Hybrid display

Abstract

This invention relates to hybrid displays, providing a hybrid pixel arrangement for a full-color display, comprising an inorganic LED in at least one sub-pixel and an organic emission stack in at least one other sub-pixel. In an embodiment, a first sub-pixel is configured to emit a first color and includes an inorganic LED; a second sub-pixel is configured to emit a second color and includes a first portion of a first organic emission stack configured to emit an initial color different from the first color; a third sub-pixel is configured to emit a third color different from the initial color and includes a second portion of the first organic emission stack and a first color-changing layer disposed in a stacked manner with the second portion of the first organic emission stack.

Description

[0001] Divisional application information

[0002] This application is a divisional application of the invention patent application filed on July 1, 2016, with application number "201610515769.6" and invention title "Hybrid Display".

[0003] Parties to the Joint Research Agreement

[0004] The claimed invention was made by one or more of the following parties who entered into a joint university-corporation research agreement, in the name of one or more of the following parties and / or in conjunction with one or more of the following parties: the University of Michigan Board of Trustees, Princeton University, the University of Southern California, and Universal Display Corporation. The agreement was effective on or before the date on which the claimed invention was made, and the claimed invention was made as a result of activities carried out within the scope of the agreement. Technical Field

[0005] The present invention relates to devices that include both OLEDs and inorganic light-emitting diodes or devices (LEDs), such as full-color displays, and other devices that include said devices. Background Technology

[0006] Optoelectronic devices utilizing organic materials are becoming increasingly popular for several reasons. Many of the materials used to manufacture such devices are relatively inexpensive, thus organic optoelectronic devices have the potential to achieve a cost advantage over inorganic devices. Furthermore, the inherent properties of organic materials, such as their flexibility, make them well-suited for specific applications, such as fabrication on flexible substrates. Examples of organic optoelectronic devices include organic light-emitting diodes / devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, organic materials can offer performance advantages over conventional materials. For instance, the wavelength of light emitted by an organic emitting layer can often be easily tuned using appropriate dopants.

[0007] OLEDs utilize organic thin films that emit light when a voltage is applied to the device. OLEDs are becoming an increasingly prominent technology for applications such as flat panel displays, lighting, and backlighting. Several OLED materials and configurations are described in U.S. Patents 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

[0008] One application of phosphorescent emitting molecules is in full-color displays. Industry standards for such displays require pixels suitable for emitting specific colors (called "saturated" colors). Specifically, these standards require saturated red, green, and blue pixels. Color can be measured using the CIE coordinate system, well-known in the art.

[0009] An example of a green emitting molecule is tris(2-phenylpyridine)iridium, denoted as Ir(ppy)3, which has the following structure:

[0010]

[0011] In this figure and in the figures later in this article, the valence bond from nitrogen to the metal (here, Ir) is depicted as a straight line.

[0012] As used herein, the term "organic" includes polymeric materials as well as small-molecule organic materials that can be used to manufacture organic optoelectronic devices. "Small molecule" refers to any organic material that is not a polymer, and "small molecule" can actually be quite large. In some cases, small molecules can include repeating units. For example, using long-chain alkyl groups as substituents does not remove the molecule from the "small molecule" category. Small molecules can also be incorporated into polymers, for example, as side groups on the polymer backbone or as part of the backbone. Small molecules can also act as the core portion of dendritic polymers, which consist of a series of chemical shells built upon the core portion. The core portion of a dendritic polymer can be a fluorescent or phosphorescent small-molecule emitter. Dendritic polymers can be "small molecules," and it is believed that all dendritic polymers currently used in the OLED field are small molecules.

[0013] As used herein, "top" means furthest from the substrate, and "bottom" means closest to the substrate. When the first layer is described as being "placed" "on" the second layer, the first layer is positioned further from the substrate. Unless it is specified that the first layer "contacts" the second layer, other layers may exist between the first and second layers. For example, even if various organic layers exist between the cathode and anode, the cathode may still be described as being "placed" "on" the anode.

[0014] As used herein, “solution-handleable” means capable of being dissolved, dispersed or transported in and / or deposited from a liquid medium in the form of a solution or suspension.

[0015] When a ligand is believed to directly contribute to the photosensitivity of the emitting material, the ligand can be called "photosensitive." When a ligand is believed not to contribute to the photosensitivity of the emitting material, the ligand can be called "auxiliary," but auxiliary ligands can alter the properties of photosensitivity ligands.

[0016] As used herein, and as will be understood by those skilled in the art, if a first energy level is closer to the vacuum level, then the first “highest occupied molecular orbital” (HOMO) or “lowest unoccupied molecular orbital” (LUMO) level is “greater” or “higher” than the second HOMO or LUMO level. Since the ionization potential (IP) is measured as a negative energy relative to the vacuum level, a higher HOMO level corresponds to a smaller absolute value of IP (less negative IP). Similarly, a higher LUMO level corresponds to a smaller absolute value of electron affinity (EA) (less negative EA). On a conventional energy level diagram, the vacuum level is at the top, and the LUMO levels of a material are higher than the HOMO levels of the same material. A “higher” HOMO or LUMO level appears to be closer to the top of this diagram than a “lower” HOMO or LUMO level.

[0017] As used herein, and as will be understood by those skilled in the art, if the first work function has a higher absolute value, then the first work function is “greater” or “higher” than the second work function. This is because work functions are typically measured as negative numbers relative to the vacuum level, thus implying that the “higher” work function is more negative. On a conventional energy level diagram, the vacuum level is at the top, and a “higher” work function is described as being farther from the vacuum level in the downward direction. Therefore, the definitions of HOMO and LUMO levels follow a different convention than those for work functions.

[0018] This document may describe light emitted by layers, materials, areas, and devices in terms of color. Generally, as used herein, an emitting component that produces a specific color of light may include one or more emitting layers arranged in a stacked manner on top of each other.

[0019] As used herein, a "red" layer, material, region, or device refers to a layer, material, region, or device that emits light in the range of approximately 580 nm to 700 nm; a "green" layer, material, region, or device refers to a layer, material, region, or device whose emission spectrum has a peak wavelength in the range of approximately 500 nm to 600 nm; a "blue" layer, material, or device refers to a layer, material, or device whose emission spectrum has a peak wavelength in the range of approximately 400 nm to 500 nm; and a "yellow" layer, material, region, or device refers to a layer, material, region, or device whose emission spectrum has a peak wavelength in the range of approximately 540 nm to approximately 600 nm. In some arrangements, separate layers, materials, regions, or devices may provide separate "dark blue" and "light blue" light. As used herein, in an arrangement providing separate "light blue" and "dark blue" light components, the "dark blue" component refers to a component whose peak emission wavelength is at least approximately 4 nm smaller than the peak emission wavelength of the "light blue" component. Typically, the peak emission wavelength of the "light blue" component is in the range of approximately 465 nm to 500 nm, and the peak emission wavelength of the "dark blue" component is in the range of approximately 400 nm to 470 nm, although these ranges can vary for some configurations. Similarly, a color-changing layer refers to a layer that converts or modifies light of another color to have a wavelength specified for that color. For example, a "red" filter is a filter that forms light with wavelengths in the range of approximately 580 nm to 700 nm. Generally, there are two types of color-changing layers: filters that modify the spectrum by removing unwanted wavelengths of light, and color-changing layers that convert higher-energy photons into lower-energy ones.

[0020] Further details regarding OLEDs and the definitions described above can be found in U.S. Patent No. 7,279,704, which is incorporated herein by reference in its entirety. Summary of the Invention

[0021] According to an embodiment, a pixel arrangement includes: a first sub-pixel configured to emit a first color, the first sub-pixel comprising an inorganic light-emitting diode (LED), the LED being a micro-LED; a second sub-pixel configured to emit a second color, the second sub-pixel comprising a first portion of a first organic emission stack configured to emit an initial color different from the first color; and a third sub-pixel configured to emit a third color different from the initial color. The third sub-pixel may include a second portion of the first organic emission stack and a first color-changing layer disposed in a stacked manner with the second portion of the first organic emission stack. The second color may be the initial color, such as yellow. The first color may be blue.

[0022] The first organic emitting stack may include a single organic emitting layer, or may include multiple organic emitting layers. Each layer may include one or more emitting materials that emit light of the same or different colors. The arrangement may include LEDs of only the first color. The first sub-pixel may include multiple LEDs configured to emit the first color, the multiple LEDs being connected in series, in parallel, or in a combination thereof.

[0023] LEDs can be stacked with a third portion of the first organic emission stack, for example, where the organic emission stack is an unpatterned stack.

[0024] The arrangement may include a fourth sub-pixel configured to emit a fourth color different from the initial color, wherein the fourth sub-pixel includes a third portion of a first organic emission stack and a second color-changing layer disposed in a stacked manner with the third portion of the first organic emission stack.

[0025] The pixel arrangement may include a plurality of pixels, each comprising sub-pixels of at least three, four, or more colors. Each sub-pixel containing one or more LEDs may be a sub-pixel of at least two of the plurality of pixels; that is, sub-pixels may be shared among the plurality of pixels. The resolution of the sub-pixels containing LEDs in the arrangement may be less than the pixel resolution of the arrangement.

[0026] The arrangement may include one or more base plates, each of which may be a passive or active matrix. A first base plate may be configured to drive a first sub-pixel and / or drive each of a second and third sub-pixels, or a second base plate may be configured to drive each of a second and third sub-pixels.

[0027] The first sub-pixel may be disposed on the first substrate, and each of the second and third sub-pixels may be disposed on the second substrate. The first substrate may provide a protective cover for each of the second and third sub-pixels. One or both of the substrates may be transparent and / or flexible.

[0028] At least one of the first sub-pixel and the second sub-pixel may include a top-emitting OLED or a bottom-emitting OLED, which includes a first portion of a first organic emission stack.

[0029] In one embodiment, a pixel arrangement for a light-emitting device includes: a first sub-pixel configured to emit a first color, the first sub-pixel including a plurality of inorganic LEDs electrically connected in parallel to each other; and a second sub-pixel configured to emit a second color different from the first color, the second sub-pixel including an OLED.

[0030] In one embodiment, a lighting device includes: a plurality of blue inorganic LEDs disposed in a region defining a first plane; and an unpatterned yellow organic emission stack disposed in a second plane parallel to the first plane. The yellow organic emission stack may be transparent and, during operation of the device, blue light generated by the inorganic LEDs can be transmitted through the yellow organic emission stack. Attached Figure Description

[0031] Figure 1 An organic light-emitting device was displayed.

[0032] Figure 2 An inverted organic light-emitting device without a separate electron transport layer was demonstrated.

[0033] Figure 3 A cross-sectional view of an example hybrid display in a top-launch configuration as disclosed herein is shown.

[0034] Figure 4 An example schematic pixel arrangement according to the embodiments disclosed herein is shown.

[0035] Figure 5 Examples of power consumption are shown for conventional displays as well as for various hybrid displays as disclosed herein. Detailed Implementation

[0036] Generally, an OLED comprises at least one organic layer disposed between and electrically connected to the anode and cathode. When a current is applied, holes are injected into the anode and electrons into the organic layer at the cathode. The injected holes and electrons migrate toward the electrodes with opposite charges. When electrons and holes are confined to the same molecule, "excitons" are formed, which are localized electron-hole pairs with excited energy states. When excitons relax via photoemission mechanisms, light is emitted. In some cases, excitons may be confined to polarons or excited-state complexes. Non-radiative mechanisms (such as thermal relaxation) may also occur, but are generally considered undesirable.

[0037] Early OLEDs used emitting molecules that emitted light from a single state (“fluorescence”), as disclosed, for example, in U.S. Patent No. 4,769,292, which is incorporated herein by reference in its entirety. Fluorescence emission typically occurs in timeframes of less than 10 nanoseconds.

[0038] Recently, OLEDs with emitting materials that emit light from the triplet state (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, Vol. 395, pp. 151–154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., Vol. 75, No. 3, pp. 4–6 (1999) (“Baldo-II”), are incorporated herein by reference in their entirety. Phosphorescence is described in more detail in columns 5–6 of U.S. Patent No. 7,279,704, which is incorporated herein by reference.

[0039] Figure 1 An organic light-emitting device 100 is shown. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emission layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, a cathode 160, and a barrier layer 170. The cathode 160 is a composite cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 can be fabricated by sequentially depositing the described layers. The properties and functions of these various layers, as well as the example materials, are described in more detail in columns 6-10 of US 7,279,704, which is incorporated by reference.

[0040] There are numerous examples of each of these layers. For instance, a flexible and transparent substrate-anode combination is disclosed in U.S. Patent No. 5,844,363, which is incorporated herein by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003 / 0230980, which is incorporated herein by reference in its entirety. Examples of emitter and host materials are disclosed in U.S. Patent No. 6,303,238 to Thompson et al., which is incorporated herein by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003 / 0230980, which is incorporated herein by reference in its entirety. Examples of cathodes are disclosed in U.S. Patent Nos. 5,703,436 and 5,707,745, which are incorporated herein by reference in their entirety. These cathodes comprise composite cathodes having a thin metal layer, such as Mg:Ag, overlaid with a transparent, conductive, sputter-deposited ITO layer. The principles and use of barrier layers are described in more detail in U.S. Patent No. 6,097,147 and U.S. Patent Application Publication No. 2003 / 0230980, which are also incorporated herein by reference in their entirety. Examples of implantation layers are provided in U.S. Patent Application Publication No. 2004 / 0174116, which is also incorporated herein by reference in its entirety. A description of protective layers can be found in U.S. Patent Application Publication No. 2004 / 0174116, which is also incorporated herein by reference in its entirety.

[0041] Figure 2 An inverted OLED 200 is shown. The device includes a substrate 210, a cathode 215, an emitter layer 220, a hole transport layer 225, and an anode 230. The device 200 can be fabricated by sequentially depositing the layers described herein. Because the most common OLED configuration has a cathode disposed on the anode, and the device 200 has a cathode 215 disposed beneath the anode 230, the device 200 can be referred to as an "inverted" OLED. Materials similar to those described with respect to device 100 can be used in the corresponding layers of the device 200. Figure 2 An example is provided of how some layers can be omitted from the structure of device 100.

[0042] Figure 1 and 2The simple layered structures described herein are provided as non-limiting examples, and it should be understood that embodiments of the invention can be used in combination with a wide variety of other structures. The specific materials and structures described are exemplary in nature, and other materials and structures can be used. A functional OLED can be realized by combining the described layers in different ways based on design, performance, and cost factors, or several layers can be omitted entirely. Other layers not specifically described may also be included. Materials different from those specifically described may be used. Although many examples provided herein describe various layers as comprising a single material, it should be understood that combinations of materials (e.g., mixtures of host and dopant) or more generally, mixtures may be used. Furthermore, the layers may have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. For example, in device 200, hole transport layer 225 transports holes and injects holes into emitter layer 220, and may be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED may be described as having an “organic layer” disposed between a cathode and an anode. This organic layer may comprise a single layer, or may further comprise, for example, regarding Figure 1 and 2 Multiple layers of different organic materials are described.

[0043] Structures and materials not specifically described can also be used, such as OLEDs (PLEDs) containing polymeric materials, as disclosed in, for example, U.S. Patent No. 5,247,190 to Friend et al., which is incorporated herein by reference in its entirety. As another example, an OLED with a single organic layer can be used. OLEDs can be stacked, as described, for example, in No. 5,707,745 to Forrest et al., which is incorporated herein by reference in its entirety. The OLED structure can be detached... Figure 1 and 2 The simple layered structure described herein. For example, the substrate may include angled reflective surfaces to improve out-coupling, such as the tabletop structure as described in U.S. Patent No. 6,091,195 to Forrest et al., and / or the recessed structure as described in U.S. Patent No. 5,834,893 to Bulovic et al., all of which are incorporated herein by reference in their entirety.

[0044] Unless otherwise specified, any of the layers in the various embodiments can be deposited by any suitable method. For organic layers, preferred methods include thermal evaporation, inkjet printing (e.g., as described in U.S. Patent Nos. 6,013,982 and 6,087,196, which are incorporated herein by reference in their entirety), organic vapor deposition (OVPD) (e.g., as described in U.S. Patent No. 6,337,102 to Forrest et al., which are incorporated herein by reference in their entirety), and deposition by organic vapor jet printing (OVJP) (e.g., as described in U.S. Patent No. 7,431,968, which is incorporated herein by reference in its entirety). Other suitable deposition methods include spin coating and other solution-based processes. Solution-based processes are preferably performed in a nitrogen or inert atmosphere. For other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition via a mask, cold soldering (e.g., as described in U.S. Patents 6,294,398 and 6,468,819, which are incorporated herein by reference in their entirety), and patterning associated with some of the deposition methods such as inkjet printing and OVJD. Other methods may also be used. The material to be deposited may be modified to be compatible with a specific deposition method. For example, substituents such as alkyl and aryl groups, which are branched or unbranched and preferably contain at least three carbons, may be used in small molecules to enhance their solution handling ability. Substituents having 20 or more carbons may be used, with 3-20 carbons being a preferred range. Materials with asymmetric structures may have better solution handling ability than materials with symmetric structures because asymmetric materials may have a lower tendency to recrystallize. Dendritic polymer substituents may be used to enhance the solution handling ability of small molecules.

[0045] Devices manufactured according to embodiments of the present invention may optionally further include a barrier layer. One use of the barrier layer is to protect the electrodes and organic layers from damage caused by exposure to harmful substances in the environment, including moisture, vapors, and / or gases. The barrier layer may be deposited on, under, or adjacent to a substrate or electrode, or on any other part of the device, including edges. The barrier layer may comprise a single layer or multiple layers. The barrier layer can be formed using various known chemical vapor deposition techniques and may comprise compositions having a single phase as well as compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may incorporate inorganic or organic compounds, or both. Preferred barrier layers comprise a mixture of polymeric and non-polymeric materials, as described in U.S. Patent No. 7,968,146, PCT Patent Application Nos. PCT / US2007 / 023098 and PCT / US2009 / 042829, which are incorporated herein by reference in their entirety. For the mixture to be considered a "mixture," the aforementioned polymeric and non-polymeric materials constituting the barrier layer should be deposited under the same reaction conditions and / or simultaneously. The weight ratio of polymeric material to non-polymeric material can range from 95:5 to 5:95. The polymeric and non-polymeric materials can be produced from the same precursor material. In one example, the mixture of polymeric and non-polymeric materials is essentially composed of polymeric silicon and inorganic silicon.

[0046] Devices manufactured according to embodiments of the present invention can be incorporated into a wide variety of electronic component modules (or units), which can be incorporated into various electronic products or intermediate components. Examples of such electronic products or intermediate components include displays, lighting devices (such as discrete light source devices or lighting panels), etc., which can be utilized by end-user product manufacturers. Such electronic component modules may optionally include driving electronics and / or power supplies. Devices manufactured according to embodiments of the present invention can be incorporated into a wide variety of consumer products having one or more electronic component modules (or units) incorporated therein. Such consumer products will include any kind of product containing one or more light sources and / or one or more of some type of visual display. Examples of such consumer products include flat panel displays, computer monitors, medical monitors, televisions, billboards, lights for internal or external lighting and / or signaling, head-up displays, fully or partially transparent displays, flexible displays, laser printers, telephones, mobile phones, tablet computers, tablet phones, personal digital assistants (PDAs), laptop computers, digital cameras, video cameras, viewfinders, miniature displays, 3D displays, vehicles, large-area walls, theater or stadium screens, or signs. Various control mechanisms, including passive and active matrices, can be used to control the devices manufactured according to the invention. Many of the devices are intended for use in temperature ranges comfortable for humans, such as 18 to 30 degrees Celsius, and more preferably at room temperature (20-25 degrees Celsius), but can be used outside this temperature range (e.g., -40 to 80 degrees Celsius).

[0047] When used in devices such as displays, it is convenient to compare or combine the emission stack of an OLED with or in conjunction with the pixels or subpixels of the device. For example, an OLED stack can be used as a component to generate the initial light that will ultimately be emitted through the pixels or subpixels. Generally, a "subpixel" is the smallest addressable emission area in a device such as a full-color display. A "pixel" generally comprises multiple subpixels such that during operation of the display, some or all of the subpixels within a pixel are driven to produce a composite color. In some cases, each pixel can be a "full-color pixel," that is, a full-color pixel comprising subpixels of each primary color (e.g., red / green / blue, red / green / blue / yellow, etc.) of a particular rendering scheme, which can be considered the smallest addressable imaging element and is generally capable of producing white light. In another type of configuration, individual subpixels can be included in the rendering computation using a technique typically called subpixel rendering. Such techniques may require significantly more analysis and processing time, but in some cases can produce excellent images. Subpixel rendering typically uses information about the specific pixels and subpixel geometry of a display to manipulate subpixels individually, thereby improving the visible resolution of a color display. In such devices, each “pixel” within the display may not be identical to every other pixel within the same display, as each pixel may include different subpixel colors and / or geometries. Regardless of whether full-color pixel or subpixel rendering configurations and techniques are used, individual subpixels can be distinguished from the OLED stack contained within subpixels, as disclosed herein.

[0048] A subpixel may include, or may combine, one or more color-changing layers that alter the initial light produced by the OLED stack in the subpixel. For example, a pixel may include red, green, and blue subpixels. A green subpixel may include a yellow OLED coupled to a green color-changing layer, which is a color-changing layer that alters the initial yellow light produced by the OLED into the green light ultimately emitted by the subpixel.

[0049] Within an OLED, the emission stack generates initial light, such as relative to... Figure 1-2 The emission layer (EML) shown in the diagram is disclosed. An emission stack can include one or more emission layers, as shown relative to... Figure 1-2 As disclosed. In some configurations, the emission stack may include multiple individual layers of the same or different colors, or a mixed layer that produces more than one color. Thus, each layer can be described as producing light of its corresponding color, and the stack as a whole can be described as producing light of the same or different colors as some or all of the emission layers within the stack.

[0050] In some configurations, an "emitting stack" may include emitting materials that emit light in multiple colors. For example, a yellow emitting stack may include multiple materials that emit red and green light when each material is used individually in an OLED device. When used in a yellow device, typically, the individual materials are not arranged so that they can be individually activated or addressed. That is, a "yellow" OLED stack containing these materials cannot be driven to produce red, green, or yellow light; in fact, the stack can be driven as a whole to produce yellow light. This configuration may be referred to as a yellow emitting stack even though yellow light is not directly produced at the level of individual emitters. Individual emitting materials used in an emitting layer or stack (if more than one) may be located in the same emitting layer within the device or in multiple emitting layers within the OLED. As previously indicated, in some configurations, the final color emitted by an activated subpixel may be the same as the color provided by the emitting materials in the stack defining the subpixel, for example, where a dark blue color-changing layer is stacked with a light blue emitting stack to produce a dark blue subpixel. Similarly, the color provided by a sub-pixel can be different from the color provided by the emitting material in the stack defining the sub-pixel, for example, where a green color-changing layer is stacked with a yellow emitting stack to produce a green sub-pixel. As used herein, the terms "emitting stack" or "OLED stack" refer only to the color provided in relation to... Figure 1-2The described OLED arrangement includes layers initially necessary for light generation, such as electrodes, emitting layers, transport layers, and barrier layers, but excludes color-changing layers, such as color filters and color-modifying layers. It also excludes layers such as protective films and single-layer barrier layers. As a specific example, a simple OLED stack includes an anode, a cathode, and an organic emitting material layer disposed between the anode and cathode. Corresponding subpixels may include OLED-only stacks, wherein the subpixels are intended to emit light of the same color as light generated by an organic emitting material, or may further include color-changing layers, such as color filters, wherein the subpixels are intended to emit light of a different color than light generated by an organic emitting layer. OLED stacks may also include multiple layers, which can be individually considered separate OLED stacks, for example, where one or more charge-generating layers (CGLs) are disposed between the anode and cathode, where an organic emitting material layer is disposed between the anode and CGLs, and where another organic emitting material layer is disposed between the cathode and CGLs. In this configuration, the entire stack including the anode, cathode, CGLs, and two organic emitting material layers can be considered a single OLED stack. OLED stacks can be patterned or unpatterned, depending on whether one or more organic emitting layers within the stack are patterned or unpatterned at the pixel or sub-pixel level. That is, a “patterned OLED stack” is an OLED stack in which one or more emitting layers within the stack have a pattern (e.g., a repeating arrangement of regions of emitting material spaced apart by another material). An “unpatterned OLED stack” refers to an OLED stack in which one or more associated emitting layers do not have such a pattern; for example, the emitting layers are, for instance, uniform, continuous layers within the stack. Whether an OLED stack is considered patterned or unpatterned is determined solely by whether one or more emitting layers in the stack are patterned or unpatterned at the pixel or sub-pixel level, regardless of whether one or more electrode or charge-generating layers within the stack are patterned.

[0051] In some configurations, the emitter layer and / or stack can span multiple sub-pixels within the same device, for example, where additional layers and circuitry are fabricated to allow portions of the emitter layer or stack to be individually addressable.

[0052] The emission stacks disclosed herein can be distinguished from individual emission “layers” as typically referred to in the art and as used herein. In some cases, a single emission stack may include multiple layers, for example, where a yellow emission stack is formed by sequentially using red and green emission layers. As previously described, when such layers are present in an emission stack as disclosed herein, the layers are not individually addressable; in fact, the layers are simultaneously activated or driven to produce light of the desired color for the emission stack. In other configurations, an emission stack may include a single emission layer of a single color, or multiple emission layers of the same color, in which case the color of the emission stack will be the same as the color of the emission layer, or in the same spectral region as the color of the emission layer. In some cases, “stacked” devices, i.e., devices comprising multiple sets of layers (each set can be considered a separate OLED device), may be arranged and controlled such that each individual stack within the entire stack can be individually addressable. Such configurations are further disclosed in detail in U.S. Patent Nos. 8,827,488 and 5,707,745, the disclosures of each of which are incorporated herein by reference in their entirety.

[0053] Compared to OLEDs, inorganic or conventional light-emitting diodes (LEDs) have different advantages and disadvantages. For example, LEDs can generally operate at higher brightness than OLEDs and can produce blue light more efficiently, or more efficiently over a longer lifetime. However, OLEDs typically have more performance degradation with increasing brightness, a wider spectral linewidth for similar emission colors, and can be used with a wider range of substrates. Recent technological advancements allow for the efficient fabrication and precise placement of microLEDs at predetermined locations on a substrate, making them suitable as subpixels in pixel-based devices such as full-color displays. As disclosed herein, combining microLEDs with OLEDs can allow displays to have improved performance and properties compared to similar devices using either technology independently. For example, many current OLED display arrangements have manufacturing problems associated with patterning techniques, such as particle and scaling issues when using fine metal masks for deposition, or performance and lifetime issues when using white OLEDs in conjunction with color filters. As another example, current deep blue OLEDs may have unsatisfactory lifetimes.

[0054] Micro-LED attachment is under ongoing development, but two significant issues exist in developing all-micro-LED displays. First, the typical yield of micro-LEDs may be insufficient to support full-color display manufacturing. Displays typically require near-perfect subpixel yields, so any short-circuited or disconnected micro-LEDs will be highly problematic. The second issue concerns the achievable grayscale levels of all-micro-LED displays. Micro-LEDs, especially green micro-LEDs, typically exhibit color shift when dimmed using analog or pulse-width modulation driving schemes, and the color output of red micro-LEDs is highly temperature-dependent. Therefore, all-micro-LED displays will be expected to have relatively poor color accuracy at grayscale levels. Currently, the only purely micro-LED displays in use are large installations such as bulletin boards or video walls, which are not significantly affected by these issues.

[0055] Therefore, it has been determined that the combination of micro-LEDs and emitting OLED stacks can provide an efficient and versatile hybrid display pixel arrangement. According to an embodiment, a hybrid pixel arrangement may include a first sub-pixel emitting a first color using an inorganic LED. A second sub-pixel may emit a second, different color using an organic stack that produces the initial color. The second sub-pixel may be unfiltered, i.e., it may ultimately emit the same color as the light produced by the OLED stack, or it may include a color-changing layer. A third sub-pixel may use the same emitting stack and may also use a color-changing layer to make the sub-pixel emit a color different from any of the other sub-pixels. The LED may be a micro-LED, i.e., an LED with a micrometer-scale size, for example, having a width of about 1 μm to about 50 μm, which can be suitable for relatively small applications, such as mobile devices, televisions, etc. In some embodiments, the LED may be larger, for example, suitable for larger applications, such as signs, etc. Micro-LEDs can have various shapes, including squares, rhombuses, rectangles, or other shapes. As used herein, depending on the context or the application in which the LED is used, "LED" may refer to a micro-LED or a larger LED.

[0056] More specifically, as disclosed herein, the use of blue LEDs in conjunction with red and green OLEDs can provide a practical full-color display with relatively low power consumption and relatively high brightness, lifespan, yield, color accuracy, and optical performance. As a concrete example, as disclosed herein, the combination of blue LEDs with yellow OLEDs allows for relatively simple and inexpensive manufacturing while maintaining a wide range of colors.

[0057] Furthermore, the use of LEDs in combination with OLEDs allows for improved physical arrangement and manufacturing techniques, as disclosed herein. For example, an unpatterned yellow OLED can be placed on one or more blue LEDs. Color filters can then be used to form green and red subpixels, thus forming an "RGBY" (red, green, blue, yellow) display. A preferred arrangement can share a single blue LED among multiple pixels (typically four pixels), allowing for LED redundancy and LED placement resolution lower than the overall display resolution (in some cases half or less of the display resolution), thereby overcoming or avoiding the manufacturing problems associated with precise LED placement. Reducing LED yield requirements through redundancy and using only one LED color can significantly simplify manufacturability. Using unpatterned OLED deposition (e.g., unpatterned yellow stacking) allows for a relatively high fill factor and greater possibility of fabricating stacked OLED architectures, thereby further improving lifetime and display performance by reducing power consumption. In addition, the relatively small area allocated to the blue LED subpixels allows for very high color saturation in both the light and deep red and green subpixels without incurring higher power requirements compared to conventional OLED or LED displays.

[0058] OLED stacks may include a single emitting layer, or may be in a tandem or other stacked structure. The use of a tandem structure can increase display lifetime by approximately three times and further reduce power consumption, as described in further detail below. Implementing stacked emitting layers for multiple colors is relatively difficult in conventional RGB side-by-side displays because it requires multiple deposition chambers and non-shared-layer OLED structures. According to the embodiments disclosed herein, an OLED stack including multiple emitting layers may have yellow emitting material in multiple emitting layers, or, for example, red emitting material in one layer and green emitting material in another layer of a yellow OLED stack. The advantage of using stacked red and green emitting layers within a shared yellow OLED stack to render red, green, and yellow subpixels includes a larger achieved color gamut than in a similar arrangement where a single yellow emitter is used to render yellow. Alternatively or additionally, a yellow OLED stack may include yellow and red emitting layers. More generally, multiple emitting materials can be used in one or more emitting layers within an unpatterned emitting stack as disclosed herein.

[0059] In embodiments, the hybrid display includes pixels having two inorganic LEDs and OLED sub-pixels. For example, blue sub-pixels can be provided by one or more blue LEDs, and the remaining colors by one or more OLED sub-pixels. As a more specific example, red, green, and / or yellow sub-pixels can be provided using an unpatterned yellow OLED stack incorporating red and green color-changing layers. As used herein, a color-changing layer refers to a structure such as a color filter, color-changing layer, or color-changing layer that alters the color of light transmitted through the layer. The color-changing layer does not produce initial light; in fact, it merely alters the wavelength or peak wavelength of light incident on the layer when light is transmitted through it. As another example, red, green, and / or yellow sub-pixels can be patterned using OVJP, inkjet printing, LITI, or other direct patterning processes known for manufacturing OLEDs. If patterning techniques are used, red and green OLEDs can be fabricated in a side-by-side architecture, thereby realizing a three-color RGB hybrid display.

[0060] Figure 3 A cross-sectional view of an example hybrid display in a top-emitting configuration as disclosed herein is shown. For illustrative purposes, only a through-hole from the substrate to an OLED anode is shown; however, it should be understood that other similar arrangements can be used for other OLED sub-pixels. As shown, an OLED sub-pixel 305 can be defined by the OLED anode 321, the cathode 320, and a portion of the OLED stack 325. More generally, one or more OLED sub-pixels can be defined across a region 301 of the substrate 300, as described in further detail below. One or more inorganic LED sub-pixels can also be defined in a separate region 302. Although the example is illustrated using an unpatterned cathode 320 above the individual sub-pixel anode 321, it should be understood that other configurations can be used, such as unpatterned anodes and individual cathodes, unpatterned layers spaced apart by insulators or otherwise divided into individual sub-pixels, etc.

[0061] As previously described, the OLED stack 325 may include one or more emissive materials or layers, as well as other layers present in conventional OLED devices, such as those relative to... Figure 1-2 The layers described. OLED stack 325 can be with... Figure 3The pixels shown are unpatterned stacks of regions corresponding to multiple sub-pixels arranged in a stacked manner. Multiple OLED sub-pixels can be defined by individual anodes (e.g., anode 321 defining sub-pixel 305). A color-changing layer, such as color filter 310, can be stacked with anode 321. Alternatively, color-changing layer 310 can be omitted, forming "unfiltered" OLED sub-pixels that will emit light of the same color as initially produced by OLED stack 325. Sub-pixels including color-changing layer 310 will emit light of a color determined by color-changing layer 310, which will be different from the color of light initially produced by OLED stack 325. Figure 3 The arrangement shown allows for the creation of additional sub-pixels by placing an additional anode close to anode 321, stacked separately from anode 321, and stacked with different portions of the OLED stack 325. For example, another anode placed close to anode 321 can be used to define an OLED sub-pixel that emits light of the same color as the light produced by the OLED stack 325, assuming no color-changing layer is stacked with the additional anode. If a second color-changing layer is stacked with the additional anode and a second portion of the OLED stack 325, then the additional sub-pixel will emit light of the same color as the light initially produced by the OLED stack 325.

[0062] As described in further detail herein, the TFT substrate 365 and other associated electrical structures can provide power to and control the sub-pixels within the display via a metal layer 340 disposed within a channel 345 between the substrate 365 and the sub-pixels. Electrical connections 355 from the LED 360 to the substrate 365 can provide power and / or control to the LED 360.

[0063] Subpixels may include one or more inorganic LEDs 360. Typically, the color-changing layer is not used in conjunction with the LEDs, such that the subpixel defined by the LEDs will emit light of the same color as the light initially produced by the LEDs; however, in some embodiments, the color-changing layer may be used to modify the spectral output of the LEDs. For example... Figure 3As shown, the OLED stack 325 can be disposed on or otherwise stacked with the microLEDs. This may not significantly affect the color of the light emitted by the LED subpixels because the portion of the OLED stack 325 stacked with the LEDs may not be effective and may not serve as a color-changing layer with respect to the light emitted by the LED 360. For example, the OLED stack 325 may be transparent or substantially transparent with respect to the wavelength of the light emitted by the LED 360. In some embodiments, the OLED stack may have a small effect on the color of the LED light passing through it, even when the OLED stack can be considered transparent with respect to the light emitted by the LEDs, because it may have a transmittance that varies with the wavelength of the transmitted light.

[0064] TFT 365 and associated circuitry can be formed on substrate 300, which can be glass, metal, or plastic. Substrate 300 can be flexible and / or film-coated. OLED anode contacts, such as anode 321, can then be formed using any suitable technique, for example, those known to be used with conventional OLED displays, including those previously disclosed herein.

[0065] TFT substrates can be fabricated on, for example, low-temperature plastics (e.g., thermally stable PEN), thus enabling low-temperature substrate technologies such as OTFTs or oxide TFTs. Alternatively, TFTs can be fabricated on glass, polyimide, or metal using LTP or similar technologies.

[0066] Depending on the specific structure of LED 360, the negative electrical connection to the LED can be provided by a common cathode (e.g., cathode 320) also used in the OLED device, and thus can be positioned above the LED device, as shown. Alternatively, the LED cathode can be incorporated into the TFT substrate 365, in which case there will be two power connections under each LED, such as connection 355, one of which is a conventional anode connection from the driving TFT, and the second is a common cathode connection, which can be implemented by a common cathode connection extending parallel to a row or column in the substrate and also providing a common cathode connection plane to the OLED. This configuration is desirable because connecting the LED to the common OLED cathode would require high characteristics to disrupt the organic film continuity, such that the conductive cathode is connected to the top of the LED. An example technique for implementing this configuration is to make the thickness of the planarization layer 350 less than the height of the LED. More generally, the planarization layer 350 can be used to planarize the different heights caused by using LEDs close to the OLED stack 325 and / or covered by the OLED stack, such as Figure 3As shown in the diagram. As another example, the electrical connection 355 for the LED 360 can be disposed on the top surface of the die. In this case, the die can be attached to the substrate 365, and the display is subsequently planarized, with the vias 345 etched down to the substrate for all OLED and LED sub-pixels. Metallization 340 can then be deposited and patterned to connect the substrate 365 to the OLED anode 321 via the vias 345, and also to the non-shared LED top connection. The shared LED connection can also be made by simultaneously patterned metal wires.

[0067] In the embodiments disclosed herein, one or more LEDs may be manufactured using microprinting, for example using systems available from X-Celeprint, electrostatic pick-and-place, for example using systems and techniques available from Luxvue, or any other suitable technique. The LEDs disclosed herein may be surface emitters typically having a Lambertian emission profile, or edge emitters having a relatively narrower emission profile.

[0068] In some embodiments, insulators may be stacked on the LEDs to prevent OLED stacks from being illuminated by the LEDs when they come into contact with the LED anode connection or electrode. For example, see reference... Figure 3 The schematic arrangement shown in the image allows for the placement of an insulator 335 on the LED360.

[0069] In this embodiment, after the LEDs have been placed and (if necessary) an insulator has been installed on the LEDs, the substrate can be prepared for OLED deposition. (See again...) Figure 3 In the example arrangement shown, the LED device can have a height of approximately 0.5 μm to 10 μm, allowing a planarization deposition layer 350, which can be transparent, to be coated prior to OLED deposition. The planarization layer 350 can be organic or inorganic. In some cases, the curing temperature available for planarization can be limited by the choice of substrate and baseplate technology. If the planarization layer is expected to degas and thus reduce the lifetime of the OLED emission stack, a barrier layer 330 can be deposited. The barrier layer 330 can be deposited after the planarization layer 350, rather than (for example) directly onto a plastic substrate. The thickness of the planarization layer 350 can be less than, equal to, or slightly greater than the LED height. Vias 345 can be introduced for subsequent fabrication of metallization 340 as previously described to provide electrode plates for the OLED electrodes and electrical connections to the TFT baseplate.

[0070] Various pixels can be used with the embodiments disclosed herein. In some cases, a layout with unpatterned OLED emission stacks at the pixel level may be preferred. That is, one or more unpatterned layers can be deposited in a region to form an OLED stack without using fine metal masks or other techniques to deposit individual OLED sub-pixels. Such techniques avoid the complexities inherent in using fine metal masks for vacuum-deposited OLEDs or similarly in inkjet and other patterning techniques for solution-processed OLEDs. Alternatively or additionally, OLED sub-pixels can be deposited using OVJP as previously disclosed herein.

[0071] In an embodiment, the full-color display may include a plurality of pixels, each of which has, for example: Figure 2 The pixel arrangement shown has multiple OLED subpixels in each pixel. That is, the structure shown for subpixel 305 can be reused for other subpixels within each pixel. For example, a blue LED can be paired with two or three OLED subpixels having the basic structure shown for subpixel 305. As a specific example, green, red, and yellow OLED subpixels can be used, where each OLED subpixel includes any emission stack that produces the same color as ultimately emitted by the subpixel, i.e., green, red, and yellow OLED stacks respectively. Alternatively, one or more OLED subpixels can include emission stacks that produce light of an initial color, which is then converted into the color emitted by the subpixel, as previously disclosed. Alternatively, two or more OLED subpixels can share a common OLED stack, where the shared subpixels are defined by individual electrodes, as previously disclosed. As a specific example, a yellow emission stack can be used by red and green OLED subpixels, each of which has a different color-changing layer arranged in a stacked manner with individual electrodes to form the subpixel. In some embodiments, three OLED subpixels can be used, such as red and green as previously described, and an unfiltered (i.e., without a color-changing layer) yellow OLED subpixel. The use of such an RGBY architecture can provide better performance and power consumption than conventional RGB or RGBW arrangements. Generally, blue and yellow will be used most of the time to render images, except when fully saturated green and red colors are required. This allows the display to have a high or wide color gamut without power loss.

[0072] In this embodiment, the color gamut can be further expanded by using a six-color display, for example, deep blue from an LED and five OLED sub-pixels, such as yellow, yellow, light green (550nm to 600nm), dark green (500nm to 550nm), light red (580nm to 630nm), and dark red (630nm to 700nm). In this configuration, dark green and dark red are generally used only for a small portion of the time, so their relatively low efficiency will not significantly affect the overall display power consumption. These fully saturated colors can be achieved by coating a color-changing layer on a portion of the yellow OLED stack as previously described, and further enhanced by placing the corresponding sub-pixels or corresponding portions of the emission stack in a microcavity. For example, a portion of the yellow emission stack can be placed in a microcavity to convert the spectral output to enhance dark red or dark green as needed. Such an approach can be desirable, for example, to obtain the full ITU-R Recommendation BT.2020 (“REC 2020”) color gamut.

[0073] In an embodiment, one or more LED subpixels can be shared among four pixels. This configuration can reduce the required resolution and the precision requirements for LED placement, thereby increasing manufacturing yield. Additionally, relatively large blue subpixels allow for the placement of multiple LEDs in each subpixel, providing redundancy without affecting the display's resolution, and significantly improving the display's manufacturability. As a specific example, each blue subpixel in a pixel can include two blue LEDs arranged in parallel. A contact plate can be provided for the two independent LEDs in parallel and connected to the same driver TFT. Since the driver TFT acts as a current source, the same current will flow in each blue subpixel regardless of whether both or only one LED is operational, resulting in very similar light output. This arrangement thus prevents failure of one LED without significantly affecting the display's brightness or color gamut. Similarly, multiple LEDs within a subpixel can be arranged in series to prevent short circuits. Both arrangements can be used simultaneously, for example, where two pairs of series-connected LEDs are arranged in parallel to provide synchronized protection against damage, short circuits, or other failures without significantly affecting the subpixel's visible operation or manufacturability.

[0074] Figure 4 An example schematic pixel arrangement according to embodiments disclosed herein is shown. As previously described, each pixel 401 in the arrangement may include one or more blue sub-pixels 405, each of which may include one or more inorganic LEDs 410. Figure 4In the illustrative arrangement shown, each blue emission region is shared among four sub-pixels. In this example, each of these includes two blue LEDs, but other arrangements as previously described can be used, where each blue emission region is shared among different numbers of pixels, or where each pixel includes a separate blue LED, or where the blue emission region includes one or different numbers of LEDs. Each pixel may also include yellow, green, and / or red sub-pixels, each of which may include an emitting OLED organic stack. As previously described, the OLED stack in each sub-pixel may be part of an unpatterned OLED stack, for example, where an unpatterned yellow organic stack is used in conjunction with red and green color-changing layers to form the sub-pixel shown. The use of an unpatterned OLED stack means that the sub-pixel fill factor can be determined by photolithography (e.g., by anodizing or using color-changing layers). That is, while large devices as disclosed herein may include “patterns” or may be fabricated using patterned methods on the device as a whole, the organic films in one or more OLED stacks within the device (e.g., at the individual pixel level or sub-pixel level) do not need to be patterned. Therefore, a significantly higher fill factor can be achieved compared to conventional RGB-patterned parallel OLED displays, which include individually patterned OLED emitter layers or stacks of different colors for each different colored subpixel. Additionally, blue subpixels can have the smallest fill factor as previously disclosed due to the relatively high lifetime and efficiency of blue LEDs. This, in turn, allows for larger subpixel aperture ratios for yellow or other subpixels, further improving display lifetime, and / or allowing more space to implement other architectures, such as a six-color architecture for displays with very wide color gamuts as previously described. For example, the use of unpatterned organic stacks can also improve display manufacturability since patterning at the pixel level is not required, and thus, in another way, allows for lower manufacturing costs than would otherwise be achievable.

[0075] The embodiments disclosed herein may use top- and / or bottom-emitting OLEDs. A basic OLED stack including an anode assembly can be optimized for a yellow OLED stack as previously described. Examples of various arrangements and anode patterns that can be used with the embodiments disclosed herein are provided in U.S. Patent Application No. 14 / 698,352, filed April 28, 2015 and published under U.S. Publication No. __________, the entire contents of which are incorporated herein by reference. For example, color-changing layers such as color filters can be used as disclosed herein, regardless of whether a top- or bottom-emitting OLED structure is used. For example, in a bottom-emitting structure, a color filter can be patterned on a substrate, under the OLED stack, using photolithography. For a top-emitting structure, a cover aligned with and sealed relative to the substrate (e.g., Figure 3 The color filter is patterned on the cover (315).

[0076] Because LEDs are relatively small in size compared to conventional OLED subpixel devices, transparent hybrid displays as disclosed herein can be fabricated using techniques similar to those used in conventional transparent OLED (TOLED) displays. Metal bus lines, TFTs, and LED chips can limit the overall transparency of such devices. However, unpatterned OLED stacks as disclosed herein can be fabricated as transparent without color filters. For example, a transparent yellow OLED stack can be fabricated without a color filter.

[0077] The hybrid displays and pixel arrangements disclosed herein can be flexible. For example, plastic or plastic coated with a barrier layer can be used as a substrate, having a flexible OTFT or oxide substrate. As another example, LTP can be used. Figure 3As shown, the interface between the rigid inorganic LED and the top of the TFT substrate can be a restrictive interface in a hybrid arrangement for flexibility. Therefore, for flexible displays, it is preferable that the "neutral plane" is relatively close to this interface. When the thin device is folded, the neutral plane extends through the device and defines a plane that does not unfold or fold in the flexural plane. When the device is folded, an area on one side of the neutral plane is under tensile stress, and an area on the other side is under compressive stress. To avoid peeling or cracking of the material, it may be required that the thin display include a rigid or inorganic material close to the neutral plane. The neutral plane will be in the middle of the symmetrical structure and can be moved away from this position by a material with a large Young's modulus multiplied by its thickness (specifically, if these films are placed away from the center of the device). In hybrid displays as disclosed herein, the inorganic LED will typically dominate the positioning of the neutral plane due to its thickness and rigidity. Therefore, assuming another symmetrical display structure, the neutral plane will typically be located approximately halfway up the height of the LED. The current-carrying electrodes of the OLED stack can also have relatively large Young's moduli, and therefore the position and thickness of these electrodes can determine how the neutral plane is positioned within the device. Bus lines placed under the LED near the TFT will tend to pull the neutral plane down toward the substrate, and thus closer to the microLED's interface with the substrate. Therefore, hybrid displays as disclosed herein can also allow all current-carrying electrodes to be under the microLED.

[0078] Figure 5 Examples of power consumption are demonstrated for conventional RGB displays, YB displays implemented using only conventional OLED devices, a hybrid YB arrangement with single-junction yellow as disclosed herein, and a hybrid arrangement using stacked (two devices) yellow OLED stacks as disclosed herein. As shown, the YB hybrid arrangement can achieve power savings of over 56% compared to conventional RGB OLED displays. This improved performance can be achieved through lower power consumption, smaller power supplies, or brighter displays at the same power consumption. The brightness of conventional OLED displays is generally limited by the shortest lifetime of subpixels (typically one or more blue subpixels). However, in the hybrid display architecture disclosed herein, lifetime can be increased by at least 10x, 20x, 30x, or more, thus allowing operation at higher brightness and daytime readability or HDR operation with significantly reduced image lag. Conventional phosphorescent yellow OLED devices typically operate at 3,000 cd / m². 2 The LT95 has a lifespan of approximately 50,000 hours. For applications exceeding 700 cd / m³... 2 For daytime readable displays operating below the operating temperature range, the maximum yellow subpixel brightness will be approximately 8,000 cd / m². 2This corresponds to an LT95 of approximately 7,000 hours. Using a stacked yellow OLED structure as disclosed herein can increase the lifetime by three times or more, resulting in a lifetime of 1000 cd / m². 2 A monitor lifespan exceeding 20,000 hours at or above the operating brightness of the display.

[0079] Various driving architectures can be used with the embodiments disclosed herein. Gray levels in a conventional OLED display are achieved by analog control of the OLED current through the driving TFTs in the baseboard circuitry. A similar approach can be used for LEDs, although achieving a high number of gray levels may be difficult with analog control alone, and pulse width modulation (PWM) is typically employed because it allows the LED junction temperature to remain constant and thus reduces color shift. Hybrid display arrangements as disclosed herein can be used with either driving scheme. For example, using a typical TFT baseboard (where power is continuously applied to the driving TFTs and LED and / or OLED chains), PWM can be implemented by operating the display at a higher frame rate than required and subsequently using subframes to achieve some form of digital brightness control. For example, if the display operates at 480Hz, but only 60Hz is needed for the video signal, eight subframes can exist per frame, allowing eight gray levels, which can be combined with analog control. Examples of control schemes that can be used with the embodiments disclosed herein (including those having more than three color subpixels) are provided in U.S. Application No. 14 / 605,876, filed January 26, 2015 and published under U.S. Publication No. __________, the entire contents of which are incorporated herein by reference.

[0080] In this embodiment, a PL-only organic thin film can be used, and a color-changing layer can be used to convert the blue light emitted by the LED into yellow, thus providing an apparatus including a non-actively driven OLED as disclosed herein. Blue LEDs can therefore be used for each sub-pixel, each sub-pixel being directly driven from a TFT substrate. In this configuration, the LED density can be higher, but it will only be monochromatic. The color-changing layer can also be patterned to prevent blue from being down-converted to yellow in the blue sub-pixels.

[0081] In this embodiment, production yield can be improved by testing the substrate after placing the blue LEDs but before OLED deposition. Connecting the gate and data lines together allows all blue subpixels in the device disclosed herein to be powered, enabling the camera to record LED yield before OLED deposition.

[0082] In embodiments, LED and OLED stacks as disclosed herein can be deposited on separate substrates. For example, the OLED stack can be disposed on an active matrix substrate with a top-emitting configuration. The LED components can be patterned on a cover with color filters and driven in a passive matrix mode to avoid the cost and complexity of two substrates. LEDs can generally have lower resolution than OLED stacks and are therefore more suitable for passive matrix driving.

[0083] In this embodiment, a passive matrix arrangement can be used. This extends the applicability of PMOLED displays because, under high drive conditions, only the yellow OLED needs to be considered, thus allowing for higher brightness and more row lines than would be achievable otherwise. This reduces the manufacturing cost and complexity of smaller displays and eliminates substrate temperature constraints. This configuration can be used for displays requiring relatively high flexibility, such as wearable displays.

[0084] The embodiments disclosed herein can be particularly beneficial for digital signage, which typically has requirements for high brightness, low resolution, and low frame rates. For example, conventional large signage (84 inches diagonally or larger) can achieve 2500 cd / m². 2 Under these conditions, the power consumption is 2800W. The hybrid arrangement disclosed herein can eliminate the need for a polarizer, and assuming 50% of the efficiency of the active-matrix OLED arrangement, it can consume only 600W for comparable brightness operation. For example, the embodiments disclosed herein can be used to achieve 700 cd / m² at the white point of the display. 2 or more and extract 10mW / cm 2 Or less. As used herein, the white point of a display refers to the white point correlated color temperature (CCT) value of the display. The white light emitted by a display as disclosed herein is typically defined relative to its chromaticity coordinates in the CIE 1931 XYZ color space chromaticity diagram. Typically in display applications, the white point is described by values ​​such as D65, D50, etc., which refer to white light with a correlated color temperature of 6500K (D65), 5000K (D50), etc. The embodiments disclosed herein may typically have a white point in the range of D50 to D90, but some embodiments may include a white point outside this range. These CCT values ​​correspond to a white point on the blackbody curve, but in practice, white light will not be exactly on the blackbody curve, but close to it, with some error in both the x and y coordinates. As used herein, "white light" therefore refers to a mixture of light from the subpixel that produces white light closest to the blackbody curve.

[0085] The embodiments disclosed herein can also operate at relatively high brightness compared to conventional large displays and conventional OLED displays, such as 1000 cd / m². 2 2000cd / m2 Or operate at even higher brightness. More generally, relatively high brightness can be achieved using hybrid arrangements as disclosed herein, while maintaining the advantages of OLED displays such as flexible substrates and curved displays.

[0086] It should be understood that the various embodiments described herein are merely examples and are not intended to limit the scope of the invention. For instance, many of the materials and structures described herein can be replaced with other materials and structures without departing from the spirit of the invention. The invention as claimed may therefore include variations of the specific examples and preferred embodiments described herein, as will be apparent to those skilled in the art. It should be understood that various theories regarding why the invention works are not intended to be limiting.

Claims

1. A lighting device comprising: a substrate; a plurality of blue inorganic LEDs disposed in a region defining a first plane above the substrate; and an unpatterned yellow organic emission stack disposed in a second plane parallel to the first plane and above the substrate.

2. The lighting device of claim 1, wherein the yellow organic emission stack is transparent, and wherein blue light generated by the inorganic LEDs is transmitted through the yellow organic emission stack during operation of the device.

3. The lighting device of claim 2, wherein the organic emission stack is disposed above the plurality of inorganic LEDs and the plurality of inorganic LEDs are disposed within a planarization layer.

4. The lighting device of claim 3, further comprising: a backplane disposed below the planarization layer; and one or more metal layers electrically connecting the organic emission stack to the backplane, the one or more metal layers extending through the planarization layer.

5. The lighting device of claim 4, wherein the backplane further comprises one or more electrical connections, each in direct electrical communication with at least one of the plurality of inorganic LEDs.

6. The lighting device of claim 3, further comprising a barrier layer disposed between the planarization layer and the organic emission stack.

7. The lighting device of claim 3, further comprising an anode and a cathode disposed above the planarization layer, wherein the organic emission stack is disposed between the anode and the cathode.

8. The lighting device of claim 1, wherein the lighting device is selected from the group consisting of a flat panel display, a computer monitor, a medical monitor, a television, a sign, a light for interior or exterior illumination and / or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a laser printer, a telephone, a cell phone, a tablet computer, a phablet, a personal digital assistant (PDA), a laptop computer, a digital camera, a camcorder, a viewfinder, a microdisplay, a 3-D display, a vehicle, a theater or stadium screen, or a sign.

9. The lighting device of claim 8, wherein the organic emission stack is disposed above the plurality of inorganic LEDs and the plurality of inorganic LEDs are disposed within a planarization layer.

10. The lighting device of claim 9, further comprising: a backplane disposed below the planarization layer; and one or more metal layers electrically connecting the organic emission stack to the backplane, the one or more metal layers extending through the planarization layer.

Images