TWI592461B - Semiconductor nanoparticle-based light emitting materials - Google Patents

Description

Luminescent material based on semiconductor nano particles

This invention relates to semiconductor-based luminescent layers and devices incorporating such layers. The present invention is directed to methods of making such layers.

Conventional backlight units have been composed of a cold cathode fluorescent lamp (CCFL) and a diffuser sheet to impart a large area of homogeneous white light. Due to energy and size constraints, RGB-LEDs (three primary color LEDs) have recently replaced CCFL sources (Figure 1). A further development has been combined with a sheet of conventional phosphor containing one of the conventional phosphors such as YAG (yttrium aluminum garnet) using a blue LED excitation source whereby the "phosphor layer" or "phosphor sheet" is located near or on top of the diffuser layer and Keep away from the light/excitation source (Figure 2).

Currently, phosphorescent materials for downconversion applications absorb UV or predominantly blue light and convert it to longer wavelengths, most of which currently use oxides or halophosphates doped with a third order rare earth. The white light emission is obtained by mixing a phosphor emitted in a blue, green, and red region with a phosphor of a blue or UV emitting solid state device, that is, a blue light emitting LED plus a device such as SrGa ₂ S ₄ : one green phosphor of Eu ²⁺ and one red phosphor such as SrSiEu ²⁺ or a UV light emitting LED plus a yellow phosphor such as Sr ₂ P ₂ O ₇ :Eu ²⁺ ;Mu ²⁺ and one Blue-green phosphor.

Currently, white LEDs are made by combining a blue LED with a yellow phosphor. However, color control and color rendering are not good when using this technique due to the lack of tunability of LEDs and phosphors. In addition, the use of conventional LED phosphor technology has poor color rendering due to the lack of available phosphor color (also That is, the color rendering index (CRI) <75) is under the variable frequency material.

There has been a substantial interest in utilizing the properties of composite semiconductors composed of particles having a size of about 2 to 50 nm, commonly referred to as quantum dots (QD) or nanocrystals. These materials are used in many commercial applications such as optical and electronic devices and now range from biomarkers, optoelectronics, catalysis, LEDs, general space lighting to other applications for electroluminescent displays, as well as many new and emerging applications. Size tunable electronic properties with commercial benefits. Two fundamental factors associated with the size of a single semiconductor nanoparticle result in unique properties. The first factor is the ratio of the larger surface to the volume; as the particle becomes smaller, the ratio of the number of surface atoms to the number of internal atoms increases. This makes the surface properties play an important role in the overall properties of the material. The second factor affecting many materials including semiconductor nanoparticles is that the electronic properties of the material vary with size; due to the quantum confinement effect, the energy gap gradually increases as the particle size decreases. This effect results in a discrete energy level similar to that observed in atoms and molecules, rather than as a limitation of the "in-box electrons" of the continuous energy band observed in the corresponding bulk semiconductor material. Therefore, for semiconductor nanoparticles, due to physical parameters, "electrons and holes" generated by absorbing electromagnetic radiation, photons having a larger than first exciton transition are closer together than in corresponding coarse crystal materials. In addition, Coulomb interactions cannot be ignored. This results in a narrow bandwidth emission that is dependent on the particle size and composition of the nanoparticle material. Thus, the QD has a higher kinetic energy than the corresponding macrocrystalline material and thus the energy of the first exciton transition (energy gap) increases as the particle diameter decreases.

Nuclear semiconductor consisting of a single semiconductor material and an external organic passivation layer Nanoparticles tend to have relatively low quantum efficiencies due to electron-hole recombination at the enthalpy and dangling bonds on the surface of the nanoparticle that can cause non-radiative electron-hole recombination.

One method for eliminating ruthenium and dangling bonds on the inorganic surface of QD is to coat the nanoparticles with a uniform shell of a second semiconductor. The semiconductor material typically has a much wider energy gap than the energy gap of the core to inhibit tunneling of charge carriers from the core to newly formed surface atoms of the shell. The shell material must also have a lattice mismatch that is less than the core material. Lattice mismatch occurs primarily due to the difference in bond length between the core and the atoms in the shell. Although the difference in lattice mismatch between the core material and the shell material may be only a few percent, it is sufficient to alter both the kinetics of shell deposition and particle morphology and the QY of the resulting particles. The small lattice mismatch ensures that the epitaxial growth on the surface of the shell and the core particles is indispensable to produce "nuclear-shell" particles that do not have or have a minimum of non-radiative recombination that can introduce PLQY of the reduced particles. An example is a ZnS shell grown on the surface of a CdSe or InP core. The lattice mismatch of some of the most common shell materials relative to CdSe is 3.86% in the case of CdS, 6.98% in the case of ZnSe and 11.2% in the case of ZnS.

Another method is to prepare a "core-shell" in which a "electron-hole" pair is completely confined to a single shell consisting of several monolayers of a particular material, such as a QD-quantum well structure. Here, the core is a wide bandgap material, the outer surface is a thin shell of a narrower gap material, and is terminated by another wide energy gap layer, such as using Hg instead of Cd to grow on the surface of the core nanocrystal to deposit subsequently CdS/HgS/CdS with several HgS single layers over a single CdS single layer. The resulting structure exhibits photoexcited carriers in the HgS layer that result in high PLQY and improved photochemical stability. Clear limits.

To add further stability to the QD and help limit electron-hole pairs, one of the most common methods is to grow thick and strong shells around the core. However, due to the lattice mismatch between the core material and the shell material, the interfacial strain significantly accumulates as the shell thickness increases, and can eventually be released via the formation of misfit dislocations, thereby degrading the properties of the QD. This problem can be circumvented by epitaxial growth of the compositional graded alloy layer on the core, as this can help to reduce strain at the core-shell interface. For example, in order to improve the structural stability and quantum yield of the CdSe core, one of the Cd _1-x Zn _x Se _1-y S _y graded metal layers may be directly used on the core instead of one of the ZnS shells. Due to the gradual change of shell composition and lattice parameters, the resulting graded multi-shell QD is well passivated with PLQY values in the range of 70% to 80% and exhibits enhanced photochemistry compared to simple core-shell QD. And colloidal stability.

Doping QD with atomic impurities is also an effective way to manipulate the emission and absorption properties of nanoparticles. Procedures for doping wide bandgap materials such as zinc selenide and zinc sulfide with manganese and copper (ZnSe:Mn or ZnS:Cu) have been developed. Doping with different luminescence activators in a semiconductor nanocrystal can tune photoluminescence and electroluminescence at an energy even below the energy gap of the bulk material, and the quantum size effect can tune the excitation energy according to the size of the QD. Significant changes in energy without activator-related emissions. The dopant includes a main group or a rare earth element, usually a transition metal or a rare earth element such as Mn ⁺ or Cu ²⁺ .

Coordination of atoms on the surface of any nucleus, core-shell or core multi-shell, doped or graded nanoparticles is incomplete and non-completely coordinating atoms have a suspension that makes them highly active and can cause agglomeration of particles key. This problem is protected by The machine group is used to passivate (end) the "naked" surface atoms to overcome.

If the QD is monodisperse, the use of QD in a light-emitting device has some significant advantages over the use of a more conventional phosphor, such as the ability to tune the emission wavelength, strong absorption properties, and low scattering. However, the methods used to date have been challenging due to the chemical incompatibility between the external organic surface of the QD and the type of host material in which the QD is supported. QDs can suffer from agglomeration when formulated into such materials, and once incorporated can undergo photooxidation due to oxygen transitions through the host material to the surface of the QD, which can ultimately result in a decrease in quantum yield. Although reasonable devices can be made under laboratory conditions, there are still a number of challenges to replicate on a large scale under commercial conditions. For example, during the mixing phase, the QD needs to be stable to the air.

The incorporation of a device in which a semiconductor QD is used in place of one of the conventional phosphors has been described, however, due to problems associated with the processability and stability of the QD-containing material during and after layer fabrication, it has been successfully incorporated into such layers. The only type of QD material is the relatively conventional II-VI or IV-VI QD material, such as CdSe, CdS and PbSe. Cadmium and other restricted heavy metals used in conventional QD are highly toxic elements and represent a major concern for commercial applications. The inherent toxicity of cadmium-containing QD prevents its use in any animal or human application. For example, recent studies have shown that QDs made from cadmium chalcogenide semiconductor materials can be cytotoxins in a biological environment unless protected. In particular, oxidative or chemical attack through various pathways can result in the formation of cadmium ions that can be released into the surrounding environment on the quantum surface. Although surface coatings such as ZnS can significantly reduce toxicity, it is not possible to completely eliminate toxicity, because QD can remain in cells or accumulate in the body. During the continuation, the coating may undergo some degradation to expose a long period of time of the cadmium-rich core.

Toxicity not only affects the progress of biological applications but also affects other applications including optoelectronics and communications, as heavy metal-based materials are used in many commercial products including household appliances such as IT & Telecommunication Equipment, Lighting & Electrical Tools, Toys, Leisure & Sports Equipment. It is universal. Legislation that restricts or prohibits certain heavy metals in commercial products has been implemented in many regions of the world. For example, as of July 1, 2006, the EU Directive 2002/95/EC, known as "Restrictions on the Use of Hazardous Substances in Electronic Equipment" (or RoHS), prohibits the sale of lead containing more than an agreed amount, New electrical and electronic equipment for cadmium, mercury, hexavalent chromium and polybrominated biphenyl (PBB) and polybrominated phenyl ether (PBDE) flame retardants. This law requires manufacturers to find alternative materials and develop new engineering processes for creating common electronic devices. In addition, on June 1, 2007, the European Community Regulation (EC 1907/2006) on chemicals and their safe use came into effect. This regulation deals with the registration, evaluation, authorization and restriction of chemical substances and is known as "REACH". REACH regulations give industry greater responsibility to manage risks from chemicals and provide safety information about such substances. Similar regulations are expected to extend throughout the world, including China, South Korea, Japan, and the United States.

There are currently no available luminescent layers containing heavy metal-free QD that can be produced at commercially viable cost and that emit light efficiently in the visible spectrum.

It is an object of the present invention to provide luminescent materials containing heavy metal free QD and/or methods of making such materials.

Another object is to provide luminescent materials that can be produced at commercially viable costs and/or methods of making such materials.

A further object is to provide a luminescent material that emits light efficiently in the visible spectrum and/or a method of making such materials.

Another object is to provide a formulation containing QDs that can be used to make luminescent materials and/or methods of using such formulations.

It is an object of the present invention to obviate or mitigate one or more of the problems associated with current luminescent materials and methods of making such materials.

According to a first aspect of the present invention, there is provided a light-emitting layer comprising a plurality of luminescent particles embedded in a host matrix material, each of the luminescent particles comprising embedded in a polymeric encapsulating medium One of the semiconductor nanoparticle populations.

A second aspect of the present invention provides a method of fabricating a light-emitting layer comprising a plurality of light-emitting particles embedded in a host matrix material, each of the light-emitting particles comprising a polymer encapsulated A group of semiconductor nanoparticles within a medium, the method comprising providing a dispersant comprising one of the luminescent particles, depositing the dispersant to form a film, and treating the film to produce the luminescent layer.

A third aspect of the present invention provides a light-emitting device comprising a light-emitting layer in optical communication with a light-diffusing layer, the light-emitting layer comprising a plurality of light-emitting particles embedded in a host matrix material, among the light-emitting particles Each of them comprises a population of semiconductor nanoparticles embedded in a polymeric encapsulating medium.

According to a fourth aspect of the present invention, there is provided a light emitting device comprising an illuminating layer in optical communication with a backlight, the luminescent layer comprising embedded in a body A plurality of luminescent particles within the matrix material, each of the luminescent particles comprising a population of semiconductor nanoparticles embedded in a polymeric encapsulating medium.

The introduction of semiconductor QD into the emissive material according to the invention brings several advantages. High luminous efficiency can be achieved by exciting one of the QD UV sources, thereby eliminating the need for filters, thus reducing light intensity loss. The range of colors available in the device is enhanced and can be tuned step by step by varying the size and composition of the QDs, for example, by varying the size of the CdSe or InP QD to obtain from blue to deep The color of one of the red ranges spans the entire visible spectrum. The size of the tunable InAs and PbSe QDs covers most of the near-infrared and mid-infrared regions. QD displays produce higher color purity than other types of display technologies because QDs exhibit extremely narrow emission bandwidth and can create pure blue, green, and red to produce all other colors to improve the end user's viewing experience. By customizing their synthesis, these QDs can be easily dispersed into water or organic media to enable rapid and economical device fabrication with standard printing or other solution processable technologies; this also provides the opportunity to create printable and flexible devices. . There is an increasing interest in developing flexible emissive substrates to meet the growing demand for low cost, large area, flexible and lightweight devices such as roll-up displays, electronic paper and keyboards.

The semiconductor nanoparticle preferably contains ions selected from Groups 11, 12, 13, 14, 15, and/or 16 of the periodic table, or the QDs contain one or more types of transition metal ions or d-region metal ions. The semiconductor nanoparticle may contain one or more semiconductor materials selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, InP, InAs, InSb, AlP, AlS, AlAs, AlSb, GaN. , GaP, GaAs, GaSb, PdS, PbSe, Si, Ge, MgS, MgSe, MgTe, and combinations thereof.

Preferably, the polymeric encapsulating medium comprises an optically transparent medium selected from the group consisting of: a polymer, a resin, a monolith, a glass, a sol gel, An epoxy resin, a polyoxymethylene and a (meth) acrylate. The polymeric encapsulating medium can comprise a material selected from the group consisting of poly(methyl (meth) acrylate), poly (ethylene glycol dimethacrylate), polyvinyl acetate, poly ( Divinylbenzene), poly(thioether), cerium oxide, polyepoxide, and combinations thereof.

The luminescent particles are preferably discrete microbeads, each discrete microbead being incorporated into a plurality of such semiconductor nanoparticles. The microbeads can have an average diameter of from about 20 nm to about 0.5 mm. Some or all of the nanoparticle-containing microbeads may include a core comprising a first optically transparent medium and one or more outer layers of the nanoparticle-containing microbeads or deposited on the core Or a plurality of different optically transparent media. The semiconductor nanoparticles can be confined within the core of the microbeads or can be dispersed throughout one or more of the core and/or the outer layers of the microbeads.

In the luminescent layer, the host matrix material can be selected from a wide variety of polymers, whether organic or inorganic, glass, water soluble or organic solvent soluble, biological or synthetic. For example, the following simple linear chain polymers can be used: polyacrylate, polycarbonate, polystyrene, polyethylene, polypropylene, polyketone, polyetheretherketone, polyester, polyamine, polyimine , polyacrylamide, polyolefin, polyacetylene, polyisoprene, polybutadiene, PVDF, PVC, EVA, PET, polyurethane, cellulose polymers (eg, cellulose, ethyl cellulose, isopropyl Methyl cellulose phthalate, nitrocellulose). Further examples include crosslinked polymers and/or copolymers, triblock copolymers, UV and heat cured epoxy resins. Suitable polymers can be selected from the group consisting of polystyrene/toluene matrix, trimethylolpropane triacrylate/lauryl methacrylate matrix, trimethylolpropane triacrylate/methacrylic acid Lauryl ester/polyisobutylene matrix, trimethylolpropane triacrylate/lauryl methacrylate/PIPS matrix, isodecyl acrylate/dipropylene glycol diacrylate matrix, acrylic-polystyrene/toluene matrix, and polycarbonate. Such as bentonite, kaolin, fuming silicon dioxide ^{(e.g., Cab-O-Sil TM)} , manufactured by Xia alumina, zinc oxide manufactured by Xia, inorganic clay materials can be used alone as the polymer host matrix polymer used as the organic medium or Additives to improve the performance of the final material. Any of the polymers and materials indicated above may be employed in accordance with the methods of the present invention, either alone or in combination with one or more other suitable polymers and materials.

In the method of making a light-emitting layer, the dispersant preferably has a viscosity which makes it suitable for deposition by printing or drop casting. The deposition of the dispersant is preferably carried out by printing and dropping casting. The deposited film can then be processed by a doctor blade method to form a film of uniform thickness over one surface of one of the substrates. The film can be formed to have any desired thickness but is preferably at most about 250 nm thick. Treatment of the film may also involve heating the film one or more times, for example, up to a temperature of from about 50 °C to 100 °C. Alternatively or additionally, the treatment of the film can comprise curing by any convenient means.

In a light emitting device comprising a light emitting layer in optical communication with a backlight, the device comprises a light diffusing layer between the backlight and the light emitting layer.

According to a first aspect of the present invention, a printing or drop casting is provided a dispersing agent on a substrate, the dispersing agent comprising luminescent particles dispersed in a host matrix material, each of the luminescent particles comprising a population of semiconductor nanoparticles embedded in a polymeric encapsulating medium.

Luminescent inks (i.e., inks that emit light under UV or visible light illumination) have been used in consumer products for a variety of purposes for a long time. One of the main reasons is that luminescent inks produce extremely bright and saturated colors that make the product more attractive to the human eye. Many conventional luminescent inks are made by mixing a clear base ink with various types of fluorescent pigments. While such pigments can provide the desired luminosity, in many cases, because they are capable of scattering light, they can render the ink opaque, which is often an undesirable side effect. Opacity becomes a problem when high pigment loading is necessary to achieve the desired brightness or when the ink is used as an original ink to be combined by overprinting to create one of the secondary and tertiary colors. For example, one of the clear blue inks overprinted on top of a yellow clear ink will result in a green ink. Conversely, one of the opaque blue inks overprinted on top of the other ink will hide the underlying ink regardless of its color and the final ink will continue to appear blue in the viewer's view due to its opacity.

In addition to aesthetic purposes, the need for clear inks can be understood in the context of manufacturing UV-sensitive inks that are popular among security items such as passports, personal identification cards, credit cards, chip cipher cards, banknotes, and bar code tracking products. . The primary purpose of such inks is to introduce one or more distinctive "secret" codes into the objects to make them unique and difficult to counterfeit. The ink must be transparent under natural light to be occluded and become visible only when it emits a certain color of light after UV illumination. Ideally, The color of the emitted light is tuned such that it can be substantially only recognized by a particular electronic device such that the object is less susceptible to counterfeiting and alteration. The color of the emitted light is not necessarily limited to the visible range and may also include light emitted in the infrared portion of the spectrum. Conventional phosphors currently used in most safety luminescent inks have a scattering of visible light and one of the opaque inks is perceptible to the particle size (typically in the range of a few microns).

Other conventional luminescent inks are made by mixing a clear base ink with various types of organic fluorescent dyes. These types of inks generally provide high brightness and high transparency but are generally subject to low light and water fastness (ie, a dye that resists fading due to light and water contact), usually one of which deteriorates in the presence of oxygen. phenomenon. Examples of such organic dyes include xanthene dyes, diphenyl dyes, diphenylmethane dyes, triarylmethane dyes, and mixtures thereof. Another important limitation of such organic dyes is characterized by a broad emission spectrum upon excitation by UV or visible light excitation, thereby limiting the amount and purity of available colors and thus providing limited protection against counterfeiting.

QD-based inks provide the same level of brightness without the disadvantages of conventional pigment inks or dye-based inks. If the QD is monodisperse, the use of QD has certain significant advantages, such as the ability to tune the emission wavelength, strong absorption properties, and low scattering. For QD, it has been found that it can emit light in any near-monochromatic color, where the color of the emitted light depends only on the size of the QD. QD is soluble in solvents and its physical properties can be tailored to be soluble in any type of solvent.

For its use in luminescent inks, QD must be incorporated into an ink medium while remaining completely monodisperse without significant quantum efficiency loss. Lost. The method used to date is challenging due to the chemical incompatibility between the external organic surface of the QD and the medium used in the ink, which is preferably water or a water-based solvent. This is due to the surface of the QD. The fact that it is capped by a hydrophobic organic ligand that imparts very low affinity to water or does not impart affinity for water. Hydrophilic ligand capped QDs have better affinity for water-based media but generally have worse optical properties (such as low quantum yield and broad size distribution) than their organic equivalents. In general, whether it has a hydrophilic or hydrophobic surface coating, the QD can still undergo agglomeration when formulated into such inks and once incorporated, oxygen transitions through the ink medium to the surface of the QD can result in photooxidation and quantum yield The decline. Although reasonable inks can be made under laboratory conditions, there are still a number of challenges to replicate on a large scale under commercial conditions. For example, in the mixing phase, QD needs to be stable to air.

It is highly advantageous to introduce QD into a solid substrate such as a "bead material" in accordance with the fifth aspect of the present invention. The QD beads can be incorporated into a polymer matrix or medium by dispersing the desired amount of QD bead material in a desired amount of a suitable polymer to form a QD bead ink. The resulting composite is thoroughly mixed to provide a simple and straightforward manner in which one of the uniform inks can be cured according to the particular curing procedure used for the particular polymer used and to provide a luminescent QD bead ink.

QD bead inks offer other advantages over free "naked" QD inks. By incorporating QD into the stabilizing beads, otherwise active QDs can be prevented from potentially damaging the surrounding chemical environment. In addition, by placing several QDs into a single bead, subsequent QD beads are more stable to the QD inks that typically have to undergo mechanical and thermal processing during fabrication of the luminescent product compared to bare QD. Contain Additional advantages of QD beads over bare QD include greater stability to air, moisture, and photooxidation, potentially opening up the possibility of processing quantum inks in the air and eliminating the need for expensive processing that requires an inert atmosphere. Significantly reduce manufacturing costs. The size of the beads can be tuned in diameter from 50 nm to 0.5 nm according to a custom encapsulation protocol, providing a means of controlling the viscosity of the ink. This is important because the viscosity determines how the ink flows through the mesh, how it dries, and how firmly it adheres to the substrate. If the viscosity can be controlled by the size of the beads, the practice of adding a large amount of diluent to change the viscosity can be ruled out to make the process simpler and less expensive.

Due to the nature of the encapsulation process, not only is QD agglomerated to create a uniform layer, but the QD surface is not destroyed or substantially modified and the QD maintains its original electronic properties to tightly control the specifications of the QD bead ink. QD beads allow for efficient color mixing of QDs in inks, as the blends can be in QD-containing beads, that is, each bead contains several different size/color emitting QDs, or beads of different colors and have the same size/color A mixture of all QDs within a particular bead, that is, some beads contain all blue QDs, some beads contain all green QDs and some beads contain all red QDs.

The hydrophobic coated QD can be encapsulated into beads composed of a hydrophilic polymer to impart novel surface properties, such as water solubility. This is especially important for the manufacture of water-based QD inks that have many excellent qualities and are particularly environmentally friendly. There are numerous regulations that have identified organic solvents commonly used as color developing agents in printing inks as dangerous. Hazardous waste regulations limit the treatment options for all wastes that are mixed with such inks that are generally organic in nature (eg, toluene, ethanol, isopropanol) and highly flammable. Come Chemicals derived from the decomposition of such wastes are also toxic and special measures must be taken in the printing industry to trap these chemicals and avoid their release in the environment. Water-based inks provide an attractive alternative to one of these organic solvents and one of the means of eliminating contamination and many regulatory constraints on the printing process.

The same concept can be applied to beads composed of oppositely charged polymers, for example, a bead process can be used to modify the QD surface by switching surface charges using a suitable polymer. The QD surface charge is one of the important parameters in nanotoxicity because it has been observed that a specific charge on the surface of the QD can trigger the initiation of certain destructive molecular pathways via contact initiation. Changing the surface charge via the bead encapsulation process can provide an easy way to circumvent this problem.

The bead seal can therefore be considered as a simple process for providing more options by avoiding the use of harsh test conditions and thus limiting potential damage to QD and providing more options in the amount and type of resin that can be used to disperse and process the QD beads. One way to tune the surface functionality of QD.

Under certain test conditions, the bead coating can be selectively modified or removed during/before certain stages of ink preparation, meaning that the ink can be considered to be one of the media used to deliver the QD. Thus QD beads represent one way to control the release and delivery of QD, which may, for example, protect the QD during certain stages of the printing process and separate it from the incompatible material or enhance the QD in one Affinity in a particular ink solvent is important.

A first preferred embodiment of a QD bead ink according to the present invention comprises a green-emitting QD cerium oxide bead in a polystyrene/toluene matrix. First form a suitable amount of QD beads to be subsequently added thereto (in this case, InP/ZnS core/shell) QD beads) polystyrene/toluene mixture. The resulting mixture is then treated (eg, heated, mixed, etc.) to ensure that the QD bead particles are satisfactorily dispersed in the polystyrene/toluene mixture to produce a clear green QD bead ink.

A second preferred embodiment of a QD bead ink according to the present invention comprises a red luminescent acrylate bead in an LED acrylate matrix. First, a mixture containing one of the initiators Irgacure 819, trimethylolpropane triacrylate (TMPTM) and lauryl methacrylate was formed. The InP/ZnS core/shell QD acrylate beads were then dispersed in an acrylate mixture to produce a red QD bead ink.

A third preferred embodiment of a QD bead ink according to the present invention comprises a red luminescent acrylate bead in a flexible acrylate matrix comprising trimethylolpropane triacrylate (TMPTM) and Polyisobutylene (PIB). In an alternate embodiment, PIPS can be used in place of PIB. A mixture containing one of the initiators Irgacure 819 and TMPTM is formed. A separate mixture of PIB and lauryl methacrylate is also formed. The amount of TMPTM used in this embodiment is relatively less than that used in the second preferred embodiment to ensure that the degree of crosslinking of the acrylate matrix is small and thus is greater than the acrylate matrix produced in the second preferred embodiment. More flexible. The two mixtures are then combined to produce a yellowish ink matrix. InP/ZnS core/shell QD acrylate beads were then dispersed in the yellowish matrix to produce a red QD bead ink.

QD phosphors offer several advantages over free "naked" QD phosphors.

By incorporating QD into the stable bead, it is possible to prevent activity in other aspects. QD potentially damages the surrounding chemical environment. In addition, by placing several QDs into a single bead, the subsequent QD bead is compared to the bare QD for the chemical, mechanical, thermal requirements required to incorporate the QD into most commercial applications such as downconversion materials, phosphorescent materials. And light processing is more stable. Additional advantages of QD-containing beads compared to bare QD include greater stability to air, moisture, and photo-oxidation, potentially opening up the possibility of processing quantum inks in the air and eliminating the need for expensive processing that requires an inert atmosphere This significantly reduces manufacturing costs. The bead size can be tuned in diameter from 50 nm to 0.5 nm according to a custom encapsulation protocol, providing a means of controlling the viscosity of the ink and enabling a range of inexpensive and commercially available deposition techniques.

Due to the nature of the encapsulation process, not only is QD agglomerated to create a uniform layer, but the QD surface is not destroyed or substantially modified and the QD maintains its original electronic properties to tightly control the specifications of the QD bead ink phosphor. QD beads permit efficient color mixing of QDs in phosphors, as the blend can be in QD-containing beads, that is, each bead contains several different size/color emitting QDs, or beads of different colors and have the same size/color One of a mixture of all QDs within a particular bead, that is, some beads contain all green QDs and all other red QDs (see Figures 5 through 7 below).

The hydrophobic coated QD can be encapsulated into beads composed of a hydrophilic polymer to impart novel surface properties, such as water solubility. This is especially important for making water-based QD inks. The same concept can be applied to beads composed of oppositely charged polymers. This can be considered as the amount of resin available for use by avoiding the use of harsh test conditions and thus limiting potential damage to the QD and for dispersing and processing the QD beads used to make the phosphor device. And the type aspect provides one of the more simple ways to tune one of the surface functionalities of QD.

Bead encapsulation can help reduce the formation of strains that typically affect the phosphor sheets produced by conventional encapsulation methods and that have an adverse effect on the optical properties of the sheet. In addition, no further film encapsulation is required, as the QD in the film has been encapsulated by surrounding beads, potentially halving the cost of the current manufacturing process requiring a final film encapsulation.

Under certain test conditions, the bead coating can be selectively modified or removed during/before certain stages of phosphor sheet preparation, meaning that QD bead ink can be used as a medium to deliver QD. Thus QD beads represent one way to control the release and delivery of QD, which may, for example, protect the QD during certain stages of the printing process and separate it from incompatible materials or (for example) In terms of it, it is more important to disperse the water-insoluble QD in an aqueous medium.

An important achievement of the present invention is the encapsulation of QD in an encapsulating medium that imparts stability to QD without altering its properties and its processability. Embedding the colloidal QD in a host matrix has the major advantage of protecting the QD from its surrounding chemical environment, air, moisture, and oxygen and enhancing its light stability. One of the challenges, however, is to find a transparent host matrix that can act as a conductive layer and that is non-emissive (eg, does not interfere with light emitted by a primary source (eg, LED) and light emitted by the QD). Polymer matrices need to be stable under strong illumination and high energy (i.e., UV sources) and for certain applications also require some stability at elevated temperatures.

The aspect of the invention relates to a QD bead phosphor made from a QD-containing bead structure Sheet and method of producing QD bead phosphor plate.

One of the methods for making a QD bead phosphor sheet in accordance with one aspect of the present invention. The first preferred embodiment employs green ceria beads in a polystyrene/toluene matrix. The two spacers are secured to a sheet of polyethylene terephthalate (PET) with a constant gap (eg, 15 mm) defined therebetween. A predetermined volume of QD bead ink, such as the ink set forth above in a first preferred embodiment of a QD bead ink, is then drop cast onto the area of the PET sheet in the middle of the spacers. The ink is then evenly distributed between the spacers and then heated to remove the solvent. The resulting film exhibited significant fluorescence under bright ambient light conditions.

One of the methods for making a QD bead phosphor sheet in accordance with one aspect of the present invention uses a red acrylate bead in an LED acrylate matrix. One of a predetermined volume of QD bead ink (for example, an ink according to the second preferred embodiment of the ink described above) is drop cast onto a glass mold and then cured to produce a QD bead polymer membrane.

One of the methods for making a QD bead phosphor sheet in accordance with one aspect of the present invention uses a red acrylate bead in a flexible acrylate matrix. One of a predetermined volume of QD bead ink (for example, an ink according to the third preferred embodiment of the ink described above) is drop cast onto a glass mold and then cured to produce a QD bead polymer membrane.

All three of the above preferred embodiments successfully produced QD bead phosphor sheets that exhibited better optical performance.

The invention describes the preparation of a QD phosphor sheet, which is called "bead" embedded in an optically transparent and chemically stable medium. Made of QD - The term beads as used herein may mean any material of three dimensional shape, selection or size - using a variety of techniques. The preparation of the beads can be accomplished by several processes, including by incorporating the QDs directly into the polymer matrix of the resin beads or by immobilizing the QDs in the polymer beads by physical entrapment.

In the semiconductor nanoparticle material employed in various aspects of the invention, the core material may comprise any one or more of the following types of materials.

a compound of II-VI comprising a first element from one of group 12 (II) of the periodic table and a second element from group 16 (VI) of the periodic table and including but not limited to CdSe, CdTe, ZnS, ZnSe, ZnTe , ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdHgSeS , ternary and quaternary materials of CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe.

An II-V compound that incorporates a first element from one of the families 12 of the periodic table and a second element from a family 15 of the periodic table and includes ternary and quaternary materials and dopant materials. Nanoparticle materials include, but are not limited to, Zn ₃ P ₂ , Zn ₃ As ₂ , Cd ₃ P ₂ , Cd ₃ As ₂ , Cd ₃ N ₂ , Zn ₃ N ₂ .

A III-V compound comprising a first element from one of Groups 13 (III) of the Periodic Table and a second element from Group 15 (V) of the Periodic Table and ternary and quaternary materials. Examples of nanoparticle nuclear materials include, but are not limited to, BP, AlP, AlAs, AlSb; GaN, GaP, GaAs, GaSb; InN, InP, InAS, InSb, AlN, BN, GaNP, GaNAs, InNP, InNAs, GAInPAs, GaAlPAs, GaAlPSb, GaInNSb, InAlNSb, InAlPAs, InAlPSb.

A III-VI compound comprising a first element from one of the families 13 of the periodic table and a second element from the family 16 of the periodic table and comprising ternary and quaternary materials. Nanoparticle materials include, but are not limited to, Al ₂ S ₃ , Al ₂ Se ₃ , Al ₂ Te ₃ , Ga ₂ S ₃ , Ga ₂ Se ₃ , In ₂ S ₃ , In ₂ Se ₃ , Ga ₂ Te ₃ , In ₂ Te ₃ .

An IV compound comprising the elements Si, Ge, SiC and SiGe from Group 14 (IV).

An IV-VI compound comprising a first element from one of Groups 14 (IV) of the Periodic Table and a second element from Group 16 (VI) of the Periodic Table and including but not limited to PbS, PbSe, PbTe, SnSeS, SnSeTe , ternary and quaternary materials of SnSTe, PbSeS, PbSeTe, PbSTe, SnPbSe, SnPbTe, SnPbSeTe, and SnPbSTe.

The material of any buffer layer or any (any) shell layer grown on the nanoparticle core may comprise any one or more of the following materials.

IIA-VIB (2-16) material incorporating a first element from one of Group 2 of the periodic table and a second element from Group 16 of the periodic table and including ternary and quaternary materials and dopant materials. Nanoparticle materials include, but are not limited to, MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe.

IIB-VIB (12-16) material incorporating a first element from one of the families 12 of the periodic table and a second element from the family 16 of the periodic table and including ternary and quaternary materials and dopant materials. Nanoparticle materials include, but are not limited to, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe.

An II-V material that incorporates a first element from one of the families 12 of the periodic table and a second element from a family 15 of the periodic table and includes ternary and quaternary materials and dopant materials. Nanoparticle materials include, but are not limited to, Zn ₃ P ₂ , Zn ₃ As ₂ , Cd ₃ P ₂ , Cd ₃ As ₂ , Cd ₃ N ₂ , Zn ₃ N ₂ .

A III-V material that incorporates a first element from one of the families 13 of the periodic table and a second element from a family 15 of the periodic table and includes ternary and quaternary materials and dopant materials. Nanoparticle materials include, but are not limited to, BP, AlP, AlAs, AlSb; GaN, GaP, GaAs, GaSb; InN, InP, InAs, InSb, AlN, BN.

A III-IV material that incorporates a first element from one of the families 13 of the periodic table and a second element from a family 14 of the periodic table and includes ternary and quaternary materials and dopant materials. Nanoparticle materials include, but are not limited to, B ₄ C, Al ₄ C ₃ , Ga ₄ C.

A III-VI material that incorporates a first element from one of the families 13 of the periodic table and a second element from a family 16 of the periodic table and includes ternary and quaternary materials. Nanoparticle materials include, but are not limited to, Al ₂ S ₃ , Al ₂ Se ₃ , Al ₂ Te ₃ , Ga ₂ S ₃ , Ga ₂ Se ₃ , In ₂ S ₃ , In ₂ Se ₃ , Ga ₂ Te ₃ , In ₂ Te ₃ .

An IV-VI material that incorporates a first element from one of the families 14 of the periodic table and a second element from a family 16 of the periodic table and includes ternary and quaternary materials and dopant materials. Nanoparticle materials include, but are not limited to, PbS, PbSe, PbTe, Sb ₂ Te ₃ , SnS, SnSe, SnTe.

a nanoparticle material that incorporates a first element of any one of the transition metals from the periodic table and a second element of any one of the elements of the d region of the periodic table and includes ternary and quaternary materials and doping material. Nanoparticle materials include, but are not limited to, NiS, CrS, CuInS ₂ , CuInSe ₂ , CuGaS ₂ , CuGaSe ₂ .

The QD of III-V semiconductors has reduced toxicity compared to IIB-VI compounds, providing a potential alternative to the widely used cadmium-based QD. However, the research and application of III-V semiconductor QD is limited by its synthetic difficulty. Although the most widely studied semiconductor materials in the InP system III-V cluster, the synthesis of InP QD and conventional III-V semiconductors by conventional chemical methods existing in the prior art does not produce most IIB with and including CdSe and CdS. The QD of the same optical and physical properties of VI semiconductor nanocrystals. The QD made by this conventional chemical method is characterized by poor electronic properties including relatively low PLQY. These limitations significantly impede the use of heavy metal-free semiconductor QDs in launch devices. Another issue of concern in the electronics industry is the need to supply multiple grams of QD to mass produce commercial products while conventional methods may only deliver microgram quantities of such materials.

"Capping agent" - the outermost particle layer

Coordination of atoms on the surface of any nucleus, core-shell or core multi-shell, doped or graded nanoparticles is incomplete and non-completely coordinating atoms have a suspension that makes them highly active and can cause agglomeration of particles key. This problem is overcome by protecting (capping) the "naked" surface atoms by protecting the organic groups.

The outermost layer (end capping agent) of the organic or sheathing material helps to inhibit particle-particle agglomeration, further protects the nanoparticle from its surrounding electronic and chemical environment and provides chemical bonds to other inorganic, organic or biological materials. One means. In many cases, the blocking agent is used in the preparation of nanoparticles. A solvent consisting of a Lewis base compound or a Lewis base compound diluted with an inert solvent such as a hydrocarbon. There is a lone pair of electrons on the Lewis base blocker, which can coordinate to the surface of the nanoparticle and include mono- or polydentate ligands such as phosphine (trioctylphosphine, triphenylphosphine). , tert-butylphosphine, etc.), phosphine oxide (trioctylphosphine oxide, triphenylphosphine oxide, etc.), alkylphosphonic acid, alkylamine (octadecylamine, hexadecylamine, octylamine, etc. ), arylamine, pyridine, long-chain fatty acids (myristic acid, oleic acid, undecylenic acid, etc.), thiophene, but as will be understood by those skilled in the art, are not limited to such materials.

Surface modified QD

The outermost layer (blocking agent) of a QD may also consist of a coordinating ligand and an additional functional group that can be used as a chemical bond to other inorganic, organic or biological materials, whereby the functional group is directed away from the QD surface and can be used To join/react/interact with other available molecules, such as amines, alcohols, carboxylic acids, esters, hydrazine chlorides, anhydrides, ethers, alkyl halides, decylamines, alkenes, alkanes, alkynes, propadiene, amino acids, Azides, groups, and the like, but as will be appreciated by those skilled in the art, are not limited to such functionalized molecules. The outermost layer (blocking agent) of a QD may also consist of a coordinating ligand and a functional group which is polymerizable and which can be used to form a polymer layer around the particles.

The outermost layer (blocking agent) can also be directly bonded to the outermost inorganic layer, for example, by an S-S bond between an inorganic surface (ZnS) and a thiol-terminated molecule. These may also have additional functional groups that can be used to form a polymer around the particle or for further reaction/interaction/chemical bonding that does not bond to the surface of the particle.

QD beads (QD beads)

The light stability of the QD employed in the various aspects of the invention is enhanced by incorporating QD into the optical indicator bead. Considering the initial step of incorporating the QD into the bead, a first option is to incorporate the QD directly into the polymer matrix of the resin bead. A second option is to immobilize the QD in the polymer beads via physical entrapment. These methods can be used to construct a population of beads containing only a single type of QD (eg, one color) by incorporating a single type of QD into the beads. Alternatively, two or more types of QDs can be constructed by incorporating a mixture of two or more types of QDs (eg, materials and/or sizes) into the beads ( For example, two or more colors). The mixed beads can then be combined in any suitable ratio to emit secondary light of any desired color after excitation by a primary light emitted by a primary source (eg, an LED). This example is illustrated in Figures 5-7, which schematically illustrate QD bead illumination devices, each of which includes: a) beads comprising a multi-color QD such that each bead emits white two Secondary light; b) a plurality of beads, each of which contains a QD of a single color such that each bead emits a single color of light but a combination of beads of different colors produces white secondary light; and c) a bead that contains a single color The QD is such that the mixture of one of the beads emits a secondary light of a single color, for example, red.

Incorporating QD during bead formation

With regard to the first option, for example, at least one, more preferably two or more polymerizable ligands (optionally one ligand excess) may be used to treat semiconductor nanoparticle based on hexadecyl-terminated CdSe to cause ten Displacement of at least some of the hexamine capping layer and the polymerizable ligand. End cap layer and polymerizable ligand The displacement can be achieved by selecting one of the structures having a structure similar to trioctylphosphine oxide (TOPO), a polymerizable ligand or a plurality of polymerizable ligands having one of the CdSe-based nanoparticles. One of the known and very high affinity ligands. It should be understood that this basic method can be applied to other nanoparticle/ligand pairs to achieve a similar effect. That is, for any particular type of nanoparticle (material and/or size), it may be similar to a known surface combination by selection in some aspects (eg, having a similar physical and/or chemical structure). The polymerizable ligand of one of the ligands of the ligand is selected to select one or more suitable polymerizable surface-binding ligands. Once the nanoparticles have been surface modified in this manner, they can be added to several microscale polymerization-monomer components to form various QD-containing resins and beads. Another option is to polymerize one or more polymerizable monomers from which an optically transparent medium is to be formed in the presence of at least a portion of the semiconductor nanoparticles to be incorporated into the optically clear medium. The resulting material is covalently incorporated into the QDs and appears to be highly colored, even after the extended Socrates extraction cycle.

Examples of polymerization methods that can be used to construct QD-containing beads include, but are not limited to, suspension, dispersion, emulsion, activity, anion, cation, RAFT, ATRP, expansion, ring closure metathesis, and ring opening metathesis. The initiation of the polymerization reaction can be caused by any suitable method of reacting the monomers with each other (for example, by using radicals, light, ultrasound, cations, anions or heat). A preferred method involves suspension polymerization of a heat cure from one or more polymerizable monomers from which an optically transparent medium is to be formed. The polymerizable monomers preferably comprise methyl (meth) acrylate, ethylene glycol dimethacrylate and vinyl acetate. This combination of monomers has been shown to exhibit with existing commercially available LED encapsulants It is excellently compatible and has been used to produce one of the illuminating devices that exhibits a significant improvement over substantially one of the devices previously prepared using prior art methods. Other preferred polymerizable single systems can be polymerized epoxy or polyepoxide monomers using any suitable mechanism (e.g., curing by ultraviolet light irradiation).

The QD-containing microbeads can be produced by dispersing a known QD population in a polymer matrix, curing the polymer and subsequently grinding the resulting solid material. This becomes particularly applicable to relatively hard and brittle after the polymer solids, such as many of the common polyepoxide or epoxy polymers (e.g., from the United States Optocast Electronic Materials Company ^TM 3553).

The QD-containing beads can be produced simply by adding QD to the mixture of reagents used to construct the beads. In some cases, QD (primary QD) will be used to isolate from the reaction used to synthesize QD and is therefore typically coated with an inert external organic ligand layer. In an alternative procedure, a ligand exchange process can be performed prior to the bead formation reaction. Here, one or more chemically active ligands are added in excess to one of the initial QD solutions applied to an inert external organic layer (for example, this may also be a ligand for a QD that also contains a polymerizable moiety). After a suitable incubation time, for example by isolating the QDs by precipitation and subsequent centrifugation, washing the QDs and subsequently incorporating the QDs into a mixture of reagents used in the bead formation reaction/process in.

These two QD incorporation strategies will result in statistical random incorporation of QD into the beads and thus the polymerization will result in beads containing statistically similar amounts of QD. It will be apparent to those skilled in the art that the size of the bead can be controlled by selecting the polymerization reaction used to construct the bead and additionally, once a polymerization process has been selected, The bead size is controlled by selecting appropriate reaction conditions (e.g., by stirring the reaction mixture more rapidly in a suspension polymerization to produce smaller beads). Furthermore, the shape of the beads can be easily controlled by combining whether or not a reaction selection procedure is carried out in a mold. The composition of the beads can be altered by altering the composition of the monomer mixture from which the beads are constructed. Similarly, the beads can also be crosslinked with varying amounts of one or more crosslinkers (e.g., divinylbenzene). If the bead configuration has a high degree of crosslinking (eg, greater than 5 mole percent crosslinker), it may be desirable to incorporate a consistent pore former (eg, toluene or cyclohexane) during the reaction used to construct the beads. The use of a uniform pore agent in such a manner leaves a permanent pore in the matrix constituting each bead. These holes can be large enough to allow the QD to enter the bead.

QD can also be incorporated into the beads using techniques based on reverse emulsion. The QDs can be mixed with the precursor of the optically clear coating material and then the QDs can be introduced into a stable inverse latex containing, for example, an organic solvent and a suitable salt. After agitation, the precursors form microbeads that can be collected around the QDs using any suitable method, such as centrifugation. If desired, one or more additional surface layers or shells of the same or different optically transparent materials can be added prior to isolating the QD containing the beads by adding a greater amount of the necessary shell precursor material.

Incorporate QD into prefabricated beads

Regarding the second option for incorporating the QD into the bead, the QDs can be immobilized in the polymer beads via physical entrapment. For example, one of the polymer beads can be used to culture one of the QD solutions contained in a suitable solvent (eg, an organic solvent). Removal of the solvent using any suitable method results in the QD becoming fixed within the matrix of the polymeric beads. The QDs remain fixed at In the beads, unless the sample is resuspended in the solvent in which one of the QDs is readily soluble (eg, an organic solvent). Optionally, at this stage, the outside of the beads can be sealed. Another option is to attach at least a portion of the entities of the semiconductor nanoparticles to the preformed polymer beads. Depending on whether the portion of the semiconductor nanoparticles is immobilized in the polymer matrix of the pre-formed polymer beads or by the portion of the semiconductor nanoparticles and the pre-formed polymer beads Chemical, covalent, ionic or physical connections are made. Examples of preformed polymer beads include polystyrene, polydivinylbenzene, and polythiol.

The QD can be irreversibly incorporated into the preformed beads in a number of ways (e.g., chemical, covalent, ionic, physical (e.g., by embedding) or any other form of interaction). If preformed beads are to be used to incorporate the QD, the solvent of the bead may be chemically inert (eg, polystyrene) or alternatively may be chemically active/functionalized (eg, Merrifield's resin) The chemical functionality may be introduced during the construction of the bead, for example by incorporating a chemically functional monomer, or alternatively may be performed in a bead construction process, for example by performing one Chloromethylation reactions to introduce chemical functionality. Additionally, chemical functionality can be introduced by thereby causing the chemically active polymer to undergo polymeric grafting or other similar process with one of the bead outer layer/accessible surface. More than one such post-structural derivation process can be implemented to introduce chemical functionality onto/on the beads.

As with the incorporation of QD into the bead during the bead formation reaction (i.e., the first option described above), the preformed bead can be of any shape, size, and composition and can have any degree of crosslinking and if consistent The structure of the pore agent may contain There are permanent holes. The QD can be embedded into the beads by incubating a QD solution in an organic solvent and applying the solvent to the beads. The solvent must be capable of wetting the beads and in the case of lightly crosslinked beads (preferably 0% to 10% crosslinked and optimally 0% to 2% crosslinked), except that QD is solvated, The solvent should also swell the polymer matrix. Once the QD-containing solvent has been cultured by means of the beads, the QD-containing solvent is removed (eg, by heating the mixture and evaporating the solvent) and the QD becomes embedded in the polymer matrix constituting the beads or the other is selected by The added QD is not readily soluble therein and is mixed with the first solvent to precipitate the QD in one of the second solvents in the polymer matrix constituting the beads. If the bead is not chemically active, the fixation may be reversible, or if the bead is chemically active, the QD may be permanently retained by chemical, covalent, ionic or any other form of interaction. Within the polymer matrix.

Incorporating QD into a sol gel to produce glass

An optically clear medium that is a sol gel and glass that is expected to be incorporated into QD can be formed in a manner similar to that described above for incorporation of QD into the bead during the bead formation process. For example, a single type of QD (eg, a color) can be added to the reaction mixture to produce a sol gel and glass. Alternatively, two or more types of QDs (eg, two or more colors) may be added to the reaction mixture used to produce the sol gel and glass. The sol gel and glass produced by such procedures may have any shape, morphology or 3-dimensional structure. For example, the particles can be spherical, dished, rod, oval, square, rectangular, or any of a variety of other possible configurations.

Stability enhancing additive

By incorporating QD into the beads in the presence of a material that acts as a stability enhancing additive, and optionally providing a protective surface coating to the beads, excluding or at least reducing harmful species such as moisture, oxygen and/or free radicals The change, thereby enhancing the physical, chemical and/or light stability of the semiconductor nanoparticle.

An additive can be combined with "naked" semiconductor nanoparticles and precursors during the initial stages of the bead production process. Alternatively, or in addition, an additive may be added after the semiconductor nanoparticles have been embedded in the beads.

Alone or during the following manner may be grouped according to their intended function of the process may be formed in a bead of any additives added to form a desirable combination of: a mechanical seal: Xia prepared silicon dioxide ^{(e.g., Cab-O-Sil TM)} , ZnO , TiO ₂ , ZrO, Mg stearate, Zn stearate, all used as a filler to produce mechanical seals and / or reduce porosity; capping agent: tetraalkylphosphonic acid (TDPA), oil Acid, stearic acid, polyunsaturated fatty acid, sorbic acid, Zn methacrylate, Mg stearate, Zn stearate, isopropyl myristate. Some of these additives have multiple functions and can act as a capping agent, a radical scavenger and/or a reducing agent; a reducing agent: ascorbyl palmitate, alpha-tocopherol (vitamin E), octanethiol, Tert-butylhydroxyanisole (BHA), butylated hydroxytoluene (BHT), gallic acid ester (propyl, lauryl, octyl, and the like) and metabisulfite (eg, sodium or potassium) Salt); radical scavenger: benzophenone; and hydride reactant: 1,4-butanediol, 2-hydroxyethyl methacrylate, allyl methacrylate, 1,6 heptadiene 4-Alcohol, 1,7-octadiene and 1,4-butadiene.

The choice of the additive or the additives for a particular application will depend on the nature of the semiconductor nanoparticle material (eg, the sensitivity of the nanoparticle material to physical, chemical, and/or photoinduced degradation), the nature of the original matrix material. (eg, the degree of penetration of potentially harmful species such as free radicals, oxygen, moisture, etc.), the intended function of the final material containing the primary particles and the device (eg, the operating conditions of the material or device), and the fabrication of the final material Or the process conditions required for the device. In view of this, one or more suitable additives can be selected from one of the above lists to suit any desirable semiconductor nanoparticle application.

Bead surface coating material

Once the QD is incorporated into the bead, the formed QD bead can be further coated with a suitable material to provide a protective barrier for each bead to prevent potentially harmful species (eg, oxygen, moisture, or free radicals) from the external environment. Pass through the bead material or diffuse to the semiconductor nanoparticle. Thus, semiconductor nanoparticles are less sensitive to their surrounding environment and the various processing conditions typically required for the application of nanoparticles in applications such as phosphor sheets and devices incorporating such sheets.

Preferably, the coating prevents oxygen or any type of oxidant from passing through a barrier of the bead material. The coating may prevent the free radical species from passing through a barrier and/or preferably be a moisture barrier such that moisture in the environment surrounding the bead is inaccessible to the semiconductor nanoparticle incorporated within the bead.

The coating can provide a coating of any desired thickness on one of the surfaces of the bead as long as it provides the desired level of protection. The surface layer coating can be large It is about 1 to 10 nm thick and up to about 400 to 500 nm thick or thicker. Preferred layer thicknesses range from 1 nm to 200 nm, more preferably from about 5 to 100 nm.

The coating may comprise an inorganic material such as a dielectric (insulator), a metal oxide, a metal nitride or a ceria-based material (e.g., a glass).

The metal oxide may be a single metal oxide (ie, an oxide ion combined with a single type of metal ion, such as Al ₂ O ₃ ), or may be a mixed metal oxide (ie, with two or two An oxide ion of a combination of the above types of metal ions, for example, SrTiO ₃ ). The (the) metal ion of the (mixed) metal oxide may be selected from any suitable family of the periodic table (such as Group 2, 13, 14, or 15), or may be a transition metal, d-region metal or lanthanide metal.

Preferred metal oxides are selected from the group consisting of Al ₂ O ₃ , B ₂ O ₃ , Co ₂ O ₃ , Cr ₂ O ₃ , CuO, Fe ₂ O ₃ , Ga ₂ O ₃ , HfO ₂ , In ₂ O ₃ , MgO, Nb ₂ O ₅ , NiO, SiO ₂ , SnO ₂ , Ta ₂ O ₅ , TiO ₂ , ZrO ₂ , Sc ₂ O ₃ , Y ₂ O ₃ , GeO ₂ , La ₂ O ₃ , CeO ₂ , PrO _x (x=suitable integer), Nd ₂ O ₃ , Sm ₂ O ₃ , EuO _y (y=suitable integer), Gd ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , SrTiO ₃ , BaTiO ₃ , PbTiO ₃ , PbZrO ₃ , Bi _m Ti _n O (m=suitable integer; n=suitable integer), Bi _a Si _b O (a = appropriate integer; b = appropriate integer), SrTa ₂ O ₆ , SrBi ₂ Ta ₂ O ₉ , YSCO ₃ , LaAlO ₃ , NdAlO ₃ , GdScO ₃ , LaScO ₃ , LaLuO ₃ , Er ₃ Ga ₅ O ₁₃ .

Preferred metal nitrides may be selected from the group consisting of BN, AlN, GaN, InN, Zr ₃ N ₄ , Cu ₂ N, Hf ₃ N ₄ , SiN _c (c = appropriate integer), TiN, Ta ₃ N ₅ , Ti-Si-N, Ti-Al-N, TaN, NbN, MoN, WN _d (d=suitable integer), WN _e C _f (e=suitable integer; f=suitable integer).

The inorganic coating can comprise cerium oxide in any suitable crystal form.

The coating can be incorporated into an inorganic material that incorporates an organic or polymeric material, such as an inorganic/polymer hybrid, such as a ceria-acrylate hybrid material.

The coating may comprise a polymeric material that may be a saturated or unsaturated hydrocarbon polymer, or may incorporate one or more heteroatoms (eg, O, S, N, halo) or heteroatom-containing functional groups (eg, carbonyl). , cyano, ether, epoxide, decylamine and the like).

Examples of preferred polymeric coating materials include acrylate polymers (e.g., poly(meth) acrylate, polybutyl methacrylate, polymethyl methacrylate, alkyl cyanoacrylate, polyethylene glycol dimethyl methacrylate). Acrylate, vinyl acetate, etc., epoxide (eg, EPOTEK 301 A+ B heat-cured epoxy, EPOTEK OG112-4 single-component UV-cured epoxy or EX0135A and B heat-cured epoxy), polyfluorene Amine, polyimine, polyester, polycarbonate, polysulfide, polyacrylonitrile, polydiene, polystyrene polybutadiene copolymer (craton), perylene, poly(p-phenylene) Methyl (poly-p-xylylene), polyetheretherketone (PEEK), polyvinylidene fluoride (PVDF), polydivinylbenzene, polyethylene, polypropylene, polyethylene terephthalate (PET) ), polyisobutylene (butyl rubber), polyisoprene and cellulose derivatives (methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl methyl cellulose phthalate) Acid esters, nitrocellulose) and combinations thereof.

Aspects of the invention relate to a phosphor layer or sheet made of QD dispersed in a polymer matrix in the form of beads. These QD-containing beads have several advantages. The beads prevent QD agglomeration and result in an emissive layer with improved performance. The beads can be made by avoiding the use of harsh conditions and thus limiting one of the simple processes that can cause potential damage to the QD during its incorporation. The result is that the QD embedded in the beads retains its original electronic properties and the added benefit of enhanced protection from the surrounding chemical environment and photo-oxidation compared to the bare spots. This results in greater tolerance to the processing conditions required to be incorporated into the solid state structure and can translate into a reduction in total manufacturing cost. The ability to incorporate QD into a variety of polymers provides the ability to improve the dispersion and processability of QD materials in a wide variety of resins (both hydrophobic and hydrophilic), enabling the creation of applications such as lighting and display technology. New possibilities for phosphor layers.

Preferred illustrative embodiments of the various aspects of the present invention will now be described with reference to the following reference examples, examples, and drawings.

Instance section

The following is a description of the method for producing QD (including heavy metal free QD), incorporating QD into beads, and formulating QD beads containing ink according to aspects of the present invention, and other aspects according to the present invention for use by QD beads. Description of a method of making a QD phosphor sheet, layer or film.

Reference Example 1: Preparation of CdSe/ZnS Core/Shell QD Preparation of CdSe nuclear QD

Hexadecylamine (HDA, 500 g) was placed in a three-necked round bottom flask and degassed by heating to 120 ° C under a dynamic vacuum for > 1 hour. The solution was then cooled to 60 ° C and [HNEt ₃ ] ₄ [Cd ₁₀ Se ₄ (SPh) ₁₆ ] (0.718 g, 0.20 mmol) was added via a side port under a strong nitrogen stream. Will TOPSe and Me ₂ Cd. TOP (4 mmol each) was added dropwise to the reaction vessel, the temperature was raised to 110 ° C and the reaction was allowed to stir for 2 hours, after which the solution was dark yellow. The equivalent molar amount of TOPSe and Me ₂ Cd was carried out while gradually increasing at a rate of 0.2 ° C / min. The TOP is further added dropwise. A total of 42 millimoles of TopSe and 42 millimoles of Me ₂ Cd were used. TOP. When the PL emission maximum has reached ~600 nm, the reaction is stopped by cooling to 60 ° C and then adding 300 mL of dry ethanol or acetone. This production is further precipitated by one of the dark red particles isolated by filtration. The resulting CdSe QD was recrystallized by redissolving it in toluene, filtering it through diatomaceous earth and then reprecipitating it with warm ethanol to remove any excess HDA and any unreacted by-products. This produced 10.10 grams of HDA-terminated CdSe QD with a maximum light emission λ = 585 nm and a FWHM (full width at half maximum) = 35 nm.

Growth of a ZnS shell on CdSe core QD

HDA (800 g) was placed in a three-necked round bottom flask which was dried and degassed by heating to 120 ° C under a dynamic vacuum for > 1 hour. After the solution was subsequently cooled to 60 ° C, 9.23 g of CdSe QD prepared as above was added. Then a total of 20 mL of 0.5 M Me ₂ Zn was added to the octylamine by dropwise addition. The HDA was heated to 220 ° C after the TOP solution and 20 mL of a 0.5 M sulfur solution. Three injections of 3.5 mL, 5.5 mL, and 11.0 mL of each solution were performed, whereby 3.5 mL of sulfur was first added dropwise until the intensity of the PL maximum approached zero. Then add 3.5 mL of Me ₂ Zn dropwise. TOP until the intensity of the PL maximum has reached a maximum. This cycle is repeated as the PL maximum reaches a higher intensity after each cycle. After reaching a PL maximum intensity at the end of the cycle, additional shelling reagent is added until the PL intensity is between 5% and 10% below its maximum, and the reaction is annealed at 150 ° C for 1 hour. . The reaction mixture was then cooled to 60 ° C thereby adding 300 mL of dry "warm" ethanol to cause precipitation of the particles. The resulting CdSe/ZnS QD was redissolved in toluene and filtered through diatomaceous earth and then reprecipitated from hot ethanol to remove any excess HDA. This produced 12.08 g of HDA-terminated CdSe/ZnS core/shell QD with a light emission maximum λ = 590 nm and FWHM = 36 nm (see Figure 8). The photoluminescence quantum yield (PLAY) of the core/shell material ranges from 50% to 90% at this stage.

Reference Example 2: Preparation of InP/ZnS Core/Shell QD Preparation of InP core QD (400-800 nm emission)

Dibutyl ester (100 mL) and myristic acid (10.1 g) were placed in a three-necked flask and degassed under vacuum at 70 ° C for one hour. After this period, nitrogen was introduced and the temperature was raised to 90 °C. A cluster of ZnS molecules [Et ₃ NH] ₄ [Zn ₁₀ S ₄ (SPh) ₁₆ ] (4.7 g) was added and the mixture was agitated for 45 minutes. The temperature is then raised to 100 ° C, followed by indium myristic acid In (MA) ₃ (1 M in ester, 15 mL) followed by (TMS) ₃ P (1 M in ester, 15 mL) Add by drop. The reaction mixture was agitated while raising the temperature to 140 °C. Further additions to In(MA) ₃ (1 M, 35 mL) (with stirring for 5 min) and (TMS) ₃ P (1 M, 35 mL) were carried out at 140 °C. The temperature was then slowly raised to 180 ° C and further dropwise addition of In(MA) ₃ (1 M, 55 mL) followed by (TMS) ₃ P (1 M, 40 mL) was carried out. By adding the precursor in the manner described above, the InP QD growth can be increased from 500 nm to 750 nm, thereby stopping the reaction and allowing it to reach the desired emission peak position. Stirring at this temperature lasted for half an hour. After this period, the temperature was lowered to 160 ° C and the reaction mixture was annealed for a maximum of 4 days (at a temperature of from 20 ° C to 40 ° C below the temperature of the reaction). A UV lamp is also used at this stage to aid in the annealing process.

The nanoparticles were isolated by the addition of dry degassed methanol (about 200 mL) via cannula technique. The precipitate was stabilized and then the methanol was removed via a cannula with a filter plug. Dry degassed chloroform (about 10 mL) was added to wash the solid. The solid was dried under vacuum for 1 day. This produced 5.60 g of InP core nanoparticles with a maximum light emission λ = 630 nm and FWHM = 70 nm.

Operation processing after InP core QD

The PLQY of InP QD prepared by the method described above is enhanced by treatment with dilute hydrofluoric acid (HF) acid. The QDs were dissolved in anhydrous degassed chloroform (~270 mL) and a 50 mL portion was taken and placed in a polypropylene flask. The HF solution was prepared by injecting 3 mL of a 60% w/w HF solution in water with 17 mL of pre-degassed THF by means of a disposable polypropylene syringe.

Reference Example 3: Incorporation of QD into suspended polymer beads

Preparation of 1% wt/vol polyvinyl acetate (PVA) water-soluble by stirring for 12 hours followed by extensive degassing of nitrogen through the solution for 1 hour. liquid. The monomers (methyl methacrylate and ethylene glycol dimethacrylate) were also degassed by bubbling nitrogen and used without further purification. The initiator AIBN (0.012 g) was placed in the reaction vessel and placed under three vacuum/nitrogen cycles to ensure the absence of oxygen.

The CdSe/ZnS core/shell QD prepared as above was added as a solution containing toluene to the reaction vessel and the solvent was removed under reduced pressure. Degassed methyl methacrylate (0.98 mL) was then added followed by degassed ethylene glycol dimethacrylate (0.15 mL). The mixture was then agitated at 800 rpm for 15 minutes to ensure that the QDs were completely dispersed in the monomer mixture. A 1% solution of PVA (10 mL) was then added and the reaction was stirred for 10 minutes to ensure suspension. The temperature was then raised high to 72 ° C and the reaction was allowed to continue for 12 hours.

The reaction was then cooled to room temperature and the beaded product was washed with water until the washings became clear, followed by methanol (100 mL), methanol / tetrahydrofuran (1:1, 100 mL), tetrahydrofuran (100 mL), tetrahydrofuran / Methyl chloride (1:1, 100 mL), dichloromethane (100 mL), dichloromethane/tetrahydrofuran (1:1, 100 mL), tetrahydrofuran (100 mL), tetrahydrofuran/methanol (1:1, 100 mL) , methanol (100 mL). The QD-containing beads (QD beads) were then dried under vacuum and stored under nitrogen.

Reference Example 4: Adsorption of QD into prefabricated beads

Polystyrene microspheres with 1% divinylbenzene and 1% thiol comonomer were suspended in toluene (1 mL) by shaking and sonication. The microspheres were centrifuged (6000 rpm, approximately 1 min) and the supernatant was decanted. Repeat this operation for a second wash with one of toluene and then suspend the pellet in toluene (1 In mL).

The InP/ZnS QD prepared as above was dissolved (one excess, typically 5 mg of QD for 50 mg of microspheres) in chloroform (0.5 mL) and filtered to remove any insoluble material. The QD-chloroform solution was added to the microspheres contained in toluene and allowed to vibrate on a shaker plate at room temperature for 16 hours to be thoroughly mixed.

The QD microspheres are centrifuged into a pellet and the supernatant from any of the QD processes present is removed. The pellets were washed twice (by above) with toluene (2 mL), the pellets were suspended in toluene (2 mL) and the pellets were then transferred directly to a glass vial. The glass vial was placed inside a centrifuge tube, centrifuged and the excess toluene was decanted.

Reference Example 5: Incorporation of DQ into cerium oxide beads

InP/ZnS core/shell QD (70 mg) prepared as above and 0.1 mL of (3-(trimethoxymethyl decyl) propyl methacrylate (TMOPMA) followed by 0.5 mL of n-decanoate ( TEOS) was mixed to form a clear solution that was kept for night incubation under N ₂ . The mixture was then injected into 10 mL of inverse microemulsion (cyclohexane / contained in a 50 mL flask at 600 rpm agitation). CO-520, 18 ml / 1.35 g). The mixture was allowed to stir for 15 min and then 0.1 mL of 4% NH ₄ OH was injected to initiate the bead formation reaction. The reaction was stopped the next day and the reaction solution was centrifuged to collect Solid phase. The obtained particles were washed twice with 20 mL of cyclohexane and then dried under vacuum.

Instance Example 1 - Formation of a Semiconductor QD Bead Ink (Green in Polystyrene/Toluene Matrix) Color cerium oxide beads)

Inside a nitrogen-filled glove box, toluene (25 g) was injected into a glass vial with a magnetic stirrer and the vial was sealed. The vial was placed on a hot plate and the toluene was heated to a lower 60 °C with agitation at 250 rpm for 5 min before adding a predetermined amount of polystyrene resin (8.3 g). Once all of the polystyrene had dissolved, the speed of the stirrer was lowered to 150 rpm, the temperature was lowered to 40 ° C and the resulting mixture was kept agitated for 12 hours. After this cycle, 2 g of the latter solution was transferred to a smaller glass vial inside the nitrogen-filled glove box. A magnetic stirrer was introduced into the vial, which was then sealed and placed on a hot plate preheated to 60 °C. The latter solution was agitated at 250 rpm for 5 minutes before adding a predetermined amount of InP/ZnS core/shell QD beads (0.2 g). The resulting mixture was agitated at 60 ° C for a period of up to 12 hours and exposed to ultrasound for 5 to 20 minutes to aid particle dispersion. This process produces a clear green QD bead ink. The InP/ZnS core/shell QD beads used in this test were characterized by a maximum light emission λ _PL = 544 nm, FWHM = 56 nm and PLQY = 39%.

Example 2 - Formation of a Semiconductor QD Bead Ink (Red Acrylate Bead in LED Acrylate)

Everything is done in a UV-protected atmosphere. A predetermined amount of initiator Irgacure 819 (6 mg) was placed in a glass vial containing one of the magnetic stirrers. The vial is then sealed and filled with nitrogen. Trimethylolpropane triacrylate (0.63 mL) was injected into the vial. The mixture was agitated at 250 rpm for 30 min until all solids were dissolved. A predetermined amount of lauryl methacrylate (1.37 mL) was then injected into the vial and The mixture was allowed to stir for 1 hour. 200 mg of InP/ZnS core/shell QD acrylate beads (PLQY=47%, Pl=614 nm, FWHM: 59 nm) were added to the acrylate mixture and allowed to stir under nitrogen for 1 hour to produce the following characteristics. One of the inks: EQE = 48%, Pl = 614 nm, FWHM = 58 nm.

Example 3 - Formation of a Semiconductor QD Bead Ink (Red Acrylate Bead in Flexible Acrylate Matrix (10% TMPTM, 2% PIB))

Everything is done in a UV-protected atmosphere. A predetermined amount of Irgacure 819 (6 mg) was placed in a glass vial containing one of the magnetic stirrers. The vial is then sealed and filled with nitrogen. Trimethylolpropane triacrylate (TMPTM) (0.22 mL) was injected into the vial. The mixture was agitated at 250 rpm for 30 min until all solids were dissolved. In parallel, 20 w/v% of polyisobutylene (PIB) in lauryl methacrylate (0.18 mL) was added to a lauryl methacrylate (1.60 mL) in a nitrogen-filled vial and the mixture was made Stir for 15 minutes. The resulting polyisobutylene/lauryl methacrylate mixture was added to the initiator/trimethylolpropane triacrylate mixture and allowed to stir for 1 hour to produce a yellowish ink base. Then, 200 mg of InP/ZnS core/shell QD acrylate beads (PLQY%=47%, Pl=614 nm, FWHM: 59 nm) were added to the latter mixture and allowed to stir under nitrogen for 1 hour to produce One of the following characteristics: EQE = 48%, Pl = 614 nm, FWHM = 58 nm.

Example 4 - Making a semiconductor QD bead phosphor sheet (green ceria beads in a polystyrene/toluene matrix)

A doctor blade system was constructed as follows: An air gun was used to clean a PET sheet of a predetermined size to remove dust particles. Two spacers of a predetermined thickness were strapped to the PET substrate to ensure a constant gap (15 mm) between the spacers. The PET substrate was then transferred to a nitrogen-filled glove box. A predetermined amount of QD bead ink (0.2 mL) was drop cast onto the area between the spacers on the PET substrate using a 2 mL plastic syringe. Using a slide as a blade, the ink is evenly distributed between the spacers. The substrate was placed on a hot plate preheated at 70 ° C and heated for 10 min to remove the solvent. The resulting film exhibited significant fluorescence under bright ambient light conditions. The optical properties were determined using a fluorescence spectrometer equipped with a cumulative ball attachment: photoluminescence emission maxima λ _PL = 550 nm, FWHM = 55 nm and PLQY = 31%.

Example 5 - Formation of a Semiconductor QD Bead Phosphor Sheet (Red Acrylate Beads in LED Acrylate Matrix)

In a nitrogen-filled glove box, one of the predetermined volumes of QD bead ink (50 μL, EQE=48%, Pl=614 nm, FWHM=58 nm) was drop cast onto a glass mold (300 μm well) and used A medium pressure mercury lamp (45 mW/cm ² , 4 minutes) was irradiated to produce a QD bead polymer film (EQE = 45%, Pl = 611 nm, FWHM = 58 nm).

Example 6 - Formation of a Semiconductor QD Bead Phosphor Sheet (Red Acrylate Bead in a Flexible Acrylate Matrix (10% TMPTM, 2% PIB))

Inside a nitrogen-filled glove box, one of the predetermined volumes of QD bead ink (50 μL, EQE=48%, Pl=614 nm, FWHM=58 nm) was drop cast onto a glass mold (300 μm well well) and used. A medium pressure mercury lamp (45 mW/cm ² , 4 minutes) was irradiated to produce a QD bead polymer film (EQE = 40%, Pl = 607 nm, FWHM = 57 nm).

The present invention provides QD-containing beads that are formulated into printable inks that can subsequently be used to make luminescent sheets, layers or film materials. These methods have been developed to be sufficiently flexible and stable to enable the QD to emit light of any desired wavelength for processing into the luminescent ("phosphor") layer material. The materials can be made to emit light of a predetermined wavelength when illuminated by, for example, UV or blue light. The color of the visible light emitted by a phosphor layer can be tuned from green to deep red depending on the size of the QD and the process used to incorporate the QD into the chemically stable bead. The QD-containing beads may contain QDs of different sizes and/or types, and thus, for example, a QD bead may contain one, two or more QDs of different sizes and/or chemical compositions. Depending on the number of QDs of each type present, the bead will provide a particular color upon excitation. These properties also enable in-bead color tuning by combining different amounts of different color QDs into a particular bead. By modifying the encapsulation process, the QD can be given novel functionality, giving the option of dispersing the QD in a variety of commercially available resins that can be used to make conventional phosphor devices. In addition to the size of the tunable beads (for example, tuned from 50 nm to 0.5 mm in diameter), the viscosity of the resulting QD bead/resin dispersion is also controlled.

Due to the nature of the encapsulation process, not only is QD agglomerated to create a uniform layer, but the QD surface is not destroyed or substantially modified so that the QD maintains its original electronic properties. In this manner, the choice of QD (size, color, chemical composition, single or multiple types, etc.), bead material, and ink formulation can be initially implemented and subsequently used to produce a phosphor sheet that conforms to a particular specification. QD beads have enhanced protection from "naked" QDs in terms of chemical attack caused by the surrounding environment (eg, air, oxygen, and moisture) The additional benefit of QD during QD bead ink formulation and phosphor sheet formation and during subsequent incorporation of the phosphor sheet into the final illumination device is enhanced.

1 is a schematic diagram of a prior art backlight unit incorporated into one of the conventional LEDs; FIG. 2 is a schematic diagram of a prior art backlight unit incorporating one of the light-emitting layers commonly referred to as a "phosphor sheet"; FIG. 3 is based on A preferred embodiment of the present invention incorporates a schematic diagram of one of the first embodiments of a backlight unit that combines a layer of green QD beads with a layer of red QD beads, one of the QD bead phosphor sheets; and FIG. 4 is another embodiment of the present invention. The preferred embodiment incorporates a schematic diagram of a second embodiment of a backlight unit that combines green and red QD beads in one of the QD bead phosphor sheets in the same layer; Figure 5 shows how multiple colors can be used (in this case) The lower, red and green) QDs are combined in the same bead so that each bead emits a schematic diagram of white secondary light when illuminated by a primary light source (in this case a blue light source); Figure 6 shows how monochromatic can be The QD is encapsulated within the bead and then the QD beads of different colors are combined in a device such that the device emits a schematic of one of the white secondary lights when illuminated by a primary light source (in this case a UV light source); Monochrome (in this case, red) QD encapsulation The beads were subsequently incorporated into a device so that the device emits when illuminated by the same QD primary light source (LED chip in this case) of the secondary color a schematic view of one light; Figure 8 shows the UV-vis (UV) of CdSe/ZnS core/shell QD in toluene used in the preparation of the ink according to the aspect of the invention and in the preparation of the phosphor sheet according to another aspect of the present invention. Light-visible light absorption spectrum and PL (fluorescence) spectrum; and FIG. 9 shows toluene used in the preparation of the ink according to the aspect of the present invention and in the production of the phosphor sheet according to other aspects of the present invention. UV-vis absorption spectrum and PL spectrum of InP/ZnS core/shell QD.

Claims (28)

An illuminating layer comprising a plurality of luminescent particles embedded in a host matrix material, each of the luminescent particles comprising a population of semiconductor nanoparticles embedded in a polymeric encapsulating medium, wherein the polymeric encapsulating medium A first polymer is included and the host matrix material comprises a second polymer. The luminescent layer of claim 1, wherein the semiconductor nanoparticles comprise ions selected from Groups 11, 12, 13, 14, 15 and/or 16 of the periodic table, or one or more types of transition metal ions or Zone metal ions. The luminescent layer of claim 1, wherein the semiconductor nanoparticles comprise one or more semiconductor materials selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, InP, InAs, InSb AlP, AlS, AlAs, AlSb, GaN, GaP, GaAs, GaSb, PbS, PbSe, Si, Ge, MgS, MgSe, MgTe, and combinations thereof. The luminescent layer of claim 1, wherein the polymeric encapsulating medium comprises an optically transparent medium selected from the group consisting of: a polymer, a resin, a monolith, a glass, A sol gel, an epoxy resin, a polyoxymethylene and a (meth) acrylate. The luminescent layer of claim 1, wherein the polymeric encapsulating medium comprises a material selected from the group consisting of poly(methyl (meth) acrylate), poly (ethylene glycol dimethacrylate) ), polyvinyl acetate, poly(divinylbenzene), poly(thioether), cerium oxide, polyepoxide, and combinations thereof. The luminescent layer of claim 1, wherein the luminescent particles are discrete microbeads, each of which incorporates a plurality of the semiconductor nanoparticles. The luminescent layer of claim 6, wherein the microbeads have an average diameter of from 20 nm to 0.5 mm. The luminescent layer of claim 6, wherein some or all of the nanoparticle-containing microbeads comprise a core comprising a first optically transparent medium and a same or one or more different optically transparent medium deposited on the core One or more outer layers. The luminescent layer of claim 8, wherein the semiconductor nanoparticles are confined within the core of the microbeads or dispersed throughout one or more of the core and/or the outer layers of the microbeads. The luminescent layer of claim 1, wherein the host matrix material is selected from the group consisting of an organic polymer or an inorganic polymer. The luminescent layer of claim 1, wherein the host matrix material is selected from the group consisting of polyacrylate, polycarbonate, polystyrene, polyethylene, polypropylene, polyketone, polyetheretherketone, Polyester, polyamide, polyimine, polypropylene decylamine, polyolefin, polyacetylene, polyisoprene, polybutadiene, PVDF, PVC, EVA, PET, polyurethane and one Cellulose polymer. The luminescent layer of claim 1, wherein the host matrix material is selected from the group consisting of a crosslinked polymer, a copolymer, and an epoxy resin. The luminescent layer of claim 1, wherein the host matrix material is selected from the group consisting of polystyrene/toluene matrix, trimethylolpropane triacrylate/lauryl methacrylate matrix, trishydroxyl Propane tripropylene Acid ester / lauryl methacrylate / polyisobutylene matrix, trimethylolpropane triacrylate / lauryl methacrylate / PIPS matrix, isodecyl acrylate / dipropylene glycol diacrylate matrix, acrylic - polystyrene / toluene Matrix and polycarbonate. The luminescent layer of claim 1, wherein the host matrix material is selected from the group consisting of bentonite, kaolin, fumed cerium oxide, fumed alumina, and fumed zinc oxide. The luminescent layer of claim 1, wherein the first polymer and the second polymer are formed by an emulsion or a reverse emulsion. The luminescent layer of claim 1, wherein the polymeric encapsulating medium is an acrylate and the host matrix material is an epoxy resin. The luminescent layer of claim 15, wherein the host matrix material is cured by irradiation with ultraviolet light. The luminescent layer of claim 16, wherein the host matrix material is cured by irradiation with ultraviolet light. A method of fabricating a light-emitting layer comprising a plurality of luminescent particles embedded in a host matrix material, each of the luminescent particles comprising a population of semiconductor nanoparticles embedded in a polymeric encapsulating medium, the method Including providing a dispersant containing one of the luminescent particles, depositing the dispersant to form a film and processing the film to produce the luminescent layer, wherein the polymeric encapsulating medium comprises a first polymer and the host matrix material comprises a first Two polymers. The method of claim 19, wherein the dispersing agent has a formulation suitable for Printing or drop casting to deposit one of the viscosities. The method of claim 19, wherein depositing the dispersant is accomplished by printing or drop casting. The method of claim 19, wherein the film has a thickness of up to 250 nm. The method of claim 19, wherein treating the film comprises annealing. The method of claim 23, wherein the annealing comprises heating the film to a temperature of up to 300 °C. A dispersing agent suitable for printing or dropping onto a substrate, the dispersing agent comprising luminescent particles dispersed in a host matrix material, each of the luminescent particles comprising one embedded in a polymeric encapsulating medium A population of semiconductor nanoparticles, wherein the polymeric encapsulating medium comprises a first polymer and the host matrix material comprises a second polymer. An illumination device comprising a light-emitting layer in optical communication with a light-diffusing layer, the light-emitting layer comprising a plurality of light-emitting particles embedded in a host matrix material, each of the light-emitting particles comprising a polymerized capsule A population of semiconductor nanoparticles within the encapsulating medium, wherein the polymeric encapsulating medium comprises a first polymer and the host matrix material comprises a second polymer. A light emitting device comprising an illuminating layer in optical communication with a backlight, the luminescent layer comprising a plurality of luminescent particles embedded in a host matrix material, each of the luminescent particles comprising embedded in a polymeric encapsulating medium A population of semiconductor nanoparticles, wherein the polymeric encapsulating medium comprises a first polymer and the host matrix material comprises a second polymer. The illuminating device of claim 27, wherein the device further comprises a light diffusing layer between the backlight and the luminescent layer.