Light converter assemblies with enhanced heat dissipation
10374137 · 2019-08-06
Assignee
Inventors
Cpc classification
Y10T428/24802
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T428/24777
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H01L33/644
ELECTRICITY
F21Y2115/30
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B32B2255/28
PERFORMING OPERATIONS; TRANSPORTING
F21V29/83
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y10T428/24851
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H01L33/507
ELECTRICITY
B32B15/04
PERFORMING OPERATIONS; TRANSPORTING
B32B2250/44
PERFORMING OPERATIONS; TRANSPORTING
Y10T428/24322
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T428/24843
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T428/24917
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
B32B7/12
PERFORMING OPERATIONS; TRANSPORTING
Y10T428/24942
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
B32B3/266
PERFORMING OPERATIONS; TRANSPORTING
C04B2237/72
CHEMISTRY; METALLURGY
B32B18/00
PERFORMING OPERATIONS; TRANSPORTING
B32B2307/422
PERFORMING OPERATIONS; TRANSPORTING
Y10T428/24331
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
B32B3/10
PERFORMING OPERATIONS; TRANSPORTING
C04B2237/592
CHEMISTRY; METALLURGY
Y10S428/913
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
B32B15/20
PERFORMING OPERATIONS; TRANSPORTING
H01L33/508
ELECTRICITY
Y10T428/24926
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
C04B2237/86
CHEMISTRY; METALLURGY
B32B3/02
PERFORMING OPERATIONS; TRANSPORTING
Y10T428/24752
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F21K9/64
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F21K9/64
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B32B3/02
PERFORMING OPERATIONS; TRANSPORTING
B32B3/10
PERFORMING OPERATIONS; TRANSPORTING
Abstract
The present disclosure is directed to light converter assemblies with enhanced heat dissipation. A light converter assembly may comprise a confinement material applied to at least a first substrate and a phosphor material also deposited on the first substrate so as to be surrounded by the confinement material. The first substrate may be hermetically sealed to a second substrate using the confinement material so that the phosphor material is confined between the substrates and protected from atmospheric contamination. The substrates may comprise, for example, sapphire to allow for light beam transmission and heat conductance. Confinement materials that may be employed to seal the first substrate to the second substrate may include, for example, silicon or a metal (e.g., silver, copper, aluminum, etc.) The phosphor material may comprise, for example, at least one quantum dot material.
Claims
1. A light converter assembly comprising: a first substrate and a second substrate, the first and second substrates comprising a light transmissive, thermally conductive material; a phosphor material disposed between the first and second substrates; a confinement material disposed between the first and second substrates, the confinement material surrounding the phosphor material and bonding the first and second substrates together to hermetically seal the phosphor material between the first and second substrates, wherein the confinement material has a thermal conductivity greater than 10 W/m*K, wherein the confinement material comprises two layers, and wherein a first layer of the confinement material is deposited on a surface of the first substrate and a second layer of the confinement material is deposited on a surface of the second substrate; and a heat sink attached to the second substrate and the first layer of the confinement material on the first substrate, wherein the first substrate is larger than the second substrate such that an interfacial area of the first substrate and the heat sink is increased, and wherein the heat sink comprises an aperture positioned so that an excitation beam is able to impinge on the phosphor material.
2. The light converter assembly according to claim 1, wherein the heat sink covers a side surface of the second layer of the confinement material.
3. The light converter assembly according to claim 1, wherein the phosphor material is arranged within an opening in the second layer of the confinement material.
4. The light converter assembly according to claim 3, wherein a further opening, aligned with the opening in the second layer of the confinement material, is formed in the first layer of the confinement material, wherein the phosphor material is further arranged within the further opening.
5. The light converter assembly according to claim 3, wherein a recess, aligned with the opening in the second layer of the confinement material, is formed in the surface of the second substrate, wherein the phosphor material is further arranged within the recess.
6. The light converter assembly according to claim 3, wherein the first layer of the confinement material covers a top surface of the phosphor material completely, and wherein the second layer of the confinement material covers a side surface of the phosphor material completely.
7. The light converter assembly according to claim 1, wherein the first and second layers of the confinement material covers at least about 50% of the corresponding first and second substrate surface to which it is applied.
8. The light converter assembly according to claim 7, wherein the first and second layers of the confinement material cover at least about 75% of the corresponding first and second substrate surface to which it is applied.
9. The light converter assembly according to claim 8, wherein the first and second layers of the confinement material cover at least about 50% of the corresponding first and second substrate surface to which it is applied.
10. The light converter assembly according to claim 1, wherein the first and second substrates comprise sapphire.
11. The light converter assembly according to claim 10, wherein the confinement material has a thermal conductivity greater than a thermal conductivity of the first and second substrates.
12. The light converter assembly according to claim 10, wherein the confinement material has a thermal conductivity of at least 100 W/m*K.
13. The light converter assembly according to claim 10, wherein the confinement material comprises at least one of silicon, aluminum, silver or copper.
14. The light converter assembly according to claim 13, wherein the first and second substrates are flat plates and the confinement material is silicon.
15. The light converter assembly according to claim 1, wherein the first and second layers of the confinement material have a different composition.
16. The light converter assembly according to claim 1, further comprising a bonding facilitator material, wherein the bonding facilitator material is disposed between the first and second layers of the confinement material.
17. The light converter assembly according to claim 1, further comprising a reflective material located between the first and second substrates in an area corresponding to at least an area of the phosphor material.
18. The light converter assembly according to claim 17, wherein the reflective material has a composition that is the same as the confinement material.
19. The light converter assembly according to claim 1, wherein the phosphor material comprises a plurality of quantum dots deposited substantially in one or more monolayers.
20. The light converter assembly according to claim 19, wherein the phosphor material further comprises at least one layer of a coating to prevent agglomeration of the plurality of quantum dots.
21. The light converter assembly according to claim 20, wherein the coating comprises aluminum oxide.
22. A light converter assembly comprising: a first substrate and a second substrate, the first and second substrates comprising a light transmissive thermally conductive material; a phosphor material disposed between the first and second substrates; and a confinement material disposed between the first and second substrates, the confinement material surrounding the phosphor material and bonding the first and second substrates together to hermetically seal the phosphor material between the first and second substrates, wherein the confinement material has a thermal conductivity greater than 10 W/m*K, wherein the confinement material comprises two layers, wherein a first layer of the confinement material is deposited on a surface of the first substrate and a second layer of the confinement material is deposited on a surface of the second substrate, wherein the phosphor material is located in an opening of the second layer of the confinement material, wherein the first layer of the confinement material covers a top surface of the phosphor material completely, and wherein the second layer of the confinement material covers a side surface of the phosphor material completely.
23. The light converter assembly according to claim 22, further comprising a heat sink coupled to at least one of the first and second substrates.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Reference should be made to the following detailed description which should be read in conjunction with the following figures, wherein like numerals represent like parts:
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(10) Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications and variations thereof will be apparent to those skilled in the art.
DETAILED DESCRIPTION
(11) The present disclosure is directed to light converter assemblies with enhanced heat dissipation. An example light converter assembly may comprise a confinement material applied to a surface of a first substrate and a phosphor material also deposited on the first surface so as to be surrounded by the confinement material. The first substrate may be sealed to a second substrate using the confinement material so that the phosphor material is confined between the substrates. The substrates may comprise, for example, sapphire to allow for light beam transmission and heat conductance. Confinement materials that may be employed to seal the first substrate to the second substrate may include, for example, silicon or a metal (e.g., silver, copper, aluminum, etc.) to provide high heat conductance and preferably an airtight seal to prevent atmospheric contamination of the phosphor material. The phosphor material may comprise any known organic or inorganic phosphor material. Preferably, the phosphor material is comprised of quantum dots. Example assembly configurations may comprise, for example, sizing the phosphor deposition on the first surface based on an area of an excitation beam to be applied to the phosphor material, quantum dots being deposited substantially in monolayers with or without a coating to prevent agglomeration of the quantum dots, the first and second substrates having different sizes with or without the addition of components such as heat sinks to enhance heat dissipation, the addition of materials such reflective material, bonding facilitator material, etc.
(12) In one embodiment, a light converter assembly may comprise, for example, at least a first substrate, a second substrate, a phosphor material and a confinement material. The phosphor material may be deposited on at least a surface of the first substrate. The confinement material may be applied to at least the first substrate in an area surrounding the phosphor material. It may also be applied in a similar fashion to the second substrate. The confinement material may provide one or more of several useful functions in the various embodiments of the invention described herein including confining the phosphor material between the first and second substrates, bonding the substrates together, forming a reflective surface, providing high heat conduction between the substrates to promote heat dissipation, and generating a hermetic seal to isolate the phosphor material from the ambient atmosphere. (As used herein, a hermetic seal, or hermetically sealing, generally refers to a seal, or forming a seal, that is airtight.)
(13) In at least one example implementation, at least one of the first and second substrates may comprise sapphire. Preferably, the confinement material has a thermal conductivity greater 10 W/m/K, and more preferably greater than the thermal conductivity of the substrate material, even more preferably the confinement material has a thermal conductivity of at least 100 W/m/K (e.g., silicon, aluminum, silver, copper, etc.). The confinement material preferably has a low gas permeability to protect the phosphor material from atmospheric contamination. The phosphor material preferably comprises at least one quantum dot material including at least one of core/shell structures or giant thick shell structures. For example, the phosphor material may comprise a plurality of quantum dots deposited substantially in monolayers. In this instance, the phosphor material may further comprise at least one layer of a coating (e.g., aluminum oxide) to prevent agglomeration of the plurality of quantum dots.
(14) In the same or a different implementation, the phosphor material may be deposited over an area on the surface equal to or larger than a cross-sectional area of an excitation beam employed to excite the phosphor material. The light converter assembly may also comprise a reflective material applied in an area corresponding to at least the area of the phosphor material deposited on the first substrate. The phosphor material may further be deposited on the surface of the second substrate in an area within the confinement material corresponding to at least the area of the phosphor material deposited on the first substrate. The light converter assembly may further comprise a bonding facilitator material to facilitate bonding of the first and second substrates. In at least one example implementation, a recess may be formed in the first substrate, the phosphor material being deposited into the recess in the first substrate. In the same or a different implementation, a heat sink may be coupled to at least one of the first and second substrates. An example method consistent with the present disclosure may comprise applying a confinement material to at least a first substrate, depositing a phosphor material on at least the surface of the first substrate so that the confinement material surrounds the phosphor material; and sealing the first surface to a second substrate using the confinement material.
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(16) Example light converter assembly 100 is disclosed in
(17) Phosphor material 104 preferably comprises at least one quantum dot material. Generally, a quantum dot material comprises nanocrystals of a material (e.g., a semiconductor material) that are of a size small enough to display quantum confinement properties. Due to the quantum confinement effects, the energy differences between electronic states of a quantum dot are a function of both the composition and the physical size of the quantum dot. Thus, the optical and optoelectronic properties of quantum dots can be tuned and adjusted by changing the physical size of the quantum dots. More preferably, the material of quantum dots may be inorganic semiconductor nanocrystals comprising Group IV elements, Group II-VI compounds, Group II-V compounds, Group III-VI compounds, Group III-V compounds, Group IV-VI compounds, Group compounds, Group II-IV-VI compounds, or Group II-IV-V compounds, alloys thereof and/or mixtures thereof, including ternary and quaternary alloys and/or mixtures. Examples include, but are not limited to, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, GaSe, InN, InP, InAs, InSb, TlN, TlP, TlAs, TlSb, PbO, PbS, PbSe, PbTe, alloys thereof, and/or mixtures thereof, including ternary and quaternary alloys and/or mixtures. The quantum dots may be doped, such as ZnSe:Mn, whose emission is related to both the dopant and the size of the quantum dots. The quantum dots may have a core/shell structure. Quantum dots cores, which can be made from any of the above materials, typically lose some quantum efficiency due to the non-radiative processes at the surface defects, such as dangling bonds. Ligands may passivate some of them but not efficiently enough. Overcoating of the core with a shell of larger bandgap material, such as ZnSe or ZnS, results in passivation of surface defects and an increase of the quantum efficiency. The quantum dots also may be overcoated with ligands to prevent aggregation in the matrix. The ligands may be crosslinked to form polymeric micelles around the quantum dots. Colloidal quantum dots may exhibit narrow-band emission (e.g., saturated color) along with broad absorption spectrum (e.g., the quantum dot may be usable with a broad range of excitation sources). When employed in a LARP device, an excitation beam (e.g., a laser beam) causes the quantum dot material to generate a light emission having characteristics different that the excitation beam. The characteristics of the light emission (e.g., etendue, color, intensity, etc.) may be controlled based on the composition of the quantum dots. For example, the peak emission wavelength of the quantum dots may be tuned to within nanometers based on nanocrystal size, material composition, architecture of the core/shell structure, etc. Further to generating a light emission via laser excitation as in LARP (e.g., using a laser diode), other light sources that may be employed to generate an excitation beam may comprise, for example, a light emitting diode (LED) such as a high flux LED, etc.
(18) Confinement material 106 may be composed of a variety of materials based on desired functional characteristics. The desirable functional characteristics may comprise, for example, the ability to seal substrate 102 to substrate 108, high heat conductance, low gas permeability, etc. More specifically, the performance of light converter assembly 100 may benefit if the longitudinal heat transfer coefficient of the confinement material 106, h.sub.c=.sub.c/l>10.sup.6 W/m.sup.2/K, where .sub.c is the longitudinal thermal conductivity of the confinement material, and l is the thickness of the confinement material. For typical LARP conditions with absorbed laser flux densities of 10.sup.7 W/m.sup.2 and a confinement material thickness of 5 m, this translates into a temperature difference across the phosphor material on the order of 10K. This estimate takes the area over which most of the longitudinal heat transfer occurs is roughly equal to the area of the laser spot A. Therefore the temperature difference TP/Ah.sub.c, where P is the laser power and T is the temperature difference across the phosphor. The minimal .sub.c in this case is 5 W/m/K. In order to ensure proper heat dissipation, the confinement material 106 should have a thermal conductivity of at least 10 W/m/K, which is substantially above that of typical organic bonding materials. If the substrate material thickness is much thinner than the laser spot size, then the estimate above underestimates the temperature difference and it is preferable to have .sub.c be greater than the thermal conductivity of the first and second substrate materials, and more preferably .sub.c>100 W/m/K. Low gas permeability may isolate phosphor material 104 from atmospheric contamination (e.g., which may reduce conversion efficiency). The linear coefficient of thermal expansion for confinement material 106 may also be considered if, for example, larger temperature variations are possible (e.g., based on the particular application for which light converter assembly 100 is intended). Confinement layer composition will be discussed with respect to
(19) Confinement material 106 may be applied to a surface of substrates 102 and/or 108 using a variety of application methods, preferably in one or more layers as shown. For example, confinement material 106 may be applied on a surface via a silicon-to-sapphire wafer bond, or may be deposited on a surface via evaporation, epitaxy, chemical vapor deposition (CVD), physical vapor deposition (PVD), sputtering etc. When being applied to a surface, confinement material 106 may be patterned to leave openings for the later deposition of phosphor material 104. Patterning may be performed by, for example, photolithography or selective deposition (e.g., wherein some sacrificial material may be pre-deposited in the area intended for deposition of the QDs), etc. Final sealing may occur at a relatively low temperature to avoid damaging phosphor material 104. For example, wafer bonding silicon-to-sapphire may generate clean and smooth silicon surfaces for use in sealing (e.g., fusing) substrate 102 to substrate 108 at a temperature that would be safe for phosphor material 104. Confinement material 106 may be configured as a single layer or multiple layers bonded together to create an area on the surface of substrate 102 or substrate 108 that confines phosphor material 104. Preferably, the layer of the confinement material covers at least about 50% of the surface of the side of the substrate to which it is applied. More preferably, the coverage is at least about 75% and most preferably at least about 90% of the surface of the side of the substrate to which it is applied. In a preferred embodiment, the confinement material fills the entire space between the substrates with the exception of the region where the phosphor is deposited. As shown in
(20) It is important to note that fabrication of the disclosed optical components may be done on an industrial scale. A variety of methods may be utilized. In particular, confinement material 106 (e.g., silicon or a metal such as aluminum, copper or silver) may be applied to the surface of substrates 102 and/or 108 with precise thickness and uniformity. Microelectronics industry methods may provide such capability. Silicon is a preferred material given its high thermal conductivity, moderate thermal expansion coefficient compared to the sapphire and the ready-to-use technologies available for making silicon-on-sapphire substrates such as low temperature wafer bonding. Moreover, deposition of quantum dots can be done by mass production methods such as inkjet printing, layer transfer etc.
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(23) Transmissive configuration 310 may be configured to receive excitation beam 306 from one side of a light converter assembly and generate light emission 308 from the opposite side of the light converter assembly or both sides of the light converter assembly. For example, unidirectional emission may be achieved by applying a dichroic coating 314 to the excitation side of the light converter assembly. The dichroic coating will pass the short wavelength excitation beam 306 while reflecting longer-wavelength, backward-directed light emissions from phosphor material 104. To avoid spatial expansion of any backward-directed light emissions because of light propagation within the substrate, the dichroic coating 314 may be applied to the surface of substrate 102 proximate to phosphor material 104. In one embodiment, additional phosphor material 312 may also be deposited on substrate 102 over an area corresponding to at least the area over which phosphor material 104 is deposited on the surface of substrate 108 (e.g., confinement material 106A may be patterned similar to confinement material 106B to reserve this area for deposition of additional phosphor material 312). Since substrates 102 and 108 may be composed of a light transmissive material (e.g., sapphire), excitation beam 306 may be received through substrate 102, converted by additional phosphor material 312 and/or phosphor material 104, and emitted as light emission 308 through substrate 108. In a preferred embodiment, excitation beam 306 and light emission 308 pass through substrates 102, 108 without being substantially absorbed or scattered. As in example 300, confinement material 106A and 106B does not have to be optically non-absorbing and may comprise, for example, silicon, gold, silver, copper, or aluminum. It is important to note that the example assembly configurations disclosed in
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(30) As used in this application and in the claims, a list of items joined by the term and/or can mean any combination of the listed items. For example, the phrase A, B and/or C can mean A; B; C; A and B; A and C; B and C; or A, B and C. As used in this application and in the claims, a list of items joined by the term at least one of can mean any combination of the listed terms. For example, the phrases at least one of A, B or C can mean A; B; C; A and B; A and C; B and C; or A, B and C.
(31) While the principles of the invention have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the invention. Other embodiments are contemplated within the scope of the present invention in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.