WO2021030926A1

WO2021030926A1 - Passivation layer for photoaligned quantum rod enhancement film for lcds

Info

Publication number: WO2021030926A1
Application number: PCT/CN2019/100910
Authority: WO
Inventors: Swadesh Kumar GUPTA; Maksym Fedorovich PRODANOV; Valerii Vladimirovich VASHCHENKO; Abhishek Kumar SRIVASTAVA
Original assignee: Zhuhai Roumei Technology Co., Ltd.
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2021-02-25
Also published as: CN114341719A

Abstract

A passivation layer for the photoaligned quantum rod enhancement film (QREF), includes a substrate with organic-inorganic multiple layers and a barrier adhesive layer. A passivation layer and QREF are coated onto a polymer substrate. Additional polymer layers can be coated onto the substrate, together with a planarization layer, followed by a coating of an inorganic layer to provide a high oxygen and water barrier properties for photoaligned QREFs. An adhesive layer is coated onto the top of QREF, followed by face-to-face lamination and polymerization process for two QREFs providing good passivation for the photoaligned QREFs. Additional passivating layers or QREF layers can also be deposited onto the obtained film. Thus, fabricated passivation multilayer provides high barrier against water and oxygen exposure. The water vapour transmission rate (WVTR) for fabricated passivation layer shows as low as 8.06 x 10^-7gm^-2 day^-1 at 60°C and 100% R. H., which confirms the low water penetration through barrier film. The film is also characterized for Oxygen Transmission Rate (OTR), which is less than 4.93x10^-3 cc/m ²/day revealing the low oxygen penetration through barrier film.

Description

Passivation layer for photoaligned quantum rod enhancement film for LCDs

Technology field

This invention involves in the technology field, particularly involves packaging management system and method for the nano-material based thinfilms.

Background technology

Quantum dots enhancement film (QDEF) are employed in liquid crystal displays as backlighting devices. QDEF is fabricated by adding red and green emitting Quantum dots (QDs) combined together in a polymer matrix that is laminated between two barrier layers. QDEFs add more colors to LCD system providing better image quality which covers more visible spectrum than conventional LED backlight.

However, power efficiency for LCDs with QDEF is still low. Quantum rods (QRs) , on other hand, have the properties of polarized emission with similar color spectrum as QDs. QRs show 2D confinement and because of the anisotropic shape, fine structure splitting of 1D ground exciton state and dielectric screening of electromagnetic fields favors light absorption and emission along the long axis of the rod. Quantum rods need to be aligned for polarized emission and thus require special layer for alignment of red and green QRs with compatible matrix which provide good alignment and uniform distribution to QRs embedded in it. Photoalignment is straightforward technique providing alignment of liquid crystalline polymer (LCP) and thereby QRs dispersed into the LCP matrix. However, barrier layer structure for the Photoaligned Quantum rod enhancement film (QREF) requires modification to ensure high passivation against water and oxygen.

The QRs are highly sensitive to degradation like QDs, so the photoaligned QREF should have good barrier properties against the water and oxygen penetration, which degrade the performance of the QRs. The Passivation layers protect the QRs in the interior regions of the laminate construction from damage caused by oxygen or water exposure, but the cut edges of the photoaligned QREF expose the adhesive material to the atmosphere. In the edge regions, the protection of the QREF is primarily dependent on the barrier properties of the matrix and the adhesive layer. Therefore, a modified passivation layer containing adhesive layer with better barrier properties is needed for protection of QRs in photoaligned QREF from degradation for longer life stability.

As QRs need alignment in matrix layer, common polymer matrix layers used for QDs cannot be used. Also adhesive materials cannot be mixed in matrix material as it will result in degradation of alignment properties. Thus a matrix material with good barrier and alignment properties is prerequisite for polarized light emissive photoaligned QRs film.

Contents of the invention

This invention is designed to solve at least one problem existing in current technologies. For this purpose, this invention provides a kind of Passivation layer for photoaligned quantum rod enhancement film for LCDs.

Passivation layer for encapsulation of at least one photoaligned quantum rod enhancement film, deposited on to the photoalignment layer, for LCDs comprising:

i. at least one substrate;

ii. at least one inorganic layer;

which shows a good protection of photoaligned quantum rod enhancement film from oxygen and humidity.

Preferably, the passivation layer for encapsulation photoaligned quantum rod enhancement film as per claim 1, comprises at least one adhesive layer.

Preferably, wherein the substrate comprises polyethylene naphthalate, polyethylene terephthalate.

Preferably, the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate is a light guide plate for backlight.

Preferably, wherein the substrate comprises polymer from polyester and polyalkyd family.

Preferably, wherein the substrate comprises polymer from polyvinyl chloride family.

Preferably, wherein the substrate comprises polymer from polysiloxanes family.

Preferably, wherein the substrate comprises polymer of ionomers family.

Preferably, wherein the substrate comprises polypropylene.

Preferably, wherein the substrate comprises polymer from fluorinated ethylene family.

Preferably, wherein the substrate comprises polymer from styrene methyl methacrylate family.

Preferably, wherein the substrate comprises polymer from Styrene Acrylonitrile Resin family.

Preferably, wherein the substrate comprises polystyrene.

Preferably, wherein the substrate comprises polymer from polyaryletherketone family.

Preferably, wherein the polymer of polyaryletherketone family is polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, polyetherketoneetherketoneketone.

Preferably, wherein the substrate comprises polymer from polyimide family.

Preferably, wherein the substrate comprises polymer from polycarbonate family.

Preferably, wherein the substrate comprises polymer from cyclic olefin copolymer family.

Preferably, wherein the substrate comprises polymer from polysulfones family.

Preferably, wherein the substrate comprises acrylic polymers.

Preferably, wherein the substrate comprises polymers from acrylonitrile-butadiene-styrene (ABS) family.

Preferably, wherein the substrate of the passivation layer as per claim 1, wherein the substrate comprises polymer from acrylonitrile styrene acrylate (ASA) family.

The substrate thickness is in the range of 50-1000μm.

Preferably, wherein the substrate thickness of is in range 100-400μm.

Passivation layer contained at least one planarization layer coated onto the said substrate.

Preferably, wherein the planarization layer comprises organic polymer, siloxane polymer, silicate, metal oxides, fluorine doped tin oxide or the mixture of thereof.

Preferably, wherein Al ₂O ₃ is deposited onto the substrate as planarization layer.

Preferably, wherein Al ₂O ₃ is deposited onto the substrate of thickness is in the range of 50nm-5μm.

Preferably, wherein the thickness of the Al ₂O ₃ is deposited onto the substrate is in 200nm.

An inorganic layer is coated on to one side of substrate, at least, for tight passivation of photo aligned quantum rod enhancement film.

Preferably, wherein the inorganic layer thickness is in the range of 50nm-5μm.

Preferably, wherein the inorganic layer thickness is 200nm.

Preferably, wherein the inorganic layer comprises silicates, phosphosilicates, mechanically deposited glass frit, oxides and nitrides of silicon, aluminium, tin, indium, boron and titanium.

Preferably, wherein the inorganic layer comprises combination of two different inorganic layer.

Preferably, wherein the inorganic layer is SiO ₂ layer.

Preferably, wherein the passivation layer comprises a combination of organic or inorganic layer.

Preferably, wherein the passivation layer comprises a combination of alternate organic and inorganic layer.

Preferably, wherein the passivation layer comprises multiple layers having a combination of alternate organic and inorganic layer.

Preferably, wherein the passivation layer comprises three layers consisting the alternate combination organic and inorganic layer.

Preferably, wherein the inorganic layer as per claim 31 also serve as planarization layer for the said substrate as per claim 26.

Preferably, wherein the passivation layer comprises one substrate coated with protecting layer, and another inorganic layer on top of enhancement film.

Preferably, protecting layer is an inorganic layer.

Preferably, wherein the passivation layer comprises PET substrate coated with inorganic layer, and another inorganic layer on top of enhancement film.

Preferably, wherein the passivation layer comprises PET substrate coated with inorganic layer, and another inorganic layer on top of enhancement film and organic layer above inorganic layer.

Preferably, wherein the substrate is a PET substrate of thickness 70μm, Inorganic layer is SiO ₂ layer of thickness 200nm.

The passivation layer comprises light guide plate as substrate coated with inorganic layer, and another inorganic layer on top of enhancement film.

Preferably, wherein the passivation layer comprises light guide plate as substrate coated with inorganic layer, and another inorganic layer on top of enhancement film and organic layer above inorganic layer.

Preferably, wherein the substrate is a light guide plate of thickness 400μm, Inorganic layer is SiO ₂ layer of thickness 200nm.

An adhesive layer is used for face-to-face lamination of the two photo aligned quantum rod enhancement films deposited on to the single organic-inorganic passivation layer.

Preferably, wherein the adhesive layer is used for face-to-face lamination of the two photo aligned quantum rod enhancement films deposited on to the separate single organic-inorganic passivation layer comprising additionally planarization layers.

Preferably, wherein the adhesive layer comprises polymer glue.

Preferably, wherein the polymer glue is epoxy resin, ethylene-vinyl acetate (a hot-melt glue) , phenol formaldehyde resin, polyamide, polyester resins, polyethylene (a hot-melt glue) , polypropylene, polysulfides, polyurethane (e.g. Gorilla Glue) , polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, polyvinylpyrrolidone, rubber cement, silicones, silyl modified polymers, styrene acrylic copolymer are mixture thereof.

Preferably, wherein the adhesive layer comprises monomer glue.

Preferably, wherein monomer glue is acrylonitrile, cyanoacrylate, acrylic or resorcinol glue.

Preferably, wherein the adhesive layer comprises glue material which can be cured thermally or optically or drying.

Preferably, wherein the adhesive layer comprises UV-curable adhesive.

Preferably, wherein the adhesive layer thickness is in the range of 2-30μm.

Preferably, wherein adhesive layer contains nanoparticles.

Passivation layer is designed, wherein the substrate is a PET substrate, Inorganic layer is SiO ₂ layer, adhesive layer is a UV curable adhesive layer.

Preferably, wherein the substrate is a PET substrate of thickness 70μm, Inorganic layer is SiO ₂ layer of thickness 200nm, adhesive layer is a UV curable adhesive layer of thickness 10μm.

Preferably, wherein the substrate is a light guide plate, Inorganic layer is SiO ₂ layer, adhesive layer is a UV curable adhesive layer.

Preferably, wherein the substrate is a light guide plate of thickness 400μm, Inorganic layer is SiO ₂ layer of thickness 200nm, adhesive layer is a UV curable adhesive layer of thickness 10μm.

Preferably, wherein one substrate is a PET substrate, another substrate is light guide plate, Inorganic layer is SiO ₂ layer, adhesive layer is a UV curable adhesive.

Preferably, wherein the substrate is a PET substrate of thickness 70μm, another substrate is light guide plate of thickness 400μm, Inorganic layer is SiO ₂ layer of thickness 200nm, adhesive layer is a UV curable adhesive layer of thickness 10μm.

Passivation layer for photoaligned quantum rod enhancement film for the LCD backlight is proposed. Passivation layer includes a substrate with organic-inorganic multiple layers and a barrier adhesive layer. A polymer substrate is used to coat passivation layers and QREF on the top of it. Polymer layer may be coated with a planarization layer followed by coating of inorganic layer for high barrier properties. Inorganic layer is additionally used for deposition of thin layer of photoalignment material (azo-dye) for alignment of QREF matrix and QRs therein. An adhesive passivation layer is coated on top of QREF followed by face-to-face lamination and polymerization process for two photoaligned QREFs sealing purpose providing passivation from sides. In addition, displacement of red-and green emitters in two separate layers exclude the issue of re-absorption comparing to all emitters in one-layer structure, typically used for QDEF. Additional passivation and QREF layers can be further deposited on the top of the obtained film. Fabricated passivation multilayer provides high barrier properties from moisture and oxygen penetration. The water vapour transmission rate (WVTR) for fabricated passivation layer show as low as 8.06 x 10 ^-7 g m ^-2 day ^-1 at 60℃ and 100%R. H. which confirms the low water penetration through barrier film. The film is also characterized by Oxygen Transmission Rate (OTR) less than 4.93x10 ^-3 cc/m ²/day revealing the low oxygen penetration through barrier film.

Description with diagrams

Embodiments of present disclosure includes the passivation layer for photoaligned quantum rod enhancement film for LCD backlighting. QRs emits polarized light when illuminated with low wavelength source than emitting wavelength. QRs are highly sensitive to degradation, when come to exposure of humidity and oxygen. Thus passivation layers are required to provide encapsulation of QREF from humidity and oxygen.

Passivation layer for QREF contains a substrate used for deposition of photoalignment material followed by QREF which also work as an encapsulation layer. Passivation layer comprises organic and inorganic multiple layer structure for providing high barrier to photoligned QREF from oxygen and humidity. Overall passivated QREF film contains also an adhesive barrier layer to glue and seal the red and green QREF layers and to provide encapsulation from the side regions.

In one embodiment, passivation layer contains at least one substrate (101) , one inorganic layer (102) and one adhesive layer (105) with alignment layer (103) and QREF layer (104) (Figure 1)

In one embodiment, passivation layer contains one substrate (201) , two inorganic layers (202) and one adhesive layer (205) with alignment layer (203) and QREF layer (204) (Figure 2) .

In one embodiment, passivation layer contains at least one substrate (301) , one planarization layer (302) , one inorganic layer (303) and one adhesive layer (306) with alignment layer (303) and QREF layer (304) (Figure 3) .

In one embodiment, passivation layer contains one substrate (401) , two planarization layers (402) , two inorganic layer (403) and one adhesive layer (406) with alignment layer (403) and QREF layer (404) (Figure 4) .

The substrate used for deposition of QREF layer can be any material which provide good thermal and mechanical stability with high transmittance in visible region.

In one example the substrate comprises polyethylene naphthalate. The polyethylene naphthalate is of

In one example substrate comprises polyethylene terephthalate. The polyethylene terephthalate from Crystal, Impet, Laer+, Mylar, Rynite, Valox or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of polyester and polyalkyd family. The polymer of polyester and polyalkyd family can be from Aropol, CosmicAlkyd, BMC-Cyglas, Durez, Cirrasol, CHS-ALKYD or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of polyvinyl chloride family. The polymer of polyvinyl chloride family can be from Geon, OxyVinyls, Benvic, Tygon, Vestolite or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of polysiloxanes family. The polymer of polysiloxanes family can be from

Silopren ^TM,

or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of ionomers family. The polymer of ionomers family can be from

Primacore ^TM, Optema ^TM or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polypropylene. The polypropylene family can be from Adstif, Eltex, Hostalen, Ineos PP, Inspire, Moplen, Profax, Petrothene, Profax PP, Seetec, Unipol PPo or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of fluorinated ethylene family. The polymer of fluorinated ethylene family can be from Neoflon, Teflon FEP, Dyneon FEPo or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of styrene methyl methacrylate family. The polymer of styrene methyl methacrylate family can be from

Rhoplex ^TM, Texicryl or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of Styrene Acrylonitrile Resin family. The polymer of Styrene Acrylonitrile Resin family can be from LG SAN, Luran, Lustran, RTP SAN, Tyril or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polystyrene (General Purpose –GPPS) . The polystyrene can be from Cellofoam, Styrofoam, Styron, Styropek, Styropor or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of Methyl Methacrylate Acrylonitrile Butadiene Styrene copolymer family.

In one example the substrate comprises polymer of polyaryletherketone family. The polymer of polyaryletherketone family is polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, polyetherketoneetherketoneketone.

In one example the substrate comprises polymer of polyimide family. The polymer of polyimide family can be from Duratron, Kerimid, Matrimid, Kapton, Kinel, Upilex, Upimol, Vespel or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of polycarbonate family. The polymer of polycarbonate family can be from Marlon, Durolon, Lupilon, Lupoy, Panlite, Lexan, Thermoclear, Macrolux, Polycasa SPC, Makrolon, Sunlite, Corotherm or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of cyclic olefin copolymer family. The polymer of cyclic olefin copolymer family can be from Apel, Arton, Topas, DCPD HP, Zeonex, Zeonor or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymer of polysulfones family. The polymer of polysulfones family can be from Acudel, Eviva, Quadrant PSU, RTP-PSU, Tecason, Udel, Ultrason S, Veradel or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises acrylic polymers. The acrylic polymer can be from Dow Acrylates, Acronal, Aroset, Acrydic, Plextol, Dow Acrylates, Acronal, Aroset, Acrydic, Plextol,

AC,

Hytem, Vamac, DerGom, Kurarity or their structural analogues with different names or the mixture of thereof.

In one example the substrate comprises polymers of acrylonitrile-butadiene-styrene (ABS) family. The substrate of acrylonitrile-butadiene-styrene (ABS) family is Cevian, Cycolac, Lustran, Magnum, Malecca or their structural analogues with different names or the mixture of thereof.

In one example the passivation layer substrate comprises polymer of acrylonitrile-styrene (SAN) family.

In one example the substrate comprises polymer of acrylonitrile styrene acrylate (ASA) family. The substrate of acrylonitrile styrene acrylate (ASA) family is Centrex, Geloy, Kibisan, Luran, Terblend or their structural analogues with different names or the mixture of thereof.

The substrate thickness is calibrated to sustain the polarized emission from nano rod enhancement film.

In one embodiment the planarization layer in passivation layer is used to reduce the roughness and defects on substrate. The planarization layer comprises organic polymer, siloxane polymer, silicate, metal oxides, fluorine doped tin oxide or the mixture of thereof.

In one embodiment the inorganic layer is coated on one side of substrate for tight passivation of quantum rod enhancement film.

In some embodiment the inorganic layer is coated on one side of planarized substrate for tight passivation of quantum rod enhancement film.

In some embodiment the inorganic layer is coated on both side of substrate for tight passivation of quantum rod enhancement film.

In some embodiment the inorganic layer is coated on both side of planarized substrate for tight passivation of quantum rod enhancement film.

In one example the inorganic layer comprises silicates, phosphosilicates.

In one example the inorganic layer comprises mechanically deposited glass frit.

In one example the inorganic layer comprises oxides and nitrides of silicon, e.g. SiO ₂, Si ₃N ₄.

In one example the inorganic layer comprises oxides of basic metals. Oxide of basic metal contains Al ₂O ₃, In ₂O ₃, SnO ₂. etc.

In one example the inorganic layer comprises oxides of titanium.

In one example the inorganic layer is combination of two inorganic layer e.g. TiO ₂/SiO ₂, TiO ₂/Al ₂O ₃.

Inorganic layer is coated on substrate using atomic layer deposition (ALD) , plasma enhanced chemical vapor deposition technique (PECVD) or sputter deposition.

The adhesive layer in passivation layer is used for face-to-face lamination of the two polarized emissive film (QREF) , comprising emitters with different wavelengths in each QREF, deposited on single or multiple organic-inorganic passivation layer (see example on Figure 5, 6 and 7) . Such a structure of the film solves the problem of re-absorption wherein the part of emitted light is absorbed by another type of emitter.

In one embodiment, the adhesive layer (505) is used for laminating the passivated QREF film with another passivated QREF film. Where each passivation layer contains a substrate (501) , one inorganic layer (502) with photoalignment layer (503) and QREF layer (504) .

In one embodiment, the adhesive layer (606) is used for laminating the passivated QREF film with another passivated QREF film. Where each passivation layer contains a substrate (601) , one planarization layer (602) , one inorganic layer (603) with photoalignment layer (604) and QREF layer (605) .

In one embodiment, the adhesive layer (707) is used for laminating the passivated QREF film with another passivated QREF film. Where one passivation layer contains one type of substrate (701) , one inorganic layer (703) with photoalignment layer (704) and QREF layer (705) , while another passivation layer contains light guide plate as substrate (702) , one inorganic layer (703) with photoalignment layer (704) and QREF layer (705) .

Light guide plate is a film used in LCD backlights which guides and emits the light coming from the LEDs.

In one example the adhesive layer comprises polymer glue. The polymer glue is epoxy resin, ethylene-vinyl acetate (a hot-melt glue) , phenol formaldehyde resin, polyamide, polyester resins, polyethylene (a hot-melt glue) , polypropylene, polysulfides, polyurethane (e.g. Gorilla Glue) , polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, polyvinylpyrrolidone, rubber cement, silicones, silyl modified polymers, styrene acrylic copolymer.

In one example the adhesive layer comprises monomer glue. The monomer glue is acrylonitrile, cyanoacrylate, acrylic or resorcinol glue.

The adhesive layer comprises glue material mixed with nanoparticles.

The nanoparticles in adhesive layer has definite size. In one example the size of nanoparticle is 400nm, 410nm, 420nm, 430nm, 440nm, 450nm, 460nm, 470nm, 480nm, 490nm and 500nm.

In one example nanoparticle size is 500nm, 600nm, 700nm, 800nm, 900nm and 1 μm. In another example the nanoparticle size is 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm and 10 μm. More preferably the size of nanoparticle is between 410nm to 1 μm.

The adhesive layer comprises glue material which can be cured by use of chemical, thermal or optical treatment.

In some embodiment the adhesive layer comprises UV-curable adhesive.

In some embodiment adhesive layer comprises Thermal-curable adhesive

In some embodiment the adhesive layer comprises combination of thermal and UV curable adhesive.

In another structure of passivation layer for QREF, there is no adhesive layer.

In one embodiment, passivation layer contains only one substrate (801) , one protecting layer (802) on top of substrate, one alignment layer (803) , one mixed QREF layer (804) and one inorganic layer (805) on top of QREF layer (804) .

In one embodiment, passivation layer contains only one substrate (901) , one protecting layer (902) on top of substrate, one alignment layer (903) , one mixed QREF layer (904) , one inorganic layer (905) on top of QREF layer (904) , one organic layer (906) on top of Inorganic layer (905) .

In one example, the protecting layer is inorganic layer.

In one example, the protecting layer is multiple organic-inorganic layer.

In one example, the substrate is a PET film.

In one example, the substrate is light guide plate for LCD backlight.

Procedure for fabricating inorganic passivation layer.

The inorganic passivation layer can be fabricated on top of the substrate layer using Sputter deposition, atomic layer deposition (ALD) or Plasma-enhanced chemical vapor deposition (PECVD) methods.

For ALD, any modern deposition system can be used. Thus, Picosun Oy Sunale R200 ALD, BENEQ TFS500, Sentech SI ALD LL system, Oxford Instruments open load ALD system (OpAL) , Oxford Instruments FlexAl reactor are good example of the possible equipment. For deposition of inorganic layers, proper precursors should be chosen. Thus, to form Al ₂O ₃ layer trimethyl aluminium together with H ₂O is used whereas for MgO deposition Mg (CpMe) ₂/H ₂O is a typical choice. For TiO ₂ ALD layer tetrakis- (dimethylamino) titanium, tetrakis (diethylamino) titanium, tetrakis (ethylmethylamino) titanium, TiCl ₄ as well as novel PrimeTiTM, StarTiTM and TyALDTM precursors may be used. For deposition of SiO ₂ use of catalysts such as Lewis bases is needed. Typically, NH ₃ or pyridine are used. The use of tetraethoxysilane (TEOS) as SiO ₂ precursor is also possible. Other appropriate precursors are tris [dimethylamino] silane, bis [diethylamino] silane, dichlorosilane, silane AP-LTO 330 precursor, 3DMAS, BDEAS and oxygen precursors, such as oxygen and nitrous oxide. Plasma-deposited silicon nitride can be formed from silane and ammonia or nitrogen. The plasma enhancement can be generally achieved by radio frequency (RF) , alternating current (AC) or direct current (DC) discharges using corresponding tools. The deposition process paremeters, including pulsing timing, temperature, oxygen/ozone flow rate, plasma power and pressures can be optimized to achieve desired thickness and layer quality.

Different techniques can be used in case of sputter deposition. Among them are Gas flow sputtering, Reactive sputtering, Ion-beam sputtering, Ion-assisted deposition as well as HiTUS and HiPIMS methods. Pulsed laser deposition can be used as sputtering deposition technique in which an active control for layer-by-layer growth is possible.

The thickness of inorganic passivation layer should be sufficiently large (≥ 3 nm) so as to be continuous. However, it also should be sufficiently thin to have the desired properties, such as visible light transmittance and flexibility.

Procedure for coating of Adhesive layer

Adhesive layer coating is required to seal the two QREF layer deposited on photoaligned substrate. Thus first the photoalignment layer is prepared on inorganic layer of substrate and then QREF is printed on photoaligned layer. For adhesive layer deposition different techniques can be applied including but not limited to Die, Rod, Reverse Roll and Flex bar coating. Cold and hot-melt coaters can be used. Preferably low temperature adhesive layer coating process is used with a subsequent UV curing after lamination. Other embodiments include polymer glues like epoxy resin, ethylene-vinyl acetate (a hot-melt glue) , phenol formaldehyde resin, polyamide, polyester resins, polyethylene (a hot-melt glue) , polypropylene, polysulfides, polyurethane (e.g. Gorilla Glue) , polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, polyvinylpyrrolidone, rubber cement, silicones, silyl modified polymers, styrene acrylic copolymer.

Synthetic monomer glues from a family of acrylonitrile, cyanoacrylate, acrylic or resorcinol glues can be applied as adhesive layer material to be deposited by low temperature method and subsequent UV curing.

Procedure for lamination

Various assembly fixtures can be used for lamination of the two passivated QREFs after adhesive coating. Precise positioning and pressurizing is generally required to achieve void-free and strong enough lamination contact. Generally, it is desirable to use as high a clamping pressure as the material can withstand without being crushed. Normally a moderate pressure of 0.1 to 10 MPa should be applied in a suitable press. The laminated parts can be placed in an appropriate vacuum chamber or plastic box/bag which is then evacuated allowing atmospheric pressure to apply the clamping force as well as to remove gas bubbles from the two laminated material interfaces. The curing is applied in the same time during the lamination process resulting in formation of hard bonding of two photoaligned QREFs. The time of lamination/curing may vary for different adhesive agents ranging typically from 1 to 60 minutes.

Complete procedure for preparation of encapsulated QREF is shown in figure 10.

Testing

Water vapor transmission rate and oxygen transmission rate

For measurement of water vapor transmission rate (WVTR) of the obtained passivation films different techniques can be used. Thus, for initial quick testing MOCON method is appropriate allowing fast assessing of WVTR value as low 5×10 ^-2 to 5×10 ^-3g m ^-2/day, depending on the MOCON instrument model as MOCON PERMATRAN-W Model 398 WVTR and MOCON PERMATRAN-W Model 700. Other more sensitive techniques, such as Calcium test and tritiated water (HTO) permeation, can be used for the further precise testing of water transmission property. Thus HTO permeation test is very sensitive, with a detection limit as low as 10 ^-6g m ^-2/day, but the relative humidity (RH) cannot be easily varied in this static system. The Ca test possess even higher sensitivity though duration of the experiment can also be considerably longer than either of the other two techniques due to the potentially long lag times, which are dependent on the WVTR of the film. Increasing of temperature and/or RH can speed up the measurements by all the methods when the target is relative comparison of different samples. In addition, it will result in possibility to apply MOCON instrument as the WVTR will considerably increase with increase of temperature. In any case, these conditions need to be closely matched to accurately compare the WVTRs of different samples.

For Oxygen Transmission Rate measurements different ASTM standard test methods can be applied, such as D3985, F2622, F1927 or F1307. Thus, MOCON OX-TRAN ^@instrument Model 2/22 (10x) , Model 2/22 (L) equipped with coulometric sensor is an example consistent with ASTM D3985 standard to measure as low as 5x10 ^-2 to 5x10 ^-4 cc m ^-2/day. Dry conditions and standardized temperature is preferable for measurement and comparison of OTR for different samples.

For both key passivation properties (WVTR and OTR) the measurement should be averaged through the proper number of film pieces (from each sample) for avoiding sample variables such as effect of film defects and actual difference of barrier properties of different film regions.

The representative examples

Example 1

Passivation layer is fabricated for QREF (Figure 1) by using an organic substrate with thickness 50μm, 60μm, 70μm, 80μm, 90μm and 100μm and coated with inorganic layer on organic substrate with thickness of 30nm, 40nm, 50nm, 100nm, 500nm and 1μm. The alignment layer is coated on the inorganic layer with thickness of 10nm, 20nm, 30nm, 40nm and 50 nm. Quantum rod film is deposited on alignment layer with thickness of 1μm, 2μm, 3μm, 4μm, 5μm, 10μm and 20μm. A barrier adhesive is deposited on cured QREF of thickness 1μm, 2μm, 3μm, 4μm and 5μm, 10μm, 20μm.

The Mocon limit test is performed on this passivation layer unit for fast assessment of WVTR using instrument MOCON PERMATRAN-W Model 700 WVTR testing system (commercially available from MOCON, Inc., Minneapolis, MN) (standardized against ASTM F-1249/Tappi T-557) . The sample is placed between a dry and a wet chamber to form a diffusion cell. An atmosphere with a RH of 100%is supplied to the wet chamber with a temperature of 60 ℃ (as per ASTM F1249) .

For passivation layer containing substrate thickness of 70μm, inorganic layer of 200nm and barrier adhesive layer of 10μm, a WVTR of 4.91x10 ^-3 g/m ²/day is obtained, which is close to the limit of this instrument.

To estimate the WVTR more accurately for passivation layer, Ca degradation test is conducted with electrical analysis of Ca metal, which includes a monitoring system with an automatic acquisition function to implement dynamic monitoring for resistivity variation. The 200 nm thick Ca film with length/width (L/W) of 40/80 mm was deposited on the patterned Au electrodes (100 nm) in the shape of two narrow bars. This structure is glued onto the barrier film of interest with an epoxy seal and UV cured. The samples were placed in an oven at constant temperature (60℃) and humidity (100%) , while the electrical measurements were carried out using two electrodes connected by an SMU probe and Keithley 2420 source meter. The change of conductance, as a function of time, dG/dt, is used to calculate the effective WVTR values according to the following equation

where n denotes the molar equivalent of the degradation reaction (n=2) , δ _Ca is the Ca resistivity and ρ _Ca the density of Ca (～ 1.55 g/cm ²) , dG/dt is the linear fitting in the conductance change verses time. M [H ₂O] and M [Ca] are the molar masses for water vapour, 18 amu, and Ca, 40.1 amu, respectively.

The rate of change of conductance of Ca metal is plotted with time in hours to calculate the WVTR of passivation layer (Figure 11) . A WVTR of 8.06 x 10 ^-7 g m ^-2 day ^-1 is obtained for this passivation layer.

OTR measurement is performed with MOCON OX-TRAN Model 2/22 (L) (standardized against ASTM D3985) OTR testing system with the same sample as described in example 1. The sample is placed in cell to put in between a nitrogen and oxygen chamber to form a diffusion cell. An atmosphere with a 0%RH is supplied to the oxygen and nitrogen chamber with a temperature of 35 ℃ under pressure of 0.1Mpa. A OTR of 4.93x10- ³ cc/m ²/day is obtained close to the instrument limit.

Deposition of inorganic layer on both side of organic substrate as shown in Figure 2 provide no significant improvement of WVTR and OTR values compared to single layer deposition.

Example 2

Passivation layer is fabricated for QREF (Figure 3) by using an organic substrate with thickness 50μm, 60μm, 70μm, 80μm, 90μm and 100μm and coated with planarization layer of thickness 30nm, 40nm, 50nm, 80nm, 100nm, 200nm and 500nm on organic substrate. The inorganic layer on planarization layer is coated with thickness of 30nm, 40nm, 50nm, 100nm, 500nm and 1μm. The alignment layer is coated on top of the inorganic layer with thickness of 10nm, 20nm, 30nm, 40nm and 50 nm. Quantum rod film is deposited on alignment layer with thickness of 1μm, 2μm, 3μm, 4μm, 5μm, 10μm and 20μm. An adhesive is deposited on cured QREF of thickness 1μm, 2μm, 3μm, 4μm and 5μm, 10μm.

The Mocon limit test is performed on this passivation layer unit for fast assessment of WVTR using instrument MOCON PERMATRAN-W (R) Model 700 WVTR testing system (commercially available from MOCON, Inc., Minneapolis, MN) (standardized against ASTM F-1249/Tappi T-557) . The sample is placed between a dry and a wet chamber to form a diffusion cell. An atmosphere with a RH of 100 %is supplied to the wet chamber with a temperature of 60℃ (as per ASTM F1249) .

For passivation layer containing substrate thickness of 70μm, planarization layer 200nm, inorganic layer of 200nm and barrier adhesive layer of 10μm, a WVTR of 4.95x10- ³ g/m ²/day is obtained, which is close to the limit of this instrument.

ORT measurement is performed with MOCON OX-TRAN Model 2/22 (L) (standardized against ASTM D3985) OTR testing system with the same sample as described in example 2. The sample is placed in cell to put in between a nitrogen and oxygen chamber to form a diffusion cell. An atmosphere with 0%RH is supplied to the oxygen and nitrogen chamber with a temperature of 35 ℃ under pressure of 0.1Mpa. A OTR of 4.90x10- ³ cc/m ²/day is obtained close to the instrument limit.

Deposition of planarization layer on both side of organic substrate with two inorganic layer as given in figure 4 show no significant improvement of WVTR and OTR values compared to single layer deposition.

Example 3

Passivation layer is fabricated for two QREF contained different (red and green) emitters in each QREF (Figure 5) by using PET substrates with thickness 70μm. Inorganic layer of SiO ₂ on organic substrate is coated with thickness of 200nm. The photo alignment layer is coated on inorganic layer with thickness of 10nm. Quantum rod film is deposited on alignment layer with thickness of 20μm. An adhesive is deposited on cured QREF of thickness 10μm. Two obtained films were face to face laminated by homogeneous planar pressurising mechanism with pressure around 0.4 MPa in a vacuum chamber to remove gas bubbles from the two laminated material interfaces.

OTR and WVTR were measured using the same equipment as in example 1 and were found to be close to the instrument limit.

Degree of polarization

As Red QRs (1201) and green QRs (1202) are aligned by photoalignment layer, QREF show polarized emission. Since the red QREF (1203) and green QREF (1204) are attached with an adhesive layer (1205) as shown in Figure 12, the effect on degree of polarization of emission of QREF has been checked. The QREF show a degree of polarization (DOP) of 0.75 given by DOP= (I _max-I _min) / (I _max+I _min) , where I _max and I _min is the intensity of emission when passed through a polarizer parallel and perpendicular to its transmission axis respectively. Variation in intensity of emission with polarizer axis rotation for QREF before and after lamination is shown in Figure 13. The change in intensities after lamination is very small and under experimental error. The calculated DOP for each film is found to be nearly similar i.e. close to 0.75.

Color performance

Emission from the QREF can be effected by the high temperature during different processing for preparation of encapsulation of film. Color co-ordinates of emission from QREF is measured using Konica Minolta (CS-2000) spectroradiometer before and after lamination of QREF given in Figure 14a. No obvious change is observed after laminating two QREF with adhesive. Spectrum of emission from the laminated QREF and emission from used QR solution is recorded using Ocean Optics spectrometer (USB4000) . QREF show no shift in emission wavelength and FWHM compared to emission from QR solutions (Figure 14b) .

QREF (1501) is given in Figure 15a. When putting the QREF on blue backlight (1502) , QREF show white emission due to color mixing. Using a LCD (1503) on top QREF backlight unit different color can be observed.

Claims

Passivation layer for encapsulation of at least one photoaligned quantum rod enhancement film, deposited on to the photoalignment layer, for LCDs comprising:

i. at least one substrate;

ii. at least one inorganic layer;

which shows a good protection of photoaligned quantum rod enhancement film from oxygen and humidity.
The passivation layer for encapsulation photoaligned quantum rod enhancement film as per claim 1, comprises at least one adhesive layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polyethylene naphthalate, polyethylene terephthalate.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate is a light guide plate for backlight.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from polyester and polyalkyd family.
The substrate of the passivation layer as for photoaligned quantum rod enhancement film per claim 1, wherein the substrate comprises polymer from polyvinyl chloride family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from polysiloxanes family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer of ionomers family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polypropylene.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from fluorinated ethylene family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from styrene methyl methacrylate family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from Styrene Acrylonitrile Resin family.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polystyrene.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from polyaryletherketone family.
The polymer as per claim 14, wherein the polymer of polyaryletherketone family is polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, polyetherketoneetherketoneketone.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from polyimide family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from polycarbonate family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from cyclic olefin copolymer family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymer from polysulfones family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises acrylic polymers.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate comprises polymers from acrylonitrile-butadiene-styrene (ABS) family.
The substrate of the passivation layer as per claim 1, wherein the substrate comprises polymer from acrylonitrile styrene acrylate (ASA) family.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the substrate thickness is in the range of 50-1000μm.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 3, wherein the substrate thickness is 70μm.
The substrate of the passivation layer for photoaligned quantum rod enhancement film as per claim 4, wherein the substrate thickness is in range 100-400μm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, contained at least one planarization layer coated onto the said substrate.
The passivation layer for photoaligned quantum rod enhancement film as per claim 26, wherein the planarization layer comprises organic polymer, siloxane polymer, silicate, metal oxides, fluorine doped tin oxide or the mixture of thereof.
The planarization layer as per claim 26, wherein Al ₂O ₃ is deposited onto the substrate.
The planarization layer as per claim 28, wherein Al ₂O ₃ is deposited onto the substrate of thickness is in the range of 50nm-5μm.
The planarization layer as per claim 28, wherein the thickness of the Al ₂O ₃ is deposited onto the substrate is 200nm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the inorganic layer is coated on to one side of substrate, at least, for tight passivation of photo aligned quantum rod enhancement film.
The inorganic layer as per claim 31, wherein the inorganic layer thickness is in the range of 50nm-5μm.
The inorganic layer as per claim 31, wherein the inorganic layer thickness is 200nm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the inorganic layer comprises silicates, phosphosilicates, mechanically deposited glass frit, oxides and nitrides of silicon, aluminium, tin, indium, boron and titanium.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the inorganic layer comprises combination of two different inorganic layer.
The inorganic layer as per claim 34, wherein the inorganic layer is SiO ₂ layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the passivation layer comprises a combination of organic or inorganic layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the passivation layer comprises a combination of alternate organic and inorganic layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 38, wherein the passivation layer comprises multiple layers having a combination of alternate organic and inorganic layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 39, wherein the passivation layer comprises three layers consisting the alternate combination organic and inorganic layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the inorganic layer as per claim 31 also serve as planarization layer for the said substrate as per claim 26.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the passivation layer comprises one substrate coated with protecting layer, and another inorganic layer on top of enhancement film.
The protecting layer as per claim 42 is an inorganic layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 42, wherein the passivation layer comprises PET substrate coated with inorganic layer, and another inorganic layer on top of enhancement film.
The passivation layer for photoaligned quantum rod enhancement film as per claim 42, wherein the passivation layer comprises PET substrate coated with inorganic layer, and another inorganic layer on top of enhancement film and organic layer above inorganic layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 44, wherein the substrate is a PET substrate of thickness 70μm, Inorganic layer is SiO ₂ layer of thickness 200nm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 42, wherein the passivation layer comprises light guide plate as substrate coated with inorganic layer, and another inorganic layer on top of enhancement film.
The passivation layer for photoaligned quantum rod enhancement film as per claim 42, wherein the passivation layer comprises light guide plate as substrate coated with inorganic layer, and another inorganic layer on top of enhancement film and organic layer above inorganic layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 47, wherein the substrate is a light guide plate of thickness 400μm, Inorganic layer is SiO ₂ layer of thickness 200nm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the adhesive layer is used for face-to-face lamination of the two photo aligned quantum rod enhancement films deposited on to the single organic-inorganic passivation layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1, wherein the adhesive layer is used for face-to-face lamination of the two photo aligned quantum rod enhancement films deposited on to the separate single organic-inorganic passivation layer comprising additionally planarization layers.
The adhesive layer as per claim 2 and 51, wherein the adhesive layer comprises polymer glue.
The adhesive layer as per claim 2 and 52, wherein the polymer glue is epoxy resin, ethylene-vinyl acetate (a hot-melt glue) , phenol formaldehyde resin, polyamide, polyester resins, polyethylene (a hot-melt glue) , polypropylene, polysulfides, polyurethane (e.g. Gorilla Glue) , polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, polyvinylpyrrolidone, rubber cement, silicones, silyl modified polymers, styrene acrylic copolymer are mixture thereof..
The adhesive layer as per claim 2 and 51, wherein the adhesive layer comprises monomer glue.
The adhesive layer as per claim 54 , wherein monomer glue is acrylonitrile, cyanoacrylate, acrylic or resorcinol glue.
The adhesive layer as per claim 2 and 51, wherein the adhesive layer comprises glue material which can be cured thermally or optically or drying.
The adhesive layer as per claim 2 and 51, wherein the adhesive layer comprises UV-curable adhesive.
The adhesive layer as per claim 2 and 51, wherein the adhesive layer thickness is in the range of 2-30μm.
The adhesive layer as per claim 2 and 49, wherein adhesive layer contains nanoparticles.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1 and 2, wherein the substrate is a PET substrate, Inorganic layer is SiO ₂ layer, adhesive layer is a UV curable adhesive layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 60, wherein the substrate is a PET substrate of thickness 70μm, Inorganic layer is SiO ₂ layer of thickness 200nm, adhesive layer is a UV curable adhesive layer of thickness 10μm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1 and 2, wherein the substrate is a light guide plate, Inorganic layer is SiO ₂ layer, adhesive layer is a UV curable adhesive layer.
The passivation layer for photoaligned quantum rod enhancement film as per claim 60, wherein the substrate is a light guide plate of thickness 400μm, Inorganic layer is SiO ₂ layer of thickness 200nm, adhesive layer is a UV curable adhesive layer of thickness 10μm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 1 and 2, wherein one substrate is a PET substrate, another substrate is light guide plate, Inorganic layer is SiO ₂ layer, adhesive layer is a UV curable adhesive.
The passivation layer for photoaligned quantum rod enhancement film as per claim 64, wherein the substrate is a PET substrate of thickness 70μm, another substrate is light guide plate of thickness 400μm, Inorganic layer is SiO ₂ layer of thickness 200nm, adhesive layer is a UV curable adhesive layer of thickness 10μm.
The passivation layer for photoaligned quantum rod enhancement film as per claim 60, show good WVTR and OTR performance with values 8.06 x 10 ^-7 g m ^-2 day ^-1 and 4.93x10 ^-3 cc/m ²/day respectively.