Electrophoretic deposition of converter materials onto thin non-conductive substrates

Abstract

A method of preparing a converter layer comprises: conducting electrophoresis to deposit particles of a converter material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; and fixing the particles of the converter material with a binder material and / or an inorganic coating to prepare the converter layer. A converter component for a light emitting diode (LED) comprises: a converter layer comprising: electrophoretically-deposited converter particles in combination with one or more or the following: a binder material; an inorganic coating of the converter particles, and the binder material when present; and a filler material.

Description

ELECTROPHORETIC DEPOSITION OF CONVERTER MATERIALS ONTO THIN NON-CONDUCTIVE SUBSTRATESTECHNICAL FIELD

[0001] The present disclosure relates to electrophoretic deposition of converter materials, including phosphor materials, onto non-conductive substrates, preferably thin non-conductive substrates. The present disclosure also relates generally to converter layers including such electrophoretically-deposited converter materials for phosphor-converted light emitting diodes (pc-LEDs), and devices and arrays including the same. The electrophoretically-deposited converter materials, in particular phosphor materials, are densely-packed onto the non-conductive substrates. Converter layers comprise: the electrophoretically-deposited converter materials including converter particles, in particular phosphor particles, in combination with one or more of the following: binder materials; an inorganic coating of the converter particles and binder materials; and optionally one or more filler materials.BACKGROUND

[0002] Semiconductor light-emitting devices or optical power emitting devices (such as devices that emit ultraviolet (UV) or infrared (IR) optical power), including light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, and edge emitting lasers, are among the most efficient light sources currently available. Due to their compact size and lower power requirements, for example, semiconductor light or optical power emitting devices (referred to herein as LEDs for simplicity) are attractive candidates for light sources, such as camera flashes, for hand-held battery-powered devices, such as cameras and cell phones. They may also be used, for example, for other applications, such as for automotive lighting, torch for video, and general illumination, such as home, shop, office and studio lighting, theater / stage lighting and architectural lighting.

[0003] High-intensity / brightness light emitting devices capable of operation across the visible spectrum include Group lll-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as Ill-nitride materials. Typically, Ill-nitride light emitting devices are fabricated by epitaxially growing a stack of semiconductor layers of differentcompositions and dopant concentrations on a growth substrate such as a sapphire, silicon, silicon carbide, Ill-nitride, or other suitable substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. Sapphire is often used as the growth substrate due to its wide commercial availability and relative ease of use. The stack grown on the growth substrate typically includes one or more n-type layers doped with, for example, Si, formed over the substrate, a light emitting or active region formed over the n-type layer or layers, and one or more p-type layers doped with, for example, Mg, formed over the active region.

[0004] Phosphor converted LEDs (pc-LEDs) include a converter layer, e.g., a phosphor layer on an LED pump. The phosphor layer absorbs energy and converts an entering wavelength to a lower-energy wavelength. For example, the phosphor layer down-converts high energy LED light into a more desirable color spectrum. In practice, the phosphor layer composition and structure are chosen to meet desired performance criteria. Reliability is a requirement for pc-LEDs. Demand for pc-LEDs operating at high power levels has been on the rise, which in turn presents a need for pc-LED materials that operate at high temperatures while maintaining good stability.

[0005] A number of applications require thin layers of densely packed converter particles, e.g., phosphor particles, layers that are just a few particle diameters thick. Such layers cannot be applied by for instance blade-coating of phosphor in a silicone binder or by spin-coating as the phosphor particles easily disturb the liquid flow in the formation of the layer. Spray coating is also difficult to control for thin layers.

[0006] The presence of organic materials in conventional phosphor layers renders them prone to degradation under at high optical flux and temperature, and hence can lead to premature reliability failures of pc-LEDs.

[0007] There is a need to develop methods for depositing thin layers of densely packed converter particles, e.g., phosphor particles, and for preparing converter layer / designs that can overcome reliability shortcomings at extreme operating conditions.SUMMARY

[0008] Provided herein are converter layers of LEDs, and LED devices and arrays and light sources including the same, and methods of making the same. In one or more aspects, converter layers, namely, phosphor layers, are deposited on thinnon-conductive substrates by electrophoretic deposition. Preferably, these layers are thin and densely packed. As to reliability shortcomings in the state of the art, thin, densely packed layers have advantages, for instance, with respect to control of scattering and better thermal conductivity as compared to traditionally-prepared layers of converter particles.

[0009] In an aspect, methods of preparing a converter layer comprise: conducting electrophoresis to deposit particles of a converter material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; and fixing the particles of the converter material with a binder material and / or an inorganic coating to prepare the converter layer.

[0010] Another aspect provides methods of making an inorganic phosphor component for a light emitting diode (LED) comprising: conducting electrophoresis to deposit phosphor particles in a suspension composition onto a polycrystalline ceramic plate of a phosphor material to prepare a first intermediate structure; fixing the phosphor particles with a binder material derived from a sol-gel material, and / or an inorganic coating to prepare a second intermediate structure; and disposing a filler material among the phosphor particles and the binder material and / or the inorganic coating to prepare a converter layer on the polycrystalline ceramic plate; and removing any organic materials of at least the suspension composition and the sol-gel material to prepare the inorganic phosphor component.

[0011] A further aspect is a converter component for a light emitting diode (LED) comprising: a converter layer comprising: electrophoretically-deposited converter particles in combination with one or more or the following: a binder material; an inorganic coating of the converter particles, and the binder material when present; and a filler material.

[0012] Another aspect is light emitting diode (LED) array comprising: mesas comprising stacks of semiconductor layers including an active region; and the converter component of any embodiment herein affixed to the mesas.

[0013] In another aspect, a method of manufacturing a light emitting source comprises: affixing a converter component according to any embodiment herein on a light emitting diode (LED) or an array of LEDs.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. The line drawings herein are not to scale.

[0015] FIGS. 1A-1 B, 2A-2B, 3A-3B, and 4 are cross-section schematic views of converter components comprising converter layers according to various embodiments;

[0016] FIGS. 5A, 5B, and 5C provide schematic views illustrating in crosssection a portion of an electrophoretic deposition (EPD) cell without (FIG. 5A) and with (FIGS. 5B and 5C) a thin non-conducting substrate positioned therein;

[0017] FIGS. 6A-6F are cross-section schematic views of a converter component during operations of a method of making the same using electrophoretic deposition according to an embodiment;

[0018] FIG. 7 is a process flow diagram of the method of making a converter component according to FIGS. 6A-6F;

[0019] FIGS. 8A-8H are cross-section schematic views of a converter component and ultimately a converter layer during operations of a method of making the same using electrophoretic deposition according to an embodiment;

[0020] FIG. 9 is a process flow diagram of the method of making a converter component according to FIGS. 8A-8H; and

[0021] FIG. 10 schematically illustrates an exemplary headlight illumination system comprising converter components and / or converter layers according to embodiments herein.DETAILED DESCRIPTION

[0022] Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways.

[0023] The term "substrate" as used herein according to one or more embodiments refers to a structure, intermediate or final, having a surface, or portion of a surface, upon which a process acts. In addition, reference to a substrate in some embodiments also refers to only a portion of the substrate, unless the context clearly indicates otherwise. Further, reference to depositing on a substrate according to some embodiments includes depositing on a bare substrate, or on a substrate with one or more films or features or materials deposited or formed thereon.

[0024] In one or more embodiments, the "substrate" means any substrate or material surface formed on a substrate upon which film processing is performed during a fabrication process. A “device substrate” is a substrate of a final product or device. In exemplary embodiments, a substrate surface on which processing is performed includes materials such as silicon, silicon oxide, silicon on insulator (SOI), strained silicon, amorphous silicon, doped silicon, carbon doped silicon oxides, germanium, gallium arsenide, glass, sapphire, and any other suitable materials such as metals, metal nitrides, Ill-nitrides (e.g., GaN, AIN, InN and alloys), metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, light emitting diode (LED) devices, including uLED devices. Substrates in some embodiments are exposed to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and / or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in some embodiments, any of the film processing steps disclosed are also performed on an underlayer formed on the substrate, and the term "substrate surface" is intended to include such underlayer as the context indicates.

[0025] Methods of depositing thin films include but are not limited to: sputter deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced atomic layer deposition (PEALD), plasma enhanced chemical vapor deposition (PECVD), and combinations thereof.

[0026] Reference to LED refers to a light emitting diode that emits light when current flows through it. In one or more embodiments, for example head lamps, the LEDs herein have one or more characteristic dimensions (e.g., height, width, etc.) in a range of greater than or equal to 1 micrometer to less than or equal to 300 micrometers, and all values and subranges therebetween. In one or embodiments,one or more dimensions of height and width have values in a range of 40 to 300 micrometers. Reference herein to micrometers allows for variation of ±1 -5%. In some instances, the LEDs are referred to as micro-LEDs (uLEDs or pLEDs), referring to a light emitting diode having one or more characteristic dimensions (e.g., height, width, etc.) on the order of micrometers or tens of micrometers.

[0027] Converter layers, namely phosphor layers absorb energy, converting an entering wavelength to a lower-energy higher wavelength. Herein, in one or more aspects, the converter layers comprise phosphor particles as down-converter material. Other down-converter materials may be semiconductor nanoparticles (quantum dots), which may be used in combination with phosphor particles.

[0028] The present disclosure includes preparation of a converter layer, e.g., a phosphor layer, on a thin substrate, which can be glass-based, sapphire, garnet, alumina, or another material, e.g., a thin, non-conducting material. A densely-packed particle layer is applied by electrophoretic deposition on a thin non-conductive substrate, preferably followed by burn-out of all organics. These layers can be used to adjust the luminescent properties of sintered light converters like an yttrium aluminum garnet plate or to apply phosphor onto a substrate with defined scattering properties, e.g., a ceramic converter, which can be mounted onto an LED.

[0029] Reference to a “non-conductive” substrate means that the substrate is effective as an insulator. Many ceramics and polymers are considered insulators, whereas metals and semiconductor materials are not. In one or more aspects, a non- conductive substrate has a conductivity of below 1010(Ohm.m)-1.

[0030] Reference to a “densely-packed” particle layer means that the layer has a desired maximum particle volume fraction, depending on polydispersity and shape. In one or more aspects, a densely-packed particle layer has a maximum particle volume fraction value of approximately 50% in volume, and preferably for monodisperse spheres, the value is around 64% (random close packing).

[0031] There is a need for developing methods to deposit thin layers of densely packed converter particles, e.g., phosphor particles, onto substrates, e.g., nonconducting substrates for use in LEDs, in particular uLEDs. Depositing layers that are just a few particle diameters thick is challenging, and methods that include bladecoating, spin-coating, and spray-coating can be inadequate. Electrophoreticdeposition (EPD) is a way to apply densely packed particles layers onto a substrate. Traditionally, EPD has been a method for depositing thin layers suitable only for conducting substrates. It was surprisingly found that electrophoretic deposition is an efficient way to apply phosphor layers onto thin non-conducting substrates. FIGS. 5A- 50 provide schematic views illustrating in cross-section a portion of an EPD cell 1 without (FIG. 5A) and with (FIGS. 5B and 50) a thin non-conducting substrate 20 positioned therein. In FIGS. 5A-5C, a first electrode 21 a and a second electrode 21 b of the EPD cell are separated by a distance “d”. In use, an electric field (E) (V / d) is applied to the cell. The first electrode 21 a is subjected to a first voltage Vi and the second electrode 21 b is subjected to a second voltage V2. A potential difference 2, e.g., delta voltage (AV), which is |Vi - V2I, is equal to E * d. Turing to FIG. 5A, the EPD cell is a capacitor in the absence of electrochemical reactions which charges when a potential difference is applied. In FIG. 5B, upon introduction of the thin nonconducting substrate 20 having a thickness di into the cell, the distance between the first and second electrodes 21 a and 21 b becomes d2. The thickness di is negligible compared to d2. As shown in FIG. 50, which is a simplified version of FIG. 5B, because the substrate thickness is thin / negligible, any potential drop over this thickness is insignificant, even if dielectric constants differ. The presence of a thin, non conductive substrate with thickness di does not change the properties of the capacitor much, the difference between d, which is for instance 0.5-1 cm, and d2 is negligible. In some aspects, di is in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers, including all values and subranges therebetween, including greater than or equal to 15 micrometers to less than or equal to 100 micrometers, and greater than or equal to 20 micrometers to less than or equal to 50 micrometers.

[0032] A comparison between current during electrophoretic deposition of a YAG phosphor for a conducting surface (stainless steel) and deposition on thin (170 pm) glass or (100 pm) alumina (non-conducting) attached to a stainless steel electrode was conducted. The initial current was the same for stainless steel versus the non-conducting substrates, the current decrease as a function of time was much stronger for the non-conducting substrates.

[0033] While EPD is standard technology on a conducting substrate, for thin substrates and using suspensions of low conductivity, it was unexpectedly found that electrophoretic deposition is an efficient way to apply phosphor layers. Some applications include deposition of a phosphor layer onto a sintered ceramic plate like a doped yttrium aluminum garnet, where it can serve to change the emitted spectrum. This enables making warm-white converters, with a ceramic yttrium alumina garnet material as the base. Other applications include deposition of a phosphor layer onto an undoped yttrium aluminum garnet, which can be sized into plates of desired dimensions, which offers better control than glass or sapphire. Another application is the application of phosphor layers for mounting onto blue emitting LEDs having a thin intermediate layer with a defined scattering. The phosphor layer can be made onto the thin substrate separately which can subsequently be binned and be glued to the LED, which will improve the color yield of the EPD process in manufacturing of PC-LEDs.

[0034] A “thin” substrate as used herein has a thickness that does not noticeably change potential drop properties of an EPD cell.

[0035] Sintered ceramic phosphor plates are used for conversion in pc-LEDs, especially for automotive applications these are used in many products. These plates consist of a single phosphor only. Therefore it is difficult to tune a correlated color temperature (CCT), a color point, a color rendering index or other properties like color rendering index (CRI) and / or R9 (how accurately a light source will reproduce strong red colors) for the specific application. Application of a phosphor on top of the ceramic plate / substrate, should preferably be a thin dense packed particle layer, with the option to keep the system completely inorganic. EPD in combination with for instance sol-gel and atomic layer deposition to bind the particle offers such an opportunity. Further layers, for instance, mirror layers can subsequently be applied. Such a component can also be used for the conversion of blue laser light,

[0036] Another application that requires a thin densely packed phosphor layer is an automotive head lamp including a microLED array. Such head lamps should not only have high lumen output, but also be able to have a strong contrast between on and off pixels. The densely packed, thin, highly scattering converter layers help to achieve this. The yield of phosphor deposition directly on the LED-array is not high and rework is cumbersome. The proposed process allows to deposit a phosphor layeron a thin substrate, which can, after checking for the color point and homogeneity, be attached to the LED-array. Before mounting onto an LED, all organics can be removed by a thermal or photo-thermal treatment as the ceramic and phosphor are very temperature stable.

[0037] Monolithic ceramic phosphor layers are typically relied upon for higher temperature pc-LED applications, but these have limited color tunability and color quality range. The electrophoretically-deposited converter layers herein advantageously offer wider color tunability range and improved color quality while meeting high-temperature reliability requirements.

[0038] Devices herein include converter components and / or converter layers that comprise electrophoretically-deposited converter particles. Electrophoretically- deposited converter particles are densely-packed and are just a few particles, for example 2-3 particles, thick. In some aspects, the converter layers comprise a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers, and all values and sub-ranges therebetween, including greater than or equal to 2 micrometers to less than or equal to 5 micrometers, and greater than or equal to 10 micrometers to less than or equal to 50 micrometers. The converter layers are prepared on thin non-conductive substrates, which may or may not be removed for a final application.

[0039] FIG. 1A is a cross-section schematic view of a converter component comprising a converter layer according to an embodiment. The converter component 10A comprises a converter layer 15A, e.g., a phosphor layer, on a thin, nonconducting substrate 20. A plurality of converter particles 25, e.g., phosphor particles, is electrophoretically-deposited onto the substrate 20. In this embodiment, an inorganic coating 30 is present on the converter particles 25 and on a first surface of the substrate 20. No filler material is included among the converter particles.

[0040] FIG. 1 B is a cross-section schematic view of a converter component comprising a converter layer according to an embodiment, analogous to that of FIG. 1A with the addition of a filler material. The converter component 10B comprises a converter layer 15B, e.g., a phosphor layer, on a thin, non-conducting substrate 20. A plurality of converter particles 25, e.g., phosphor particles, is electrophoretically- deposited onto the substrate 20. In this embodiment, an inorganic coating 30 ispresent on the converter particles 25 and on a first surface of the substrate 20. A filler material 35 is among the converter particles 25 with the inorganic coating 30. In some embodiments, the substrate 20 is removed, and the converter layer 15 is transferred to a suitable device.

[0041] FIG. 2A is a cross-section schematic view of a converter component comprising a converter layer according to an embodiment. The converter component 40A comprises a converter layer 45A, e.g., a phosphor layer, on a thin, nonconducting substrate 20. A plurality of converter particles 25, e.g., phosphor particles, is electrophoretically-deposited onto the substrate 20. In this embodiment, a binder material 50 is present between portions of the converter particles 25 and a first surface of the substrate 20. No filler material is included among the converter particles and the binder material 50.

[0042] FIG. 2B is a cross-section schematic view of a converter component comprising a converter layer according to an embodiment, analogous to that of FIG. 2A with the addition of a filler material. The converter component 40B comprises a converter layer 45B, e.g., a phosphor layer, on a thin, non-conducting substrate 20. A plurality of converter particles 25, e.g., phosphor particles, is electrophoretically- deposited onto the substrate 20. In this embodiment, a binder material 50 is present between portions of the converter particles 25 and a first surface of the substrate 20. A filler material 35 is among the converter particles 25 and the binder material 50. In some embodiments, the substrate 20 is removed, and the converter layer 45B is transferred to a suitable device.

[0043] FIG. 3A is a cross-section schematic view of a converter component comprising a converter layer according to an embodiment. The converter component 70A comprises a converter layer 75A, e.g., a phosphor layer, on a thin, nonconducting substrate 20. A plurality of converter particles 25, e.g., phosphor particles, is electrophoretically-deposited onto the substrate 20. In this embodiment, both an inorganic coating 30 is present on the converter particles 25 and on a surface of the substrate 20; and a binder material 50 is present between portions of the converter particles 25 with the inorganic coating 30 and a first surface of the substrate 20. No filler material is among the converter particles 25 with the inorganic coating 30 and the binder material 50.

[0044] FIG. 3B is a cross-section schematic view of a converter component comprising a converter layer according to an embodiment, analogous to that of FIG. 3A with the addition of a filler material. The converter component 70B comprises a converter layer 75B, e.g., a phosphor layer, on a thin, non-conducting substrate 20. A plurality of converter particles 25, e.g., phosphor particles, is electrophoretically- deposited onto the substrate 20. In this embodiment, both an inorganic coating 30 is present on the converter particles 25 and on a surface of the substrate 20; and a binder material 50 is present between portions of the converter particles 25 with the inorganic coating 30 and a first surface of the substrate 20. A filler material 35 is among the converter particles 25 with the inorganic coating 30 and the binder material 50. In some embodiments, the substrate 20 is removed, and the converter layer 75B is transferred to a suitable device.

[0045] FIG. 4 is a cross-section schematic view of a converter component comprising a converter layer according to an embodiment, which is analogous to FIG. 1 with the addition of a mirror layer. In this regard, FIGS. 2-3 could also have a mirror layer added to a surface of the converter layer opposite the substrate. In FIG. 4, the converter component 80 comprises a converter layer 85, e.g., a phosphor layer, on a thin, non-conducting substrate 20. A plurality of converter particles 25, e.g., phosphor particles, is electrophoretically-deposited onto the substrate 20. In this embodiment, an inorganic coating 30 is present on the converter particles 25 and on a first surface of the substrate 20. A filler material 35 is among the converter particles 25 with the inorganic coating 30. A mirror layer 90 is disposed on a surface of the converter layer 85 opposite that of the substrate 20. In some embodiments, the substrate 20 is removed, and the converter layer 15 is transferred to a suitable device.

[0046] In one or more aspects, converter components for light emitting diodes (LEDs), including microLEDs, comprise, consist essentially or, or consist of: a converter layer comprising: electrophoretically-deposited converter particles in combination with one or more or the following: a binder material; an inorganic coating of the converter particles, and the binder material when present; and a filler material. Preferably, the particles of converter material are densely-packed on the thin non- conductive substrate.

[0047] In one or more embodiments, the converter layer comprises a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers, including all values and subranges therebetween.

[0048] In one or more embodiments, the filler material is present, being selected from the group consisting of: alumina, silica, aluminosilicate, and combinations thereof. In other embodiments, the filler material comprises a silicone.

[0049] In one or more embodiments, the binder material is present. In some embodiments, the binder material comprises inorganic particles, preferably silica.

[0050] In some embodiments, the converter component and / or converter layer is inorganic, substantially inorganic, and / or completely inorganic, meaning that the component or layer has been treated to remove any organic material remaining from processing materials.

[0051] In some aspects, converter component and / or converter layer comprises a mirror layer on a surface of the converter layer opposite the thin non-conductive substrate. In one or more embodiments, the mirror layer comprises a metal film (for example, aluminum (Al), silver (Ag), gold (Au)) or a metal oxide multilayer stack.

[0052] In one or more embodiments, the converter component further comprises a thin non-conductive substrate. The thin non-conductive substrate non- conductive substrate may comprise a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers, including all values and subranges therebetween.

[0053] In some aspects, the thin non-conductive substrate comprises a ceramic or a glass. In an embodiment, the thin non-conductive substrate comprises a ceramic that is a polycrystalline ceramic plate of a phosphor material. In a detailed embodiment, the thin non-conductive substrate is Lumiramic™, which a Ce(lll) doped garnet material ceramic suitable as a monolithic ceramic segment. The phosphor material is preferably a garnet material. The garnet material preferably comprises: a Ce(lll) doped garnet material as follows: ((Mli_x_yMllxMil|y)3(Ali_zMlvz)50 i2 with M1is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr, Ce, Er, Nd, or Eu, and MIVis Gd or Sc, wherein with 0 < x < I ; 0 < y<0, I und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials (MSi2O2N2), wherein M = alkaline earth.

[0054] In embodiments, the converter components and / or converter layers, preferably phosphor layers, may be formed for use with a semiconductor structure that emits blue light. In some embodiments, the converter particles comprise one or more types of phosphor particles. The phosphor particles may include, for example, particles of a yellow emitting wavelength converting material or green and red emitting wavelength converting materials, which will produce white light when the light emitted by the respective phosphors combines with the blue light emitted by the light emitting semiconductor structure. In other embodiments, the converter component or layer may be formed for use with a semiconductor structure that emits UV light. In such embodiments, the phosphor particles may include, for example, particles of blue and yellow wavelength converting materials or particles of blue, green and red wavelength converting materials. Phosphor particles emitting other colors of light may be added to tailor the spectrum of light emitted from the LED.

[0055] In embodiments, the phosphor particles may be composed of Y3AlsOi2:Ce3+. The phosphor particles may be an amber to red emitting rare earth metal-activated oxonitridoalumosilicate of the general formula (Cai-x-y-zSrxBayMgz)i- n(Ah-a+ Ba)Sii- N3- O :REn wherein 0<x<1 , 0<y<1 , 0<z<1 , 0<a<1 , 0<b<1 and 0.002<n<0.2, and RE may be selected from europium(ll) and cerium(lll).

[0056] In other embodiments, the phosphor particles may include aluminum garnet phosphors with the general formula (Lui-x-y-a-bYxGdy)3(Ali-zGaz)50i2: CeaPr , wherein 0<x<1 , 0<y<1 , 0<z<0.1 , 0<a<0.2 and 0<b<0.1 , such as Lu3AlsOi2:Ce3+and Y3AlsOi2:Ce3+, which emits light in the yellow-green range; and (Sri-x-yBaxCay)2-zSi5-aAlaN8-aOa:Euz2+, wherein 0<a<5, 0<x<1 , 0<y<1 , and 0<z<1 such as Sr2Si5Ns:Eu2+, which emits light in the red range. Other green, yellow and red emitting phosphors may also be suitable, including (Sri-a-bCa Bac)SixNyOz:Eua2+; (a=0.002-0.2, b=0.0- 0.25, c=0.0-0.25, x=1 .5-2.5, y=1 .5-2.5, z=1 .5-2.5) including, SrSi2N2O2:Eu2+; (Sn-u-v- xMguCavBax)(Ga2-y-zAlylnzS4):Eu2+including, for example, SrGa2S4:Eu2+; Sn- xBaxSiO4:Eu2+; and (Cai-xSrx)S:Eu2+wherein 0<x<1 including, CaS:Eu2+and SrS:Eu2+. Other suitable phosphors include, CaAISiN3:Eu2+,(Sr,Ca)AISiN3:Eu2+, and (Sr, Ca, Mg, Ba, Zn)(AI, B, In, Ga)(Si, Ge)N3:Eu2+.

[0057] In other embodiments, the phosphor particles may also have a general formula (Sri-a-bCa BacMgdZne)SixNyOz:Eua2+, wherein 0.002<a<0.2, 0.0<b<0.25,0.0<c<0.25, 0.0<d<0.25, 0.0<e<0.25, 1.5<x<2.5, 1.5<y<2.5 and1 .5<z<2.5. The phosphor particles may also have a general formula of MmAaBbOoNmZz where an element M is one or more bivalent elements, an element A is one or more trivalent elements, an element B is one or more tetravalent elements, O is oxygen that is optional and may not be in the phosphor plate, N is nitrogen, an element Z that is an activator, n=2 / 3m+a+4 / 3b-2 / 3o, wherein m, a, b can all be 1 and o can be 0 and n can be 3. M is one or more elements selected from Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium) and Zn (zinc), the element A is one or more elements selected from B (boron), Al (aluminum), In (indium) and Ga (gallium), the element B is Si (silicon) and / or Ge (germanium), and the element Z is one or more elements selected from rare earth or transition metals. The element Z is at least one or more elements selected from Eu (europium), Mg (manganese), Sm (samarium) and Ce (cerium). The element A can be Al (aluminum), the element B can be Si (silicon), and the element Z can be Eu (europium).

[0058] The phosphor particles may also be an Eu2+activated Sr — SiON having the formula (Sri-a-bCabBac)SixNyOx:Eua, wherein a=0.002-0.2, b=0.0-0.25, c=0.0-0.25, x=1 .5-2.5, y=1 .5-2.5.

[0059] The phosphor particles may also be a chemically-altered Ce: YAG (Yttrium Aluminum Garnet) phosphor that is produced by doping the Ce: YAG phosphor with the trivalent ion of praseodymium (Pr). The phosphor particles may include a main fluorescent material and a supplemental fluorescent material. The main fluorescent material may be a Ce: YAG phosphor and the supplementary fluorescent material may be europium (Eu) activated strontium sulfide (SrS) phosphor (“Eu:SrS”). The main fluorescence material may also be a Ce: YAG phosphor or any other suitable yellow-emitting phosphor, and the supplementary fluorescent material may also be a mixed ternary crystalline material of calcium sulfide (CaS) and strontium sulfide (SrS) activated with europium ((CaxSri_x)S:Eu2+). The main fluorescent material may also be a Ce:YAG phosphor or any other suitable yellow-emitting phosphor, and the supplementary fluorescent material may also be a nitrido-silicate doped with europium. The nitrido-silicate supplementary fluorescent material may have the chemical formula (Sri-x-y-zBaxCay)2Si5N8:Euz2+where 0<x, y<0.5 and 0<z<0.1.

[0060] In embodiments, the phosphor particles may include strontium-lithium- aluminum: europium (II) ion (SrLiAh l\ :Eu2+) class (also referred to as SLA), including MUAI3N4: Eu2+(M = Sr, Ba, Ca, Mg). In a specific embodiment, the phosphor particles may be selected from the following group of luminescent material systems: MLiAhlX Eu (M=Sr, Ba, Ca, Mg), M2SiO4:Eu (M=Ba, Sr, Ca) , MSei-xSx:Eu (M=Sr, Ca, Mg), MSr2S4:Eu (M=Sr, Ca), M2SiF6:Mn (M=Na, K, Rb), M2TiF6:Mn (M=Na, K, Rb), MSiAIN3:Eu (M=Ca, Sr), M8Mg(SiO4)4CI2:Eu (M=Ca, Sr), M3MgSi2O8:Eu (M=Sr, Ba, Ca), MSi2O2N2:Eu (M=Ba, Sr, Ca), M2Si5-xAlxOxN8-x:Eu (M=Sr, Ca, Ba). However, other systems may also be of interest and may be protected by a coating. Also combinations of particles of two or more different luminescent materials may be applied, such as e.g. a green or a yellow luminescent material in combination with a red luminescent material.

[0061] In embodiments, the phosphor particles may include a blend of any of the above-described phosphors.

[0062] Direction, beam width, and beam shape of light emitted from each LED can be modified by optical elements. The optical elements a single optical element or a multiple optic elements. Optical elements can include converging or diverging lenses, aspherical lens, Fresnel lens, or graded index lens, for example. Other optical elements such as mirrors, beam diffusers, filters, masks, apertures, collimators, or light waveguides are also included. Optical elements can be positioned at a distance from the LEDs that allows receipt and redirection of light from multiple LEDs. Alternatively, optical elements can be set atop each LED to individually guide, focus, or defocus emitted LED light. Optical elements can be directly attached to the LEDs, attached to LEDs via a transparent interposer or plate, or held at a fixed distance from LEDs by surrounding substrate attachments.

[0063] FIGS. 6A-6F are cross-section schematic views of a converter component during operations of a method of making the same using electrophoretic deposition (EPD) according to an embodiment, and FIG. 7 is a process flow diagram of the method of making a converter component 700 according to FIGS. 6A-6F.

[0064] To facilitate an EPD process on a non-conductive substrate, conductivity of a suspension composition is preferably very low and the substrate is thin. To make such a suspension composition, the particles to be deposited are dispersed in anapolar solvent. According to some embodiments, to obtain a colloidally stable suspension that can be manipulated in an electric field, a polymeric stabilizer and a charging agent are added. A conductivity of the suspension composition may be on the order of pS / cm, for instance in a range of 6-30 pS / cm. The apolar solvent generally has a low dielectric constant, and in such systems, no electrochemical reactions at the electrodes have been identified that regulate the current through the system during electrophoretic deposition. As a consequence, the electric field that is initially present if a voltage is applied, is determined by the geometry and dielectric constants. The strength of the field and the charge on the particles regulate the deposition, (e.g., FIGS. 5A, 5B, 50), during deposition the current drops faster as charge generation at the electrode cannot occur. The substrate can be a ceramic material, for instance a garnet, like an Yttrium Aluminum Garnet (YAG) with a known light scattering or it can be a ultra-thin glass. Substrates can have a thickness of 200 pm and below, to for instance 40 pm or 20 pm or 10 pm.

[0065] With reference to FIG. 6A and FIG. 7, at operation 710, electrophoresis is conducted in a cell having a first electrode 21 a and a second electrode 21 b to deposit particles of a converter material, e.g., phosphor particles, onto a thin non- conductive substrate (thickness of substate in FIGS. 6A-6F is not to scale, it is enhanced for clarity). The substrate 20 is attached to a first electrode 21 b by suitable means, e.g., a tape or inserted into a holder, and makes contact with the second electrode 21 b (for illustration purposes only, either electrode can be used) at one side. A suspension composition comprising particles of converter material 26 in a liquid carrier, e.g., an apolar liquid, such as such as alkanes, or mixtures of alkanes commercially available as isopar or shellsol and other materials such as a polymeric stabilizer, such as a poly(alkyl) methacrylate, and / or a charging agent, such as chrome-anthralinate. Upon application of an electrical potential to the first and second electrodes 21 a and 21 b, a layer 24 of particles 25 is formed on the substrate 20, which prepares a first intermediate structure.

[0066] At operation 720 of FIG. 7, and shown in FIG. 6B, the substrate 20 having the layer 24 of particles 25 is removed from the second electrode 21 b.

[0067] At operation 740a of FIG. 7, optionally, the substrate comprising the particles is subject to a removal treatment, e.g., by curing to remove any organicmaterials of the suspension composition. Possible organic residues, for instance resulting from the polymeric stabilizer in the suspension can be removed at high temperature only, or in combination with UV radiation or an oxygen (O2) plasma treatment. In one or more embodiments, the substrate is treated to remove organics.

[0068] At operation 730 of FIG. 7, and shown in FIG. 60, the particles 25 are fixed to prepare the converter layer. Fixing the particles 25 of the converter material comprises a binder material and / or an inorganic coating. To fix the particles 25 to the substrate 20 and to each other, a binder material applied by for example a sol-gel coating or a coating technique, for example, an atomic layer deposition technique, or both can be used. FIG. 60 shows fixing the particles with a binder by way of a sol-gel coating 51 for illustration purposes. It is understood that alternatively or in combination with the binder, the particles could be fixed with the inorganic coating applied by, for example, atomic layer deposition.

[0069] A sol-gel coating process can be carried out as a dip-coating process into a solution of a sol-gel material. The material accumulates in the “necks” between particles and particles and surface, which is depicted as the binder material 50 in FIG. 6D. A goal is to create enough strength for handling and the next step(s). Fixation of the particles may also be conducted by application of an atomic layer deposition (ALD) coating of an inorganic coating, conformally over all particles and substrate. A combination, first the sol-gel coating process, followed by ALD may also be conducted. Upon fixing of the particles 25 with a binder material derived from the solgel material, and / or the inorganic coating, a second intermediate structure is prepared depicted in FIG. 6D. A non-limiting example of a sol-gel material includes: TEOS [Tetraethyl orthosilicate: Si(OC2H5)4; EtOH [ethanol]; HCI [hydrochloric acid], which is subjected to a duration of hydrolysis and dilution dilute in an alcohol. The hydrolysis reaction is carried out to form silanols, which can subsequently react to form siloxanes. The TEOS (tetra-ethoxysilane) is ultimately converted to SiO2, which is an exemplary binder material.

[0070] At operation 740b of FIG. 7, and shown in FIG. 6D, the second intermediate structure comprising the particles 25 fixed with the binder material 50, is optionally subject to curing and / or removal of any organics. Possible organic residues, for instance resulting from the polymeric stabilizer in the suspension can beremoved at high temperature only, or in combination with UV radiation or an oxygen (O2) plasma treatment. In the event that both a sol-gel coating process and an inorganic coating process are conducted, the curing and / or removal of organic generally occurs after the sol-gel process and before the inorganic coating process. In one or more embodiments, the second intermediate structure is treated to remove organics.

[0071] At operation 750 of FIG. 7, and shown in FIG. 6E, a filler material 35 is disposed among the particles 25 and the binder material 50 to prepare converter layer 45 on the substrate 20.

[0072] At operation 760 of FIG. 7, and shown in FIG. 6F, the converter layer 45 on the substrate 20 is affixed to an LED or LED array 100, including a uLED or uLED array, by an adhesive 95.

[0073] Thereafter at operation 770 of FIG. 7, any further processing of the structure may optionally be conducted to prepare the structure for final applications. Further processing includes but is not limited to deposition of a mirror layer onto the structure. Generally, the structure may be treated so that the surface is smooth enough to accept the mirror layer. In addition, additional layers, e,g. metal, may be deposited to facilitate good adhesion of the mirror. Further processing also includes but is not limited to position of optical features onto the structure.

[0074] With reference to FIG. 8A and FIG. 9, at operation 910 (analogous to FIG. 6A and 710 of FIG. 7), electrophoresis is conducted in a cell having a first electrode 21 a and a second electrode 21 b to deposit particles of a converter material, e.g., phosphor particles, onto a thin non-conductive substrate (thickness of substate in FIGS. 8A-8H is not to scale, it is enhanced for clarity). The substrate 20 is attached to a first electrode 21 b by suitable means, e.g., a tape or inserted into a holder, and makes contact with the second electrode 21 b (for exemplary purposes only, either electrode can be used) at one side. Upon application of an electrical potential to the first and second electrodes 21 a and 21 b, a layer 24 of particles 25 is formed on the substrate 20, which prepares a first intermediate structure.

[0075] At operation 920 of FIG. 9, and shown in FIG. 8B, (analogous to FIG. 6B and 720 of FIG. 7), the substrate 20 having the layer 24 of particles 25 is removed from the second electrode 21 b.

[0076] At operation 930 of FIG. 9, and shown in FIGS. 8C-8D, the particles 25 are fixed to prepare the converter layer. In this embodiment, fixing the particles 25 of the converter material comprises both a binder material and an inorganic coating. To fix the particles 25 to the substrate 20 and to each other in this embodiment, a binder material 50 be applied by for example a sol-gel coating discussed with respect to FIG. 7C and shown in FIG. 8C, and a coating technique, for example, an atomic layer deposition technique to apply an inorganic coating 30 on the particles 25 and a first surface of the substrate 30.

[0077] Upon fixing of the particles 25 with a binder material derived from the sol-gel material, and / or the inorganic coating, a second intermediate structure is prepared depicted in FIGS. 8C-8D.

[0078] At operation 940 of FIG. 9, and shown in FIG. 8E, the second intermediate structure comprising the particles 25 fixed with the binder material 50 and inorganic coating 30 is affixed to a transfer body 22. As shown in FIG. 8F and also part of operation 940 of FIG. 9, the substrate 20 is released. The transfer body in some embodiments is a release layer such as a UV release tape or a thermal release tape that is removed after transfer of the converter layer to the device in the next operation. The transfer body may also be released by dissolving it from the structure.

[0079] At operation 950 of FIG. 9, and shown in FIG. 8G, the converter layer 45 on the transfer body 22 is affixed to an LED or LED array 100, including a uLED or uLED array, by methods known in the art.

[0080] At operation 960 of FIG. 9, and shown in FIG. 8H, the transfer body is removed.

[0081] Thereafter at operation 970, any further processing of the structure may optionally be conducted to prepare the structure for final applications. Further processing includes but is not limited to deposition of a mirror layer onto the structure. Generally, the structure may be treated so that the surface is smooth enough to accept the mirror layer. In addition, additional layers, e.g., metal, may be deposited to facilitate good adhesion of the mirror. Further processing also includes but is not limited to position of optical features onto the structure.

[0082] In summary, methods herein comprise: preparing a converter layer, the method comprising: conducting electrophoresis to deposit particles of a convertermaterial in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; and fixing the particles of the converter material with a binder material and / or an inorganic coating to prepare the converter layer.

[0083] In one or more embodiments, the method further comprises: disposing a filler material among the particles of the converter material and the binder material and / or the inorganic coating such that the converter layer further comprises the binder material.

[0084] In one or more embodiments, the method further comprises: attaching the converter layer to a transfer body and removing the thin non-conductive substrate from the converter layer.

[0085] In some aspects, the conducting of the electrophoresis comprises: positioning a first surface of the thin non-conductive substrate adjacent to a first electrode of a pair of electrodes; exposing the thin non-conductive substrate to the suspension composition comprising the converter material dispersed in an apolar liquid; and applying an electrical field to the pair of electrodes, whereby at least a portion of the particles of the converter material deposit onto a second surface of the thin non-conductive substrate, to prepare the first intermediate structure.

[0086] In some aspects, the fixing of the particles of converter material comprises: conducting a sol-gel process by exposing the first intermediate structure to a solution of a sol-gel material, the sol-gel material including a precursor of the binder material and a carrier, and converting the precursor of the binder material to the binder material; and / or conducting thin film deposition of an inorganic material conformally over the particles of the converter material, and the binder material when present, to prepare the inorganic coating.

[0087] In one or more embodiments, the method further comprises: removing any organic materials of at least the suspension composition and the sol-gel material. In some embodiments, the removing of any of the organic materials of at least the suspension composition and the sol-gel material comprises exposing the converter layer to heat. In some embodiments, the removing of any of the organic materials of at least the suspension composition and the sol-gel material comprises exposing the converter layer to UV radiation or an oxygen plasma treatment.

[0088] In some aspects, the disposing of the filler material comprises conducting atomic layer deposition (ALD) of a metal oxide on the converter layer, the metal oxide preferably selected from the group consisting of aluminum oxide, hafnium oxide, titanium oxide, and zirconium oxide. In some aspects, the disposing of the filler material comprises conducting chemical vapor deposition (CVD) techniques. In a detailed embodiment, the disposing of the filler material comprises depositing a silicone in the converter layer.

[0089] In one or more embodiments, the method further comprises: depositing a mirror material on the converter layer.APPLICATIONS

[0090] The converter components and / or converter layers can be used in various applications.

[0091] For example, a converter component according to FIG. 5 comprising a substrate; a converter layer including converter particles, an inorganic coating (e.g., AI2O3), and a filler material (e.g., AI2O3); and a mirror layer is suitable for a laser projection system. An exemplary laser projection system is one where a blue laser is used to excite a Lumiramic™ plate (Ce(lll) doped garnet material ceramic). For such an application, light intensity is very high and a completely inorganic construction is preferred for reliability and longevity. In this application, a red phosphor can be deposited on top of the Lumiramic™ plate by way of the techniques herein, for instance a BSSN [(Ba,Sr)2 Si5Ns:Eu or SLA Sr[LiAl3N4]:Eu2+], which offers an advantage of increasing CRI / R9. Advantageously, converter layers, e.g., red phosphor, herein on the order of 2-5 micrometers can be used for tuning color point.

[0092] The converter components and / or converter layers herein can also be used for a pixelated head lamp array consisting of micro-LEDs. The amount of phosphor needed to reach the desired color point has tight boundaries, a deviation of less than 1 pm in thickness leads to an unacceptable color point of the LED-array. As it is difficult to tune electrophoretic deposition to such narrow boundaries, application of the phosphor layer onto a substrate, which is subsequently attached to the LED- array, is very advantageous to the yield of the process, as the phosphor layer on the substrates can be measured separately, and therefore be binned to the exactwavelength of the blue chips. The substrate onto which the particles are deposited generally is very thin, not to lose too much contrast and it should have some level of scattering to avoid light propagation along the substrate as much as possible. Thin garnet materials can be suitable for such a substrate, they can be prepared down to 10 pm.

[0093] FIG. 10 schematically illustrates an exemplary headlight illumination system 1000 utilizing LEDs disclosed herein. The headlight illumination system 1000 comprises an LED illumination array and lens system 1002 in electrical communication with an LED driver 1004. The headlight illumination system 1000 also comprises a controller 1006, such as a microprocessor. The controller 1006 is coupled to the LED driver 1004. The controller 1006 may also be coupled to one or more auxiliary components 1008 and sensors 1010 associated with the headlights, and operate in accordance with instructions and profiles stored in memory 1012.

[0094] Sensors 1010 may include, for example, positional sensors (e.g., a gyroscope and / or accelerometer) and / or other sensors that may be used to determine the position, speed, and orientation of system 1000. The signals from the sensors 1010 may be supplied to the controller 1006 to be used to determine the appropriate course of action of the controller 1006 (e.g., which LEDs are currently illuminating a target and which LEDs will be illuminating the target a predetermined amount of time later).

[0095] In operation, illumination from some or all of the pixels of the LED array in 1002 may be adjusted - deactivated, operated at full intensity, or operated at an intermediate intensity. As noted above, beam focus or steering of light emitted by the LED array in 1002 can be performed electronically by activating one or more subsets of the pixels, to permit dynamic adjustment of the beam shape without moving optics or changing the focus of the lens in the lighting apparatus.

[0096] LED illumination arrays and lens systems such as described herein may support various other beam steering or other applications that benefit from finegrained intensity, spatial, and temporal control of light distribution. These applications may include, but are not limited to, precise spatial patterning of emitted light from pixel blocks or individual pixels. Depending on the application, emitted light may be spectrally distinct, adaptive over time, and / or environmentally responsive. The lightemitting pixel arrays may provide pre-programmed light distribution in various intensity, spatial, or temporal patterns. Associated optics may be distinct at a pixel, pixel block, or device level. An example light emitting pixel array may include a device having a commonly controlled central block of high intensity pixels with an associated common optic, whereas edge pixels may have individual optics. In addition to flashlights, common applications supported by light emitting pixel arrays include video lighting, camera flashes, architectural and area illumination, and street lighting.

[0097] In some embodiments, each LED device in a light source array can be separately controlled, while in other embodiments groups of LEDs can be controlled as a block. In still other embodiments, both single LEDs and groups of LEDs can be controlled. To reduce overall data management requirements, control can be limited to on / off functionality or switching between relatively few light intensity levels. In other embodiments, continuous changes in lighting intensity are supported. Both individual and group level control of light intensity is contemplated. In one embodiment, overlapping or dynamically selected zones of control are also possible, with for example, overlapping groups of light emitters in the array being separately controllable despite having common LEDs depending on lighting requirements. In one embodiment, intensity can be separately controlled and adjusted by setting appropriate ramp times and pulse width for each LED using a pulse width modulation. This allows staging of LED activation to reduce power fluctuations, and to provide superior luminous intensity control.

[0098] Programmable light emitting arrays such as disclosed herein may also support a wide range of applications that benefit from fine-grained intensity, spatial, and temporal control of light distribution. This may include, but is not limited to, precise spatial patterning of emitted light from blocks or individual LEDs. Depending on the application, emitted light may be spectrally distinct, adaptive over time, and / or environmentally responsive. In some embodiments, the light emitting arrays may provide pre-programmed light distribution in various intensity, spatial, or temporal patterns. The emitted light may be based at least in part on received sensor data and may be used for optical wireless communications. Associated optics may be distinct at single or multiple LED level. An example light emitting array may include a device having a commonly controlled central block of high intensity LEDS with an associatedcommon optic, whereas edge positioned LEDs may have individual optics. Common applications supported by light emitting LED arrays include camera or video lighting, architectural and area illumination, and street lighting.

[0099] Programmable light emitting arrays may be used to selectively and adaptively illuminate buildings or areas for improved visual display or to reduce lighting costs. In addition, light emitting arrays may be used to project media facades for decorative motion or video effects. In conjunction with tracking sensors and / or cameras, selective illumination of areas around pedestrians may be possible. Spectrally distinct LEDs may be used to adjust the color temperature of lighting, as well as support wavelength specific horticultural illumination.

[0100] Street lighting is an important application that may greatly benefit from use of programmable light emitting arrays. A single type of light emitting array may be used to mimic various street light types, allowing, for example, switching between a Type I linear street light and a Type IV semicircular street light by appropriate activation or deactivation of selected LEDs. In addition, street lighting costs may be lowered by adjusting light beam intensity or distribution according to environmental conditions or time of use. For example, light intensity and area of distribution may be reduced when pedestrians are not present. If LEDs are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions.

[0101] Programmable light emitting LEDs are also well suited for supporting applications requiring direct or projected displays. For example, automotive headlights requiring calibration, or warning, emergency, or informational signs may all be displayed or projected using light emitting arrays. This allows, for example, modifying directionality of light output from a automotive headlight. If a light emitting array is composed of a large number of LEDs or includes a suitable dynamic light mask, textual or numerical information may be presented with user guided placement. Directional arrows or similar indicators may also be provided.EMBODIMENTS

[0102] Various embodiments are listed below. It will be understood that the embodiments listed below may be combined with all aspects and other embodiments in accordance with the scope of the invention.

[0103] Embodiment (a). A method of preparing a converter layer, the method comprising: conducting electrophoresis to deposit particles of a converter material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; and fixing the particles of the converter material with a binder material and / or an inorganic coating to prepare the converter layer.

[0104] Embodiment (b). The method of embodiment (a) further comprising: disposing a filler material among the particles of the converter material and the binder material and / or the inorganic coating such that the converter layer further comprises the filler material.

[0105] Embodiment (c). The method of embodiment (a) or (b) further comprising: attaching the converter layer to a transfer body and removing the thin non-conductive substrate from the converter layer.

[0106] Embodiment (d). The method of one of embodiments (a) to (c), wherein the thin non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers.

[0107] Embodiment (e). The method of one of embodiments (a) to (d), wherein the particles of converter material are densely-packed on the thin non- conductive substrate.

[0108] Embodiment (f). The method of one of embodiments (a) to (e), wherein the particles of converter material in combination yield a layer on the thin non- conductive substrate, the layer comprising a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

[0109] Embodiment (g). The method of one of embodiments (a) to (f), wherein the conducting of the electrophoresis comprises: positioning a first surface of the thin non-conductive substrate adjacent to a first electrode of a pair of electrodes; exposing the thin non-conductive substrate to the suspension composition comprising the converter material dispersed in an apolar liquid; and applying an electrical field to the pair of electrodes, whereby at least a portion of the particles of the convertermaterial deposit onto a second surface of the thin non-conductive substrate, to prepare the first intermediate structure.

[0110] Embodiment (h). The method of embodiment (g), wherein the suspension composition further comprises: a polymeric stabilizer and / or a charging agent.

[0111] Embodiment (i). The method of embodiment (h), wherein the suspension composition comprises a conductivity in a range of greater than or equal to 6 pS / cm to less than or equal to 30 pS / cm.

[0112] Embodiment (j). The method of one of embodiments (a) to (i), wherein the fixing of the particles of converter material comprises: conducting a solgel process by exposing the first intermediate structure to a solution of a sol-gel material, the sol-gel material including a precursor of the binder material and a carrier, and converting the precursor of the binder material to the binder material; and / or conducting thin film deposition of an inorganic material conformally over the particles of the converter material, and the binder material when present, to prepare the inorganic coating.

[0113] Embodiment (k). The method of embodiment (j) further comprising removing any organic materials of at least the suspension composition and the sol-gel material.

[0114] Embodiment (I). The method of embodiment (k) wherein the removing of any of the organic materials of at least the suspension composition and the sol-gel material comprises exposing the converter layer to heat.

[0115] Embodiment (m). The method of embodiment (k) wherein the removing of any of the organic materials of at least the suspension composition and the sol-gel material comprises exposing the converter layer to UV radiation or an oxygen plasma treatment.

[0116] Embodiment (n). The method of any one of embodiments (b) to (m), wherein the disposing of the filler material comprises deposition a metal oxide on the converter layer, the metal oxide preferably selected from the group consisting of aluminum oxide, hafnium oxide, titanium oxide, and zirconium oxide, optionally deposition includes conducting atomic layer deposition (ALD) techniques and / or conducting chemical vapor deposition (CVD) techniques.

[0117] Embodiment (o). The method of embodiment (b), wherein the disposing of the filler material comprises depositing a silicone in the converter layer.

[0118] Embodiment (p). The method of one of embodiments (a) to (o), wherein the thin non-conductive substrate comprises a ceramic or a glass.

[0119] Embodiment (q). The method of embodiment (p), wherein the thin non-conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material, which is preferably a garnet material, which preferably comprises: a Ce(lll) doped garnet material ((Mli_x_yMllxMil|y)3(Ali_zMlvz)50 i2 with M1is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr, Ce, Er, Nd, or Eu, and MIVis Gd or Sc, wherein with 0 < x < I ; 0 < y<0, I und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials (Msi2O2N2), wherein M = alkaline earth.

[0120] Embodiment (r). The method of one of embodiments (a) to (q) further comprising depositing a mirror material on the converter layer.

[0121] Embodiment (s). A method of making an inorganic phosphor component for a light emitting diode (LED) comprising: conducting electrophoresis to deposit phosphor particles in a suspension composition onto a polycrystalline ceramic plate of a phosphor material to prepare a first intermediate structure; fixing the phosphor particles with a binder material derived from a sol-gel material, and / or an inorganic coating to prepare a second intermediate structure; and disposing a filler material among the phosphor particles and the binder material and / or the inorganic coating to prepare a converter layer on the polycrystalline ceramic plate; and removing any organic materials of at least the suspension composition and the sol-gel material to prepare the inorganic phosphor component.

[0122] Embodiment (t). The method of embodiment (s), wherein the polycrystalline ceramic plate comprises: a Ce(lll) doped garnet material 1 is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr,wherein with 0 < x < I ; 0 < y<0, I und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials (MSi2O2N2), wherein M= alkaline earth.

[0123] Embodiment (u). The method of embodiment (s) or (t), wherein the removing of any of the organic materials of at least the suspension composition andthe sol-gel material comprises: heating the second intermediate structure, or exposing the second intermediate structure to UV radiation or an oxygen plasma treatment.

[0124] Embodiment (v). The method of one of embodiments (s) to (u), wherein the disposing of the filler material comprises depositing an alumina or a silicone on the second intermediate structure.

[0125] Embodiment (w). The method of one of embodiments (s) to (v), wherein the suspension composition comprises a conductivity in a range of greater than or equal to 6 pS / cm to less than or equal to 30 pS / cm.

[0126] Embodiment (x). A converter component for a light emitting diode (LED) comprising: a converter layer comprising: electrophoretically-deposited converter particles in combination with one or more or the following: a binder material; an inorganic coating of the converter particles, and the binder material when present; and a filler material.

[0127] Embodiment (y). The converter component of embodiment (x) further comprising: a thin non-conductive substrate.

[0128] Embodiment (z). The converter component of embodiment (y), wherein the thin non-conductive substrate non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers.

[0129] Embodiment (aa). The converter component of one of embodiments (x) to (z), wherein the particles of converter material are densely-packed on the thin non-conductive substrate.

[0130] Embodiment (bb). The converter component of one of embodiments(x) to (aa), wherein the converter layer comprises a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

[0131] Embodiment (cc). The converter component of one of embodiments(y) to (bb) further comprising a mirror layer on a surface of the converter layer opposite the thin non-conductive substrate.

[0132] Embodiment (dd). The converter component of one of embodiments (y) to (cc), wherein the thin non-conductive substrate comprises a ceramic or a glass.

[0133] Embodiment (ee). The converter component of embodiment (dd), wherein the thin non-conductive substrate comprises the ceramic that is apolycrystalline ceramic plate of a phosphor material, which preferably is a garnet material, which preferably comprises: a Ce(lll) doped garnet material 1 is Y or Lu; M" is Gd, La, or Yb; M"i is Tb, Pr,wherein with 0 < x < I ; 0 < y<0, I und 0 < z < 1 ; or a Ce(lll) and / or Eu(ll) doped nitridosilicate ( / VfeSisNs) and oxonitridosilicate materials (MSi2O2N2), wherein M= alkaline earth.

[0134] Embodiment (ff). The converter component of one of embodiments (y) to (ee), comprising the filler material, wherein the filler material is selected from the group consisting of: alumina, silica, aluminosilicate, and combinations thereof.

[0135] Embodiment (gg). The converter component of one of embodiments (y) to (ee), comprising the filler material, wherein the filler material comprises a silicone.

[0136] Embodiment (hh). The converter component of one of embodiments (y) to (gg), comprising the binder material, wherein the binder material comprises inorganic particles.

[0137] Embodiment (ii). The converter component of embodiment (hh), wherein the inorganic particles comprise silica.

[0138] Embodiment (jj). The converter component of one of embodiments(x) to (ii), wherein the converter particles comprise one or more types of phosphor particles.

[0139] Embodiment (kk). The converter component of one of embodiments (x) to (jj), which is completely inorganic.

[0140] Embodiment (II). A light emitting diode (LED) array comprising: mesas comprising stacks of semiconductor layers including an active region; and the converter component of one of embodiments (x) to (kk) affixed to the mesas.

[0141] Embodiment (mm). The LED array of embodiment (II), wherein the mesas have at least one characteristic dimension of greater than or equal to 1 micrometer less than or equal to 300 micrometers.

[0142] Embodiment (nn). The LED array of embodiment (II) or (mm) further comprising a thin non-conductive substrate on which the converter component is disposed.

[0143] Embodiment (oo). The LED array of one of embodiments (II) to (nn) further comprising a phosphor layer disposed on the mesas to which the converter component is affixed.

[0144] Embodiment (pp). The LED array of embodiment (oo) effective in an automotive head lamp system.

[0145] Embodiment (qq). The LED array of one of embodiments (II) to (nn) further comprising a mirror layer on the converter component on a surface opposite that of the thin non-conductive substrate.

[0146] Embodiment (rr). The LED array of embodiment (qq) effective in a laser projection system.

[0147] Embodiment (ss). The LED array of one of embodiments (II) to (rr), which is completely inorganic.

[0148] Embodiment (tt). A light source comprising: the LED array of one of embodiments (II) to (ss) attached to a device substrate.

[0149] Embodiment (uu). The light source of embodiment (tt), wherein one or groups of light emitting diodes (LEDs) of the array are individually addressable.

[0150] Embodiment (vv). A method of manufacturing a light emitting source comprising: affixing a converter component according to one of embodiments (x) to (kk) on a light emitting diode (LED) or an array of LEDs.

[0151] Embodiment (ww). The method of embodiment (vv) further comprising: identifying a baseline color point distribution of one or a group of LEDs of the array of LEDs, binning a collection of converter components before the affixing of the converter component, wherein the converter component that is affixed is chosen from the collection of converter component due to the converter component comprising one or more desired converting features to adjust the array of LEDs to achieve a desired color point distribution.

[0152] Reference throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as "in one or more embodiments," "in certainembodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0153] Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of this invention may be practiced in the absence of an element / step not specifically disclosed herein.

Claims

What is claimed is:1 . A method of preparing a converter layer, the method comprising: conducting electrophoresis to deposit particles of a converter material in a suspension composition onto a thin non-conductive substrate to prepare a first intermediate structure; and fixing the particles of the converter material with a binder material and / or an inorganic coating to prepare the converter layer.

2. The method of claim 1 further comprising: disposing a filler material among the particles of the converter material and the binder material and / or the inorganic coating such that the converter layer further comprises the filler material.

3. The method of claim 1 further comprising: attaching the converter layer to a transfer body and removing the thin non-conductive substrate from the converter layer.

4. The method of claim 1 , wherein the thin non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers, and / or wherein the particles of converter material in combination yield a layer on the thin non-conductive substrate, the layer comprising a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

5. The method of claim 1 , wherein the particles of converter material are densely- packed on the thin non-conductive substrate.

6. The method of claim 1 , wherein the conducting of the electrophoresis comprises: positioning a first surface of the thin non-conductive substrate adjacent to a first electrode of a pair of electrodes; exposing the thin non-conductive substrate to the suspension composition comprising the converter material dispersed in an apolar liquid; andapplying an electrical field to the pair of electrodes, whereby at least a portion of the particles of the converter material deposit onto a second surface of the thin non-conductive substrate, to prepare the first intermediate structure.

7. The method of claim 6, wherein the suspension composition further comprises: a polymeric stabilizer and / or a charging agent, and / or the suspension composition comprises a conductivity in a range of greater than or equal to 6 pS / cm to less than or equal to 30 pS / cm.

8. The method of claim 1 , wherein the fixing of the particles of converter material comprises: conducting a sol-gel process by exposing the first intermediate structure to a solution of a sol-gel material, the sol-gel material including a precursor of the binder material and a carrier, and converting the precursor of the binder material to the binder material; and / or conducting thin film deposition of an inorganic material conformally over the particles of the converter material, and the binder material when present, to prepare the inorganic coating.

9. The method of claim 8 further comprising removing any organic materials of at least the suspension composition and the sol-gel material.

10. The method of claim 2, wherein the disposing of the filler material comprises depositing a metal oxide on the converter layer, and / or depositing a silicone in the converter layer.11 . The method of claim 1 , wherein the thin non-conductive substrate comprises a ceramic or a glass, preferably the thin non-conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material.

12. The method of claim 1 further comprising depositing a mirror material on the converter layer.

13. A converter component for a light emitting diode (LED) comprising: a converter layer comprising: electrophoretically-deposited converter particles in combination with one or more or the following: a binder material; aninorganic coating of the converter particles, and the binder material when present; and a filler material.

14. The converter component of claim 13 further comprising: a thin non-conductive substrate.

15. The converter component of claim 14, wherein the thin non-conductive substrate non-conductive substrate comprises a thickness in a range of greater than or equal to 10 micrometers to less than or equal to 200 micrometers and / or wherein the converter layer comprises a thickness in a range of greater than or equal to 2 micrometers to less than or equal to 50 micrometers.

16. The converter component of claim 14, wherein the particles of converter material are densely-packed on the thin non-conductive substrate.

17. The converter component of claim 14 further comprising a mirror layer on a surface of the converter layer opposite the thin non-conductive substrate.

18. The converter component of claim 14, wherein the thin non-conductive substrate comprises a ceramic or a glass, preferably the thin non-conductive substrate comprises the ceramic that is a polycrystalline ceramic plate of a phosphor material.

19. The converter component of claim 13, which is completely inorganic.

20. A light emitting diode (LED) array comprising: mesas comprising stacks of semiconductor layers including an active region; and the converter component of claim 13 affixed to the mesas.

Images