Patent Application
20180237337
The disclosure relates generally to sealed devices, and more particularly to sealed devices comprising quantum dots, laser diodes, light emitting diodes, or other light emitting structures, as well as display and optical devices comprising such sealed components.
Sealed glass packages and casings are increasingly popular for application to electronics and other devices that may benefit from a hermetic environment for sustained operation. Exemplary devices which may benefit from hermetic packaging include televisions, sensors, optical devices, organic light emitting diode (OLED) displays, 3D inkjet printers, laser printers, solid-state lighting sources, and photovoltaic structures. For instance, displays comprising OLEDs or quantum dots (QDs) may call for sealed hermetic packages to prevent the possible decomposition of these materials at atmospheric conditions.
Glass, ceramic, and/or glass-ceramic substrates can be sealed by placing the substrates in a furnace, with or without an epoxy or other sealing material. However, the furnace typically operates at high processing temperatures which are unsuitable for many devices, such as OLEDs and QDs. Glass substrates can also be sealed using glass frit, e.g., by placing glass frit between the substrates and heating the frit with a laser or other heat source to seal the package. Frit-based sealants can include, for instance, glass materials ground to a particle size ranging typically from about 2 to 150 microns. The glass frit material can be mixed with a negative CTE material having a similar particle size to lower the mismatch of thermal expansion coefficients between substrates and the glass frit.
Glass frit materials typically have a glass transition temperature (Tg) greater than 450° C. and thus may require processing at elevated temperatures to form a hermetic seal. Such a high-temperature sealing process can be detrimental to temperature-sensitive workpieces. Further, the negative CTE inorganic fillers in the frit paste can negatively impact the transparency of the frit, resulting in an opaque seal. Accordingly, it would be advantageous to provide sealed devices which are both transparent and hermetic, as well as methods for forming such devices at lower temperatures suitable for encapsulating heat-sensitive workpieces.
The disclosure relates, in various embodiments, to sealed devices comprising a glass substrate comprising a first surface; an inorganic substrate comprising a second surface; a sealing layer in contact with at least a portion of the first surface and at least a portion of the second surface; and at least one seal bonding the glass substrate to the inorganic substrate via the sealing layer, wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K, wherein at least one of the first or second surfaces comprises at least one cavity containing at least one quantum dot and at least one LED component, and wherein the seal extends around the at least one cavity.
Sealed devices comprising laser diodes are also disclosed herein, the devices comprising a glass substrate comprising a first surface; an inorganic substrate comprising a second surface; a sealing layer in contact with at least a portion of the first surface and at least a portion of the second surface; and at least one seal bonding the glass substrate to the inorganic substrate via the sealing layer, wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K, wherein at least one of the first or second surfaces comprises at least one cavity containing at least one laser diode, and wherein the seal extends around the at least one cavity.
Further disclosed herein are sealed devices comprising a glass substrate comprising a first surface, a doped inorganic substrate comprising a second surface; and at least one seal bonding the glass substrate to the doped inorganic substrate, wherein the doped inorganic substrate comprises a thermal conductivity of greater than about 2.5 W/m-K and at least about 0.05 wt % of at least one dopant chosen from ZnO, SnO, SnO2, or TiO2. In some embodiments, the glass substrate may be bonded directly to the inorganic substrate or may be bonded by way of a sealing layer.
Methods for making such sealed devices are also disclosed, the methods comprising placing at least one quantum dot and at least one LED component in at least one cavity on a first surface of a glass substrate or a second surface of an inorganic substrate; positioning a sealing layer over at least a portion of the first surface or at least a portion of the second surface; bringing the first surface into contact with the second surface with the sealing layer positioned therebetween to form a sealing interface; and directing a laser beam operating at a predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate, the seal extending around the at least one cavity containing the at least one quantum dot and the at least one LED component, wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K.
Further disclosed herein are methods of making a sealed device comprising a laser diode, the methods comprising placing at least one laser diode in at least one cavity on a first surface of a glass substrate or a second surface of an inorganic substrate; positioning a sealing layer over at least a portion of the first surface or at least a portion of the second surface; bringing the first surface into contact with the second surface with the sealing layer positioned therebetween to form a sealing interface; and directing a laser beam operating at a predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate, the seal extending around the at least one cavity containing the at least one laser diode, wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K.
Additional methods disclosed herein include methods for making a sealed device, the methods comprising doping an inorganic substrate with at least one dopant absorbing at a predetermined wavelength; bringing a first surface of a glass substrate into contact with a second surface of the doped inorganic substrate to form a sealing interface; and directing a laser beam operating at the predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate, wherein the inorganic substrate has a thermal conductivity greater than about 2.5 W/m-K.
Still further disclosed herein are methods for making a sealed device, the methods comprising bringing a first surface of a glass substrate and a second surface of an inorganic substrate into contact with a sealing layer to form a sealing interface; and directing a laser beam operating at a predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate; wherein a difference between the CTE of the glass substrate and the CTE of the inorganic substrate is less than about 20×10−7/° C., and wherein the inorganic substrate has a thermal conductivity greater than about 2.5 W/m-K.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the methods as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description present various embodiments of the disclosure, and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure and, together with the description, serve to explain the principles and operations of the disclosure.
The following detailed description can be further understood when read in conjunction with the following drawings in which, where possible, like numerals are used to refer to like elements, and:
Disclosed herein are sealed devices comprising at least two substrates chosen from glass, glass-ceramic, and/or ceramic substrates. Exemplary sealed devices can include, for example, sealed devices encapsulating quantum dots, LEDs, laser diodes (LDs), and other light emitting structures. Display and optical devices comprising such sealed components are also disclosed herein. Displays such as televisions, computers, handheld devices, watches, and the like can comprise a backlight comprising quantum dots (QDs) as color converters. Exemplary optical devices can include but are not limited to sensors, watches, biosensors, and other devices configured to contain embodiments described herein. In some embodiments, QDs can be packaged, for example, in a glass tube, capillary, or sheet, e.g., a quantum dot enhancement film (QDEF) or encapsulated device such as a chiplet. Such films or devices can be filled with quantum dots, such as green and red emitting quantum dots, and can be sealed at both ends and/or around the periphery. Due to the temperature sensitivity of QDs, backlights using quantum dot material avoid direct contact between the quantum dot material and the light source, e.g., LED. Thus, as shown in
Various embodiments of the disclosure will now be discussed with reference to
Devices
Disclosed herein are sealed devices comprising a glass substrate comprising a first surface; an inorganic substrate comprising a second surface; a sealing layer in contact with at least a portion of the first surface and at least a portion of the second surface; and at least one seal bonding the glass substrate to the inorganic substrate via the sealing layer, wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K, wherein at least one of the first or second surfaces comprises at least one cavity containing at least one quantum dot and at least one LED component, and wherein the seal extends around the at least one cavity. Backlights and display devices comprising such sealed devices are also disclosed herein.
Cross-sectional views of two non-limiting embodiments of a sealed device 200 are illustrated in
In the non-limiting embodiment depicted in
In the non-limiting embodiment depicted in
One exemplary low pass filter 217a, 217b, 217c, includes a thin film stack made from multiple layers of high refractive index and low refractive index materials. In some embodiments, the stack includes an odd number of layers; in other embodiments, the stack includes an even number of layers. In some embodiments, the plural layers include 2 or more layers, 3 or more layers, 4 or more layers, 5 or more layers, 6 or more layers, 7 or more layers, 8 or more layers, 9 or more layers, 10 or more layers, 11 or more layers, 12 or more layers, 13 or more layers, 14 or more layers, 15 or more layers, 16 or more layers, 17 or more layers, 18 or more layers, 19 or more layers, 20 or more layers, 21 or more layers, 22 or more layers, 23 or more layers, 24 or more layers, 25 or more layers, 26 or more layers, 27 or more layers, 28 or more layers, 29 or more layers, and so on. In one embodiment, an exemplary filter comprises multiple alternating layers of a suitable high refractive index material and a suitable low refractive index material. Exemplary high refractive index materials include, but are not limited to, Nb2O5, Ta2O5, TiO2, and compound oxides thereof. Exemplary low refractive index materials include, but are not limited to, SiO2, ZrO2, HfO2, Bi2O3, La2O3, Al2O3, and compound oxides thereof. In one embodiment, an exemplary filter includes alternating layers of Nb2O5 and SiO2 to a total thickness of approximately 1.8 μm which can be designed to pass light at 450 nm while reflecting 550 nm and 632 nm as provided in Table 1 below.
Exemplary filter embodiments can be used between a side lit or direct lit light guide plates and adjacent QD material, i.e., intermediate the QD material and light guide plates or as described above with reference to
The first substrate 201, second substrate 207 and/or third substrate 215 can, in some embodiments, be chosen from glass substrates and may comprise any glass known in the art for use in display and other electronic devices. Suitable glasses can include, but are not limited to, aluminosilicate, alkali-aluminosilicate, borosilicate, alkali-borosilicate, aluminoborosilicate, alkali-aluminoborosilicate, and other suitable glasses. These substrates may, in various embodiments, be chemically strengthened and/or thermally tempered. Non-limiting examples of suitable commercially available substrates include EAGLE XG , Lotus™, Iris™, Willow®, and Gorilla® glasses from Corning Incorporated, to name a few. Glasses that have been chemically strengthened by ion exchange may be suitable as substrates according to some non-limiting embodiments.
According to various embodiments, the first, second, and/or third glass substrates 201, 207, 215 may have a compressive stress greater than about 100 MPa and a depth of layer of compressive stress (DOL) greater than about 10 microns. In further embodiments, the first, second and/or third glass substrate may have a compressive stress greater than about 500 MPa and a DOL greater than about 20 microns, or a compressive stress greater than about 700 MPa and a DOL greater than about 40 microns. In non-limiting embodiments, the first, second and/or third glass substrate can have a thickness of less than or equal to about 3 mm, for example, ranging from about 0.1 mm to about 2.5 mm, from about 0.3 mm to about 2 mm, from about 0.5 mm to about 1.5 mm, or from about 0.7 mm to about 1 mm, including all ranges and subranges therebetween.
The first, second and/or third glass substrates can, in various embodiments, be transparent or substantially transparent. As used herein, the term “transparent” is intended to denote that the substrate, at a thickness of approximately 1 mm, has a transmission of greater than about 80% in the visible region of the spectrum (400-700 nm). For instance, an exemplary transparent substrate may have greater than about 85% transmittance in the visible light range, such as greater than about 90%, or greater than about 95%, including all ranges and subranges therebetween. In certain embodiments, an exemplary glass substrate may have a transmittance of greater than about 50% in the ultraviolet (UV) region (200-400 nm), such as greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, greater than about 80%, greater than about 85%, greater than about 90%, greater than about 95%, or greater than about 99% transmittance, including all ranges and subranges therebetween.
According to various embodiments, the second substrate 207 can be chosen from inorganic substrates, such as inorganic substrates having a thermal conductivity greater than that of glass. For example, suitable inorganic substrates may include those with a relatively high thermal conductivity, such as greater than about 2.5 W/m-K (e.g., greater than about 2.6, 3, 5, 7.5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 W/m-K), for instance, ranging from about 2.5 W/m-K to about 100 W/m-K, including all ranges and subranges therebetween. In some embodiments, the thermal conductivity of the inorganic substrate can be greater than 100 W/m-K, such as ranging from about 100 W/m-K to about 300 W/m-K (e.g., greater than about 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 W/m-K), including all ranges and subranges therebetween.
According to various embodiments, the inorganic substrate can comprise a ceramic substrate, which can include ceramic or glass-ceramic substrates. In a non-limiting embodiment, the second substrate 207 can comprise aluminum nitride, aluminum oxide, beryllium oxide, boron nitride, or silicon carbide, to name a few. The thickness of the inorganic substrate can range, in certain embodiments, from about 0.1 mm to about 3 mm, such as from about 0.2 mm to about 2.5 mm, from about 0.3 mm to about 2 mm, from about 0.4 mm to about 1.5 mm, from about 0.5 mm to about 1 mm, from about 0.6 mm to about 0.9 mm, or from about 0.7 mm to about 0.8 mm, including all ranges and subranges therebetween. In additional embodiments, the inorganic substrate may have little or no absorption at a given laser operating wavelength, e.g., at UV wavelengths (200-400nm), or at visible wavelengths (400-700nm). For instance, the second inorganic substrate may absorb less than about 10% at the laser's operating wavelength, such as less than about 5%, less than about 3%, less than about 2%, or less than about 1% absorption, e.g., from about 1% to about 10%. At visible wavelengths the inorganic substrate may, in some embodiments, be transparent or scattering.
In still further embodiments, the second inorganic substrate may be doped with at least one dopant capable of absorbing light at a predetermined wavelength, e.g., at the predetermined operating wavelength of a laser. Dopants can include, for example, ZnO, SnO, SnO2, TiO2, and the like. In some embodiments, the dopant can be chosen from compounds absorbing at UV wavelengths (200-400 nm). The dopant can be incorporated into the inorganic substrates in an amount sufficient to induce absorption of the inorganic substrate at the predetermined wavelength. For instance, the dopant can be incorporated into the inorganic substrate at a concentration of greater than about 0.05 wt % (500 ppm), for example, ranging from about 500 ppm to about 106 ppm. In some embodiments, the dopant concentration can be greater than about 0.5 wt %, greater than about 1 wt %, greater than about 2 wt %, greater than about 3 wt %, greater than about 4 wt %, greater than about 5 wt %, greater than about 6 wt %, greater than about 7 wt %, greater than about 8 wt %, greater than about 9 wt %, or greater than about 10 wt %, including all ranges and subranges therebetween. According to additional embodiments, the dopant may have a concentration greater than about 10 wt %, e.g., about 20 wt %, 30 wt %, 40 wt %, 50 wt %, 60 wt %, 70 wt %, 80 wt %, or 90 wt %, including all ranges and subranges therebetween. In further embodiments, the doped inorganic substrate may comprise about 100% dopant, e.g., in the case of a ZnO ceramic substrate.
According to various embodiments, the first, second and/or third substrates may be chosen such that the coefficients of thermal expansion (CTEs) of the substrates are substantially similar. For example, the CTE of the third or second substrate can be within about 50% of the CTE of the first substrate, such as within about 40%, within about 30%, within about 20%, within about 15%, within about 10%, or within about 5% of the CTE of the first substrate. By way of a non-limiting example, the CTE of the first glass substrate (at a temperature ranging from about 25-400° C.) can range from about 30×10−7/° C. to about 90×10−7/° C., such as from about 40×10−7/° C. to about 80×10−7/° C., or from about 50×10−7/° C. to about 60×10−7/° C. (such as about 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90×10−7/° C.), including all ranges and subranges therebetween. According to non-limiting embodiments, the glass substrates can be Corning® Gorilla® glass having a CTE ranging from about 75 to about 85×10−7/° C., or Corning® EAGLE XG®, Lotus™, or Willow® glasses having a CTE ranging from about 30 to about 50×10−7/° C. The second substrate can comprise an inorganic, e.g., ceramic or glass-ceramic substrate, having a CTE (at a temperature ranging from about 25-400° C.) ranging from about 20×10−7/° C. to about 100×10−7/° C., such as from about 30×10−7/° C. to about 80×10−7/° C., from about 40×10−7/° C. to about 70×10−7/° C., or from about 50×10−7/° C. to about 60×10−7/° C. (such as about 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100×10−7/° C.), including all ranges and subranges therebetween.
While
Moreover, while
The at least one cavity 209 can have any given depth, which can be chosen as appropriate, e.g., for the type and/or shape and/or amount of the item (e.g., QD, LED, and/or LD) to be encapsulated in the cavity. By way of non-limiting embodiment, the at least one cavity 209 can extend into the first and/or second substrates to a depth of less than about 1 mm, such as less than about 0.5 mm, less than about 0.4 mm, less than about 0.3 mm, less than about 0.2 mm, less than about 0.1 mm, less than about 0.05 mm, less than about 0.02 mm, or less than about 0.01 mm, including all ranges and subranges therebetween, such as ranging from about 0.01 mm to about 1 mm. It is also envisioned that an array of cavities can be used, each cavity having the same or a different depths, the same or a different shapes, and/or the same or a different sizes, as compared to the other cavities in the array.
The at least one cavity 209 can, in some embodiments, comprise at least one quantum dot 205. Quantum dots can have varying shapes and/or sizes depending on the desired wavelength of emitted light. For example, the frequency of emitted light may increase as the size of the quantum dot decreases, e.g., the color of the emitted light can shift from red to blue as the size of the quantum dot decreases. When irradiated with blue, UV, or near-UV light, a quantum dot may convert the light into longer red, yellow, green, or blue wavelengths. According to various embodiments, the quantum dot can be chosen from red and green quantum dots, emitting in the red and green wavelengths when irradiated with blue, UV, or near-UV light. For instance, the LED component can emit blue light (approximately 450-490 nm), UV light (approximately 200-400 nm), or near-UV light (approximately 300-450nm).
Additionally, it is possible that the at least one cavity can comprise the same or different types of quantum dots, e.g., quantum dots emitting different wavelengths. For example, in some embodiments, a cavity can comprise quantum dots emitting both green and red wavelengths, to produce a red-green-blue (RGB) spectrum in the cavity. However, according to other embodiments, it is possible for an individual cavity to comprise only quantum dots emitting the same wavelength, such as a cavity comprising only green quantum dots or a cavity comprising only red quantum dots. For instance, the sealed device can comprise an array of cavities, in which approximately one-third of the cavities may be filled with green quantum dots and approximately one-third of the cavities may be filled with red quantum dots, while approximately one-third of the cavities may remain empty (so as to emit blue light). Using such a configuration, the entire array can produce the RGB spectrum, while also providing dynamic dimming for each individual color.
Of course it is to be understood that cavities containing any type, color, or amount of quantum dots in any ratio are possible and envisioned as falling within the scope of the disclosure. It is within the ability of one skilled in the art to choose the configuration of the cavity or cavities and the types and amounts of quantum dots to place in each cavity to achieve a desired effect. Moreover, although the devices herein are discussed in terms of red and green quantum dots for display devices, it is to be understood that any type of quantum dot can be used, which can emit any wavelength of light including, but not limited to, red, orange, yellow, green, blue, or any other color in the visible spectrum (e.g., 400-700nm).
Exemplary quantum dots can have various shapes. Examples of the shape of a quantum dot include, but are not limited to, sphere, rod, disk, tetrapod, other shapes, and/or mixtures thereof. Exemplary quantum dots may also be contained in a polymer resin such as, but not limited to, acrylate or another suitable polymer or monomer. Such exemplary resins may also include suitable scattering particles including, but not limited to, TiO2 or the like.
In certain embodiments, quantum dots comprise inorganic semiconductor material which permits the combination of the soluble nature and processability of polymers with the high efficiency and stability of inorganic semiconductors. Inorganic semiconductor quantum dots are typically more stable in the presence of water vapor and oxygen than their organic semiconductor counterparts. As discussed above, because of their quantum-confined emissive properties, their luminescence can be extremely narrow-band and can yield highly saturated color emission, characterized by a single Gaussian spectrum. Because the nanocrystal diameter controls the quantum dot optical band gap, the fine tuning of absorption and emission wavelength can be achieved through synthesis and structure change.
In certain embodiments, inorganic semiconductor nanocrystal quantum dots comprise Group IV elements, Group II-VI compounds, Group II-V compounds, Group III-VI compounds, Group III-V compounds, Group IV-VI compounds, Group I-III-VI 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.
In certain embodiments a quantum dot can include a shell over at least a portion of a surface of the quantum dot. This structure is referred to as a core-shell structure. The shell can comprise an inorganic material, more preferably an inorganic semiconductor material, An inorganic shell can passivate surface electronic states to a far greater extent than organic capping groups. Examples of inorganic semiconductor materials for use in a shell include, but are not limited to, Group IV elements, Group II-VI compounds, Group II-V compounds, Group -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.
In some embodiments, quantum dot materials can include II-VI semiconductors, including CdSe, CdS, and CdTe, and can be made to emit across the entire visible spectrum with narrow size distributions and high emission quantum efficiencies. For example, roughly 2 nm diameter CdSe quantum dots emit in the blue while 8 nm diameter particles emit in the red. Changing the quantum dot composition by substituting other semiconductor materials with a different band gap into the synthesis alters the region of the electromagnetic spectrum in which the quantum dot emission can be tuned. In other embodiments, the quantum dot materials are cadmium-free. Examples of cadmium-free quantum dot materials include InP and InxGax-1P. In an example of one approach for preparing InxGax-1P, InP can be doped with a small amount of Ga to shift the band gap to higher energies in order to access wavelengths slightly bluer than yellow/green. In an example of another approach for preparing this ternary material, GaP can be doped with In to access wavelengths redder than deep blue. InP has a direct bulk band gap of 1.27 eV, which can be tuned beyond 2 eV with Ga doping. Quantum dot materials comprising InP alone can provide tunable emission from yellow/green to deep red; the addition of a small amount of Ga to InP can facilitate tuning the emission down into the deep green/aqua green. Quantum dot materials comprising InxGax-1P (0<x<1) can provide light emission that is tunable over at least a large portion of, if not the entire, visible spectrum. InP/ZnSeS core-shell quantum dots can be tuned from deep red to yellow with efficiencies as high as 70%. For creation of high CRI white QD-LED emitters, InP/ZnSeS can be utilized to address the red to yellow/green portion of the visible spectrum and InxGax-1P will provide deep green to aqua-green emission.
In some embodiments, e.g., see
A first surface of the first substrate 201 and a second surface of the second substrate 207 can be joined by a seal or weld 211. The seal 211 can extend around the at least one cavity 209, thereby sealing the workpiece within the cavity. For example, as shown in
In other non-limiting embodiments, the device can comprise a sealing layer disposed between and connecting the first and second substrates. For example, as shown in
In general, suitable sealing layer materials can include low Tg glasses and suitably reactive oxides of copper or tin. By way of non-limiting example, the sealing layer can comprise a glass with a Tg of less than or equal to about 400° C., such as less than or equal to about 350° C., about 300° C., about 250° C., or about 200° C., including all ranges and subranges therebetween, such as ranging from about 200° C. to about 400° C. Suitable sealing layers and methods are disclosed, for instance, in U.S. patent application Nos. 13/777,584; 13/891,291; 14/270,828; and 14/271,797, all of which are incorporated herein by reference in their entireties.
The thickness of the sealing layer 315 can vary depending on the application and, in certain embodiments, can range from about 0.1 microns to about 10 microns, such as less than about 5 microns, less than about 3 microns, less than about 2 microns, less than about 1 micron, less than about 0.5 microns, or less than about 0.2 microns, including all ranges and subranges therebetween. The sealing layer 315 can have, in various embodiments, an absorption at the laser's operating wavelength (at room temperature) of greater than about 10%, greater than about 15%, greater than about 20%, greater than about 25%, greater than about 30%, greater than about 35%, greater than about 40%, greater than about 45%, or greater than about 50%, including all ranges and subranges therebetween, such as from about 10% to about 50%. For example, the sealing layer can be absorbing at UV wavelengths (200-400 nm), e.g., having an absorption of greater than about 10%. In some embodiments, the sealing layer can be transparent or substantially transparent to visible light, e.g., having a transmission of greater than about 80% in the visible region of the spectrum (400-700 nm).
As shown in
The seal 211 between the first and second substrates as depicted in
The first and second substrates can, in various embodiments be sealed together as disclosed herein, to produce a seal or weld around the at least one cavity. In certain embodiments, the seal or weld may be a hermetic seal, e.g., forming one or more air-tight and/or waterproof pockets in the device. For example, at least one cavity can be hermetically sealed such that the cavity is impervious or substantially impervious to water, moisture, air, and/or other contaminants. By way of non-limiting example, a hermetic seal can be configured to limit the transpiration (diffusion) of oxygen to less than about 10−2 cm3/m2/day (e.g., less than about 10−3/cm3/m2/day), and limit transpiration of water to about 10−2 g/m2/day (e.g., less than about 10−3, 10−4, 10−5, or 10−6 g/m2/day). In various embodiments, a hermetic seal can substantially prevent water, moisture, and/or air from contacting the components protected by the hermetic seal.
According to certain aspects, the total thickness of the sealed device can be less than about 6 mm, such as less than about 5 mm, less than about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1.5 mm, less than about 1 mm, or less than about 0.5 mm, including all ranges and subranges therebetween. For example, the thickness of the sealed device can range from about 0.3 mm to about 3 mm, such as from about 0.5 mm to about 2.5 mm, or from about 1 mm to about 2 mm, including all ranges and subranges therebetween.
The sealed devices disclosed herein may be used in various display devices or display components including, but not limited to backlights or backlit displays such as televisions, computer monitors, handheld devices, and the like, which can comprise various additional components. The sealed devices disclosed herein can also be used as illuminating devices, such as luminaires and solid state lighting applications. For example, a sealed device comprising quantum dots in contact with at least one LED die can be used for general illumination, e.g. mimicking the broadband output of the sun. Such lighting devices can comprise, for example, quantum dots of various sizes emitting at various wavelengths, such as wavelengths ranging from 400-700 nm.
Also disclosed herein are sealed devices comprising laser diodes, the devices comprising a glass substrate comprising a first surface; an inorganic substrate comprising a second surface; a sealing layer in contact with at least a portion of the first surface and at least a portion of the second surface; and at least one seal bonding the glass substrate to the inorganic substrate via the sealing layer, wherein the inorganic substrate has a thermal conductivity of at least 2.5 W/m-K, wherein at least one of the first or second surfaces comprises at least one cavity containing at least one laser diode, and wherein the seal extends around the at least one cavity. Hermetically packaged laser diodes can be useful in optical devices, printers, and the like.
Referring to
It is to be understood that the embodiments disclosed with respect to sealed devices 200 (comprising QD/LED) can be incorporated into sealed devices 500 (comprising LD) without limitation. For example, the first glass substrate 501 and second inorganic substrate 507 can be chosen from similar materials and can have similar properties as those disclosed above for substrates 201 and 207 in
Further disclosed herein are sealed devices comprising a glass substrate comprising a first surface, a doped inorganic substrate comprising a second surface; and at least one seal bonding the glass substrate to the doped inorganic substrate, wherein the doped inorganic substrate comprises a thermal conductivity of greater than about 2.5 W/m-K and at least about 0.05 wt % of at least one dopant chosen from ZnO, SnO, SnO2, or TiO2. In some embodiments, the glass substrate may be bonded directly to the inorganic substrate or may be bonded by way of a sealing layer.
Referring to
It is to be understood that the embodiments disclosed with respect to sealed devices 200 (comprising QD/LED) and 500 can be incorporated into sealed devices 600 without limitation. For example, the first glass substrate 601 and second inorganic substrate 607 can be chosen from similar materials and can have similar properties as those disclosed above for substrates 201 and 207 in
Similarly, the seal 611 can be formed in a manner similar to that described for seal 211 above, using similar sealing layers 315, 415 and patterns as described with respect to
Methods
Disclosed herein are methods for making sealed devices, the methods comprising placing at least one quantum dot and at least one LED component in at least one cavity on a first surface of a glass substrate or a second surface of an inorganic substrate; positioning a sealing layer over at least a portion of the first surface or at least a portion of the second surface; bringing the first surface into contact with the second surface with the sealing layer positioned therebetween to form a sealing interface; and directing a laser beam operating at a predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate, the seal extending around the at least one cavity containing the at least one quantum dot and the at least one LED component, wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K.
Also disclosed herein are methods of making a sealed device comprising a laser diode, the methods comprising placing at least one laser diode in at least one cavity on a first surface of a glass substrate or a second surface of an inorganic substrate; positioning a sealing layer over at least a portion of the first surface or at least a portion of the second surface; bringing the first surface into contact with the second surface with the sealing layer positioned therebetween to form a sealing interface; and directing a laser beam operating at a predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate, the seal extending around the at least one cavity containing the at least one laser diode, wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K.
Further disclosed herein are method for making a sealed device, the methods comprising doping an inorganic substrate with at least one dopant absorbing at a predetermined wavelength; bringing a first surface of a glass substrate into contact with a second surface of the inorganic substrate to form a sealing interface; and directing a laser beam operating at the predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate, wherein the inorganic substrate has a thermal conductivity greater than about 2.5 W/m-K.
Still further disclosed herein are methods for making a sealed device, the methods comprising bringing a first surface of a glass substrate and a second surface of an inorganic substrate into contact with a sealing layer to form a sealing interface; and directing a laser beam operating at a predetermined wavelength onto the sealing interface to form a seal between the glass substrate and the inorganic substrate, wherein a difference between the CTE of the glass substrate and the CTE of the inorganic substrate is less than about 20×10−7/° C., and wherein the inorganic substrate has a thermal conductivity of greater than about 2.5 W/m-K.
According to various embodiments, a sealing layer can optionally be applied to at least a portion of the glass substrate or at least a portion of the inorganic substrate prior to sealing. As discussed above, the first (glass) or second (inorganic) substrate may comprise at least one cavity. Cavities can be provided in the first or second substrates, e.g., by pressing, molding, cutting, or any other suitable method. The sealing layer, if present, can be applied over any such cavity, or can be framed around the cavity. In some embodiments, at least one quantum dot and at least one LED component can be placed in the cavity. In alternative embodiments, at least one laser diode can be placed in the cavity. In further embodiments, a workpiece can be placed in the cavity.
According to various embodiments, the inorganic substrate may be a doped inorganic substrate. Doping can be carried out, for instance, during formation of the inorganic substrate, e.g., at least one dopant or precursor thereof can be added to the batch materials used to form the inorganic substrate. Suitable dopants can include, for example, ZnO, SnO, SnO2, TiO2, and the like. Exemplary dopant concentrations may include, for instance, greater than about 0.05 wt % (e.g., greater than about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt %, and so on).
The first surface and second surface can then be brought into contact, optionally with the sealing layer positioned therebetween, to form a sealing interface. The substrates thus contacted can be sealed, e.g., around at least one cavity. According to various non-limiting embodiments, sealing can be carried out by laser welding. For example, a laser can be directed at or on a sealing interface such that the sealing layer absorbs the laser energy and heats the interface to a temperature near the Tg of the glass substrate. Melting of the sealing layer and/or glass substrate can thus form a bond between the first and second substrates. Alternatively, a sealing layer may not be present and the second inorganic substrate may be doped such that it absorbs the laser energy and heats the interface to a temperature near the Tg of the glass substrate. In various embodiments, laser sealing can be carried out at temperatures at or near room temperature, such as from about 25° C. to about 50° C., or from about 30° C. to about 40° C., including all ranges and subranges therebetween. While heating at the sealing interface may cause a temperature increase exceeding these temperatures, such heating is localized at the sealing region, thus decreasing the risk of damage to any heat-sensitive work pieces to be encapsulated in the device.
The laser may be chosen from any suitable laser known in the art for glass substrate welding. For example, the laser may emit light at UV (˜200-400 nm), visible (˜400-700 nm), or infrared (˜700-1600 nm) wavelengths. According to various embodiments, the laser may operate at a predetermined wavelength ranging from about 300 nm to about 1600 nm, such as from about 350 nm to about 1400 nm, from about 400 nm to about 1000 nm, from about 450 nm to about 750 nm, from about 500 nm to about 700 nm, or from about 600 nm to about 650 nm, including all ranges and subranges therebetween. In certain embodiments, the laser may be a UV laser operating at about 355 nm, a visible light laser operating at about 532 nm, or a near-infrared laser operating at about 810 nm, or any other suitable NIR wavelength. According to additional embodiments, the laser operating wavelength may be chosen as any wavelength at which the first glass substrate is substantially transparent and the sealing layer and/or inorganic substrate is absorbing. Exemplary lasers include IR lasers, argon ion beam lasers, helium-cadmium lasers, and third-harmonic generating lasers, to name a few.
In certain embodiments, the laser beam can have an average power ranging from about 0.2 W to about 50 W, such as from about 0.5 W to about 40 W, from about 1 W to about 30 W, from about 2 W to about 25 W, from about 3 W to about 20 W, from about 4 W to about 15 W, from about 5 W to about 12 W, from about 6 W to about 10 W, or from about 7 W to about 8 W, including all ranges and subranges therebetween. The laser may operate at any frequency and may, in certain embodiments, operate in a pulsed, modulated (quasi-continuous), or continuous manner. In some embodiments, the laser may operate in burst mode, each burst comprising a plurality of individual pulses. In some non-limiting embodiments, the laser may have a repetition rate ranging from about 1 kHz to about 1 MHz, such as from about 5 kHz to about 900 kHz, from about 10 kHz to about 800 kHz, from about 20 kHz to about 700 kHz, from about 30 kHz to about 600 kHz, from about 40 kHz to about 500 kHz, from about 50 kHz to about 400 kHz, from about 60 kHz to about 300 kHz, from about 70 kHz to about 200 kHz, or from about 80 kHz to about 100 kHz, including all ranges and subranges therebetween.
According to various embodiments, the beam may be directed at and focused on the sealing interface, below the sealing interface, or above the sealing interface. The beam spot diameter on the interface may be less than about 1 mm in some non-limiting embodiments. For example, the beam spot diameter may be less than about 500 microns, such as less than about 400 microns, less than about 300 microns, or less than about 200 microns, less than about 100 microns, less than 50 microns, or less than 20 microns, including all ranges and subranges therebetween. In some embodiments, the beam spot diameter may range from about 10 microns to about 500 microns, such as from about 50 microns to about 250 microns, from about 75 microns to about 200 microns, or from about 100 microns to about 150 microns, including all ranges and subranges therebetween.
According to various embodiments, sealing the substrate can comprise scanning or translating a laser beam along the substrates (or the substrates can be translated relative to the laser) using any predetermined path to produce any pattern, such as a square, rectangular, circular, oval, or any other suitable pattern or shape, for example, to hermetically seal at least one cavity in the device. The translation speed at which the laser beam (or substrate) moves along the interface may vary by application and may depend, for example, upon the composition of the first and second substrates and/or the focal configuration and/or the laser power, frequency, and/or wavelength. In certain embodiments, the laser may have a translation speed ranging from about 1 mm/s to about 1000 mm/s, for example, from about 5 mm/s to about 750 mm/s, from about 10 mm/s to about 500 mm/s, or from about 50 mm/s to about 250 mm/s, such as greater than about 100 mm/s, greater than about 200 mm/s, greater than about 300 mm/s, greater than about 400 mm/s, greater than about 500 mm/s, or greater than about 600 mm/s, including all ranges and subranges therebetween.
According to various embodiments disclosed herein, the laser wavelength, pulse duration, repetition rate, average power, focusing conditions, and other relevant parameters may be varied so as to produce energy sufficient to weld the first and second substrates together by way of the sealing layer. It is within the ability of one skilled in the art to vary these parameters as necessary for a desired application. In various embodiments, the laser fluence (or intensity) is below the damage threshold of the first and/or second substrate, e.g., the laser operates under conditions intense enough to weld the substrates together, but not so intense as to damage the substrates. In certain embodiments, the laser beam may operate at a translation speed that is less than or equal to the product of the diameter of the laser beam at the sealing interface and the repetition rate of the laser beam.
It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.
It is also to be understood that, as used herein the terms “the,” “a,” or “an,” mean “at least one,” and should not be limited to “only one” unless explicitly indicated to the contrary. Thus, for example, reference to “a cavity” includes examples having one such “cavity” or two or more such “cavities” unless the context clearly indicates otherwise. Similarly, a “plurality” or an “array” is intended to denote two or more, such that an “array of cavities” or a “plurality of cavities” denotes two or more such cavities.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
All numerical values expressed herein are to be interpreted as including “about,” whether or not so stated, unless expressly indicated otherwise. It is further understood, however, that each numerical value recited is precisely contemplated as well, regardless of whether it is expressed as “about” that value. Thus, “a dimension less than 10 mm” and “a dimension less than about 10 mm” both include embodiments of “a dimension less than about 10 mm” as well as “a dimension less than 10 mm.”
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.
While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase “comprising,” it is to be understood that alternative embodiments, including those that may be described using the transitional phrases “consisting” or “consisting essentially of,” are implied. Thus, for example, implied alternative embodiments to a method comprising A+B+C include embodiments where a method consists of A+B+C, and embodiments where a method consists essentially of A+B+C.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the disclosure may occur to persons skilled in the art, the disclosure should be construed to include everything within the scope of the appended claims and their equivalents.
This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 62/249,691 filed on Nov. 2, 2015, U.S. Provisional Application Ser. No. 62/214,548 filed on Sep. 4, 2015 and U.S. Provisional Application Ser. No. 62/204,122 filed on Aug. 12, 2015, the contents of each of which are relied upon and incorporated herein by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2016/046495 | 8/11/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62204122 | Aug 2015 | US | |
| 62214548 | Sep 2015 | US | |
| 62249691 | Nov 2015 | US |
