Codes: G02F 1/133516 Methods for their manufacture, e.g. printing, electro-deposition or photolithography
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/133617 Illumination with ultraviolet light; Luminescent elements or materials associated to the cell
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 2203/055 wavelength filtering
• CPC Class Codes: H10K 85/611 Charge transfer complexes
• CPC Class Codes: H10K 85/657 Polycyclic condensed heteroaromatic hydrocarbons

Abstract

Color conversion films for a LCD (liquid crystal display) having RGB (red, green, blue) color filters, as well as such displays, formulations, precursors and methods are provided, which improve display performances with respect to color gamut, energy efficiency, materials and costs. The color conversion films absorb backlight illumination and convert the energy to green and/or red emission at high efficiency, specified wavelength ranges and narrow emission peaks. For example, rhodamine-based fluorescent compounds are used in matrices produced by sol gel processes and/or UV (ultraviolet) curing processes which are configured to stabilize the compounds and extend their lifetime—to provide the required emission specifications of the color conversion films. Film integration and display configurations further enhance the display performance with color conversion films utilizing various color conversion elements.

Claims

1. An LCD (liquid crystal display) comprising:

a color conversion film;

RGB (red, green, blue) color filters; and

a backlight source providing white illumination;

wherein the color conversion film comprises at least one rhodamine-based fluorescent (RBF) compound selected to absorb illumination from the backlight source of the LCD and have a red emission peak; and

wherein the at least one RBF compound is red-fluorescent and defined by Formula 1;

2. The LCD of claim 1, wherein said color conversion film is produced at least partially by a sol gel process carried out using, to provide a matrix for the at least one RBF compound, a formulation comprising:

an ESOR (epoxy silica ormosil) solution comprising TEOS (tetraethyl orthosilicate), at least one silane precursor, and GLYMO ((3-Glycidyloxypropyl) trimethoxysilane),

a DURS (diurethane siloxane) powder comprising isocyanate-functionalized silica nanoparticles and ethylene glycol, and

a transition metal alkoxide matrix solution.

3. The LCD of claim 1, wherein the at least one RBF compound is selected to shift some of a yellow region in the white illumination into the red transmission region of the R color filter.

4. The LCD of claim 2, wherein ratios (wt/vol/vol (mg/ml/ml)) of the DURS/the ESOR/and the transition metal alkoxide matrix solution are 15-25/1-3/1.

5. The LCD of claim 2, wherein the ESOR is prepared under acidic conditions.

6. The LCD of claim 2, wherein the at least one silane precursor comprises PhTMOS (trimethoxyphenylsilane) or a TMOS (trimethoxysilane) with fluorine substituents.

7. The LCD of claim 1, wherein the color conversion film is in an LCD panel.

8. A color conversion film prepared by a sol gel process from a formulation comprising:

an ESOR (epoxy silica ormosil) solution comprising TEOS (tetraethyl orthosilicate), at least one silane precursor, and GLYMO ((3-Glycidyloxypropyl) trimethoxysilane);

a DURS (diurethane siloxane) powder comprising isocyanate-functionalized silica nanoparticles and ethylene glycol;

a transition metal alkoxide matrix solution; and

at least one red-fluorescent rhodamine-based fluorescent (RBF) compound is defined by Formula 1 according to claim 1.

9. The color conversion film of claim 8, wherein the at least one silane precursor comprises PhTMOS (trimethoxyphenylsilane) or a TMOS (trimethoxysilane) with fluorine substituents.

10. The color conversion film of claim 8, wherein the at least one RBF compound is supramolecularly encapsulated within the film or covalently embedded within the color conversion film.

11. The color conversion film of claim 8, wherein the at least one RBF compound is bonded to the film via PMMA (poly-methyl-methacrylate) linkers.

12. An LCD, comprising at least one color conversion film of claim 8, a backlight unit comprising a white backlight source and a LCD panel having RGB color filters.

13. The LCD of claim 12, wherein the color conversion film is further configured to shift some of a yellow region in white illumination provided by the white backlight source into a red transmission region of the R color filter.

14. The color conversion film of claim 8, further configured to direct self-assembly of molecules of the at least one RBF compound to yield polarization of at least part of the illumination by the color conversion film.

15. An LCD comprising at least one color conversion film of claim 14, a backlight unit comprising a white backlight source and a LCD panel having RGB color filters, wherein the at least one color conversion film replaces at least one polarizer film in the LCD.

20. A method comprising configuring a LCD with RGB color filters and white backlight illumination to have at least one color conversion film produced by:

preparing a hybrid sol-gel precursor formulation from;

an ESOR (epoxy silica ormosil) solution comprising TEOS (tetraethyl orthosilicate), at least one silane precursor, and GLYMO ((3-Glycidyloxypropyl) trimethoxysilane);

a DURS (diurethane siloxane) powder comprising isocyanate-functionalized silica nanoparticles and ethylene glycol; and

a transition metal alkoxide matrix solution,

mixing the prepared hybrid sol-gel precursor with at least one RBF (rhodamine-based fluorescent) compound; and

spreading the mixture and drying the spread mixture to form a film,

wherein the at least one RBF compound and/or the color conversion film production are configured to enhance a red illumination component in the white backlight illumination by shifting some of a yellow region in the white backlight illumination into a red transmission region of the R color filter wherein the at least one RBF compound is defined by Formula 1 according to claim 1.

21. The method of claim 20, wherein said preparing of the hybrid sol-gel precursor formulation is carried out under acidic conditions.

22. The method of claim 20, further comprising evaporating alcohols from the mixture prior to said spreading.

16. A color conversion film for a LCD (liquid crystal display) having RGB (red, green, blue) color filters, the color conversion film comprising at least one rhodamine-based fluorescent (RBF) compound selected to absorb illumination from a backlight source of the LCD and have a red emission peak, wherein the backlight source of the LCD provides white illumination and the at least one RBF compound is red-fluorescent and defined by Formula 1:

17. A color conversion film for a LCD (liquid crystal display) having RGB (red, green, blue) color filters, the color conversion film comprising at least one rhodamine-based fluorescent (RBF) compound selected to absorb illumination from a backlight source of the LCD and have a red emission peak, wherein the backlight source of the LCD provides white illumination and the at least one RBF compound is red-fluorescent and defined by Formula 1:

18. An LCD (liquid crystal display) comprising:

A color conversion film;

RGB (red, green, blue) color filters; and

a backlight source providing white illumination;

wherein the color conversion film comprises at least one rhodamine-based fluorescent (RBF) compound selected to absorb illumination from the backlight source of the LCD and have a red emission peak;

and wherein the at least one RBF compound is red-fluorescent and defined by Formula 1;

19. An LCD (liquid crystal display) comprising:

a color conversion film;

RGB (red, green, blue) color filters; and

a backlight source providing white illumination;

wherein the color conversion film comprises at least one rhodamine-based fluorescent (RBF) compound selected to absorb illumination from the backlight source of the LCD and have a red emission peak and wherein the at least one RBF compound is red-fluorescent and defined by Formula 1;