JP2013509714A - Light emitting diode (LED) device comprising nanocrystals - Google Patents

Abstract

  The present invention provides a light emitting diode (LED) device comprising a composition of hermetically sealed luminescent nanocrystals and a container. The present invention further provides a display including an LED device. Suitably, the LED device is a white light LED device.

Description

  The present invention relates to a method of light emitting diode (LED) device comprising a light emitting nanocrystal, suitably a white light LED. The invention further relates to a display system comprising an LED device.

  Luminescent nanocrystals exposed to air and moisture are subject to oxidative damage, often resulting in a loss of luminescence. The use of luminescent nanocrystals in applications such as downconversion layers, filtering layers often exposes luminescent nanocrystals to high temperatures, high intensity light, environmental gases and moisture. These factors, coupled with the requirement for long emission lifetimes in these applications, often limit the use of luminescent nanocrystals or require frequent replacement. Accordingly, there is a need for methods and compositions that enable hermetic nanocrystals to be hermetically sealed, thereby extending service life and increasing luminescence intensity.

  There is also a need for light emitting diode (LED) devices that use hermetically sealed nanocrystals including white light LED devices.

  In one embodiment, the present invention provides a light emitting diode (LED) device. Suitably, the LED device comprises a blue light emitting LED and a hermetically sealed container comprising a plurality of light emitting nanocrystals. The container is positioned relative to the LED to facilitate down conversion of the luminescent nanocrystals.

  Suitable hermetically sealed containers include plastics such as glass capillaries or glass tubes. In an exemplary embodiment, the hermetically sealed container is spaced from the LED. Suitably, the luminescent nanocrystals emit green and red light. Exemplary light emitting nanocrystals used in LED devices include CdSe or ZnS, and core / shell light emission including CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS, or CdTe / ZnS. Includes luminescent nanocrystals that are nanocrystals. In an exemplary embodiment, the luminescent nanocrystals are dispersed in a polymer matrix. The present invention further provides a display system including an LED device.

  In other embodiments, the invention provides an LED, a hermetically sealed container comprising a plurality of light emitting nanocrystals optically coupled to the LED, and light optically coupled to the hermetically sealed container. A light emitting diode (LED) device including a guide is provided. Suitably, the first portion of light emitted from the LED is downconverted by the light emitting nanocrystal, and the second portion of light emitted from the LED and the light downconverted from the light emitting nanocrystal is emitted from the light guide. Is done.

  In the exemplary embodiment, the LED emits blue light. Suitably, a first portion of the blue light emitted from the LED is downconverted to green and red light by the luminescent nanocrystals. Suitably the second portion of blue light, green light and red light are combined to produce white light.

  Exemplary hermetically sealed containers include plastic or glass containers such as glass capillaries having at least one dimension between about 100 μm and about 1 mm. Suitably, the luminescent nanocrystal comprises CdSe or ZnS and may be a core / shell nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS. The luminescent nanocrystals can be dispersed in a polymer matrix. In a suitable embodiment, the hermetically sealed container is spaced from the LED. In an embodiment, the LED device of the present invention is a white light LED device.

  The present invention further provides a display system that includes the display described herein and a plurality of LED devices. Suitably, the display at least partially surrounds the light guide. A first portion of light emitted from the LED is down-converted by the luminescent nanocrystal, and a second portion of light emitted from the LED and the light down-converted from the luminescent nanocrystal is emitted from the light guide on the display Is displayed. In an exemplary embodiment, a hermetically sealed container is optically coupled to at least two LEDs.

  In another embodiment, the present invention provides a composite material. The composite material includes a first polymeric material having a first composition. The composite further includes a second polymeric material having a second composition and a plurality of luminescent nanocrystals dispersed in the second polymeric material. The second polymeric material is dispersed in the first polymeric material.

Suitably, the first polymeric material comprises epoxy or polycarbonate and the second polymeric material comprises aminosilicone. In embodiments, the luminescent nanocrystals emit green light and / or red light. Suitably, the luminescent nanocrystal comprises CdSe or ZnS or is a core / shell luminescent nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS. be able to. In other embodiments, the composite includes an inorganic layer of SiO ₂ , TiO _2, or AlO ₂ that hermetically seals the composite. Suitably, the composite has an optical density of about 0.5 to about 0.9 (eg about 0.8) and a path length of about 50 μm to about 200 μm (eg about 100 μm) at the blue LED wavelength.

  The present invention further provides a method of preparing a luminescent nanocrystalline composite material. The method suitably includes the step of dispersing a plurality of luminescent nanocrystals in the first polymeric material to form a mixture of luminescent nanocrystals and the first polymeric material. The mixture is cured and fine particles are generated from the cured mixture. The fine particles are dispersed in the second polymeric material to produce a composite material. Suitably, a crosslinking agent is added to the mixture prior to curing. In an exemplary embodiment, fine particles are produced by ball milling the cured mixture. The composite can be a film.

  In another embodiment, the present invention provides a light emitting diode (LED) device. The LED device is an LED, a light guide optically coupled to the LED, and a plurality of light emitting nanocrystals dispersed in regions within the light guide, the regions extending along the length of the light guide Luminescent nanocrystals. The light emitted from the LED is down-converted by the nanocrystal and exits the surface of the light guide. Suitably, the luminescent nanocrystals emit blue, green and red light and the LED emits ultraviolet light. Blue, red and green light combine to produce white light.

  In other embodiments, a first portion of light emitted from the LED is down-converted by the nanocrystal, and a second portion of light emitted from the LED and the down-converted light exits the surface of the light guide. Suitably, the LED emits blue light. The first part of the blue light emitted from the LED is down-converted to green and red light by the light emitting nanocrystals, suitably the second part of the blue light, the green light and the red light are combined into white light Produce.

  Exemplary nanocrystals used in LED devices include CdSe or ZnS, core / shell nanocrystals including CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS. be able to.

  Suitably, the light guide includes one or more reflectors. The region in the light guide is suitably a layer of luminescent nanocrystals. In an exemplary embodiment, the thickness of the region varies along the length of the light guide, suitably increasing from the LED along the length of the light guide (eg, linearly). In an exemplary embodiment, the LED device is a white light LED device. The present invention further provides a display including an LED device.

  Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or others may be learned by practice of the invention. The advantages of the invention will be realized and attained by the structure and particularly pointed out in the written description and claims hereof as well as the appended drawings.

  It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide additional explanation of the claimed invention. is there.

  The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the present invention, and together with the description, explain the principles of the invention and allow those skilled in the art to understand the invention. Helps to implement and use.

FIG. 1 illustrates a hermetically sealed luminescent nanocrystal composition according to an embodiment of the present invention. FIG. 2 illustrates a method according to an embodiment of the present invention for hermetically sealing a container containing luminescent nanocrystals. FIG. 3 illustrates a hermetically sealed luminescent nanocrystal composition according to an embodiment of the present invention that includes a separately sealed composition. FIG. 4 is a diagram showing a hermetically sealed container according to an embodiment of the present invention comprising luminescent nanocrystals. FIG. 5 illustrates a hermetically sealed composition according to an embodiment of the present invention further comprising a microlens. 6A-6C illustrate a hermetically sealed composition according to an embodiment of the present invention further comprising a light focusing device. FIG. 7A is a diagram illustrating an LED device according to an embodiment of the present invention. FIG. 7B is a diagram showing light down-conversion from the LED device of the present invention. 8A to 8C are diagrams showing a modification of the LED device of the present invention. FIG. 9 shows an LED device of the present invention including a reflector. FIGS. 10A-10B illustrate a hermetically sealed capillary according to an embodiment of the present invention. FIG. 11 is a diagram illustrating a display device according to an embodiment of the present invention. FIG. 12 is a diagram illustrating a luminescent nanocrystal composite material according to an embodiment of the present invention. FIG. 13 is a flow diagram of a method for preparing a luminescent nanocrystalline composite material according to an embodiment of the present invention. FIG. 14 is a diagram illustrating an LED device including a light guide having a region of nanocrystals according to an embodiment of the present invention. 15A-15C are diagrams illustrating the light intensity output of an LED device that includes a light guide having nanocrystalline regions. 16A-16C are diagrams illustrating the light intensity output of an LED device that includes a light guide having nanocrystalline regions of increasing thickness.

  Next, the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, like reference numbers indicate identical or functionally similar elements.

  It is understood that the specific embodiments shown and described herein are examples of the present invention and that these embodiments are not intended to limit the scope of the invention in any way. Should. In fact, for simplicity, conventional electronics, manufacturing, semiconductor devices, and nanocrystal, nanowire (NW), nanorod, nanotube and nanoribbon technologies, and other functional aspects of the system (and the configuration of the individual operating components of the system) Element) may not be described in detail herein.

  The present invention provides various compositions comprising nanocrystals, including luminescent nanocrystals. Various properties of the luminescent nanocrystals, including absorption properties, emission properties and refractive index properties can be adjusted and adjusted for different applications. As used herein, the term “nanocrystal” refers to a nanostructure that is substantially single crystal. The nanocrystal has at least one region or characteristic dimension having a dimension from less than about 500 nm to less than about 1 nm. As used herein, “about” when referring to a numerical value means a value that is ± 10% of the stated value (eg, “about 100 nm” includes a size range of 90 nm to 110 nm. To do). It will be readily appreciated by those skilled in the art that the terms “nanocrystal”, “nanodot”, “dot” and “quantum dot” represent similar structures, and these terms are used interchangeably herein. . The invention further encompasses the use of polycrystalline or amorphous nanocrystals. As used herein, the term “nanocrystal” further encompasses “luminescent nanocrystals”. As used herein, the term “luminescent nanocrystal” means a nanocrystal that emits light when excited by an external energy source (suitably light). As used herein when describing hermetic sealing of nanocrystals, it should be understood that in suitable embodiments, the nanocrystals are luminescent nanocrystals.

  In general, the above characteristic dimension region is along the smallest axis of the structure. The material properties of the nanocrystals can be substantially uniform, or can be non-uniform in certain embodiments. The optical properties of nanocrystals can be determined by their particle size, chemistry or surface composition. The ability to adjust the size of the luminescent nanocrystals to a range of about 1 nm to about 15 nm allows the light emission range within the entire light spectrum to provide great versatility in color rendering. Particle encapsulation provides robustness against chemical and UV degradation agents.

Nanocrystals used in the present invention, including luminescent nanocrystals, can be produced using any method known to those skilled in the art. Suitable methods and exemplary nanocrystals are described in US patent application Ser. No. 11 / 034,216, filed Jan. 13, 2005, US patent application Ser. No. 10/796, filed Mar. 10, 2004. No. 832, US Pat. No. 6,949,206, and US Provisional Application No. 60 / 578,236, filed Jun. 8, 2004. The disclosures of each of these documents are each hereby incorporated by reference in their entirety. The nanocrystals used in the present invention can be made from any suitable material, including inorganic materials, more suitably inorganic conductors or semiconductor materials. Suitable semiconductor materials include those disclosed in US patent application Ser. No. 10 / 796,832, including any type of semiconductor including II-VI, III-V, IV-VI and IV semiconductors. Including. Suitable semiconductor materials include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si ₃ N ₄ , Ge ₃ N ₄ , Al ₂ O ₃ , (Al, Ga, In) 2 (S, Se, Te) 3, Al 2 CO, and Including species or more of said semiconductor suitable combination.

  In certain embodiments, the semiconductor nanocrystal can include a dopant from the group consisting of a p-type dopant or an n-type dopant. Nanocrystals useful in the present invention can further comprise II-VI or III-V semiconductors. Examples of II-VI or III-V semiconductor nanocrystals are any combination of Group II elements of the periodic table such as Zn, Cd, Hg and any Group VI element such as S, Se, Te, Po And any combination of Group III elements of the Periodic Table such as B, Al, Ga, In, Tl and any Group V element such as N, P, As, Sb, Bi.

  Nanocrystals useful in the present invention, including luminescent nanocrystals, can further include ligands conjugated, coordinated, associated, or deposited to the surface of the nanocrystal as described throughout. Suitable ligands are known to those skilled in the art, including those disclosed in U.S. Patent Application No. 11 / 034,216, U.S. Patent Application No. 10 / 656,910 and U.S. Provisional Application No. 60 / 578,236. Any ligand group that has been identified. The disclosures of each of these documents are each incorporated herein by reference. The use of such ligands can enhance the ability of nanocrystals to be incorporated into various solvents and matrices including polymers. Increasing the miscibility of nanocrystals in various solvents and matrices (ie, the ability to be mixed without separation) makes the nanocrystals a polymer composition so that the nanocrystals do not aggregate together and therefore do not scatter light. Allows distribution throughout the object. Such ligands are described herein as “miscibility enhancing” ligands.

  As used herein, the term nanocomposite refers to a matrix material comprising nanocrystals distributed or embedded therein. Suitable matrix materials can be any material known to those skilled in the art including polymeric materials, organic and inorganic oxides. The nanocomposites of the present invention can be a layer, encapsulant, coating or film as described herein. In embodiments of the invention referring to layers, polymer layers, matrices or nanocomposites, these terms are used interchangeably and the embodiments described with reference to these terms are It should be understood that it is not limited to a type of nanocomposite and encompasses any matrix material or layer described herein or known in the art.

  Downconverting nanocomposites (e.g., as disclosed in US patent application Ser. No. 11 / 034,216) emit light that is tuned to absorb light of a particular wavelength and then emit light at a second wavelength. Utilizing the release characteristics of the nanocrystals, thereby enhancing the performance and efficiency of the active source (eg, LED). As discussed above, the use of luminescent nanocrystals in such down-conversion and other filtering or coating applications often exposes the nanocrystals to high temperatures, high intensity light (eg, LED sources), external gases and moisture. Exposure to these conditions can reduce the efficiency of the nanocrystals and thereby shorten the effective product life. To solve this problem, the present invention provides a method for hermetically sealing luminescent nanocrystals, as well as hermetically sealed containers and compositions comprising luminescent nanocrystals.

Light emitting nanocrystalline phosphors Any method known to those skilled in the art can be used to produce nanocrystalline phosphors, suitably suitable for inorganic nanomaterial phosphors. Solution phase colloidal methods for controlled growth are used. Alivisatos, A.D. P. "Semiconductor clusters, nanocrystals, and quantum dots", Science, 271: 933 (1996), X. Peng, M.M. Schlamp, A.M. Kadavanich, A.M. P. Alivitas, “Epitaxial growth of high luminance CdSe / CdS Core / Shell nanocrystals with photoaccessibility and electronic accessibility”, J. Am. Am. Chem. Soc. 30: 7019-7029 (1997), and C.I. B. Murray, D.M. J. et al. Norris, M.M. G. Bawendi, “Synthesis and characterization of nearly monodisperse CdE (E = sulfur, selenium, tellurium) semiconductor nanocrystals”, J. Am. Am. Chem. Soc. 115: 8706 (1993). The disclosures of these documents are hereby incorporated by reference in their entirety. This manufacturing process technology boosts low-cost processability that does not require clean rooms and expensive manufacturing equipment. In these methods, a metal precursor that undergoes thermal decomposition at high temperatures is rapidly injected into a hot solution of organic surfactant molecules. These precursors decompose at high temperatures and react to produce nanocrystalline nuclei. After this initial nucleation phase, the growth phase begins by adding monomer to the growing crystal. The result is independent crystalline nanoparticles in solution with organic surfactant molecules covering the surface.

  Using this method, synthesis occurs as the first nucleation event that takes place over a few seconds, followed by crystal growth at a high temperature for a few minutes. In order to change the nature and progress of the reaction, parameters such as temperature, type of surfactant present, precursor material, surfactant to monomer ratio, etc. can be varied. The temperature controls the structural stage of the nucleation event, the precursor decomposition rate and the growth rate. Organic surfactant molecules are involved in both solubility and nanocrystal shape control. The ratio of surfactant to monomer, the ratio between surfactants, the ratio between monomers and the concentration of individual monomers strongly influence the growth kinetics.

  In a suitable embodiment, CdSe is used as a nanocrystalline material, in one example as a nanocrystalline material for visible light downconversion. This is because the synthesis of this material is relatively mature. By using universal surface chemistry, nanocrystals that do not contain cadmium can be used instead.

In core / shell luminescent nanocrystalline semiconductor nanocrystals, light-induced emission occurs from the band edge state of the nanocrystal. Band edge emission from luminescent nanocrystals competes with radioactive and non-radiative decay channels resulting from surface electronic states. X. Peng et al. Am. Chem. Soc. 30: 7019-7029 (1997). As a result, the presence of surface defects such as dangling bonds provides non-radiative recombination centers and contributes to a decrease in emission efficiency. One efficient and permanent way to deactivate and remove this surface trap state is to epitaxially grow an inorganic shell material on the surface of the nanocrystal. X. Peng et al. Am. Chem. Soc. 30: 7019-7029 (1997). The shell material has a larger bandgap so as to provide a potential step to localize electrons and holes to the core such that the electron level is type I with respect to the core material. Can choose). As a result, the probability of nonradioactive recombination can be reduced.

  The core-shell structure is obtained by adding an organometallic precursor containing a shell material to a reaction mixture containing a core nanocrystal. In this case, growth does not occur following the nucleation event, but the core acts as a nucleus and the shell grows from the surface of the core. The reaction temperature is kept low to promote the addition of shell material monomer to the core surface and prevent independent nucleation of the shell material nanocrystals. A surfactant is present in the reaction mixture to induce controlled growth of the shell material and ensure solubility. A uniform epitaxial growth shell is obtained when there is a low lattice mismatch between these two materials.

Exemplary materials for preparing core-shell luminescent nanocrystals include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, Co, Au, BN, BP , BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe , CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuBCu, _{, Si 3 N 4, Ge 3} N 4, Al 2 O 3, (Al, Ga, _{n) 2 (S, Se,} Te) 3, Al 2 CO, and a suitable combination of two or more of the material. Exemplary core-shell luminescent nanocrystals used in the practice of the present invention include, but are not limited to, CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS, (as core / shell), Including CdTe / ZnS and others.

In one embodiment of a hermetically sealed luminescent nanocrystal composition and a container comprising a luminescent nanocrystal, the present invention provides a method of hermetically sealing a composition comprising a plurality of luminescent nanocrystals. Suitably the method includes disposing a barrier layer on the composition to encapsulate the luminescent nanocrystal. As discussed throughout, the terms “hermetic”, “hermetic” and “hermetic” pass throughout the container or penetrate into the composition and / or contact the luminescent nanocrystals. Compositions, containers, and / or luminescent nanocrystals were prepared in such a manner that the amount of gas (eg, air) or moisture was reduced to a level that did not substantially affect the performance (eg, luminescence) of the nanocrystals. Used to indicate that Thus, a “hermetically sealed composition”, eg, a hermetically sealed composition containing luminescent nanocrystals, allows a certain amount of air (or other gas, liquid or moisture) to penetrate into the composition and emit light. A composition that does not allow contact with the nanocrystal and, as a result, the performance (eg, luminescence) of the nanocrystal is not substantially affected or affected (eg, reduced).

  As used throughout, a plurality of luminescent nanocrystals means two or more nanocrystals (ie nanocrystals of 2, 3, 4, 5, 10, 100, 1,000, 1,000,000, etc.) To do. Suitably, the composition comprises luminescent nanocrystals having the same composition, but in other embodiments, the plurality of luminescent nanocrystals can be of various different compositions. For example, the luminescent nanocrystals can all emit at the same wavelength, or in other embodiments, the composition can include luminescent nanocrystals that emit at different wavelengths.

  As shown in FIG. 1, in one embodiment, the present invention provides a composition 100 that includes a plurality of luminescent nanocrystals 104. Compositions of the present invention include any nanocrystals described throughout, and other nanocrystals known in the art, such as those disclosed in US patent application Ser. No. 11 / 034,216. Nanocrystals can be prepared.

  In suitable embodiments, the composition 100 includes a plurality of luminescent nanocrystals 104 dispersed throughout the matrix 102. As used throughout, dispersion includes a uniform (ie, substantially uniform) distribution / arrangement of nanocrystals and a non-uniform (ie, substantially non-uniform) distribution / arrangement. Suitable matrices for use in the compositions of the present invention include polymers and organic and inorganic oxides. Suitable polymers for use in the matrix of the present invention include any polymer known to those skilled in the art that can be used for such purposes. In suitable embodiments, the polymer is substantially translucent or substantially transparent. Such polymers include, but are not limited to, poly (vinyl butyral); poly (vinyl acetate); epoxy resin; urethane; silicone and, without limitation, polyphenylmethylsiloxane, polyphenylalkylsiloxane, polydiphenylsiloxane, polydialkyl Silicone derivatives including siloxanes, fluorinated silicones, vinyl and hydride substituted silicones; acrylic polymers and copolymers formed from monomers including but not limited to methyl methacrylate, butyl methacrylate and lauryl methacrylate; styrene-based polymers As well as polymers crosslinked with bifunctional monomers such as divinylbenzene.

  Any suitable method, for example, mixing nanocrystals into a polymer and casting a film, mixing nanocrystals with monomers and polymerizing them together, mixing nanocrystals into a sol-gel The luminescent nanocrystals used in the present invention can be converted to polymers (or other suitable materials such as waxes, oils, etc. using methods to form oxides or any other method known to those skilled in the art. ) Can be embedded in the matrix. As used herein, the term “embedding” is used to indicate that a luminescent nanocrystal is surrounded or encapsulated by a polymer that constitutes the major component of the matrix. Suitably, the luminescent nanocrystals are uniformly distributed throughout the matrix, although in other embodiments, the luminescent nanocrystals can be distributed according to an application-specific uniformity distribution function. Should.

  The thickness of the composition of the present invention can be controlled by any method known in the art, such as spin coating and screen printing. The luminescent nanocrystal compositions of the present invention can be of any desired size, shape, configuration and thickness. For example, the compositions of the present invention can take the form of layers as well as other shapes such as disks, spheres, cubes or blocks, tubes and the like. The various compositions of the present invention can be of any necessary or desired thickness, but suitably the composition thickness (ie one dimension) is on the order of about 100 mm to less than about 1 mm. . In other embodiments, the thickness of the polymer layer of the present invention can be on the order of tens to hundreds of microns. The luminescent nanocrystals can be embedded in various compositions / matrices at any loading ratio suitable for the desired function. Suitably, the luminescent nanocrystals are loaded in a ratio from about 0.001% to about 75% by volume, depending on the application, matrix and type of nanocrystal used. Appropriate loading ratios can be readily determined by one skilled in the art and are further described herein for specific applications. In an exemplary embodiment, the amount of nanocrystals loaded into the luminescent nanocrystal composition is on the order of about 10% by volume to parts per million (ppm) level.

  Suitably, the size of the luminescent nanocrystals used in the present invention is from less than about 100 nm to less than about 2 nm. In suitable embodiments, the luminescent nanocrystals of the present invention absorb visible light. As used herein, visible light is electromagnetic radiation having a wavelength from about 380 nanometers to about 780 nanometers visible to the human eye. Visible light can be separated into various colors in the spectrum, such as red, orange, yellow, green, blue, indigo, and purple. The photon filtering nanocomposites of the present invention can be constructed to absorb light comprising any one or more of these colors. For example, the nanocomposites of the present invention can be constructed to absorb blue light, red light or green light, combinations of such colors, or any intermediate color of these colors. As used herein, blue light includes light having a wavelength from about 435 nm to about 500 nm, green light includes light from about 520 nm to 565 nm, and red light from about 625 nm to about 740 nm. Including light. One skilled in the art can construct nanocomposites that can filter these wavelengths or any combination of wavelengths between these colors, and such nanocomposites are embodied by the present invention.

  In other embodiments, the luminescent nanocrystal has a size and composition such that the luminescent nanocrystal absorbs photons in the ultraviolet, near infrared, and / or infrared spectra. As used herein, the ultraviolet spectrum includes light from about 100 nm to about 400 nm, the near infrared spectrum includes light from a wavelength of about 750 nm to about 100 μm, and the infrared spectrum ranges from about 750 nm to about 100 μm. Includes light up to 300 μm.

  In the practice of the present invention, luminescent nanocrystals of any suitable material can be used, but in certain embodiments, the nanocrystals can be ZnS, InAs or CdSe nanocrystals, or Nanocrystals can include various combinations to form a population of nanocrystals used in the practice of the present invention. As discussed above, in other embodiments, the luminescent nanocrystal is a core / shell nanocrystal such as CdSe / ZnS, CdSe / CdS, InP / ZnS.

In order to hermetically seal the composition of the present invention, a barrier layer is disposed on the composition. For example, as shown in FIG. 1, a barrier layer 106 is disposed on a matrix 102 containing luminescent nanocrystals 104, thereby producing a hermetically sealed composition. The term “barrier layer” is used throughout to indicate a layer, coating, sealant or other material disposed on the matrix 102 to hermetically seal the composition. Examples of barrier layers include any material layer, coating or substance that can create a hermetic seal on the composition. Suitable barrier layers include inorganic layers, suitably inorganic oxides such as oxides of Al, Ba, Ca, Mg, Ni, Si, Ti, Zr. Exemplary inorganic oxide layer including _{SiO 2, TiO 2, AlO 2} . As used throughout, the terms “place” and “place” include any suitable method of depositing a barrier layer. For example, the arrangement may include layering, coating, spraying, sputtering, plasma-assisted chemical vapor deposition, atomic layer deposition, or other suitable method of depositing a barrier layer on the composition. In a suitable embodiment, sputtering is used to place a barrier layer on the composition. Sputtering includes a physical vapor deposition process in which high energy ions are used to bombard the material element source, the material element source emits atomic vapor, and then the atomic vapor is deposited as a thin layer on the substrate. . See, for example, U.S. Patent Nos. 6,541,790, 6,107,105, and 5,667,650. The disclosures of each of these documents are each hereby incorporated by reference in their entirety.

  In other embodiments, barrier layer placement can be performed using atomic layer deposition. In applications such as LED coatings, luminescent nanocrystal compositions, such as polymer layers containing nanocrystals, often have complex geometries and features. For example, LED components such as bonding wires, solder connections, etc. are often in direct contact with the polymer layer or even contained within the polymer layer. In order to properly hermetically seal the nanocrystalline composition, a barrier layer that is virtually defect free (ie pinhole free) is often required. Furthermore, the arrangement of the barrier layer should not degrade the polymer or nanocrystal. Thus, in a suitable embodiment, atomic layer deposition is used to place the barrier layer.

Atomic layer deposition (ALD) can include placing an oxide layer (eg, TiO ₂ , SiO ₂ , AlO _2, etc.) on the emissive nanocrystal composition, or in other embodiments, nitrides Deposition of a non-conductive layer such as (eg silicon nitride) can be used. ALD deposits an atomic layer (i.e., only a few molecules thick) by alternately supplying reactant and purge gases. Thin coatings with high aspect ratios, uniformity within the recesses, and good electrical and physical properties can be formed. Suitably, the barrier layer deposited by the ALD method has a low impurity concentration and a thickness of less than 1000 nm, suitably less than about 500 nm, less than about 200 nm, less than about 50 nm, less than about 20 nm or less than about 5 nm.

  For example, in a suitable embodiment, two reaction gases, A and B, are used. When only the reaction gas A flows into the reaction chamber, the atoms of the reaction gas A are chemically adsorbed onto the luminescent nanocrystal composition. Next, the remaining reaction gas A is purged with an inert gas such as Ar or nitrogen. Next, the reaction gas B flows in, and the chemical reaction between the reaction gases A and B occurs only on the surface where the reaction gas A of the luminescent nanocrystal composition is adsorbed. It is formed.

In embodiments where a non-conductive layer such as a nitride layer is disposed, SiH ₂ Cl ₂ and remote plasma assisted NH ₃ are suitably used to dispose the silicon nitride layer. This embodiment can be performed at low temperatures and does not require the use of reactive oxygen species.

  The use of ALD to place the barrier layer on the luminescent nanocrystal composition produces a barrier layer that is virtually pinhole free, regardless of the substrate morphology. By repeating these deposition steps, the thickness of the barrier layer can be increased, whereby the layer thickness of the atomic layer unit can be increased with the number of repetitions. In addition, the barrier layer can be further coated with additional layers (eg, by sputtering, CVD or ALD) to protect the barrier layer or further strengthen the barrier layer.

  Suitably, the ALD process utilized in the practice of the present invention is performed at a temperature of less than about 500 ° C, suitably less than about 400 ° C, less than about 300 ° C, or less than about 200 ° C.

  Exemplary barrier materials include organic materials designed to clearly reduce oxygen and moisture transmission. Examples include filled epoxy resins (such as alumina filled epoxy resins) and liquid crystal polymers.

  As discussed throughout, the matrix 102 suitably comprises a polymer substrate. Accordingly, the present invention employs any of the various methods disclosed herein or other various methods known in the art to place a barrier layer on a composition. A method of hermetically sealing a composition comprising luminescent nanocrystals, suitably a polymer substrate comprising luminescent nanocrystals.

  The ability to use a polymer substrate as the matrix 102 is simply forming the composition in various shapes and configurations by molding or otherwise manipulating the composition into the desired shape / orientation. Enable. For example, a solution / suspension of luminescent nanocrystals (eg, luminescent nanocrystals in a polymer matrix) can be prepared. This solution can then be placed in the desired mold to form the required shape and then cured (eg, cooled or heated depending on the type of polymer) to form a solid or semi-solid structure. For example, a cap-shaped or disk-shaped mold can be prepared for placement on or over the LED. This allows for the preparation of a composition that can be used, for example, as a downconverting layer. Following preparation of the desired shape, a barrier layer is placed over the composition to hermetically seal the composition and thereby prevent the luminescent nanocrystals from oxidizing.

  In additional embodiments, a composition comprising luminescent nanocrystals (eg, a polymer composition) can be placed directly on a desired substrate or article (eg, an LED). The luminescent nanocrystal composition (eg, solution or suspension) can then be cured and then a barrier layer can be placed over the composition, thereby hermetically sealing the composition directly on the desired substrate or article. Can be stopped. Such embodiments therefore do not require the preparation of a separate composition, but instead allow the composition to be prepared directly on the desired article / substrate (eg, light source or other final product). To.

  In another embodiment, the present invention provides a method for hermetically sealing a container comprising a plurality of luminescent nanocrystals. Suitably, the method includes providing a container, introducing luminescent nanocrystals into the container, and then sealing the container. For example, an exemplary method of hermetically sealing a luminescent nanocrystal container is shown in the flowchart 200 of FIG. 2 with respect to FIGS. In the case of FIG. 2, in step 202, a container is prepared, for example, the container 302 or 402 of FIGS. As used herein, “container” refers to any suitable article or container for holding nanocrystals. As used herein, it should be understood that “containers” containing luminescent nanocrystals and “compositions” containing luminescent nanocrystals represent different embodiments of the invention. A “composition” comprising luminescent nanocrystals refers to a matrix, such as a polymer substrate, solution or suspension, comprising nanocrystals dispersed throughout. As used herein, a “container” is a carrier, container or pre-formed into which luminescent nanocrystals (often a composition of luminescent nanocrystals, such as a polymer matrix containing luminescent nanocrystals) are introduced. Refers to the goods. Examples of containers include, but are not limited to, polymers or glass structures such as tubes, molded or formed vessels, containers. In an exemplary embodiment, the container is formed by extruding a polymer or glass material into a desired shape, such as a tube (circular, rectangular, triangular, elliptical or other desired cross section) or similar structure. be able to. Any polymer, including the polymers described throughout, can be used to form the container used in the practice of the present invention. Exemplary polymers for preparing containers used in the practice of the present invention include, but are not limited to acrylic resins, poly (methyl methacrylate) (PMMA), and various silicone derivatives. Additional materials can also be used to form the containers used in the practice of the present invention. For example, the container can be prepared from metal, various glasses, ceramics, and the like.

  For example, as shown in FIG. 2, after the container is prepared at step 202, then at step 204, a plurality of luminescent nanocrystals 104 are introduced into the container. As used herein, “introduced” includes any suitable method of providing luminescent nanocrystals into a container. For example, by injecting a luminescent nanocrystal into a container, placing it in the container, allowing it to be sucked into the container (eg, by using a suction or vacuum mechanism), and into the container, eg, by using an electromagnetic field Luminescent nanocrystals can be introduced into the container by induction or other suitable methods. Suitably, the luminescent nanocrystals are present in a solution or suspension, such as a polymer solution, thereby helping to introduce the nanocrystals into the container. In an exemplary embodiment, the luminescent nanocrystals 104 can be drawn into a container, such as a tubular container 302 as shown in FIG. In other embodiments, as shown in FIG. 4, a container 402 having a cavity or void 404 into which the luminescent nanocrystal 104 can be introduced can be prepared. For example, a solution of luminescent nanocrystals 104 can be introduced into the cavity 404 of the container 402.

  Following the introduction of the luminescent nanocrystals into the container, the container is then hermetically sealed, as shown in step 206 of FIG. Examples of methods for hermetically sealing a container include, but are not limited to, methods for heat sealing the container, methods for ultrasonic welding the container, methods for soldering the container, or methods for adhering the container. For example, as shown in FIG. 3, the container 302 can be sealed at any number of locations to form various numbers of seals 304 throughout the container. In an exemplary embodiment, the container 302 may be heat sealed at various locations throughout the container, for example, by heating the container and then “pinching” the container at various sealing locations (304). it can.

  In a suitable embodiment, a polymer or glass tube can be used as the container 302, as shown in FIG. The solution of luminescent nanocrystals 104 can then be drawn into the container by simply applying a vacuum to one end of the container. The container 302 is then sealed by heating the container and "clamping" the container at various sealing locations or seals 304 over the entire length of the container or by using other sealing mechanisms described throughout. can do. In this way, the container 302 can be separated into various individual portions 306. These parts can be held together as a single sealed container 308 or separated into individual pieces, as shown in FIG. The hermetic sealing of the container 302 can be performed such that each individual seal 304 separates the same nanocrystalline solution. In other embodiments, the seal 304 can be formed such that separate portions of the container 302 each contain different nanocrystal solutions (ie, different nanocrystal compositions, sizes or densities).

  In other embodiments, the luminescent nanocrystals can be placed in cavities / voids 404 formed in the container 402, as shown in FIG. Container 402 can be manufactured using any suitable process. For example, the container 402 can be injection molded into any desired shape or configuration. The cavities / voids 404 can be prepared during the initial preparation step (ie, during molding) or can be added subsequently after formation. The luminescent nanocrystal 104 is then introduced into the cavity / void 404. For example, luminescent nanocrystals can be injected or placed into the cavity / void 404 of the container 402. Suitably, the solution of luminescent nanocrystals fills the entire container, but the container need not be completely filled with nanocrystals. However, if the entire container is not filled, substantially all the air in the container needs to be removed prior to sealing to ensure that the luminescent nanocrystals are hermetically sealed. As shown in FIG. 4, in an exemplary embodiment, the container may be formed by gluing or welding a cover or lid 406 to the container or otherwise sealing the container with the cover or lid 406. 402 can be hermetically sealed. Suitably, the cover 406 is made from the same material as the container 402 (and can suitably be partially attached prior to sealing), but the cover 406 may comprise a different material than the container 402. . In additional embodiments, materials such as organic materials designed to clearly reduce oxygen and moisture permeation can be used to cap or seal the container 402. Examples include filled epoxy resins (such as alumina filled epoxy resins) and liquid crystal polymers.

  The ability to produce custom designed containers, for example by molding, extruding or otherwise forming the container, can introduce luminescent nanocrystals into it and hermetically seal it Allows the preparation of highly specialized parts. For example, a shape can be produced that closely follows the perimeter of an LED or other light source (eg, used to deliver downconversion into other optical components). In addition, various films, discs, layers and other shapes can be prepared. In an exemplary embodiment, several different containers are prepared, each of which can contain a different composition of luminescent nanocrystals (ie, each composition emits a different color of light) and then their separate The containers can be used together to produce the desired performance characteristics. In other embodiments, a container having multiple cavities or reservoirs into which the luminescent nanocrystals can be introduced can be prepared.

  While the luminescent nanocrystal 104 can be hermetically sealed into the containers 302, 402 while still in solution, the luminescent nanocrystal solution is suitably cured prior to hermetic sealing (eg, FIG. 2). Step 210). As used herein, “curing” refers to the process of hardening a solution of luminescent nanocrystals (eg, a polymer solution). Curing can be accomplished by simply drying the solution and evaporating the solvent, or curing can be accomplished by heating the solution or by exposing the solution to light or other external energy. be able to. Following curing, the containers can be hermetically sealed using various methods described throughout.

In order to prevent the luminescent nanocrystals from oxidatively degrading, the exemplary embodiment does not require an additional hermetic seal. For example, encapsulating luminescent nanocrystals in a glass or polymer container provides sufficient protection from oxygen and moisture that does not require further modification. However, in additional embodiments, additional antioxidant levels can be added to hermetically sealed containers by placing a barrier layer on the container. For example, as shown in step 208 of FIG. As described throughout, exemplary barrier layers include inorganic layers such as inorganic oxides such as SiO ₂ , TiO ₂ , AlO ₂ and organic materials. Any method of placing the barrier layer on the container can be used, but suitably the barrier layer is sputtered onto the container or placed on the container by ALD. As shown in FIG. 3, a barrier layer 106 can be disposed on a container having a plurality of sealed portions, or on individual portions after sealing and separation from each other, The container (310, 312) hermetically sealed can be manufactured.

In suitable embodiments of the present invention, the various steps of producing a hermetically sealed container of luminescent nanocrystals are performed in an inert atmosphere. For example, suitable, steps 204, 206 and 208 are all in an inert atmosphere (and 210 if necessary), i.e. in a vacuum, and / or N only ₂ or other inert gas (one or several) of Performed in an existing atmosphere.

In additional embodiments, the present invention provides hermetically sealed compositions and containers comprising a plurality of luminescent nanocrystals. In an exemplary embodiment, the luminescent nanocrystal comprises one or several semiconductor materials (described throughout), suitably a core / shell luminescence such as CdSe / ZnS, CdSe / CdS, InP / ZnS, etc. It is a nanocrystal. Generally, the size of the luminescent nanocrystal is about 1-50 nm, suitably about 1-30 nm, more suitably about 1-10 nm, for example about 3-9 nm. In an exemplary embodiment, as described throughout, hermetically sealed compositions and containers of the present invention include a barrier layer overlying the composition (eg, barrier layer 106 overlying composition 100 of FIG. 1), Optionally, a barrier layer covering the container (eg, barrier layer 106 covering container 302 of FIG. 3) is included. Exemplary types of barrier layers include those described throughout, such as inorganic layers such as SiO ₂ , TiO ₂ , AlO ₂ .

  In addition to creating various shapes, orientations and sizes of containers that hermetically seal the luminescent nanocrystals, additional changes can be made to those containers / compositions. For example, the container / composition may be adjusted to the shape of the lens for light source filtration or other modifications. In additional embodiments, the container / composition can be modified, for example, by preparing a reflector or similar device and attaching it to the container / composition.

  Furthermore, a micropattern can be formed directly in the composition or container to form a planar (or curved) microlens. This can be performed during the molding process or in a subsequent embossing step. Micropatterns are often used to manufacture planar microlenses when limited space is available, such as within a display. An example of this technology includes a 3M corporation brightness enhancement film with a 20 to 50 micron prism formed on the surface. In a suitable embodiment, the present invention provides that the luminescent nanocrystals are hermetically sealed within the encapsulated polymer (or within the container), and then the encapsulated polymer is micropatterned such that microlenses are formed. Providing microlenses. For example, as shown in FIG. 5, the microlens assembly 500 is suitably placed on the LED 506 supported by the substrate 508 or otherwise in contact with the LED 506. A hermetically sealed composition 502 including a layer 504 is included. The surface of the composition 502 can be shaped into a variety of shapes thereby forming a microlens, for example to include a series of microprisms 510 as shown in FIG.

  In an exemplary embodiment, the use of a microlens in combination with a hermetically sealed composition of the present invention allows the amount of emitted light from the LED / emitting nanocrystal to be captured (and thus emitted from the composition). Allows for an increase in For example, adding a microprism or other microlens assembly to the hermetically sealed composition and container of the present invention is suitably compared to a composition that does not include a microprism or other microlens assembly. , Increasing the amount of light captured by more than about 10% (eg, about 10-60%, about 10-50%, about 10-40%, about 20-40% or about 30-40%). This increase in the amount of light captured is directly correlated to an increase in the total amount of light emitted from the composition or container.

  In suitable embodiments, a dichroic mirror can be attached or otherwise associated with a container / composition that forms a lens placed over the light source. The dichroic mirror can transmit light of a specific wavelength and reflect other light. As light from the light source enters the lens-shaped container / composition, the photons can enter the container / composition and excite various light-emitting nanocrystals within the hermetically sealed interior. When the luminescent nanocrystals emit light, the photons can exit the container / composition, but cannot reflect towards the initial light source (since they are reflected by the dichroic mirror). In embodiments, a suitable container / composition can then be formed that fits over a light source (eg, an LED). Dichroic mirrors allow light from the light source to enter and excite the internal luminescent nanocrystals, but the emitted light can only exit the container / composition in a direction away from the light source and reflect back into the light source This is blocked by the dichroic mirror. For example, blue light from an LED source is allowed to pass through a dichroic mirror, exciting the encapsulated luminescent nanocrystal, which then emits green light. This green light is reflected by the dichroic mirror and cannot be reflected back into the light source.

  As discussed herein, in a suitable embodiment, the hermetically sealed luminescent nanocrystal composition of the present invention is used in combination with an LED or other light source. These encapsulated nanocrystal / LED applications are well known to those skilled in the art and include: For example, such encapsulated nanocrystals / LEDs are described in microprojectors (see, eg, US Pat. Nos. 7,180,566 and 6,755,563. The disclosures of these documents are hereby incorporated by reference in their entirety. Cell phone; personal digital assistant (PDA); personal media player; gaming device; laptop computer; digital versatile disc (DVD) player and other video output devices; Can be used in applications such as head-up or head-down (and other) displays for automobiles and aircraft. In additional embodiments, hermetically sealed nanocrystals can be used in applications such as digital light processor (DLP) projectors.

  In an additional embodiment, using the hermetically sealed composition and container disclosed throughout, an optical system known as etendue (ie, how wide and where the light spreads) is used. Characteristics can be minimized. A composition or container of the claimed invention is placed, layered or otherwise covered (partially covered) with an LED or other light source, and the entire area of the luminescent nanocrystal composition or container By controlling the ratio of (e.g. thickness) to the area of the LED (e.g. thickness), the amount or range of etendue can be minimized, thereby increasing the amount of light captured and emitted. Suitably, the thickness of the luminescent nanocrystal composition or container is less than about 1/5 of the thickness of the LED layer. For example, the light-emitting nanocrystal composition or container can be less than about 1/6, less than about 1/7, less than about 1/8, less than about 1/9, less than about 1/10, less than about 1/10 of the LED layer thickness. Less than 15 or less than about 1/20.

  In other embodiments, the hermetically sealed luminescent nanocrystals of the claimed invention include a system 602 that includes a light focusing device (or focusing device) 604, for example, as shown in FIGS. Can be used. In the exemplary embodiment, light focusing device 604 is prepared, attached to LED 506, or otherwise associated with LED 506. Suitably, the light focusing device 604 has the shape of a cubic or rectangular box, the bottom of the box being located on or above the LED 506 and the side of the device extending above the LED. 6A shows a cross-sectional view of device 604 taken along plane 1-1 of FIG. 6B, and FIG. 6B shows a top view of device 604, LED 506, and substrate 508. FIG. In the exemplary embodiment, device 604 includes four sides surrounding LED 506, but in other embodiments, any number (eg, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.). ) Or use a circular device so that only a single piece of material (or multiple pieces of material formed to form one continuous piece of material) surrounds the LED 506 can do. Generally, the top and bottom surfaces of the light focusing device 604 are open (ie, the device is placed directly on the top surface of the LED 506 and surrounds the LED 506), but in other embodiments, an additional piece of material causes the top surface of the device 604 to be Or the bottom surface, or both, can be closed.

  Suitably, the focusing device 604 is made from a material capable of reflecting the light produced by the LED or coated with a material that reflects light. For example, the focusing device can include polymers, metals, ceramics, and the like. In other embodiments, the inner surface (ie, the surface facing the LED) can be coated with a reflective material, such as a metal (eg, Al) or other reflective coating. This reflective coating can be deposited on the surface of the focusing device using any suitable method such as spray coating, ALD, painting, dipping, spin coating, and the like.

  Suitably, the focusing device 604 surrounds or encapsulates the hermetically sealed nanocrystal composition 504 (or hermetically sealed nanocrystal container) of the present invention so that the device is contained in the composition or container. Associated. In a suitable embodiment, the focusing device 604 is prepared separately from the LED 506 and then attached to the LED by an adhesive, such as an epoxy resin, and then the central portion of the device 604 is hermetically sealed with the nanocrystalline composition 504. Can be filled. In other embodiments, the focusing device 604 can be assembled directly on the LED 506. In other embodiments, the hermetically sealed composition can be placed on the LED, and then the focusing device can be added as a prefabricated device, or the focusing device can be built directly on the LED. In suitable embodiments, the device 604 further includes a cover (eg, a glass or polymer cover) for sealing the nanocrystalline composition 504. Such a cover can act as a hermetic seal over the nanocrystal composition or simply serve as an additional structural element that supports the nanocrystal composition and the focusing device. Such a cover can be placed directly on the top surface of the nanocrystalline composition 504, or can be placed on the top surface of the device 604, or can be placed anywhere in between.

  As shown in FIGS. 6A and 6C, in a suitable embodiment, the side of the device narrows inward at the bottom (eg, near the LED) and widens outward at the top (away from the LED), A focusing device 604 is prepared. This helps to collect the light 606 and focus it into a beam to guide the light out of the device. As shown in FIG. 6C, suitably a focusing device 604 directs light 606 exiting the LED. By using progressively narrowing or tilted sides, the light 606 emitted from the LED / nanocrystal is lost by going back and forth inside the device or simply because it cannot escape. Without being guided away from the device 604. Suitably, the use of a light focusing device in combination with the luminescent nanocrystal composition and container of the present invention can be used in microprojectors and other applications where a focused light beam is desirable or necessary.

Light emitting diode (LED) device with hermetically sealed nanocrystals In an additional embodiment, the invention includes a light emitting diode (LED) device. An exemplary LED device 700 is shown in FIG. 7A. The LED device 700 suitably includes an LED 702. The LED 702 is shown on the substrate 706 for illustrative purposes only. It should be understood that any suitable configuration of LEDs can be utilized in the practice of the present invention. In addition, multiple (ie, two or more) LEDs can be utilized for the LED device 700. The LED device 700 further includes a hermetically sealed container 708 that includes a plurality of light emitting nanocrystals 710. Container 708 is optically coupled to LED 702. The LED device 700 further includes a light guide 712 that is optically coupled to a hermetically sealed container 708.

  In an embodiment of the invention, a first portion of the light emitted from the LED is downconverted by the luminescent nanocrystal 710. A second portion of light emitted from the LED and light down-converted from the luminescent nanocrystal are emitted from the light guide 712.

  Any suitable LED, including LEDs that emit light over the entire visible spectrum and various configurations of LEDs, as well as LEDs that emit ultraviolet light (light with a wavelength of 10 nm to about 380 nm) can be incorporated into the LED device of the present invention. Can be used. Suitably, the LED 702 emits blue light. As described herein, the visible spectrum includes light having a wavelength from about 380 nm to about 780 nm that is visible to the human eye. Visible light can be separated into various colors in the spectrum, such as red, orange, yellow, green, blue, indigo, and purple. As used herein, blue light includes light having a wavelength from about 435 nm to about 500 nm, and green light includes light from about 520 nm to 565 nm, more suitably from about 525 nm to about 530 nm. , Red light includes light from about 625 nm to about 740 nm, more suitably from about 625 nm to about 640 nm.

  Suitably, the LED 702 emits blue light 716 as shown in FIG. 7B. A first portion 718 of blue light emitted from the LED is downconverted by the luminescent nanocrystal 710. As the nanocrystal absorbs this portion of the blue light, it then emits light at a second wavelength 722, 724 (see FIG. 7B). Suitably, the light emitted from the nanocrystal 710 is primarily green (eg, from about 520 nm to 565 nm, more suitably from about 525 nm to about 530 nm) and red (eg, from about 625 nm to about 740 nm, more suitably Includes light having a wavelength in the range of about 625 nm to about 640 nm. Thus, suitably, the nanocrystal 710 includes two populations of nanocrystals. One population of nanocrystals is designed to absorb blue light and emit red light, and a second population of nanocrystals is designed to absorb blue light and emit green light. The population of nanocrystals suitably includes a plurality (ie 2 or more, 10 or more, 100 or more, 1000 or more, etc.) of nanocrystals. As described herein, the ability to tailor the composition and size of the nanocrystals allows for the design of nanocrystals with specific absorption and emission characteristics.

  The “first portion” of blue light 718 refers to a percentage of blue light 716 that is emitted from the LED and down-converted from blue to another wavelength or wavelengths of light. The first portion can be any amount of the original blue light 716 emitted from the LED 702 that is less than the total amount of blue light provided by the LED (eg, from about 99% to about 1 of the blue light emitted from the LED 702). %, Suitably about 80% to about 30%, about 70% to about 40%, about 70% to about 50% or about 60%).

  A second portion 720 of blue light emitted from the LED 702 passes through the hermetically sealed container 708 and appears as blue light (suitably about 20% to about 50%, or about 20% to about 40%. %). This second portion 720 of blue light and downconverted light 722 and 724 (eg, red and green light) emitted from the nanocrystal are then emitted 726 from the light guide 712. Suitably, the blue light 720 emitted from the LED is combined with the down-converted green and red light (722 and 724) to produce white light 726 when finally emitted from the light guide. .

  In other embodiments, all light from one (or more) LEDs is down-converted by the nanocrystal, while all light from the second (third, etc.) LED is hermetically sealed. Two (or more) blue light emitting LEDs can be utilized so that they pass through the container resulting in light of red, green and blue wavelengths, which combine to produce white light.

The hermetically sealed container 708 is suitably a plastic or glass container. An exemplary hermetically sealed container is described throughout. In suitable embodiments, the hermetically sealed container is a plastic or glass (eg, borosilicate) capillary. As used herein, “capillary” refers to an elongate container having a length dimension that is longer than both its width and height dimensions. Suitably, the capillary is a tube or similar structure having a circular, rectangular, square, triangular, irregular, or other cross section. Suitably, the capillary used in the LED device of the present invention can be configured to match the shape and orientation of the LED to which the capillary is optically coupled. In an exemplary embodiment, the capillary has at least one dimension from about 100 μm to about 1 mm. In embodiments where plastic capillaries are utilized, coatings such as SiO ₂ , AlO ₂ or TiO ₂ , and others described herein may be added to provide an additional hermetic seal to the capillaries. it can.

  Suitably, the capillaries of the present invention have a thickness of about 50 μm to about 10 mm, about 100 μm to about 1 mm, or about 100 μm to about 500 μm. Thickness refers to the dimension of the capillary into the plane of the light guide. Suitably, the capillary of the present invention has a height (in the plane of the light guide) of about 50 μm to about 10 mm, about 100 μm to about 1 mm, or about 100 μm to about 500 μm. Suitably, the capillary of the present invention has a length (in the plane of the light guide) of about 1 mm to about 50 mm, about 1 mm to about 40 mm, about 1 mm to about 30 mm, about 1 mm to about 20 mm, about 1 mm to about 10 mm. Have.

  In other embodiments, the hermetically sealed compositions of luminescent nanocrystals described herein can be utilized in LED devices. In such embodiments, the hermetically sealed composition is optically coupled to the LED and light guide, thus providing light that is down-converted from the nanocrystal.

  As used herein, “light guide” refers to an optical component suitable for directing electromagnetic radiation (light) from one location to another. Exemplary light guides include polymer or glass solids such as fiber optic cables, plates, films, containers, or other structures. The size of the light guide will depend on the final application and characteristics of the LED device. In general, the thickness of the light guide will match the thickness of the LED. Other dimensions of the light guide are generally designed to extend beyond the dimensions of the LED, suitably on the order of tens of millimeters to tens to hundreds of centimeters. The light guides illustrated in the drawings represent an embodiment suitable for use in a display system or the like, but other light guides including fiber optic cables and the like may be utilized.

  Exemplary nanocrystals used in the practice of the present invention are described herein. In a suitable embodiment, the nanocrystal is a core / shell nanocrystal. Suitably, the nanocrystals comprise one or more ligands attached to their surface, which increases the solubility of the nanocrystals in the polymer material. Exemplary ligands are described herein and in US patent application Ser. No. 11 / 034,216, US patent application Ser. No. 10 / 656,910, and US provisional application No. 60 / 578,236. . Exemplary sizes of nanocrystals are further described herein.

  In suitable embodiments, the luminescent nanocrystal comprises CdSe or ZnS. Exemplary core / shell nanocrystals that can be utilized include CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS, and CdTe / ZnS nanocrystals. In exemplary embodiments, the nanocrystals are dispersed or embedded in a polymer matrix as described herein. This matrix can then be drawn into the capillaries or otherwise placed before sealing the capillaries.

  In additional embodiments, scattering material (eg, particles of material that scatter light entering the hermetically sealed container) can be added to the matrix. Suitably, the scattering medium is a particle of metal, polymer, semiconductor or other material of a size on the order of 500 nm to microns, and even millimeters. In other embodiments, the scattering material can be placed between the LED and the hermetically sealed container, or between the container and the light guide.

  The concentration of nanocrystals in a hermetically sealed container will depend on the application, nanocrystal size, nanocrystal composition, polymer matrix composition, and other factors, and is common in the art. The method can be optimized. Suitably, the luminescent nanocrystals are about 0.01% to about 50%, about 0.1% to about 50%, about 1% to about 50%, about 1% to about 40%. %, About 1% to about 30%, about 1% to about 20%, about 1% to about 10%, about 1% to about 5%, or about 1% to about Present at a concentration of 3% by weight. Of the light from the LED, suitably about 40% to about 80%, more suitably about 50% to about 70%, or about 60% is absorbed by the nanocrystals, in which case the remaining light is Suitably, it passes through a hermetically sealed container. Suitably about 10% to about 40%, or about 20% to about 30% of the light hitting the container passes through the container without being downconverted.

  As described herein, a hermetically sealed container 708 is optically coupled to both the LED 702 and the light guide 712. As used herein, “optically coupled” means that components (eg, hermetically sealed containers and LEDs) can be separated from one component to another without substantial interference. It is meant to be positioned so that it can pass through to the component. The optical coupling may be suitably achieved in an embodiment where the hermetically sealed container 708 and LED 702 are in direct physical contact, or suitably hermetically sealed container 708 (and thus as shown in FIG. 7A). In some embodiments, the nanocrystal 710) and the LED 702 are separated by a distance 704. Although FIG. 7A shows a hermetically sealed container 708 in contact with the top of the substrate 706, any suitable configuration may be used as long as light from the LED can pass through the hermetically sealed container 708. Can be used. For example, a hermetically sealed container can be positioned in the space between the top of the substrate 706 and the LED 702. In other embodiments, an optically transparent element (eg, a glass or plastic sheet or strip containing a lens) can be placed between the hermetically sealed container 708 and the LED 704. It should be noted that optical coupling does not require physical interaction between components. Rather, as long as light can pass between the components, they are considered to be optically coupled. The spacing between hermetically sealed container 708 and LED 702 results in the nanocrystals being located far from the LEDs. This distant location improves the properties (intensity, purity, color rendering, etc.) of light originating from LEDs and nanocrystals.

  In embodiments, the light guide 712 is optically coupled to the hermetically sealed container 708 via glue, tape, mechanical alignment only, etc., and combinations thereof. As shown in FIG. 7A, suitably, the light guide 712 is in direct contact with the hermetically sealed container 708. Tape, glue, or other fastening devices can be utilized to maintain physical contact between the two elements. Suitably, the fastening device is optically transparent or substantially optically transparent to pass light from the hermetically sealed container to the light guide. This can further be achieved by utilizing a polymer light guide that melts when heated, for example, such that a hermetically sealed container contacts the light guide, or Deforms and then the light guide is cooled, thereby facilitating the formation of a physical bond or contact between the two elements.

  8A-8C illustrate additional configurations of the LED device described in FIG. 7A. In FIG. 8A, the light guide 712 is shown having a tapered edge 802. Tapered edge 802 can serve to facilitate directing light emitted from the LEDs and nanocrystals into light guide 712. In FIG. 8B, a hermetically sealed container 708 as shown at 804 can be embedded in the light guide 712. This can be achieved, for example, by removing an area of the light guide 712 so that a hermetically sealed container can be inserted directly into the light guide 712. In other embodiments, as described above, the light guide 712 melts or deforms, thereby allowing the hermetically sealed container 708 to be inserted or embedded into the light guide 712. It can be heated. As illustrated in FIG. 8C, in another embodiment, hermetically sealed container 708 can be shaped as shown at 806. In an exemplary embodiment, the hermetically sealed container 708 can be shaped to act as a lens or other optical device to improve light transmission from the LED to the light guide.

  FIG. 9 shows that the device further includes one or more reflectors 902 positioned relative to the LED, the light guide, and the hermetically sealed container such that the amount of light emitted from the light guide is increased. 1 illustrates an embodiment of an LED device of the present invention. As shown in FIG. 9, the exemplary embodiment reflects any light emitted from the nanocrystals in the hermetically sealed container or bounced off the LEDs that is not guided into the light guide. As such, the reflector can be positioned behind the LED. Similarly, the side of the hermetically sealed container can further include a reflector 902 to reflect light toward the light guide. In additional embodiments, the substrate on which the LED is positioned can further include a reflective inclined side surface that helps direct light from the LED into a hermetically sealed container.

  10A-10B provide an illustration of an exemplary hermetically sealed container 708, eg, a capillary. As shown in FIG. 10B, in an embodiment, the end of the hermetically sealed container 708 (capillary) can be covered with a cap 1002. Cap 1002 is suitably made from a polymeric material that can be heated prior to application and then cooled so that the hermetically sealed container is sealed. In other embodiments, a liquid polymer solution can be used to fill the end of a hermetically sealed container and thereby seal the container. Additional methods of sealing hermetically sealed containers as described herein or other methods known in the art, such as crimping, pinching, laser sealing, heat shrinking, Alternatively, other methods of closing the container ends can be used.

  Suitably, the solution of luminescent nanocrystals dispersed in the polymer matrix is drawn into the capillary, for example by creating a vacuum using a vacuum. Suitably the polymer is then cooled and cured. The curing process often results in small bubbles that are formed in the polymer matrix. The small size bubbles in these preparations do not interfere with the optical properties of the composition or nanocrystal, and in fact, the presence of these small bubbles may cause the matrix to experience thermal cycling during manufacture or with the LED. It has been discovered that it may help reduce the pressure that increases when used.

  In a suitable embodiment, the present invention provides a white light emitting diode (LED) device. The device suitably comprises a blue light emitting LED and a hermetically sealed container comprising a plurality of light emitting nanocrystals (suitably CdSe / ZnS light emitting nanocrystals) optically coupled to the LED. The device further includes a light guide that is optically coupled to the hermetically sealed container.

  As illustrated in FIG. 7B, when the first portion of blue light 718 emitted from the LED enters the hermetically sealed container, the light is green by the luminescent nanocrystal (eg, CdSe / ZnS luminescent nanocrystal). Downconverted to light and red light (722 and 724). A second portion 720 of blue light emitted from the LED and green and red light are emitted from the light guide and combined to produce white light 726.

  As described herein, the white light LED device of the present invention suitably comprises a hermetically sealed container comprising luminescent nanocrystals spaced (distant) from the LED. The concentration of nanocrystals in the hermetically sealed container is provided so that a portion of the blue light emitted by the LED can pass through the container without being absorbed by the nanocrystals. Another part of the blue light is absorbed and then down-converted by the nanocrystals and emitted as green and red light. Red, blue and green light are then combined to produce white light when emitted from the light guide. The approach of the present invention differs from white light LEDs, where three separate light sources (eg, three LEDs) are used, or where all blue light from the LEDs is absorbed by the luminescent nanocrystals. By optimizing the concentration / density and properties of the nanocrystals, high intensity, high purity, precisely tuned white light can be produced.

  In other embodiments, the invention provides an LED, a hermetically sealed container comprising a plurality of light emitting nanocrystals optically coupled to the LED, and light optically coupled to the hermetically sealed container. A light emitting diode (LED) device including a guide is provided. The light emitted from the LED is down-converted by the nanocrystal and exits the surface of the light guide. Suitably, the luminescent nanocrystals emit blue, green and red light and the light is combined to produce white light. In such an embodiment, suitably the LED emits ultraviolet light.

  In other embodiments, the present invention provides a display system that includes an LED device as described herein. Suitably, as shown in FIG. 11, the display system 1100 includes a display 1102 and a plurality of LED devices 700. As described herein, suitably, the LED device 700 includes an LED 702 and a hermetically sealed container 708 that includes a plurality of luminescent nanocrystals that are optically coupled to the LED. The device further includes a light guide 712 that is optically coupled to the hermetically sealed container. As shown in FIG. 11, suitably the display 1102 at least partially surrounds the light guide 712.

  In an embodiment, light emitted from the luminescent nanocrystals and down-converted is emitted from the light guide and displayed on the display. The display system of the present invention can emit light over the entire range of the visible spectrum, including white light.

  In other embodiments, a first portion of the light emitted from the LED is downconverted by the luminescent nanocrystal. A second portion of light emitted from the LED and light down-converted from the luminescent nanocrystal is emitted from the light guide and displayed on the display. The display system of the present invention can emit light over the entire range of the visible spectrum, including white light. In the exemplary embodiment, the LED utilized emits blue light.

  Exemplary hermetically sealed containers (including capillaries) and luminescent nanocrystals are described herein. As shown in FIG. 11, a single hermetically sealed container 708 'is suitably optically coupled to at least two LEDs. A single hermetically sealed container can be optically coupled to two or more, three or more, four or more, five or more, ten or more LEDs. A hermetically sealed container 708 can be coupled to each individual LED, but in the display system embodiments of the present invention, the use of a single hermetically sealed container coupled to multiple LEDs. This allows easier assembly and manufacture of the display system. In embodiments where a single hermetically sealed container is coupled to multiple LEDs, suitably each LED emits blue light, a portion of which is down-converted by the nanocrystals in the container, the Part is emitted from the light guide. FIG. 11 demonstrates an embodiment in which a single light guide and a single display are utilized, but the display system of the present invention is optically coupled to each other resulting in multiple display systems. It should be understood that a light guide and multiple displays can be included.

  The hermetically sealed container containing the luminescent nanocrystals described herein can be used to retrofit existing LED display systems. By including a hermetically sealed container (eg, a capillary tube) between the display LED and the light guide, a portion of the light from the LED (suitably blue light) is combined with the LED light to produce white light. Can be converted into any desired color.

Table 1 below shows the light output from the luminescent nanocrystals of the present invention as well as the light from the blue LED used to excite the nanocrystals. The nanocrystals were spaced (distant from the LED) from the LED as described herein. Data for a traditional yttrium aluminum garnet (YAG) phosphor is also shown. FWHM = full width at half maximum.

In another embodiment, the present invention is a luminescent nanocrystal composite material 1200. As shown in FIG. 12, in an embodiment, the composite material comprises a first polymer material 1204 having a first composition, a second polymer 1202 material having a second composition, and a second polymer. A plurality of luminescent nanocrystals 710 dispersed in material 1202. Second polymeric material 1202 is dispersed in first polymeric material 1204.

  Dispersing the luminescent nanocrystals in the second polymeric material 1202 provides a method for encapsulating the nanocrystals and provides a mechanism for mixing nanocrystals of various compositions and sizes. Suitable second polymeric materials 1202 include, but are not limited to, aminosilicone, poly (vinyl butyral): poly (vinyl acetate); epoxy resin; urethane; silicone and, but not limited to, polyphenylmethylsiloxane, polyphenylalkyl Silicone derivatives including siloxanes, polydiphenylsiloxanes, polydialkylsiloxanes, fluorinated silicones, vinyl and hydride substituted silicones; acrylics formed from monomers including but not limited to methyl methacrylate, butyl methacrylate and lauryl methacrylate Including other polymers described herein, including polymers and copolymers; styrene-based polymers; and polymers crosslinked with bifunctional monomers such as divinylbenzene.

  While the second polymeric material 1202 provides a suitable environment for dispersing nanocrystals, polymers that provide efficient mixing of nanocrystals are often fragile or difficult to shape or mold Sometimes. Dispersing the nanocrystal / polymer mixture 1202 in the additional polymer material 1204 can provide a hermetic seal that can act mechanically as desired while maintaining the desired optical / downconversion properties of the luminescent nanocrystals. Enabling the production of composites that also retain the finished composition. Exemplary polymeric materials used as the first polymeric material 1204 include epoxy resins and polycarbonate. Exemplary epoxy resins and polycarbonates are well known in the art.

  Suitably, the luminescent nanocrystals dispersed in the composite material absorb light (eg, blue light) and emit green and / or red light, but other colors are also emitted from the nanocrystal. There is. Exemplary nanocrystals used in composite materials are described herein and include CdSe or ZnS containing nanocrystals, as well as CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS. Or a core / shell luminescent nanocrystal comprising CdTe / ZnS.

In other embodiments, the composite can include an inorganic layer 1206 that hermetically seals the composite. Examples of inorganic layers comprising SiO ₂ , TiO ₂ or AlO ₂ are described herein.

  Suitably, the composite material of the present invention has an optical density of about 0.5 to about 0.9 and a path length of about 50 μm to about 200 μm at the blue LED wavelength. Suitably, the composite has an optical density of about 0.5 to about 0.8, about 0.7 to about 0.8, or about 0.8 at the blue LED wavelength. Suitably, the path length of the composite material is from about 75 μm to about 150 μm, or about 100 μm. The concentration of the luminescent nanocrystals utilized in the composite material of the present invention is suitably about the same as that utilized in the hermetically sealed composition described herein. Thus, the luminescent nanocrystal is suitably about 40% to about 80%, more suitably about 50% to about 70%, or about 60% of the light hitting the composite, so that the nanocrystal can absorb about 0.01% to about 50%, about 0.1% to about 50%, about 1% to about 50%, about 1% to about 40%, about 1% to about 30% It is present at a concentration of about 1% to about 20%, about 1% to about 10%, about 1% to about 5%, or about 1% to about 3% by weight.

  The present invention further provides a method of preparing a luminescent nanocrystalline composite material. As shown in the flow diagram 1300 of FIG. 13 with respect to FIG. 12, suitably such a method comprises dispersing a plurality of luminescent nanocrystals 710 in a first polymeric material 1202 to form a luminescent nanocrystal and a first Forming a mixture 130 with one polymeric material. The mixture is then cured at 1304. At 1308, microparticles are generated from the cured mixture. At step 1310, the microparticles are dispersed in the second polymeric material 1204 to produce a composite material. The microparticles can be dispersed in the second polymeric material using various forms of mechanical mixing when the second polymeric material is in a liquid or nearly liquid state.

  Exemplary polymeric materials used in this method are described herein as suitable luminescent nanocrystals. Suitably, the luminescent nanocrystal comprises CdSe or ZnS or is a core-shell nanoparticle comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS, suitably Dispersed in aminosilicone.

  Suitably, the mixture of luminescent nanocrystals and first polymer material is mechanically processed to form microparticles. Examples of mechanical processing include ball milling, grinding, comminuting, comminuting or other methods of forming microparticles from a mixture. Chemical treatments or other treatments can also be utilized to generate microparticles. Suitably, the microparticle is a powder. Suitably, the microparticles of the mixture of nanocrystals and first polymeric material have a size on the order of about 10 μm to about 200 μm, or about 10 μm to about 100 μm, or about 20 μm to about 70 μm, or about 50 μm.

  Other structures other than the fine particles of the mixture of luminescent nanocrystals and the first polymeric material, such as films, rods, ribbons, spheres, and the like may occur. These structures can then be dispersed in the second polymeric material.

  In other embodiments, the second polymeric material can be replaced with other materials such as ceramics, glasses, or inorganic materials that have the desired optical and physical properties of the desired final product.

  In the exemplary embodiment, a crosslinker is added to the mixture at step 1306 prior to curing at 1304. Exemplary crosslinkers are the crosslinkers described herein, or other crosslinkers known in the art.

  In other embodiments, as shown in FIG. 13, the method can further include step 1312 of filming the composite material. Suitably, the composite mixture is cast on a non-stick substrate, such as a TEFLON® sheet. After the mixture is cured, the cured film can be removed from the non-stick substrate. The film can then be cut or cut to any desired size or shape.

  In additional embodiments, an inorganic layer can be disposed on the composite to provide an additional hermetic seal to the composite, as shown in step 1314 of flowchart 1300. The inorganic layer can be placed after formation of the composite material, but before the composite is made into a film, or the inorganic layer can be placed after it is made into a film (including after being cut / cut into the desired shape). it can. Described herein are methods for placing an inorganic layer on a composite, including various methods such as coating, spraying, ALD, dip coating, and the like.

  The composite material can be further extruded, molded, solvent cast, compression molded, etc. to form the desired shape and configuration of the composite. Methods and parameters for implementing these techniques are well known in the art.

  The composite material of the present invention can be utilized in the downconverting applications described herein, or other applications where downconverting layers / films / structures are desired. Accordingly, in exemplary embodiments, layers, films, tubes, strips or other suitable structures are prepared from composite materials to provide for down conversion of light from LEDs as described herein. And can be optically coupled to the LED (and / or the light guide).

In other embodiments of light guides comprising nanocrystals, the present invention provides a light emitting diode (LED) device as shown in FIGS. Suitably, LED devices 1400 and 1401 include an LED 702 and a light guide 712 that is optically coupled to the LED. A plurality of light emitting nanocrystals 710 are dispersed in regions (1404, 1404 ′) in the light guide. Suitably, the region extends along the length 1410 of the light guide. Suitably, the nanocrystal emits blue light, red light and green light. In an embodiment, the LED is an ultraviolet (UV) light emitting LED.

  In other embodiments, a first portion of the light emitted from the LED is downconverted by the nanocrystal. As shown in FIGS. 14A and 14B, a second portion of light (1412) emitted from the LED and downconverted light (1414 and 1416) exit the surface of the light guide.

  As explained throughout, the luminescent nanocrystals of the present invention suitably absorb light of a particular wavelength, then down-convert the absorbed light and emit light at a different wavelength. In the embodiment of the invention illustrated in FIGS. 14A-14B, the luminescent nanocrystals 710 are dispersed in regions 1404 and 140 'of the light guide. The light emitted from the LED travels through the length 1410 of the light guide and is suitably reflected by the reflector along the surface of the light guide. In an embodiment, some of the light emitted from the LED is emitted from the surface of the light guide as indicated at 1412. Other parts of the light emitted from the light guide are absorbed by the luminescent nanocrystals and down-converted. This downconverted light (1414 and 1416) is then emitted from the light guide. In other embodiments, the light emitted from all LEDs is down-converted by the nanocrystal.

  In an exemplary embodiment, the LED is a blue light emitting LED. As discussed in detail herein, in an exemplary embodiment, a portion of the blue light emitted from the LED is downconverted to red and green light by the luminescent nanocrystals. White light is emitted from the surface of the light guide when the emitted green 1414 and red 1416 light is combined with a portion of blue light 1412 (not down-converted) emitted from the LED. In suitable embodiments, the light guide 712 includes one or more features 1406 on the light guide emitting surface (s). The feature 1406 is suitably a pattern etched into or formed from the surface of the light guide 712 to aid in the transmission of light from the light guide. In an embodiment, feature 1406 is designed to enhance the emission of light (including blue light) emitted directly from the LED.

  In other embodiments, the LED is a UV light emitting LED, and substantially all of the light emitted from the LED is down-converted to red, green and blue light by the nanocrystal. The light is then emitted from the light guide and combined to produce white light.

  Exemplary nanocrystals for use in regions within the light guide are described herein. Suitably the nanocrystal is CdSe or ZnS, or suitably a core / shell nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS.

  As used herein, a “region” refers to an area or portion of a light guide in which luminescent nanocrystals are disposed. Suitably, as shown in FIGS. 14A-14B, regions 1404 and 1404 ′ extend along the length 1410 of the light guide 712. The light guide length 1410 is a lateral dimension extending (or substantially perpendicular) perpendicular to the LED. By orienting the light guide 712 relative to the LED 702 as shown in FIGS. 14A and 14B, the light from the LED 702 causes more of the nanocrystals 710 in the regions 1404 and 1404 ′ before exiting the light guide. Hit the part. Suitably, region 1404/1404 'is a layer of luminescent nanocrystals. The size of the region 1404/1404 ′ is determined by the overall size of the light guide, but in general, the thickness of the region will be proportional to the size of the LED (ie, on the order of tens of microns to tens of millimeters). However, the in-plane dimensions (ie length and width) of the light guide suitably span the entire light guide. In other embodiments, the region containing the nanocrystals spans the entire light guide in all dimensions (ie, is distributed throughout the light guide).

  Regions 1404/1404 ′ can be created by dispersing the nanocrystals in the polymer matrix and then forming a light guide around the polymer either before or after the polymer is cured. . Alternatively, light guides can be prepared to form regions, and then nanocrystals can be sprayed, painted, sprayed, or otherwise deposited. Other methods for generating the polymer matrix can be utilized to form the regions, including the methods described herein for forming the polymer composite. In an exemplary embodiment, the luminescent nanocrystal composite material 1200 described herein can be utilized to prepare regions of a light guide.

  Dispersing the luminescent nanocrystals into regions within the light guide provides numerous benefits and advantages throughout the system. For example, more uniform illumination of the nanocrystals can be achieved, thereby reducing the presence of local hot spots. Dispersing the nanocrystals throughout the region allows for improved heat dissipation from the nanocrystals, thus reducing the temperature of the entire nanocrystal. By reducing the optical path length from the nanocrystal to the top surface of the light guide, any loss of efficiency due to green and red photon reabsorption is reduced. Furthermore, low concentrations of nanocrystals can be utilized in the region, and thus the potential light and heat induced interaction between the nanocrystals and the material in which the nanocrystals are dispersed (eg polymer). It can reduce the effect and thereby extend the system life.

  The concentration of luminescent nanocrystals in the region of the light guide will depend on the application, the size of the nanocrystals, the composition of the nanocrystals, the composition of the polymer matrix, and other factors. Can be used and optimized. Suitably, the luminescent nanocrystals are present at a concentration lower than that utilized in the LED device embodiments described herein that utilize hermetically sealed containers, suitably about 0.01. % To about 50%, about 0.1% to about 50%, about 1% to about 50%, more suitably about 1% to about 40%, about 1% to about 30 wt%, about 1 wt% to about 20 wt%, about 1 wt% to about 10 wt%, about 1 wt% to about 5 wt%, or about 1 wt% to about 3 wt%. In general, the concentration of luminescent nanocrystals scales proportionally based on the size of the light guide. Thus, the concentration of luminescent nanocrystals utilized in a hermetically sealed container having a thickness of approximately 100 mm would be reduced by two orders of magnitude, for example for a light guide about 10 cm long.

  In the exemplary embodiment, the thickness of region 1404 ′ varies along light guide length 1410. As shown in FIG. 14B, suitably, the thickness of the region 1404 ′ can be from a minimum 1406 at the LED along the light guide length 1410 to the far end of the light guide 1408 away from the LED. Increase to the maximum. In the exemplary embodiment, the thickness increases substantially linearly along the length of the light guide. In other embodiments, the thickness can be increased in a non-linear manner and / or the maximum thickness can be achieved before reaching the far end 1408 of the light guide. The schematic shown in FIG. 14B showing the thickness of region 1404 ′ increasing linearly along both the top and bottom of the region is for illustrative purposes only, and any suitable shape of region 1404 ′. Note that / orientation can be utilized. Changing the thickness of the region provides more uniform illumination from the light guide.

  15A-15C show the intensity of light emitted from the light guide shown in FIG. 14A. Intensity is shown as a function of the relative distance from the light guide far end (1408) to 1 (1), starting from zero (0) adjacent to the LED (1406) along the light guide and away from the LED. Yes. FIG. 15A shows the intensity of both the blue light emitted (forward) from the LED and the blue light reflected in the light guide before being emitted. FIG. 15B shows the intensity of the green and red light emitted from the nanocrystals resulting from both the directly absorbed blue light from the LED (forward) and the reflected blue light. Finally, FIG. 15C is an intensity showing the combined sum of all blue light emitted from the light guide (blue sum) and the combined sum of all green and red light (green / red sum). The plot of is illustrated. As demonstrated in FIG. 15C, both blue and green / red light intensities disappear along the length of the light guide. The blue light disappears as a result of absorption over the entire length of the light guide. Since the amount of nanocrystals in the region of the light guide is constant (due to the uniform thickness of the region), the intensity of red and green light further decreases along the length of the light guide.

  16A-16C show intensity plots similar to the plots in FIGS. 15A-15C, except for the light guide configuration illustrated in FIG. 14B (region 1404 'with nanocrystals of varying thickness). The amount of emitted blue light, both advancing blue light and reflected blue light, is similar to a constant thickness region. However, comparing the green / red light intensities of FIGS. 16B-16C and FIGS. 15B-15C, better uniform green / red light is emitted from light guides having regions of varying thickness (1404 ′) You can see that This is probably a result of the increased thickness of the area 1404 'at the end of the light guide away from the LED. Because there are more nanocrystals at the far end of the light guide (even though the concentration may be consistent throughout the light guide), it absorbs more blue light and down to green and red light Can be converted.

  The present invention further provides a display system including a display, a plurality of LEDs, and a light guide optically coupled to the LEDs, wherein the display at least partially surrounds the light guide. As described herein, a plurality of luminescent nanocrystals are dispersed in regions within the light guide, the regions extending along the length of the light guide. Light from the LED is down-converted by the nanocrystals, exits the light guide, and is displayed on the display. In an embodiment, the LED is a UV light emitting LED and the nanocrystal emits red, green and blue light.

  In other embodiments, a first portion of the light emitted from the LED is downconverted by the light emitting nanocrystal, and a second portion of the light emitted from the LED and the light downconverted from the light emitting nanocrystal is the light guide. And is displayed on the display. As described herein, in an exemplary embodiment, the LED emits blue light, and a first portion of the blue light emitted from the LED is down-converted to green and red light by the luminescent nanocrystals. The Suitably, the second portion of blue light, green light, and red light are combined to produce white light.

  Exemplary nanocrystals including core-shell nanocrystals are described herein. In an exemplary embodiment, the light guide includes one or more reflectors.

  Suitably, the region containing luminescent nanocrystals is a layer of nanocrystals. In an exemplary embodiment, the thickness of the region varies along the length of the light guide, suitably from the LED along the length of the light guide, for example as described herein. Increases linearly.

(Example)
The following examples illustrate the methods and compositions of the present invention and are not intended to limit the methods and compositions of the present invention. Other suitable modifications and adaptations of the various conditions and parameters normally encountered in the synthesis of nanocrystals that would be apparent to those skilled in the art are within the spirit and scope of the present invention.

Example 1
Preparation of a hermetically sealed container A rectangular tube approximately 3 mm x 0.5 mm in size with a 2 mm x 0.5 mm cavity is prepared by extrusion of PMMA. The entire length of the tube is then filled with a solution containing fluorescent luminescent nanocrystals. The luminescent nanocrystal solution is then cured. The portions of the tube are then heat sealed to confine the nanocrystals within the tube. Suitably, this filling and sealing is performed in an inert atmosphere. A barrier layer (eg, SiO ₂ , TiO ₂ or AlO ₂ ) can then be placed on the outer surface of the tube.

  Glass capillaries manufactured by drawing can also be used to prepare hermetically sealed containers containing nanocrystals. Capillary ends are sealed by melt-sealing or by plugging with solder or adhesive or similar structure. The capillary can be filled with a solution of luminescent nanocrystals so that the entire capillary volume is filled with the same nanocrystal solution, or different nanocrystals are separated along the entire length of the capillary, The capillary can be filled with a solution of luminescent nanocrystals in several steps. For example, a first luminescent nanocrystal solution can be introduced into a capillary and then a seal can be placed adjacent to the solution (eg, other than melt sealing the capillary or plugging the capillary). . A second luminescent nanocrystal solution can then be added to the capillary and then again a seal can be placed adjacent to the solution. This process can be repeated as many times as necessary until a desired number of individual nanocrystal portions that are hermetically sealed are produced. In this way, different compositions of luminescent nanocrystals can be separated from each other in the same container, thereby producing a container containing multiple compositions (eg, colors) of luminescent nanocrystals. . In a similar embodiment, different compositions of luminescent nanocrystals (eg, compositions that emit light of different colors) can be introduced, thus allowing them to be kept separate from one another and external air And multi-lumen capillaries that can still be hermetically sealed from moisture.

Example 2
Preparation of nanocrystalline composite material Luminescent nanocrystals that emit red (630 nm) and green (530 nm) light (eg CdSe / ZnS) are incorporated into aminosilicone polymers at a concentration of 3% by weight. The aminosilicone polymer has a viscosity of 350 centipoise and contains 5% amino groups and 95% dimethylsiloxane. The resulting composition has an optical density of about 0.8 and a path length of 100 μm.

  An epoxide crosslinker is added and the material is cured to form a rubber. The cured quantum dot composition is then placed in a ball mill to a 50 μm powder.

  The powder is then mixed in 2 parts epoxy at about 30% loading to degas the polymer. The refractive indices of the nanocrystals and the epoxy are appropriately matched so that light scattering and the resulting absorption by the nanocrystals are minimized.

  The epoxy / nanocrystal mixture is cast on a TEFLON® sheet at a thickness of about 300 μm. After curing, the film is removed. The optical density of the final composite material is about 0.8 OD.

  Exemplary embodiments of the present invention have been presented. The present invention is not limited to these examples. These examples are presented herein for purposes of illustration and not for purposes of limitation. Alternative embodiments will be apparent to those skilled in the art based on the teachings contained herein (including equivalents, extensions, modifications, deflections, etc., of the embodiments described herein). Such alternative embodiments are within the scope and spirit of the present invention.

  All published articles, patents, and patent applications mentioned in this specification are by reference to the same extent as if each individual published article, patent, or patent application was individually stated to be incorporated by reference. Incorporated herein.

Claims (114)

A light emitting diode (LED) device,
(A) a blue light emitting LED;
(B) a hermetically sealed container comprising a plurality of luminescent nanocrystals;
An LED device, wherein the container is positioned relative to the LED to facilitate down-conversion of the luminescent nanocrystals.   The LED device of claim 1, wherein the hermetically sealed container is a plastic or glass tube.   The LED device according to claim 1, wherein the hermetically sealed container is a glass capillary.   The LED device of claim 1, wherein the hermetically sealed container is spaced from the LED.   The LED device of claim 1, wherein the luminescent nanocrystals emit green light and red light.   The LED device of claim 1, wherein the luminescent nanocrystal comprises CdSe or ZnS.   The LED device of claim 1, wherein the luminescent nanocrystal is a core / shell luminescent nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS, or CdTe / ZnS.   The LED device of claim 1, wherein the luminescent nanocrystals are dispersed in a polymer matrix. A display system,
(A) a display;
(B) a plurality of light emitting diode (LED) devices;
(I) a blue light emitting LED;
(Ii) a hermetically sealed container comprising a plurality of luminescent nanocrystals;
An LED device comprising:
A display system, wherein the container is positioned relative to the LED to facilitate down-conversion of the luminescent nanocrystals.   The display system of claim 9, wherein the hermetically sealed container is a plastic or glass tube.   The display system of claim 9, wherein the hermetically sealed container is a glass capillary.   The display system of claim 9, wherein the hermetically sealed container is spaced from the LED.   The display system of claim 9, wherein the luminescent nanocrystals emit green light and red light.   The display system of claim 9, wherein the luminescent nanocrystal comprises CdSe or ZnS.   10. The display system of claim 9, wherein the luminescent nanocrystal is a core / shell luminescent nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS.   The display system of claim 9, wherein the luminescent nanocrystals are dispersed in a polymer matrix. A light emitting diode (LED) device,
(A) an LED;
(B) a hermetically sealed container comprising a plurality of luminescent nanocrystals optically coupled to the LED;
(C) a light guide optically coupled to the hermetically sealed container;
A first portion of light emitted from the LED is down-converted by the light-emitting nanocrystal, and a second portion of light emitted from the LED and the light down-converted from the light-emitting nanocrystal is the Emitted from the light guide,
LED device.   The LED device of claim 17, wherein the LED emits blue light.   19. The LED device of claim 18, wherein a first portion of blue light emitted from the LED is downconverted to green and red light by the luminescent nanocrystal.   20. The LED device of claim 19, wherein the second portion of the blue light, the green light, and the red light are combined to produce white light.   The LED device according to claim 17, wherein the hermetically sealed container is a plastic or glass container.   The LED device of claim 21, wherein the hermetically sealed container is a glass capillary.   24. The LED device of claim 22, wherein the glass capillary has at least one dimension from about 100 [mu] m to about 1 mm.   The LED device of claim 17, wherein the luminescent nanocrystal comprises CdSe or ZnS.   18. The LED device of claim 17, wherein the luminescent nanocrystal is a core / shell nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS.   18. The LED device of claim 17, wherein the light guide is optically coupled to the hermetically sealed container via glue or tape.   The LED device of claim 17, wherein the hermetically sealed container is spaced from the LED.   The LED device of claim 17, wherein the luminescent nanocrystals are dispersed in a polymer matrix. A white light emitting diode (LED) device comprising:
(A) a blue light emitting LED;
(B) a hermetically sealed container comprising a plurality of CdSe / ZnS light emitting nanocrystals optically coupled to the LED;
(C) a light guide optically coupled to the hermetically sealed container;
A first portion of blue light emitted from the LED is downconverted to green and red light by the CdSe / ZnS light emitting nanocrystals, and a second portion of blue light emitted from the LED and the Green light and the red light are emitted from the light guide and combined to produce white light,
White light LED device.   30. The white light LED device of claim 29, wherein the hermetically sealed container is a plastic or glass container.   32. The white light LED device of claim 30, wherein the hermetically sealed container is a glass capillary.   32. The white light LED device of claim 31, wherein the glass capillary has at least one dimension of about 100 [mu] m to about 1 mm.   30. The white light LED device of claim 29, wherein the light guide is optically coupled to the hermetically sealed container via glue or tape.   30. The white light LED device of claim 29, wherein the hermetically sealed container is spaced from the LED.   30. The white light LED device of claim 29, wherein the CdSe / ZnS light emitting nanocrystals are dispersed in a polymer matrix. A display system,
(A) a display;
(B) a plurality of light emitting diode (LED) devices;
(I) an LED;
(Ii) a hermetically sealed container comprising a plurality of luminescent nanocrystals optically coupled to the LED;
An LED device comprising:
(C) a light guide optically coupled to the hermetically sealed container;
Wherein the display at least partially surrounds the light guide, a first portion of light emitted from the LED is down-converted by the luminescent nanocrystal, and a second portion of light emitted from the LED And the light down-converted from the luminescent nanocrystal is emitted from the light guide and displayed on the display;
Display system.   The display system of claim 36, wherein the LED emits blue light.   38. The display system of claim 37, wherein a first portion of blue light emitted from the LED is down-converted to green and red light by the luminescent nanocrystal.   40. The display system of claim 38, wherein the second portion of blue light, the green light, and the red light are combined to produce white light.   37. A display system according to claim 36, wherein the hermetically sealed container is a plastic or glass container.   41. A display system according to claim 40, wherein the hermetically sealed container is a glass capillary.   42. The display system of claim 41, wherein the glass capillary has at least one dimension from about 100 [mu] m to about 1 mm.   37. The display system of claim 36, wherein the luminescent nanocrystal comprises CdSe or ZnS.   37. The display system of claim 36, wherein the luminescent nanocrystal is a core / shell luminescent nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS, or CdTe / ZnS.   38. A display system according to claim 36, wherein the light guide is optically coupled to the hermetically sealed container via glue or tape.   The display system of claim 36, wherein the hermetically sealed container is optically coupled to at least two LEDs.   37. A display system according to claim 36, wherein the luminescent nanocrystals are dispersed in a polymer matrix. A composite material,
(A) a first polymeric material having a first composition;
(B) a second polymeric material having a second composition;
(C) a plurality of luminescent nanocrystals dispersed in the second polymeric material;
Wherein the second polymeric material is dispersed in the first polymeric material,
Composite material.   49. The composite material of claim 48, wherein the first polymeric material comprises epoxy or polycarbonate.   49. The composite material of claim 48, wherein the second polymeric material comprises aminosilicone.   49. The composite material of claim 48, wherein the luminescent nanocrystals emit green light and / or red light.   49. The composite material of claim 48, wherein the luminescent nanocrystal comprises CdSe or ZnS.   49. The composite material of claim 48, wherein the luminescent nanocrystal is a core / shell luminescent nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS. Further comprising a SiO _2, the inorganic layer of TiO ₂ or AlO ₂ for hermetically sealing the composite, the composite material of claim 48.   49. The composite material of claim 48, wherein the composite has an optical density of about 0.5 to about 0.9 and a path length of about 50 [mu] m to about 200 [mu] m.   56. The composite material of claim 55, wherein the composite has an optical density of about 0.8 and a path length of about 100 [mu] m. A method for preparing a luminescent nanocrystalline composite material comprising:
(A) dispersing a plurality of luminescent nanocrystals in a first polymer material to form a mixture of the luminescent nanocrystals and the first polymer material;
(B) curing the mixture;
(C) generating fine particles from the cured mixture;
(D) dispersing the particulates in the second polymeric material to produce a composite material;
Including methods.   58. The method of claim 57, wherein the dispersing step (a) comprises dispersing the luminescent nanocrystals in an aminosilicone.   58. The method of claim 57, wherein the dispersing step (a) comprises dispersing luminescent nanocrystals comprising CdSe or ZnS.   58. The method of claim 57, wherein said dispersing step (a) comprises dispersing luminescent nanocrystals comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS. .   58. The method of claim 57, comprising adding a cross-linking agent to the mixture prior to curing in step (b).   58. The method of claim 57, wherein the step of producing microparticles comprises ball milling the cured mixture.   58. The method of claim 57, further comprising turning the composite material into a film. A light emitting diode (LED) device,
(A) an LED;
(B) a hermetically sealed container comprising a plurality of luminescent nanocrystals optically coupled to the LED;
(C) a light guide optically coupled to the hermetically sealed container;
Light emitted from the LED is down-converted by the nanocrystal and exits the surface of the light guide.
LED device.   65. The LED device of claim 64, wherein the luminescent nanocrystal emits blue, green and red light, and the light is combined to produce white light.   The LED device according to claim 64, wherein the LED emits ultraviolet light.   The LED device of claim 64, wherein the hermetically sealed container is a plastic or glass container.   68. The LED device of claim 67, wherein the hermetically sealed container is a glass capillary.   69. The LED device of claim 68, wherein the glass capillary has at least one dimension from about 100 [mu] m to about 1 mm.   65. The LED device of claim 64, wherein the luminescent nanocrystal comprises CdSe or ZnS.   65. The LED device of claim 64, wherein the luminescent nanocrystal is a core / shell nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS.   The LED device of claim 64, wherein the light guide is optically coupled to the hermetically sealed container via glue or tape.   65. The LED device of claim 64, wherein the hermetically sealed container is spaced from the LED.   65. The LED device of claim 64, wherein the luminescent nanocrystals are dispersed in a polymer matrix. A light emitting diode (LED) device,
(A) an LED;
(B) a light guide optically coupled to the LED;
(C) a plurality of light emitting nanocrystals dispersed in a region within the light guide, wherein the region extends along the length of the light guide;
Light emitted from the LED is down-converted by the nanocrystal and exits the surface of the light guide.
LED device.   76. The LED device of claim 75, wherein the luminescent nanocrystal emits blue, green and red light, and the light is combined to produce white light.   78. The LED device of claim 76, wherein the LED emits ultraviolet light.   A first portion of light emitted from the LED is down-converted by the nanocrystal, and the light down-converted with a second portion of light emitted from the LED exits the surface of the light guide. Item 76. The LED device according to Item 75.   80. The LED device of claim 78, wherein the LED emits blue light.   80. The LED device of claim 79, wherein a first portion of blue light emitted from the LED is down-converted to green and red light by the luminescent nanocrystal.   81. The LED device of claim 80, wherein the second portion of blue light, the green light, and the red light are combined to produce white light.   76. The LED device of claim 75, wherein the nanocrystal comprises CdSe or ZnS.   76. The LED device of claim 75, wherein the nanocrystal is a core / shell nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS or CdTe / ZnS.   76. The LED device of claim 75, wherein the light guide includes one or more reflectors.   76. The LED device of claim 75, wherein the region is a layer of luminescent nanocrystals.   76. The LED device of claim 75, wherein the thickness of the region varies along the length of the light guide.   90. The LED device of claim 86, wherein the thickness increases from the LED along the length of the light guide.   90. The LED device of claim 87, wherein the thickness increases substantially linearly along the length of the light guide. A white light emitting diode (LED) device comprising:
(A) a blue light emitting LED;
(B) a light guide optically coupled to the LED;
(C) a plurality of CdSe / ZnS light emitting nanocrystals dispersed in a region within the light guide, wherein the regions extend along the length of the light guide;
A first portion of blue light emitted from the LED is down-converted to green light and red light by the CdSe / ZnS emitting nanocrystals, and the second portion of blue light, the green light and the red light A white light LED device in which light is emitted from the light guide and combined to produce white light.   90. The white light LED device of claim 89, wherein the light guide includes one or more reflectors.   90. The white light LED device of claim 89, wherein the region is a layer of CdSe / ZnS light emitting nanocrystals.   90. The white light LED device of claim 89, wherein the thickness of the region varies along the length of the light guide.   90. The white light LED device of claim 89, wherein the thickness increases from the LED along the length of the light guide.   The white light LED device of claim 90, wherein the thickness increases substantially linearly along the length of the light guide. A white light emitting diode (LED) device comprising:
(A) an ultraviolet light emitting LED;
(B) a light guide optically coupled to the LED;
(C) a plurality of CdSe / ZnS light emitting nanocrystals dispersed in a region within the light guide, wherein the regions extend along the length of the light guide;
The light emitted from the LED is down-converted to green light, red light and blue light by the CdSe / ZnS light emitting nanocrystal, and the green light, red light and blue light are emitted from the light guide. Combined to produce white light,
White light LED device.   96. The white light LED device of claim 95, wherein the light guide includes one or more reflectors.   96. The white light LED device of claim 95, wherein the region is a layer of CdSe / ZnS light emitting nanocrystals.   96. The white light LED device of claim 95, wherein the thickness of the region varies along the length of the light guide.   99. The white light LED device of claim 98, wherein the thickness increases from the LED along the length of the light guide.   100. The white light LED device of claim 99, wherein the thickness increases substantially linearly along the length of the light guide. A display system,
(A) a display;
(B) a plurality of light emitting diodes (LEDs);
(C) a light guide optically coupled to the LED, the light guide at least partially surrounding the display;
(D) a plurality of light emitting nanocrystals dispersed in a region within the light guide, wherein the region extends along the length of the light guide;
Light emitted from the LED is down-converted by the nanocrystal, exits the surface of the light guide, and is displayed on the display.
Display system.   102. The display system of claim 101, wherein the luminescent nanocrystals emit blue, green and red light.   104. The display system of claim 102, wherein the LED emits ultraviolet light.   A first portion of light emitted from the LED is down-converted by the nanocrystal, and the light down-converted with a second portion of light emitted from the LED exits the surface of the light guide. Item 101. The display system according to Item 101.   105. The display system of claim 104, wherein the LED emits blue light.   106. The display system of claim 105, wherein a first portion of blue light emitted from the LED is down-converted to green and red light by the luminescent nanocrystal.   107. The display system of claim 106, wherein the second portion of blue light, the green light, and the red light are combined to produce white light.   102. The display system of claim 101, wherein the luminescent nanocrystal comprises CdSe or ZnS.   102. The display system of claim 101, wherein the luminescent nanocrystal is a core / shell luminescent nanocrystal comprising CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS, or CdTe / ZnS.   102. The display system of claim 101, wherein the light guide includes one or more reflectors.   102. The display system of claim 101, wherein the region is a layer of luminescent nanocrystals.   102. The display system of claim 101, wherein the thickness of the region varies along the length of the light guide.   113. The display system of claim 112, wherein the thickness of the region increases along the length of the light guide from the LED.   114. The display system of claim 113, wherein the thickness increases substantially linearly along the length of the light guide.

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