Patent Publication Number: US-2022216189-A1

Title: Displays with embedded light emitters

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to U.S. Pat. No. 9,818,725, filed Aug. 4, 2015, entitled  Inorganic - Light - Emitter Display with Integrated Black Matrix  and U.S. patent application Ser. No. 16/669,493, filed Oct. 30, 2019, entitled  Displays with Unpatterned Layers of Light - Absorbing Material , each of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to displays including embedded light emitters. In some embodiments, a display includes a black matrix for reducing ambient light reflections. 
     BACKGROUND 
     Flat-panel displays are widely used in conjunction with computing devices, in portable devices, and for entertainment devices such as televisions. Such displays typically employ a plurality of pixels distributed over a display substrate to display images, graphics, or text. For example, liquid crystal displays (LCDs) employ liquid crystals to block or transmit light from a backlight behind the liquid crystals and organic light-emitting diode (OLED) displays rely on passing current through a layer of organic material that glows in response to the electrical current. 
     Most flat-panel displays are either reflective or emissive. Reflective displays, such as many e-paper displays and reflective LCDs do not emit light but rather each of the display pixels reflects or absorbs ambient light to form an image. Such displays cannot be viewed in the dark but excel in bright conditions such as a sunny day outdoors. In contrast, light-emissive displays emit light and can be viewed in the dark but are often difficult to view in bright conditions. 
     In order to improve the display contrast of light-emissive displays, display designers typically use anti-reflection layers on the front cover of displays and light-absorbing layers internal to the display to reduce ambient light reflection. For example, OLED displays often employ circular polarizers on the cover glass and LCDs use an ambient-light-absorbing black matrix in combination with color filters used to color the white light emitted by the LCD backlights. These black-matrix structures are either in a common structure with the color filters or between the viewer and the color filter. For example, U.S. Pat. No. 6,466,281, entitled  Integrated Black Matrix/Color Filter Structure for TFT - LCD , describes a light-shielding layer located above the switching transistors in the display. U.S. Patent Application Publication No. 2007/0077349, entitled  Patterning OLED Device Electrodes and Optical Material , describes a black matrix integrated into an electrically insulating layer to absorb unwanted light in an RGBW configuration. Similarly, U.S. Pat. No. 7,402,951, entitled  OLED Device having Improved Contrast , discloses a contrast enhancement element with a light-absorbing layer for absorbing ambient light. U.S. Pat. Nos. 6,812,637, 7,466,075, and 7,091,523 all describe the use of black-matrix structures to improve contrast. These light-absorbing elements or layers are located between a viewer and the light-emitting OLED pixels. 
     Outdoor inorganic LED displays for public viewing are known to have black louvers associated with individual pixels to reduce glare from the sun. However, such displays are not capable of high resolution. 
     Inorganic LED displays are also known to use black-matrix structures, as disclosed in U.S. Pat. No. 7,919,342, entitled  Patterned Inorganic LED Device , in which a patterned conductive layer between and above the patterned light emitters can act as a black matrix to absorb light and increase the display contrast. 
     Black matrix structures in conventional displays locate light-absorbing elements or layers between a viewer and the light-emitting OLED pixels. U.S. Pat. No. 9,818,725 referenced above locates a black matrix in a common layer with light emitters. Although such arrangements can be relatively effective in absorbing ambient light, display structures that employ light emitters made using flip-chip methods and thin, light-weight support structures useful in portable and wearable displays can be useful. There remains a need, therefore, for improvements in display systems, structures, and methods of manufacturing that provide improved image quality and contrast, emission efficiency, and a reduced manufacturing cost in a mechanically and environmentally robust and flexible structure. 
     SUMMARY 
     The present disclosure provides, inter alia, a display with improved flexibility and contrast together with a simple construction. Displays of the present disclosure can comprise a support comprising an optically transparent polymer, the support having a support back surface and a support front surface, and an array of light emitters. Each of the light emitters in the array of light emitters (i) has an emission side and an electrode side, (ii) comprises electrode contacts wherein at least one of the electrode contacts is disposed in or on the electrode side, (iii) is embedded in the support such that the at least one of the electrode contacts is substantially coplanar with the support back surface, and (iv) is disposed to emit light from the emission side through the support front surface when provided with power through the electrode contacts. A redistribution layer has a support side and a distribution side, the support side disposed on and in contact with at least a portion of the support back surface. The redistribution layer comprises a dielectric layer and distribution contacts on the distribution side that extend through the dielectric layer. Each of the distribution contacts is electrically connected to a respective electrode contact of one of the light emitters through the dielectric layer and the distribution side is at least partially exposed. 
     In some embodiments, the redistribution layer comprises or forms a patterned black matrix. For example, the dielectric layer can be a black matrix, or the redistribution layer can comprise a black matrix disposed on the dielectric layer. The distribution side can be at least partially exposed. 
     In some embodiments, the distribution contacts can extend through the dielectric layer and thereby electrically connect to the electrode contacts and are at least partially exposed, for example to an external device or structure. The distribution contacts can have a lower resolution than the electrode contacts, the electrode contacts of the light emitters together can have a smaller pitch than a pitch of the distribution contacts, or the electrode contacts can each have an electrode area and the distribution contacts have a distribution area that is greater than the electrode area. 
     In some embodiments, the light emitters are inorganic light-emitting diodes. The support can be flexible or can be rigid or semi-rigid (e.g., sufficiently rigid to provide mechanical support to the light emitters). The support and the dielectric layer can be flexible. Any one or combination of an integrated circuit such as a controller, a cable, and a cable connector can be electrically connected to one or more of the distribution contacts and disposed at least partially on the distribution side. 
     The support (e.g., the optically transparent polymer) can be or comprise an optically transparent mold compound or cured optically transparent adhesive. The support can be or comprise a polymer, a resin, or an epoxy. The support can be a cured material that is deposited in liquid form and then cured, for example by heat or radiation. 
     The redistribution layer can likewise be or comprise a mold compound or cured adhesive. The redistribution layer can be or comprise a polymer, a resin, or an epoxy. The redistribution layer can be a cured material that is deposited in liquid form and then cured, for example by heat or radiation. The redistribution layer can be a black matrix or comprise a black matrix, for example a patterned black matrix and can be disposed in layers, one or more of which can be a black matrix. The display can comprise a patterned black matrix disposed on the distribution side of the redistribution layer so that the redistribution layer is disposed at least partially between the patterned black matrix and the support. The redistribution layer can comprise vias extending through the dielectric layer from the distribution side to the support side and each of the distribution contacts can extend through a via to make an electrical connection to an electrode contact of the light emitters. The distribution contacts can extend into the vias thereby electrically connecting to the electrode contacts of the light emitters. 
     In some embodiments, a display comprises a support having a support back surface and a support front surface opposite the support back surface (e.g., on an opposite side of the support), an array of light emitters disposed on the support front surface or embedded in the support, each of the light emitters is disposed to emit light away from the support back surface, and a black matrix disposed on a side of the support back surface opposite the support front surface. The black matrix can be patterned. The array of light emitters can be disposed on the support front surface or be embedded in the support material. In some embodiments, each of the light emitters in the array of light emitters (i) has an emission side and an electrode side, (ii) comprises electrode contacts wherein at least one of the electrode contacts is disposed on the electrode side, and (iii) is embedded in the support such that the at least one of the electrode contacts is substantially coplanar with the support back surface, and (iv) is disposed to emit light from or through the emission side when provided with power to the electrode contacts. 
     In some embodiments, a display comprises a redistribution layer having a support side and a distribution side, the support side disposed on and in contact with at least a portion of the support back surface, the redistribution layer comprising a dielectric layer and distribution contacts on the distribution side that extend through the dielectric layer, and each of the distribution contacts is electrically connected to a respective electrode contact of one of the light emitters through the dielectric layer and the distribution side is at least partially exposed. In some embodiments, the display comprises electrical devices, for example any combination of an integrated circuit, a controller, a cable, and a cable connector electrically connected to one or combination of the distribution contacts and disposed at least partially on the distribution side. The redistribution layer can comprise the patterned black matrix. In some embodiments, the redistribution layer is at least partially between the black matrix and the support back surface. The black matrix can be patterned to provide access to the distribution contacts. 
     In some embodiments of the present disclosure, a method of making a display comprises providing a carrier substrate, providing an array of light emitters, wherein each of the light emitters in the array of light emitters (i) has an emission side and an electrode side, (ii) comprises electrode contacts wherein at least one of the electrode contacts is disposed on the electrode side, (iii) is disposed to emit light from or through the emission side when provided with power through the electrode contacts, disposing the array of light emitters on the carrier substrate so that the electrode side of each of the light emitters in the array of light emitters is adjacent to the carrier substrate, disposing a layer of optically transparent polymer (e.g., optically clear mold compound) over the array of light emitters, the optically transparent polymer forming a support having a support back surface and a support front surface, wherein the support back surface is substantially co-planar with the electrode side, removing the carrier substrate, and providing a redistribution layer having a support side and a distribution side, the support side disposed on and in contact with at least a portion of the support back surface, the redistribution layer comprising a dielectric layer and distribution contacts extending through the dielectric layer. The distribution contacts are electrically connected to the electrode contacts of each of the light emitters and the distribution side is at least partially exposed. Some methods of the present disclosure comprise patterning a black matrix on the distribution side, for example to provide access to the distribution contacts. 
     According to some embodiments of the present disclosure, a display comprises a redistribution layer comprising a dielectric layer, the redistribution layer having a distribution side and a support side and distribution contacts disposed at least partially on the distribution side. An array of light emitters is disposed on the support side. Each of the light emitters in the array of light emitters (i) has an emission side and an electrode side, (ii) comprises electrode contacts with at least one of the electrode contacts disposed in or on the electrode side and the electrode contacts are electrically connected to the distribution contacts through the dielectric layer, (iii) is disposed such that the electrode side is in contact with the support side, and (iv) is disposed to emit light away from the redistribution layer when provided with power through the electrode contacts. 
     In some embodiments, the redistribution layer is a black matrix or comprises a black matrix or the black matrix is the dielectric layer. In some embodiments, a black matrix is disposed on the distribution side of the redistribution layer and can be patterned, for example to provide access to the distribution contacts. 
     According to embodiments of the present disclosure, a pitch of the distribution contacts is greater than a pitch of the electrode contacts or an area of the distribution contacts is greater than an area of the electrode contacts. 
     According to some methods of the present disclosure, an optically transparent polymer is disposed on the support side of the redistribution layer so that the light emitters are embedded in the optically transparent polymer. 
     According to some embodiments of the present disclosure, a method of making a display comprises providing a carrier substrate, disposing a redistribution layer comprising a dielectric layer on the carrier substrate, the redistribution layer having a support side and a distribution side in contact with the carrier substrate, providing an array of light emitters, wherein each of the light emitters in the array of light emitters (i) has an emission side and an electrode side, (ii) comprises electrode contacts wherein at least one of the electrode contacts is disposed on the electrode side, and (iii) is disposed to emit light from or through the emission side when provided with power through the electrode contacts, disposing the array of light emitters on the redistribution layer so that the electrode side of each of the light emitters in the array of light emitters is adjacent to the support side, removing the carrier substrate, and forming distribution contacts on the distribution side that extend through the dielectric layer and are in electrical contact with the electrode contacts. Methods described herein can comprise disposing a layer of optically transparent polymer (e.g., optically clear mold compound) over the array of light emitters and at least partly in contact with the support side. 
     In some embodiments, methods comprise electrically connecting an electrical device to the distribution contacts. The electrical device can be disposed on, over, or in direct contact with the distribution side. Some embodiments comprise disposing a black matrix over the distribution side. 
     According to some embodiments of the present disclosure, a method of making a display comprises providing a carrier substrate, disposing a redistribution layer comprising a dielectric layer on the carrier substrate, the redistribution layer having a support side and a distribution side in contact with the carrier substrate, forming distribution contacts on the distribution side that extend through the dielectric layer, providing an array of light emitters, wherein each of the light emitters in the array of light emitters (i) has an emission side and an electrode side, (ii) comprises electrode contacts wherein at least one of the electrode contacts is disposed on the electrode side, and (iii) is disposed to emit light through the emission side when provided with power through the electrode contacts, disposing the array of light emitters on the redistribution layer so that the electrode side of each of the light emitters in the array of light emitters is adjacent to the support side and the electrode contacts are in electrical contact with the distribution contacts through the dielectric layer, and removing the carrier substrate. 
     Some methods of the present disclosure comprise disposing a layer of optically transparent polymer (e.g., optically clear mold compound) over the array of light emitters and at least partly in contact with the support side. Some embodiments comprise electrically connecting an electrical device to the distribution contacts. Some embodiments comprise disposing the electrical device on or over the distribution side. Some embodiments comprise disposing a black matrix over the distribution side. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, aspects, features, and advantages of the present disclosure will become more apparent and better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a cross section and detail illustrating embodiments of the present disclosure; 
         FIGS. 2-6  are cross sections illustrating embodiments of the present disclosure; 
         FIG. 7  is a cross section showing electrical contacts, connections, and a controller illustrating embodiments of the present disclosure; 
         FIG. 8  is an electrical schematic illustrating electrical connections useful in understanding embodiments of the present disclosure; 
         FIG. 9  is a schematic bottom view illustrating structures useful in understanding embodiments of the present disclosure; 
         FIG. 10  is a flow diagram illustrating embodiments of the present disclosure; 
         FIGS. 11A-11J  are successive cross sections illustrating construction steps according to methods of the present disclosure; 
         FIG. 12  is a flow diagram illustrating embodiments of the present disclosure; 
         FIGS. 13A-13J  are successive cross sections illustrating construction steps according to methods of the present disclosure; 
         FIG. 14  is a flow diagram illustrating embodiments of the present disclosure; and 
         FIGS. 15A-15J  are successive cross sections illustrating construction steps according to methods of the present disclosure. 
     
    
    
     The features and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The figures are not drawn to scale since the variation in size of various elements in the Figures is too great to permit depiction to scale. 
     DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS 
     Embodiments of the present disclosure provide, among other things, displays or display tiles having improved manufacturability, contrast, and flexibility. In some embodiments, an array of light emitters is embedded in a support (e.g., an optically transparent polymer support) with electrical connections to the light emitters provided at a relatively higher resolution connected to electrical connections provided in a redistribution layer (e.g., comprising a black matrix) disposed on the support at a relatively lower resolution. A local controller disposed on the redistribution layer and electrically connected through the redistribution layer to the light emitters can enable locally controlled light emitters and flexible tiles constructed with a simple and inexpensive method. 
     Referring to the cross section and detail of  FIG. 1  and the cross sections of  FIGS. 2-6 , a display  99  comprises a support  10  comprising an optically transparent polymer. Support  10  has a support back surface  14  and a support front surface  12 . Each light emitter  20  in an array  28  of light emitters  20  has an emission side  24  and an electrode side  22  and comprises electrode contacts  26 . At least one electrode contact  26  is disposed in or on electrode side  22  of light emitter  20  so that light emitters  20  emit light  60  through emission side  24  when electrical power is provided to electrode contacts  26 . Light emitters  20  are embedded in support  10  so that at least one electrode contact  26  is substantially coplanar with support back surface  14  and light emitter  20  emits light  60  through support front surface  12 . Display  99  can therefore be viewed through support front surface  12  of support  10  by an observer. By substantially coplanar is meant that at least a portion of support back surface  14  is coplanar with at least a portion of electrode contacts  26  or electrode side  22  or support  10  does not extend over electrode contacts  26  so that, with respect to support  10 , electrode contacts  26  are exposed and light emitters  20  are embedded in support  10 . As intended herein, if electrode contacts  26  are disposed on or protrude from electrode side  22  or electrode contacts  26  are indented in electrode side  22  but are exposed or otherwise accessible to other structures, they can still be “substantially coplanar” with support back surface  14 . 
     A redistribution layer  30  has a support side  32  and a distribution side  34 . Support side  32  of redistribution layer  30  is disposed on and in contact with at least a portion of support back surface  14 . Thus, electrode contacts  26  or electrode side  22  can also be substantially coplanar with support side  32  of redistribution layer  30 . Redistribution layer  30  can comprise a dielectric layer  48  and distribution contacts  36  on or in distribution side  34  that extend through dielectric layer  48 . Dielectric layer  48  can be flexible, rigid, or semi-rigid. Each of distribution contacts  36  is electrically connected to an electrode contact  26 , and can, for example, comprise electrically conductive wires  38 , for example made of metal plugs formed in vias  46  (shown in  FIG. 7  discussed below), or patterned electrically conductive metal traces disposed on or in redistribution layer  30  or support  10 . Distribution side  34  is at least partially exposed, for example one or more of distribution contacts  36  is exposed. By exposed is meant that other structures contact or could contact distribution side  34  or distribution contacts  36 , or both. Distribution contacts  36  can comprise wires  38  that extend through redistribution layer  30  or distribution contact  36  can be a unitary structure formed to extend through redistribution layer  30 . The enlargement of  FIG. 2  corresponds to  FIG. 1 . 
     The structures illustrated in  FIGS. 1-7 , for example can be relatively thin, for example less than  250  microns thick. Furthermore, the structure enables display tiles  99  with no significant bezel for a tiled display. 
     Support  10  can be a cured polymer, for example cured by heat or by ultra-violet radiation. Support  10  can be transparent, for example at least 50% (e.g., at least 60%, at least 70%, at least 80%, at least 90%, or at least 95%) transparent to visible light or light emitted by light emitters  20 , or both. Support  10  can be or comprise an optically transparent polymer (e.g., an optically transparent mold compound, an optically transparent adhesive, or an optically clear adhesive) that can be, for example, a cured optically transparent polymer formed by curing one or more liquid precursors (e.g., after coating the precursors over a substrate). Support  10  can be flexible or can be rigid or semi-rigid (e.g., sufficiently rigid to provide mechanical support to light emitters  20 ). Light emitters  20  can be adhered to as well as embedded in support  10  (e.g., when support  10  comprises an optically clear mold compound, optically transparent adhesive, or optically clear adhesive). Similarly, redistribution layer  30  can be or comprise a polymer. In some embodiments, redistribution layer  30  is or comprises an inorganic material such as a silicon oxide or nitride. Redistribution layer  30  can be patterned, for example using photolithographic methods and materials, such as a photoresist (e.g., to form vias  46  as discussed further subsequently). 
     Array  28  of light emitters  20  can comprise light emitters  20  that emit different colors of light (e.g., arranged in pixels). For example, array  28  of light emitters  20  can comprise red light emitters  20 R that emit red light, green light emitters  20 G that emit green light, and blue light emitters  20 B that emit blue light. Red, green, and blue light emitters  20 R,  20 G,  20 B are referred to herein both collectively and individually as light emitters  20 . Light emitters  20  can be, for example, inorganic light emitters such as light-emitting diodes, for example micro-LEDs. In some embodiments, micro-LEDs are micro-transfer printed and can comprise separated or broken (e.g., fractured) tethers  21  (see  FIG. 7  discussed below). Light emitters  20  can be non-native to support  10 , redistribution layer  30 , or both. Light emitters  20  can be horizontal light emitters  20  or vertical light emitters  20 . Light emitters  20  can be made in an integrated circuit process using compound semiconductors such as, for example, GaN or GaAs. Each set of red, green, and blue light emitters  20 R,  20 G,  20 B can form a pixel in display  99 . Array  28  of light emitters  20  can comprise an array of pixels. Pixels can additionally include light emitters  20  that emit light of a color other than red, green, or blue, such as, for example, yellow. Adjacent pixels can be spaced apart farther than any pair of light emitters  20  within a pixel. For a discussion of micro-transfer printing techniques that can be used to print non-native light emitters  20  to form displays  99  disclosed herein see, U.S. Pat. Nos. 8,722,458, 7,622,367 and 8,506,867, each of which is hereby incorporated by reference. 
     Electrode contacts  26  can be formed and patterned on a light emitter  20  in or on a compound semiconductor, for example by evaporative deposition and photoresist patterning of a metal such as aluminum. Electrode contacts  26  can be a designated portion of a semiconductor, such as a doped compound semiconductor, to which an electrical connection is made (e.g., with a distribution contact  36 ). Similarly, distribution contacts  36  can be formed and patterned on dielectric layer  48  and support back surface  14  of support  10 , for example by evaporative deposition and photoresist patterning of a metal, such as aluminum. 
     According to some embodiments of the present disclosure, distribution contacts  36  can have or be formed at a relatively lower resolution compared to electrode contacts  26  formed at a relatively greater resolution. For example, electrode contacts  26  can be made using photolithographic processes in an integrated circuit fabrication facility and distribution contacts  36  can be made using printed circuit board methods. “Resolution” is meant as the smallest structure dimension or structure separation on a substrate surface or the pitch between centers of repeated structures on the substrate surface in a dimension substantially parallel to the substrate surface. In some embodiments, an electrode contact pitch  42  of electrode contacts  26  (the smallest separation between the centers of two neighboring electrode contacts  26  in a dimension either within a single light emitter  20 , as shown in the  FIG. 1  detail, or between two separate neighboring light emitters  20 ) is smaller than a distribution pad pitch  44  of distribution contacts  36  (the smallest separation between the centers of two neighboring distribution contacts  36  in a dimension), as shown in  FIG. 1 . Neighboring contacts are two contacts between which there is no other contact. One or more electrode contacts  26  can have an area substantially parallel to substrate back surface  14  (or support side  32 ) that is smaller than an area of one or more distribution contacts  36  substantially parallel to distribution surface  34 . Thus, electrode contacts  26  can have an electrode area and distribution contacts  36  can have a distribution area that is greater than the electrode area. 
     As shown in  FIG. 3 , redistribution layer  30  can be or incorporate a light-absorbing dielectric material, for example redistribution layer  30  can be or comprise a black matrix  40  that is also a dielectric material  48 . Such a black matrix  40  absorbs visible light and improves the contrast of display  99  when observed by a viewer in an environment with ambient light. Black-matrix  40  can include a polymer, resin, acrylic, or curable resin, for example with cross-linking materials and can include light-absorbing particles, pigments, or dyes, for example carbon black, or black metal particles such as chromium dioxide or other metal oxides. 
     As shown in  FIG. 4 , redistribution layer  30  can comprise multiple layers including a layer of black matrix  40  and a dielectric layer  48 . Layer of black matrix  40  can also be a dielectric layer  48 . The layer of black matrix  40  can be positioned adjacent to and in contact with support back surface  14  of support  10  (as shown in  FIG. 4 ) or adjacent to and forming distribution side  34  of redistribution layer  30  (as shown in  FIG. 5 ) or between dielectric layers  48  (not shown). Referring to  FIG. 6 , black matrix  40  can be disposed over or on redistribution layer  30  as a separate layer over or on distribution contacts  36  that is patterned to expose at least a portion of one or more distribution contacts  36 . Thus, according to some embodiments, a display  99  comprises a patterned black matrix  40  disposed on distribution side  34  of redistribution layer  30  so that redistribution layer  30  is at least partially between patterned black matrix  40  and support  10 . 
     As shown in the cross section of  FIG. 7 , a display  99  according to some embodiments of the present disclosure comprises a support  10  in which is embedded light emitters  20 , for example horizontal inorganic light-emitting diodes having electrode contacts  26  on a common side of light emitters  20  and substantially flush with or slightly protruding from support back surface  14 . Horizontal inorganic light-emitting diodes can be disposed by micro-transfer printing and can comprise separated or broken (e.g., fractured) tethers  21  resulting from the particular micro-transfer printing method that is used. Horizontal light emitters  20  have at least two electrode contacts  26  disposed on a common side of the light emitter  20  (e.g., as shown in  FIG. 7 ). Light emitters  20  can be vertical light-emitting diodes with electrode contacts  26  on opposing sides of light emitter  20 . 
     Redistribution layer  30  (which can be or incorporate a black matrix  40 ) is disposed on support back surface  14 . In some embodiments, redistribution layer  30  is formed at least in part by coating a liquid (e.g., using spin, curtain hopper, or slot coating) and then curing the liquid, for example by heat or radiation. In some embodiments, the cured layer is then further processed, for example by photolithographic patterning or etching. In some embodiments, vias  46  formed in redistribution layer  30  enable distribution contacts  36  to contact electrode contacts  26  and provide electrical access to light emitters  20  from distribution side  34  of redistribution layer  30 . Vias  46  can be formed in redistribution layer  30  using photolithographic methods. Distribution contacts  36  can extend through dielectric layer  48  and are exposed on distribution side  34  of redistribution layer  30 . The portion of distribution contact  36  that extends through dielectric layer  48  can be considered a wire  38  (e.g., as labelled in  FIG. 7 ). Thus, in some embodiments of the present disclosure, redistribution layer  30  comprises vias  46  and each distribution contact  36  extends through a via  46  to make an electrical connection to an electrode contact  26 . In some embodiments, electrical conductors separate from distribution contacts  36  are disposed in vias  46  (e.g., in a multi-step process) (e.g., having a different composition). In some embodiments, a distinct wire is disposed to extend through redistribution layer  30  to electrically connect distinct distribution contacts  36  and electrode contacts  26 . In some embodiments, electrode contacts  26  protrude through redistribution layer  30  to form electrical connections to distribution contacts  36  (e.g., where redistribution layer  30  is coated and cured over support  10  and light emitters  20  at a thickness where electrode contacts  26  protrude therefrom). 
     In some embodiments, electrical structures or electrical devices  50  can be disposed over distribution side  34  of redistribution layer  30  to electrically connect to distribution contacts  36 . For example, an electrical device  50  such as an integrated circuit, a controller, a cable, or a cable connector is electrically connected to one or more of distribution contacts  36  and disposed at least partially on distribution side  34 . Electrical connections  62  (e.g., solder balls  62 ) can be disposed on distribution contacts  36  to electrically connect electrical devices  50  to light emitters  20  through electrode contacts  26  and distribution contacts  36 . Distribution pad pitch  44  (e.g., a pitch of solder balls  62 ) is larger than electrode contact pitch  42 . Electrical devices  50  can control, or provide an electrical connection to control, light emitters  20 . 
     Conventional emissive displays, for example liquid crystal displays and OLED displays, dispose a black matrix between the viewer and a light emitting device (for example, a backlight or organic light-emitting diodes). In contrast, certain embodiments of the present disclosure enable a flexible display with a black matrix  40  disposed behind light emitters  20 . Such an arrangement enables a thinner, more flexible device with reduced connection resolution. In some embodiments, when light emitters  20  are micro-transfer printed micro-light-emitting diodes (micro-LEDs) embedded in support  10 , the emissive area of light emitters  20  is relatively small (for example no more than 10%, 5%, 1%, 0.1%, or 0.01%) compared to the display area of the display, where the display area is the convex hull of light emitters  20  on support back surface  14 . Thus, black matrix  40  can effectively improve display  99  contrast ratio, especially since electrode contacts  26  and wires  38  are substantially occluded by light emitters  20  and distribution contacts  36  can be behind black matrix  40  with respect to an observer and the direction of light  60  emission. 
       FIG. 8  is a simplified electrical schematic of a display  99  illustrating distribution contacts  36  on distribution side  34  electrically connected to an electrical device  50  through matrix-addressing row and column wires  38  (thicker wires  38  represent buses).  FIG. 9  is a bottom view of support front surface  12  of support  10  illustrating light emitters  20  embedded in support  10 , distribution contacts  36 , and electrical device  50  on a side of support  10  opposite support front surface  12 . 
     The flow diagram of  FIG. 10  and successive cross sections of  FIGS. 11A-11J  illustrate methods of the present disclosure. Referring first to  FIG. 11A  a carrier substrate  70  is provided in step  100  and an array  28  of light emitters  20  is provided in step  110 , for example on a source substrate. Each light emitter  20  on a source substrate can be disposed over a sacrificial portion of a source substrate and physically connected to the source substrate by a tether  21  attached to an anchor (e.g., one or more tethers  21  to each of one or more respective anchors). Carrier substrate  70  can be, for example, a glass or semiconductor wafer or substrate and can comprise an adhesive layer (not shown). Light emitters  20  are disposed on carrier substrate  70  in step  120  so that electrode contacts  26  are adjacent to carrier substrate  70 , as shown in  FIG. 11B , for example by micro-transfer printing light emitters  20  from a source substrate to carrier substrate  70 . Light emitters  20  have an electrode side  22  with electrode contacts  26  and an emission side  24  through which light  60  is emitted when power is provided to electrode contacts  26 . Electrode side  22  is disposed in contact with, or adjacent to, carrier substrate  70 . In step  130 , and as shown in  FIG. 11C , mold compound  10  is coated over light emitters  20  and carrier substrate  70 , for example as a liquid by spray, spin, curtain hopper, or other coating means and then cured, for example by heat or radiation, such as ultra-violet radiation. Mold compound  10  can be provided as a liquid and then cured after coating to form a support  10  with a support front surface  12  and a support back surface  14 . An optional temporary support, such as a glass stiffener, can be adhered, for example with a temporary adhesive, to mold compound  10  to provide additional mechanical strength and support for the following construction steps and removed at the end of the process, for example if necessary or desired (not shown). 
     As shown in  FIG. 11D , in step  140  carrier substrate  70  is removed, for example by lift-off, etching, peeling, polishing, or grinding. In some embodiments, carrier substrate  70  comprises an ablation layer and removal is accomplished by laser ablation. Referring to  FIG. 11E , in step  150  electrode side  22  is coated to form a redistribution layer  30  having a support side  32  and a distribution side  34 , for example by spray, spin, hopper, or other coating means, on support back surface  14  so that support back surface  14  is substantially co-planar with electrode side  22  of light emitter  20 . Redistribution layer  30  can be or comprise a black matrix  40 , for example as shown in  FIGS. 3 and 11E , or can be a multi-layer structure formed in multiple coating steps and incorporating a dielectric layer  48  and black matrix  40 , as shown in  FIGS. 4 and 5 . Thus, in some embodiments, a black matrix  40  is disposed over support back surface  14  and a dielectric layer  48  is disposed over black matrix  40 , to form redistribution layer  30 . In some embodiments, a dielectric layer  48  is disposed over support back surface  14  and a black matrix  40  is disposed over dielectric layer  48 , to form redistribution layer  30 . In some embodiments, redistribution layer  30  is substantially transparent, for example as shown in  FIGS. 1 and 2 . 
     In step  160  and as shown in  FIG. 11F , vias  46  are formed extending through redistribution layer  30 , for example using photoresist and photolithography. As shown in  FIG. 11G , vias  46  are filled with a distribution conductor  35 , for example an electrically conductive material, for example, a metal such as aluminum, cured conductive inks, or transparent conductive oxides deposited by evaporation, sputtering, ink jetting, or coating, and electrically connected to electrode contacts  26  and patterned, in step  170  and as shown in  FIG. 11H , for example with photoresist using photolithographic processes to form distribution contacts  36  that are at least partially exposed. Portions of redistribution layer  30  can be at least partially exposed. 
     In some embodiments, electrical connections  62 , such as solder balls  62 , are deposited on distribution contacts  36  in step  180  and as shown (inverted) in  FIG. 11I , for example using solder bumping methods. The distribution or pitch of solder balls  62  can be at a relatively lower resolution than a relatively higher resolution or pitch of electrode contacts  26 . An electrical device  50 , such as a controller, ribbon cable with an anisotropic conductive film, or cable connector, can be soldered to solder balls  62 , in step  190  and as shown in  FIG. 11J  using conventional soldering methods. Any optional temporary support that was provided (not shown) can be removed, for example by peeling or laser lift-off. Thus, relatively high-resolution electrode contacts  26  are redistributed to relatively low-resolution distribution contacts  36 , solder balls  62  (e.g., any solder connection), and electrical connections  62  to electrical devices  50  such as integrated circuits, connectors, or cables. An electrical device  50  can control or provide electrical connections  62  to light emitters  20  through distribution contacts  36 , any wires  38 , and electrode contacts  26 . According to some embodiments of the present disclosure, a black matrix  40  is patterned on distribution side  34  after disposing redistribution layer  30  and forming distribution contacts  36  (e.g., as shown in  FIG. 6 ) to expose distribution contacts  36 . 
     In some embodiments of the present disclosure and as shown, for example, in  FIG. 3 , a display  99  comprises a support  10  having a support back surface  14  and a support front surface  12 . An array  28  of light emitters  20  is disposed on support front surface  12  or embedded in support  10  with electrode contacts  26  substantially coplanar with support back surface  14 . Each light emitter  20  emits light  60  away from support back surface  14  and, in some embodiments, through support front surface  12 . Optionally, a black matrix  40  is disposed on a side of support back surface  14  opposite support front surface  12 . In some embodiments, array  28  of light emitters  20  is disposed on support front surface  12  (not shown). In some embodiments, each of light emitters  20  in array  28  of light emitters  20  (i) has an emission side  24  and an electrode side  22 , (ii) comprises electrode contacts  26  wherein at least one electrode contact  26  is disposed on electrode side  22 , and (iii) is embedded in support  10  so that the at least one electrode contact  26  is substantially coplanar with support back surface  14 , and (iv) emits light  60  through emission side  24  when provided with power through electrode contacts  26 . 
     In some embodiments, display  99  comprises a redistribution layer  30  having a support side  32  and a distribution side  34 . Support side  32  is disposed on and in contact with at least a portion of support back surface  14 . Redistribution layer  30  can comprise a dielectric layer  48 . Distribution contacts  36  on distribution side  34  can extend through dielectric layer  48  (e.g., through vias  46  formed in dielectric layer  48 ). Each distribution contact  36  is electrically connected to an electrode contact  26  and distribution side  34  is at least partially exposed as can be distribution contacts  36 . An electrical device  50 , for example any one or combination of a controller, a cable, and a cable connector, is electrically connected to one or more of distribution contacts  36  and disposed at least partially on distribution side  34 . In some embodiments, black matrix  40  is patterned and redistribution layer  30  comprises patterned black matrix  40 . In some embodiments, redistribution layer  30  is at least partially between black matrix  40  and support back surface  14 . 
     According to some embodiments of the present disclosure, and as illustrated, for example, in the flow diagram of  FIG. 12  and successive structural cross sections of  FIGS. 13A-13J , a method of making a display  99  comprises providing a carrier substrate  70  in step  100  as shown in  FIG. 13A  and disposing or forming a redistribution layer  30  comprising a dielectric layer  48  on carrier substrate  70  in step  150  as shown in  FIG. 13B . 
     Redistribution layer  30  can have a support side  32  and a distribution side  34  where the distribution side  34  is in contact with carrier substrate  70 . In step  110 , an array  28  of light emitters  20  is provided, for example on one or more source substrates. Each light emitter  20  on a source substrate can be disposed over a sacrificial portion of the source substrate and physically connected to the source substrate by a tether attached to an anchor (e.g., one or more tethers  21  to each of one or more respective anchors). Each light emitter  20  in array  28  of light emitters  20  (i) has an emission side  24  and an electrode side  22 , (ii) comprises electrode contacts  26  wherein at least one electrode contact  26  is disposed on electrode side  22 , and (iii) emits light  60  through emission side  24  when provided with power through electrode contacts  26 . Array  28  of light emitters  20  is disposed in step  120  on redistribution layer  30 , for example by micro-transfer printing, as shown in  FIG. 13C  so that electrode side  22  of each of light emitters  20  in array  28  of light emitters  20  is adjacent to support side  32 . Optionally, in step  130  and as shown in  FIG. 13D , mold compound  10  is coated over light emitters  20  and support side  32  of redistribution layer  30 . In some embodiments, step  130  can be performed after any one of the following steps. An optional temporary support can be adhered, for example with a temporary adhesive, to mold compound  10  to provide additional mechanical strength and support for the following construction steps and removed at the end of the process, if necessary (not shown). 
     Carrier substrate  70  can be removed in step  140  and as shown in  FIG. 13E , and distribution contacts  36  formed on distribution side  34  that extend through dielectric layer  48  and are in electrical contact with electrode contacts  26 , for example by forming vias  46  in step  160  as shown in  FIG. 13F  and forming wires  38  and distribution contacts  36  (e.g., where wires  38  are portions of distribution contacts  36 ) in step  170 , for example by coating a distribution conductor  35  over distribution side  34  and vias  46  as shown in  FIG. 13G , and then patterning distribution conductor  35  to form distribution contacts  36 , for example using photoresist and photolithographic methods, as shown in  FIG. 13H . 
     In some embodiments, electrical connection materials, such as solder balls  62 , are deposited on distribution contacts  36  in step  180  and as shown (inverted) in  FIG. 131 , for example using solder bumping methods. The distribution of solder balls  62  can be at a lower resolution or pitch than a resolution or pitch of electrode contacts  26 . An electrical device  50 , such as a controller, ribbon cable, or cable connector, can be soldered to solder balls  62 , in step  190  and as shown in  FIG. 13J  using conventional soldering methods. Any optional temporary support that was provided (not shown) can be removed, for example by peeling or laser lift-off. Thus, relatively high-resolution electrode contacts  26  are redistributed to relatively low-resolution distribution contacts  36 , solder balls  62  (e.g., any solder connection), and electrical connections  62  to electrical devices  50  such as integrated circuits, connectors, or cables. An electrical device  50  can control or provide electrical connections  62  to light emitters  20  through distribution contacts  36 , any wires  38 , and electrode contacts  26 . According to some embodiments of the present disclosure, a black matrix  40  is disposed and patterned on distribution side  34  after disposing redistribution layer  30  and forming distribution contacts  36  (e.g., as shown in  FIG. 6 ). In some embodiments, a black matrix  40  is disposed over distribution side  34  for example before steps  180  and  190 . Black matrix  40  can be patterned similarly to distribution conductor  35  or redistribution layer  30  (e.g., as shown in  FIG. 6 ) to enable electrical contact to distribution contacts  36 . 
       FIGS. 13E-13J  and associated process steps can be identical to the process steps of  FIGS. 11E-11J  and the structures can be the same, but are not necessarily so. The process of  FIG. 12  differs from the process of  FIG. 10  by forming redistribution layer  30  before disposing mold compound  10 . The choice of methods can be a matter of design choice. 
     According to some embodiments of the present disclosure, a display  99  comprises a redistribution layer  30  comprising a dielectric layer  48 . Redistribution layer  30  can have a distribution side  34  and a support side  32  and distribution contacts  36  disposed at least partially on distribution side  34 . An array  28  of light emitters  20  is disposed on support side  32 . Each light emitter  20  in array  28  of light emitters  20  (i) has an emission side  24  and an electrode side  22 , (ii) comprises electrode contacts  26  wherein at least one electrode contact  26  is disposed in or on electrode side  22  and electrode contacts  26  are electrically connected to distribution contacts  36  through dielectric layer  48 , (iii) electrode side  22  is in contact with support side  32 , and (iv) each light emitter  20  emits light  60  away from redistribution layer  30  when provided with power through electrode contacts  26 . 
     In some embodiments, redistribution layer  30  comprises a black matrix  40  and a distinct dielectric layer  48  or comprises a black matrix  40 , for example in layered combinations with dielectric layer  48  (e.g., as shown in  FIGS. 4 and 5 ). As shown in  FIG. 6 , in some embodiments display  99  comprises a black matrix  40  disposed on distribution side  34  of redistribution layer  30 . In some embodiments, a pitch of distribution contacts  36  is greater than a pitch of electrode contacts  26 . In some embodiments, a pitch of electrical connections  62  (solder balls  62 ) is greater than a pitch of electrode contacts  26 . More generally, in some embodiments electrical connections  62  made to distribution contacts  36  on distribution side  34  have a greater pitch than a pitch of electrode contacts  26 . In some embodiments, an optically transparent polymer (e.g., mold compound  10  or support  10 ) is disposed on support side  32  of redistribution layer  30  and light emitters  20  so that light emitters  20  are embedded in the optically transparent polymer. 
     According to some embodiments of the present disclosure and as illustrated in the flow diagram of  FIG. 14  and successive structural cross sections of  FIGS. 15A-15J , a method of making a display  99  comprises providing a carrier substrate  70  in step  100  as shown in  FIG. 15A , disposing or forming a redistribution layer  30  comprising a dielectric layer  48  on carrier substrate  70  in step  150  as shown in  FIG. 15B . Redistribution layer  30  can have a support side  32  and a distribution side  34  where support side  32  is in contact with carrier substrate  70 . 
     Distribution contacts  36  can be formed on distribution side  34  that extend through dielectric layer  48 , for example by forming vias  46  in step  160  as shown in  FIG. 15C  and forming wires  38  and distribution contacts  36  in step  170 , for example by coating a distribution conductor  35  over distribution side  34  and vias  46  as shown in  FIG. 15D , and then patterning distribution conductor  35  to form distribution contacts  36 , for example using photoresist and photolithographic methods, as shown in  FIG. 15E . 
     In some embodiments, electrical connection materials, such as solder balls  62 , are deposited on distribution contacts  36  in step  180  and as shown (inverted) in  FIG. 15F , for example using solder bumping methods. The distribution of solder balls  62  can be at a lower resolution than a resolution of electrode contacts  26 . An electrical device  50 , such as a controller, ribbon cable, or cable connector, can be soldered to solder balls  62 , in step  190  and as shown in  FIG. 15G  using conventional soldering methods. Any optional temporary support that was provided (not shown) can be removed, for example by peeling or laser lift-off. Thus, relatively high-resolution electrode contacts  26  are redistributed to relatively low-resolution distribution contacts  36 , solder balls  62  (e.g., any solder connection), and electrical connections  62  to electrical devices  50  such as integrated circuits, connectors, or cables. An electrical device  50  can control or provide electrical connections  62  to light emitters  20  through distribution contacts  36 , any wires  38 , and electrode contacts  26 . A controller can provide electrical power, electrical signals, or both to control light emitters  20 . According to some embodiments of the present disclosure, a black matrix  40  is patterned on distribution side  34  after disposing redistribution layer  30  (e.g., as shown in  FIG. 6 ). In some embodiments, a black matrix  40  is disposed over distribution side  34  for example before steps  180  and  190 . Black matrix  40  can be patterned similarly to distribution conductor  35  or redistribution layer  30  (e.g., as shown in  FIG. 6 ) to enable electrical contact to distribution contacts  36 . In embodiments, steps  180  and  190  can be performed after any one of the following steps. 
     Carrier substrate  70  can be removed in step  140  and as shown in  FIG. 15H . In embodiments, carrier substrate  70  can be removed after any prior step after step  150 . An optional temporary support can be adhered, for example with a temporary adhesive, to support side  32  of redistribution layer  30  to provide additional mechanical strength and support for the following construction steps and removed before step  110  (described below), if necessary (not shown). 
     In step  110 , an array  28  of light emitters  20  is provided, for example on one or more source substrates. Each light emitter  20  on a source substrate can be disposed over a sacrificial portion of the source substrate and physically connected to the source substrate by a tether attached to an anchor. Each light emitter  20  in array  28  of light emitters  20  (i) has an emission side  24  and an electrode side  22 , (ii) comprises electrode contacts  26  wherein at least one electrode contact  26  is disposed on electrode side  22 , and (iii) emits light  60  through emission side  24  when provided with power through electrode contacts  26 . Array  28  of light emitters  20  is disposed in step  120  on redistribution layer  30  as shown in  FIG. 151  (inverted), for example by micro-transfer printing, so that electrode side  22  of each of light emitters  20  in array  28  of light emitters  20  is adjacent to support side  32  and distribution contacts  36  are in electrical contact with electrode contacts  26 . Optionally, in step  130  and as shown in  FIG. 15J , mold compound  10  is coated over light emitters  20  and support side  32  of redistribution layer  30 . 
     The process steps associated with  FIGS. 15A-15J  can be identical to steps described above and the structures can be the same, but are not necessarily so. The processes differ by patterning redistribution layer  30  before light emitters  20  or mold compound  10  is disposed. The choice of methods can be a matter of design choice. Those knowledgeable in the art will recognize that the steps described above (e.g., steps  100 - 190 ) can be, in some cases, performed in different orders and at different times and methods using such different orders are expressly contemplated in the present disclosure. 
     A further discussion of utilizing micro-assembly techniques (e.g., micro-transfer printing techniques) to assemble light emitters  20  in a display  99  that can be used in or adapted for use with some embodiments of the present disclosure can be found in U.S. patent application Ser. No. 14/822,868 filed Aug. 10, 2014, entitled  Compound Micro - Assembly Strategies and Devices , the contents of which are incorporated by reference herein in its entirety. A discussion of micro-LEDs and micro-LED displays that can be used in or adapted for use in the present disclosure can be found in U.S. patent application Ser. No. 14/743,981, filed Jun. 18, 2015, entitled  Micro Assembled Micro LED Displays and Lighting Elements , which is hereby incorporated by reference in its entirety. 
     A display  99  can be operated in a variety of useful ways. In one way, a controller (e.g., electrical device  50 ) provides power, a ground reference, and control signals to light emitters  20  through electrical connections  62  (e.g., solder balls  62 ), distribution contacts  36 , any wires  38 , and electrode contacts  26 . The signals can provide a passive-matrix or active-matrix control of light emitters  20  in array  28 . Light emitters  20  can be arranged in pixels and controlled as pixels in a display  99  (e.g., which is a display tile  99  in a larger display  99 ). In some embodiments, the pixels are controlled by electrical device  50  as an active-matrix or passive-matrix display  99 . Electrical device  50  is connected to light emitters  20  through electrical connections  62  and distribution contacts  36  (for example at a relatively lower resolution), wires  38 , and electrode contacts  26  (for example at a relatively higher resolution). In response to control signals from electrical device  50 , light emitters  20  emit light, for example in an active-matrix or passive-matrix control configuration. Electrical devices  50  can receive control, power, or ground signals from an external display controller or other controller (not shown in the Figures) for example through cables or cable connectors. 
     Support  10  emission side  24  can comprise or be coated with one or more of an anti-reflection layer, a protective layer, and an encapsulating layer (not shown in the Figures). Support  10  can comprise optical structures, such as, for example, lenslets or light-scattering materials, molded into support  10  or applied to support  10 , for example to modify the optical characteristics of light  60  emitted from display  99 . Support  10  can have a size of a conventional display or display tile, for example a rectangle with a diagonal length of a few centimeters to one or more meters and a thickness of 50 microns to 10 mm or even more. Before, after, or at the same time, light emitters  20  (e.g. micro-LEDs) can be provided in step  110 , using conventional photolithographic integrated-circuit processes on semiconductor substrates. Light emitters  20  that are micro-LEDs having semiconductor substrates can be much smaller than and separate, individual, discrete, and distinct from the support  10  or redistribution layer  30  and can include different materials. 
     As is understood by those skilled in the art, the terms “on,” “over” and “under” are relative terms and can be interchanged in reference to different orientations of the layers, elements, and substrates included in the present invention. For example, a first layer on a second layer, in some implementations means a first layer directly on and in contact with a second layer. In other implementations, a first layer on a second layer includes a first layer and a second layer with another layer therebetween. 
     In this application, unless otherwise clear from context or otherwise explicitly stated, (i) the term “a” may be understood to mean “at least one”; (ii) the term “or” may be understood to mean “and/or”; (iii) the terms “comprising” and “including” may be understood to encompass itemized components or steps whether presented by themselves or together with one or more additional components or steps; (iv) the terms “about” and “approximately” may be understood to permit standard variation as would be understood by those of ordinary skill in the relevant art; and (v) where ranges are provided, endpoints are included. 
     Throughout the description, where apparatus and systems are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are apparatus, and systems of the disclosed technology that consist essentially of, or consist of, the recited components, and that there are processes and methods according to the disclosed technology that consist essentially of, or consist of, the recited processing steps. 
     It should be understood that the order of steps or order for performing certain action is immaterial so long as operability is maintained. Moreover, two or more steps or actions can be conducted simultaneously in some embodiments. The disclosure has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the claimed invention. 
     PARTS LIST 
       10  support/mold compound 
       12  support front surface 
       14  support back surface 
       20  light emitter 
       20 R red-light emitter 
       20 G green-light emitter 
       20 B blue-light emitter 
       21  tether 
       22  electrode side 
       24  emission side 
       26  electrode contact 
       28  array 
       30  redistribution layer 
       32  support side 
       34  distribution side 
       35  distribution conductor 
       36  distribution contact 
       38  wire 
       40  black matrix 
       42  electrode contact pitch 
       44  distribution pad pitch 
       46  via 
       48  dielectric layer 
       50  electrical device 
       60  light 
       62  electrical connection/solder ball 
       70  carrier substrate 
       99  display/display tile 
       100  provide carrier substrate step 
       110  provide array of light emitters step 
       120  dispose light emitters on carrier substrate step 
       130  dispose mold compound on light emitters step 
       140  remove carrier substrate step 
       150  coat electrode side step 
       160  form vias step 
       170  form wires and distribution contacts step 
       180  dispose connections step 
       190  connect controller to distribution contacts step