Organic light emitting device

Abstract

The invention relates to an organic light-emitting device. A device structure is provided that includes one or more plasma OLEDs and zero or more non-plasma OLEDs. Each plasmonic OLED includes an enhancement layer including a plasmonic material that exhibits a non-radiative mode of surface plasmon resonance that is non-radiatively coupled to an organic emissive material and transfers excited state energy from the emissive material to surface plasmon polaritons in the plasmonic OLED.

Description

[0001] This application is a divisional application of an application with an application date of March 12, 2020, application number 202010171904.6, and invention name “Organic Light-Emitting Device”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application is a non-provisional application of and claims priority to U.S. Provisional Patent Application Nos. 62 / 817,436 filed on March 12, 2019 and 62 / 839,855 filed on April 29, 2019, each of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present invention relates to structures and components applicable to organic light emitting diodes (OLEDs) and devices including the same. Background Art

[0005] Optoelectronic devices utilizing organic materials are becoming increasingly popular for a variety of reasons. Many of the materials used to make the devices are relatively inexpensive, so organic optoelectronic devices have the potential to have cost advantages over inorganic devices. In addition, the inherent properties of organic materials (e.g., their flexibility) can make them more suitable for specific applications, such as manufacturing 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 have performance advantages over conventional materials. For example, the wavelength of light emitted by the organic emissive layer can generally be easily adjusted with appropriate dopants.

[0006] OLEDs utilize organic thin films that emit light when voltage is applied to the device. OLEDs are becoming an increasingly popular technology for applications such as flat panel displays, lighting, and backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

[0007] One application of phosphorescent emitting molecules is full-color displays. Industry standards for such displays require pixels that are suitable for emitting specific colors (called "saturated" colors). Specifically, these standards require saturated red, green, and blue pixels. Alternatively, OLEDs can be designed to emit white light. In conventional liquid crystal displays, an absorption filter is used to filter the emission from a white backlight to produce red, green, and blue emissions. The same technology can also be used for OLEDs. White OLEDs can be single EML devices or stacked structures. Color can be measured using CIE coordinates well known in the art.

[0008] As used herein, the term "organic" includes polymeric materials and small molecule organic materials that can be used to make organic optoelectronic devices. "Small molecule" refers to any organic material that is not a polymer, and a "small molecule" may actually be quite large. In some cases, a small molecule may include a repeating unit. For example, the use of a long chain alkyl group as a substituent does not remove a molecule from the "small molecule" category. Small molecules can also be incorporated into polymers, for example as a side group on a polymer backbone or as part of a backbone. Small molecules can also serve as the core portion of a dendritic polymer, which consists of a series of chemical shells built on the core portion. The core portion of a dendritic polymer can be a fluorescent or phosphorescent small molecule emitter. A dendritic polymer can be a "small molecule", and all dendritic polymers currently used in the field of OLEDs are considered to be small molecules.

[0009] As used herein, "top" means farthest from the substrate, while "bottom" means closest to the substrate. Where a first layer is described as being "disposed "above" a second layer, the first layer is disposed farther from the substrate. Unless it is specified that the first layer is "in contact with" the second layer, there may be other layers between the first and second layers. For example, a cathode may be described as being "disposed "above" an anode even though various organic layers are present between the cathode and the anode.

[0010] As used herein, "solution processed" means capable of being dissolved, dispersed or transported in and / or deposited from a liquid medium in the form of a solution or suspension.

[0011] When a ligand is believed to directly contribute to the photosensitive property of an emissive material, the ligand may be referred to as "photosensitive." When a ligand is believed not to contribute to the photosensitive property of an emissive material, the ligand may be referred to as "ancillary," but the ancillary ligand may alter the properties of the photosensitive ligand.

[0012] As used herein, and as will be generally understood by one skilled in the art, a first "Highest Occupied Molecular Orbital" (HOMO) or "Lowest Unoccupied Molecular Orbital" (LUMO) energy level is "greater than" or "higher than" a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since the ionization potential (IP) is measured as a negative energy relative to the vacuum energy level, a higher HOMO energy level corresponds to an IP with a smaller absolute value (a less negative IP). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) with a smaller absolute value (a less negative EA). On a conventional energy level diagram with the vacuum energy level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A "higher" HOMO or LUMO energy level appears closer to the top of this diagram than a "lower" HOMO or LUMO energy level.

[0013] As used herein, and as one skilled in the art would generally understand, a first work function is "greater than" or "higher than" a second work function if the first work function has a higher absolute value. Because work functions are typically measured as negative numbers relative to the vacuum level, this means that a "higher" work function is more negative. On a conventional energy level diagram with the vacuum level at the top, a "higher" work function is illustrated as being farther away from the vacuum level in a downward direction. Thus, the definition of HOMO and LUMO energy levels follows different rules than work functions.

[0014] As used herein, a "red" subpixel layer, material, region, or device refers to a subpixel layer, material, region, or device that emits light in the range of about 580-700nm; a "green" subpixel layer, material, region, or device refers to a subpixel layer, material, region, or device whose peak wavelength of the emission spectrum is in the range of about 500-600nm; a "blue" subpixel layer, material, or device refers to a subpixel layer, material, region, or device whose peak wavelength of the emission spectrum is in the range of about 400-500nm; and a "yellow" subpixel layer, material, region, or device refers to a subpixel layer, material, region, or device whose peak wavelength of the emission spectrum is in the range of about 540-600nm. In some arrangements, separate regions, layers, materials, regions, or devices can provide separate "deep blue" and "light blue" lights. As used herein, in an arrangement that provides independent "light blue" and "deep blue", a "deep blue" component refers to a component whose peak emission wavelength is at least about 4nm smaller than the peak emission wavelength of the "light blue" component. Typically, the peak emission wavelength of a "light blue" component is in the range of about 465-500nm, and the peak emission wavelength of a "dark blue" component is in the range of about 400-470nm, but these ranges can vary for some configurations. Similarly, a color-shifting layer refers to a layer that converts or modifies light of another color into light having a wavelength as specified for that color. For example, a "red" color filter refers to a filter that forms light having a wavelength in the range of about 580-700nm. In general, there are two types of color-shifting layers: color filters that modify the spectrum by removing undesirable wavelengths of light, and color-shifting layers that convert higher energy photons into lower energy.

[0015] As used herein, a "full-color" device, pixel, or other component refers to a component that includes red, green, and blue components and can be configured to emit a range of light across the visible spectrum. A "full-color" device may include multiple sub-pixels, each of which may be configured to emit light of one or more colors. For example, a full-color pixel may include one or more red, green, blue, and / or yellow sub-pixels, each of which emits corresponding light. For example, a red sub-pixel may emit red light as previously defined, which in combination with other sub-pixels allows the pixel to be a full-color pixel. Full-color pixels or other components may also generally be capable of emitting white light, such as by activating multiple colors of sub-pixels simultaneously. In some cases, full-color pixels may also include white or other multi-color sub-pixels or similar components.

[0016] In contrast to full-color devices, pixels, or other components, a "monochrome" subpixel or other component does not include multiple components of different colors, and typically emits light only within a single color range. For example, a red monochrome subpixel typically emits light within the red visible spectrum, i.e., 580-700 nm. A monochrome subpixel will emit all or substantially all of the visible light emitted by the subpixel within the relevant spectral range. That is, while a very small amount of energy emitted by a monochrome subpixel within the visible spectrum may fall outside the relevant color range, the difference in color will be small enough that the human eye will not perceive the difference in color.

[0017] More details regarding OLEDs and the definitions set forth 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

[0018] According to one embodiment, an organic light emitting diode / device (OLED) is also provided. The OLED may include an anode, a cathode, and an organic layer disposed between the anode and the cathode. According to one embodiment, the organic light emitting device is incorporated into one or more devices selected from the following: a consumer product, an electronic component module, and / or a lighting panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 An organic light emitting device is shown.

[0020] Figure 2 An inverted organic light-emitting device without a separate electron transport layer is demonstrated.

[0021] Figure 3 A schematic illustration of a device including a plasma OLED according to one embodiment disclosed herein is shown.

[0022] Figures 4A-4D Demonstrating the invention according to the invention disclosed herein Figure 3 Examples of specific OLED architectures of the general structure shown in FIG. Figure 4A An OLED architecture comprising one plasma OLED and two non-plasma OLED devices arranged in a stack and connected in series is shown. Figure 4B Show from Figure 4A The OLED architecture includes a down-conversion layer and a color filter. Figure 4C Display and Figure 4B Same architecture, with additional elements that modify the radiance pattern of the sub-pixels in the device. Figure 4D An example architecture is shown with multiple plasma OLED devices incorporated into a device stack that will visualize subpixels for a display.

[0023] Figures 5A-5DSchematic depiction of a device architecture showing a plasma OLED featuring broadband emission according to embodiments disclosed herein. Figure 5A A device is shown in which broadband emission from a plasmonic OLED is outcoupled as broadband light through an outcoupling layer and then converted to individual subpixels through color filters. Figure 5B A device with broadband emission from a plasmonic OLED is demonstrated, which is outcoupled as broadband light through an outcoupling layer and then converted to sub-pixel colors via a down-conversion layer. Figure 5C A device with broadband emission from a plasmonic OLED is demonstrated, which is outcoupled as broadband light through an outcoupling layer and then converted to individual sub-pixel colors by a down-conversion layer and a color filter. Figure 5D Devices with broadband emission from a plasmonic OLED are demonstrated, which are outcoupled into R, G, and B layers through compositionally distinct outcoupling layers to produce individual subpixel colors. DETAILED DESCRIPTION

[0024] In general, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When an electric current is applied, the anode injects holes and the cathode injects electrons into the organic layer. The injected holes and electrons each migrate toward the oppositely charged electrode. When electrons and holes are localized on the same molecule, an "exciton" is formed, which is a localized electron-hole pair with an excited energy state. When the exciton relaxes through a light emission mechanism, light is emitted. In some cases, the exciton can be localized on an excimer or an excited complex. Non-radiative mechanisms (such as thermal relaxation) may also occur, but are generally considered undesirable.

[0025] The first OLEDs used emissive molecules that emitted light from a singlet state ("fluorescence"), as disclosed, for example, in US Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescence emission typically occurs in a time frame of less than 10 nanoseconds.

[0026] Recently, OLEDs with emissive materials that emit light from triplet states ("phosphorescence") have been demonstrated. Baldo et al., "Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices", Nature, Vol. 395, 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, Nos. 3, 4-6 (1999) ("Baldo-II"), which are incorporated by reference in their entirety. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704, Columns 5-6, which is incorporated by reference.

[0027] Figure 1 An organic light-emitting device 100 is shown. The figure is not necessarily drawn to scale. The 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 blocking layer 170. The cathode 160 is a composite cathode having a first conductive layer 162 and a second conductive layer 164. The device 100 can be manufactured by depositing the layers in sequence. The properties and functions of these various layers and example materials are described in more detail in US 7,279,704, columns 6-10, which are incorporated by reference.

[0028] More examples of each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Patent No. 5,844,363, which is incorporated 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 by reference in its entirety. Examples of luminescent and host materials are disclosed in U.S. Patent No. 6,303,238 to Thompson et al., which is incorporated 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 by reference in its entirety. U.S. Patent Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entirety, disclose examples of cathodes comprising a composite cathode having a thin layer of a metal (e.g., Mg:Ag) with an overlying transparent, conductive, sputter-deposited ITO layer. The theory 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 incorporated by reference in their entirety. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004 / 0174116, which is incorporated by reference in its entirety. A description of protective layers can be found in U.S. Patent Application Publication No. 2004 / 0174116, which is incorporated by reference in its entirety.

[0029] Figure 2 An inverted OLED 200 is shown. The device includes a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. Device 200 can be manufactured by depositing the layers in order. Because the most common OLED configuration has a cathode disposed above the anode, and device 200 has cathode 215 disposed below anode 230, 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 device 200. Figure 2 An example is provided of how some layers may be omitted from the structure of device 100 .

[0030] Figure 1 and 2The simple layered structure illustrated in is provided by way of non-limiting example, and it should be understood that embodiments of the present invention can be used in conjunction with various other structures. The specific materials and structures described are exemplary in nature, and other materials and structures can be used. Functional OLEDs can be obtained by combining the various layers described in different ways, or the layers can be completely omitted based on design, performance and cost factors. Other layers not specifically described may also be included. Materials other than the specifically described materials can be used. Although many of the examples provided herein describe the various layers as including a single material, it should be understood that a combination of materials, such as a mixture of a host and a dopant, or more generally a mixture, can be used. In addition, 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 emissive layer 220, and may be described as a hole transport layer or a hole injection layer. In one embodiment, the OLED may be described as having an "organic layer" disposed between the cathode and the anode. This organic layer may include a single layer, or may further include, for example, Figure 1 and 2 Multiple layers of said different organic materials.

[0031] Structures and materials not specifically described may also be used, such as OLEDs containing polymeric materials (PLEDs), such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of another example, an OLED having a single organic layer may be used. OLEDs may be stacked, such as described in U.S. Pat. No. 5,707,745 to Forrest et al., which is incorporated by reference in its entirety. OLED structures may deviate from Figure 1 and 2 For example, the substrate may include angled reflective surfaces to improve out-coupling, such as a mesa structure as described in U.S. Pat. No. 6,091,195 to Forrest et al., and / or a pit structure as described in U.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated by reference in their entirety.

[0032] In some embodiments disclosed herein, an emissive layer or material (e.g. Figure 1-2) may include quantum dots. Unless expressly indicated to the contrary or indicated by the circumstances as understood by a person skilled in the art, an "emission layer" or "emission material" as disclosed herein may include an organic emissive material and / or an emissive material containing quantum dots or an equivalent structure. Such an emissive layer may include only a quantum dot material that converts light emitted by a separate emissive material or other emitter, or it may also include the separate emissive material or other emitter, or it itself may directly emit light by applying an electric current. Similarly, a color-changing layer, a color filter, an up-conversion or down-conversion layer or structure may include a material containing quantum dots, but such a layer may not be considered an "emission layer" as disclosed herein. In general, an "emission layer" or material is an "emission layer" or material that emits initial light, which may be changed by another layer (such as a color filter or other color-changing layer) that does not emit initial light itself within the device, and may also re-emit changed light with different spectral content based on the initial light emitted by the emissive layer.

[0033] Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For organic layers, preferred methods include thermal evaporation, inkjet (as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, incorporated by reference in their entirety), organic vapor phase deposition (OVPD) (as described in U.S. Pat. No. 6,337,102 to Forrest et al., incorporated by reference in their entirety), and deposition by organic vapor jet printing (OVJP) (as described in U.S. Pat. No. 7,431,968, incorporated by reference in their entirety). Other suitable deposition methods include spin coating and other solution-based processes. Solution-based processes are preferably carried out in nitrogen or an inert atmosphere. For other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding (as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entirety), and patterning associated with some of the deposition methods such as inkjet and OVJP. Other methods may also be used. The material to be deposited may be modified to make it compatible with a specific deposition method. For example, branched or unbranched substituents such as alkyl and aryl groups, preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to withstand solution processing. Substituents having 20 or more carbons may be used, and 3 to 20 carbons are a preferred range. Materials having asymmetric structures may have better solution processing than materials having symmetric structures because asymmetric materials may have a lower tendency to recrystallize. Dendritic polymer substituents may be used to enhance the ability of small molecules to withstand solution processing.

[0034] The device manufactured according to the embodiment of the present invention may further optionally include a barrier layer. One purpose of the barrier layer is to protect the electrode and the organic layer from exposure to harmful substances in an environment including moisture, steam and / or gas. The barrier layer can be deposited on a substrate, an electrode, under a substrate, an electrode, or beside a substrate, an electrode, or on any other part (including the edge) of the device. The barrier layer may include a single layer or multiple layers. The barrier layer may be formed by various known chemical vapor deposition techniques, and may include a composition having a single phase and a composition having multiple phases. Any suitable material or material combination may be used for the barrier layer. The barrier layer may be combined with an inorganic compound or an organic compound or both. A preferred barrier layer includes a mixture of a polymeric material and a non-polymeric material, as described in U.S. Patent No. 7,968,146, PCT Patent Application No. PCT / US2007 / 023098, and No. PCT / US2009 / 042829, which are incorporated herein by reference in their entirety. In order to be considered a "mixture", the aforementioned polymeric material and non-polymeric material constituting the barrier layer should be deposited under the same reaction conditions and / or deposited simultaneously. The weight ratio of polymeric material to non-polymeric material can be in the range of 95:5 to 5:95. The polymeric material and non-polymeric material can be produced from the same precursor material. In one example, the mixture of polymeric material and non-polymeric material consists essentially of polymeric silicon and inorganic silicon.

[0035] Devices manufactured according to embodiments of the present invention may be incorporated into a wide variety of electronic component modules (or units), which may be incorporated into a variety of electronic products or intermediate components. Examples of electronic products or intermediate components include display screens, lighting devices (such as discrete light source devices or lighting panels), etc. that can be utilized by end-user product manufacturers. The electronic component module may optionally include drive electronics and / or a power supply. Devices manufactured according to embodiments of the present invention may be incorporated into a wide variety of consumer products, which have one or more electronic component modules (or units) incorporated therein. A consumer product comprising an OLED is disclosed, wherein the OLED includes a compound of the present disclosure in an organic layer in the OLED. The consumer product should include any kind of product containing one or more of one or more light sources and / or a certain type of visual display. Some examples of such consumer products include flat panel displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior lighting and / or signaling, heads-up displays, fully or partially transparent displays, flexible displays, laser printers, telephones, cellular phones, tablet computers, phablets, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, video cameras, viewfinders, microdisplays (displays with a diagonal of less than 2 inches), 3-D displays, virtual reality or augmented reality displays, vehicles, video walls comprising multiple displays tiled together, theater or stadium screens, and signage. Various control mechanisms may be used to control devices made according to the present invention, including passive matrices and active matrices. Many of the devices are intended to be used in a temperature range comfortable for humans, such as 18°C ​​to 30°C, and more preferably at room temperature (20-25°C), but may be used outside this temperature range (e.g., -40°C to +80°C).

[0036] The materials and structures described herein can be applied to devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors can employ the materials and structures. More generally, organic devices such as organic transistors can employ the materials and structures.

[0037] In some embodiments, the OLED has one or more features selected from the group consisting of: flexible, rollable, foldable, stretchable, and bendable. In some embodiments, the OLED is transparent or translucent. In some embodiments, the OLED further comprises a layer comprising carbon nanotubes.

[0038] In some embodiments, the OLED further comprises a layer comprising a delayed fluorescent emitter. In some embodiments, the OLED comprises an RGB pixel arrangement or a white plus color filter pixel arrangement. In some embodiments, the OLED is a mobile device, a handheld device, or a wearable device. In some embodiments, the OLED is a display panel having a diagonal of less than 10 inches or an area of ​​less than 50 square inches. In some embodiments, the OLED is a display panel having a diagonal of at least 10 inches or an area of ​​at least 50 square inches. In some embodiments, the OLED is a lighting panel.

[0039] In some embodiments of the emission region, the emission region further comprises a body.

[0040] In some embodiments, the compound can be an emissive dopant. In some embodiments, the compound can emit light via phosphorescence, fluorescence, thermally activated delayed fluorescence (ie, TADF, also known as E-type delayed fluorescence), triplet-triplet annihilation, or a combination of these methods.

[0041] Components The OLEDs disclosed herein may be incorporated into one or more of consumer products, electronic component modules, and lighting panels. The organic layer may be an emissive layer, and the compound may be an emissive dopant in some embodiments, while the compound may be a non-emissive dopant in other embodiments.

[0042] The organic layer may also include a host. In some embodiments, two or more hosts are preferred. In some embodiments, the host used may be a) bipolar, b) electron transport, c) hole transport, or d) wide bandgap material that plays a minimal role in charge transport. In some embodiments, the host may include a metal complex. The host of the component may be an inorganic compound.

[0043] Combination with other materials

[0044] The materials described herein as being suitable for use in a particular layer in an organic light-emitting device can be used in combination with a variety of other materials present in the device. For example, the emissive dopants disclosed herein can be used in combination with a wide variety of hosts, transport layers, barrier layers, injection layers, electrodes, and other layers that may be present. The materials described or mentioned below are non-limiting examples of materials that can be used in combination with the compounds disclosed herein, and those skilled in the art can readily consult the literature to identify other materials that can be used in combination.

[0045] Different emissive and non-emissive layers and arrangements disclosed herein may use different materials. Examples of suitable materials are disclosed in U.S. Patent Application Publication No. 2017 / 0229663, which is incorporated by reference in its entirety.

[0046] Conductive dopants:

[0047] The charge transport layer can be doped with a conductivity dopant to substantially change its charge carrier density, which in turn will change its conductivity. The conductivity is increased by generating charge carriers in the matrix material, and depending on the type of dopant, a change in the Fermi level of the semiconductor can also be achieved. The hole transport layer can be doped with a p-type conductivity dopant, and an n-type conductivity dopant is used in the electron transport layer.

[0048] HIL / HTL:

[0049] The hole injection / transport material used in the present invention is not particularly limited, and any compound may be used as long as the compound is generally used as a hole injection / transport material.

[0050] EBL:

[0051] An electron blocking layer (EBL) can be used to reduce the number of electrons and / or excitons that leave the emissive layer. The presence of such a blocking layer in a device can produce substantially higher efficiency and / or longer lifetime than a similar device lacking a blocking layer. In addition, a blocking layer can be used to confine emission to desired areas of the OLED. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and / or a higher triplet energy than the emitter closest to the EBL interface. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and / or a higher triplet energy than one or more of the hosts closest to the EBL interface. In one aspect, the compound used in the EBL contains the same molecule or the same functional group as used in one of the hosts described below.

[0052] main body:

[0053] The light-emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as a light-emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complex or organic compound may be used as long as the triplet energy of the host is greater than the triplet energy of the dopant. Any host material may be used with any dopant as long as the triplet criterion is satisfied.

[0054] HBL:

[0055] A hole blocking layer (HBL) can be used to reduce the number of holes and / or excitons that leave the emissive layer. The presence of such a blocking layer in a device can result in substantially higher efficiency and / or longer lifetime than a similar device lacking a blocking layer. In addition, a blocking layer can be used to confine emission to a desired area of ​​the OLED. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and / or a higher triplet energy than the emitter closest to the HBL interface. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and / or a higher triplet energy than one or more of the hosts closest to the HBL interface.

[0056] ETL:

[0057] The electron transport layer (ETL) may include a material capable of transporting electrons. The electron transport layer may be intrinsic (undoped) or doped. Doping may be used to enhance conductivity. Examples of ETL materials are not particularly limited, and any metal complex or organic compound may be used as long as it is generally used to transport electrons.

[0058] Charge Generation Layer (CGL)

[0059] In a tandem or stacked OLED, the CGL plays a fundamental role in the performance and consists of an n-doped layer and a p-doped layer for injecting electrons and holes, respectively. Electrons and holes are supplied by the CGL and electrodes. The electrons and holes consumed in the CGL are refilled by electrons and holes injected from the cathode and anode, respectively; then, the bipolar current gradually reaches a steady state. Typical CGL materials include n- and p-conductivity dopants used in the transport layer.

[0060] When the emitting material of an emitter as disclosed herein is placed in an environment with an increased density of photon states relative to a vacuum, the emission rate of the material is generally increased due to a phenomenon known as the Purcell effect. The enhanced radiative and non-radiative rates reduce the length of time that the emitter remains in an excited state, thereby stabilizing the emitter and reducing the aging rate of the emitting material, and therefore, the OLED device as a whole. It is believed that obtaining a relatively large Purcell enhancement generally requires placing the emitting material in close proximity to a metal film or other plasma-active enhancement layer. Such configurations are described, for example, in U.S. Pat. No. 9,960,386, the disclosure of which is incorporated herein by reference in its entirety. As used herein, "plasma OLED" refers to an OLED including an enhancement layer, the enhancement layer including a plasma material that exhibits a surface plasmon resonance that is non-radiatively coupled to an organic emissive material and transfers excited state energy from the emissive material to a non-radiative mode of a surface plasmon polariton. As previously disclosed and defined, the enhancement layer provided is generally no more than a threshold distance away from the second organic emissive layer. Such an arrangement may be most important for emissive materials within a threshold distance of the enhancement layer, where the relevant threshold distance may be defined as the distance from the enhancement layer at which the total radiative decay rate constant equals the total non-radiative decay rate constant. Typically, energy coupled into the enhancement layer is lost as heat unless the device also incorporates an outcoupling layer. The embodiments disclosed herein provide techniques and arrangements that allow enhancement and / or outcoupling layers to be incorporated into OLED displays and other devices.

[0061] Typical manufacturing methods for OLED displays generally involve patterning subpixels by controlling the materials deposited on the display for each subpixel (commonly referred to as side-by-side manufacturing), or depositing a uniform OLED stack across the entire backplane, and then subsequently patterning the subpixels with elements such as color filters or down-conversion layers. A uniform OLED stack generally includes one or more blanket OLED depositions that are deposited across one or more underlying electrodes without interruption. These methods can also be combined in various forms. Examples of these and related manufacturing techniques and device arrangements are described in, for example, U.S. Pat. Nos. 9,385,168, 9,590,017, 9,424,772, 10,243,023, 10,304,906, and 10,229,956 and U.S. Publication Nos. 2015 / 0349034 and 2015 / 0349032, the disclosures of each of which are incorporated by reference in their entirety.

[0062] OLED displays with uniform OLED stacking across the entire back plane typically have stacked OLED devices therein. For example, current TV architectures typically use 3 OLEDs stacked in series to provide a white emitting device. Based on the uniform white stacked OLED deposition, the 4 sub-pixels are then patterned, such as by patterning the red sub-pixel, green sub-pixel, blue sub-pixel, and white sub-pixel using a mask, a color-changing layer (such as a color filter), etc. As another example, a blue OLED device can be stacked to produce extremely bright blue light, which can be converted into red and / or green sub-pixels by a down-conversion layer stacked with the blue device, thereby presenting a display with red (R), green (G), and blue (B) (RGB) sub-pixels. The embodiments disclosed herein provide methods and arrangements for implementing plasma OLEDs in conjunction with such devices to benefit displays in a variety of ways by utilizing the lifetime enhancement of plasma OLEDs and the stacked structure.

[0063] Figure 3 A schematic representation of the basic structure of a device as provided herein is shown. The device includes a plasma OLED 350 and zero or more, typically one or more, non-plasma OLEDs 360, 361. As used herein, a "non-plasma" OLED can be, for example, Figure 1 and 2 The OLED described herein, or any other OLED device without limiting the arrangement of components in the device to meet the requirements defined for the "enhancement layer" as described herein. The plasma OLED 350 is provided by an emission stack, which includes outer conductive layers 351, 353 with an emission stack 352 disposed therebetween. As used herein, an "emission stack" refers to a stack of layers or other components that provide at least a minimum number of layers and components that emit light, typically including a conductive layer and at least an emission layer disposed therebetween. Each "emission stack" 352, 362, 363 may also include any or all of the other organic layers and other layers disclosed herein, such as those described with reference to Figure 1 and 2, including but not limited to barrier layers, transport layers, spacer layers, etc. In a common device structure, the outermost conductive layers 351, 367 are electrodes. The "emission stack" in combination with the surrounding conductive layers provides a functional OLED device, even if it is contained in a larger device as shown, which may include multiple OLEDs each having a corresponding emission stack. Each of the conductive layers 351, 353 may be an electrode, which includes an electrical connection extending outside the device, or a charge generation layer that does not include an external connection but provides the same functionality as an electrode, i.e., charge generation within the OLED. Similarly, the non-plasma OLEDs 360, 361 are each defined by an external conductive layer and an emission stack therebetween. The first non-plasma OLED 360 includes an emission stack 362 disposed between the external conductive layers 353, 364, and the second non-plasma OLED includes an emission stack 363 disposed between the external conductive layers 364, 367. As with the plasma OLED 350, each of the conductive layers 353, 364, 367 may be an electrode or an internal charge generation layer. The conductive layer may be shared between two adjacent emission stacks. In this example, conductive layer 353 may be a charge generation layer that provides electrode-like functionality to the emission stack 352 of plasma OLED 350 and the emission stack 362 of adjacent non-plasma OLED 360. One or more of conductive layers 351, 353, 364, 367 may serve as an enhancement layer for a plasma OLED in a device such as OLED 350. In this example structure, conductive layer 351 may be an electrode that is also an enhancement layer for plasma OLED 350. Each of the devices may be described as a "stack," and the device as a whole may be described as being arranged in a "stacked configuration" because they at least partially overlap each other perpendicularly (i.e., in the direction from the lower conductive layer 367 to the upper conductive layer 351). In general, the outermost conductive layers 351, 367 will be electrodes for the stacked device. Typically, the conductive layer 367 closest to the substrate is the anode, and the upper layer 351 is the cathode, but an inverted arrangement may be used, with the lower layer 367 being the cathode of the device. Internal conductive layers such as layers 353, 364 are typically charge generation layers disposed between the emission layers of each of the OLEDs, and more specifically, between the emission stacks 352, 362, 363 that include one or more emission layers and any other layers in each OLED. Other layers and components may be disposed above the conductive layer 351, such as outcoupling layers, color filters, down conversion layers, etc. In addition, one or more other layers 390 may be disposed below the substrate, i.e., opposite the substrate from the emission stacks 350, 360, 361, or more generally, on the opposite side from the one or more emission layers in any of the structures disclosed herein.Such layers 390 may include, for example, one or more outcoupling layers, color filters, down-conversion layers, up-conversion layers, radiation pattern modifying elements, or any other color-changing or similar layers as disclosed herein, including any of the materials or structures disclosed herein for use in such layers. Examples of such structures are further described in detail herein, any of which may be used for other layers or layer 390 as shown. For example, any of the layers and structures shown herein, including but not limited to layers and components 305, 370, 365, 375, 565, 566, 567, 571, 572, 573, and combinations and variations thereof.

[0064] As this article about Figure 3 The example arrangements of the basic architecture shown in the are further disclosed in detail that the devices provided herein may include various components and layers that operate as part of or in conjunction with one or more plasma and / or non-plasma OLEDs in a stacked device. The various features of these components will now be described. Unless expressly indicated to the contrary or prohibited by the physical requirements or constraints of the individual features, each feature may be used in conjunction with each other feature without departing from the scope and content of the present invention. In addition, unless expressly described to the contrary, any of the devices and arrangements disclosed herein, whether plasma or non-plasma OLED, may include information about Figure 1 and 2 Any or all of the layers and structures described, including but not limited to emission layers, transport layers, blocking layers, color-changing layers (such as color filters), up-conversion layers or down-conversion layers, quantum dot structures, charge generation layers, electrodes, and substrates.

[0065] The outcoupling layer or components as disclosed herein may be periodic, aperiodic, or have no periodicity, including random physical arrangements. They may include dielectric materials, metals, or semiconductive materials, or combinations of these materials. In some configurations, the outcoupling layer may include additional coatings to modify the radiation pattern, as described herein with respect to radiation pattern modifying elements. Alternatively or additionally, the outcoupling layer may have a coating to reduce the reflectivity of the layer or the device as a whole.

[0066] Each emission layer (EML) disclosed herein, whether incorporated into a plasma OLED emission stack or a non-plasma OLED emission stack, can include one or more emission materials. Each emission material can emit monochromatic or colored light, examples of which include, but are not limited to, red and green emission materials to provide yellow light emission, blue and red emission materials to provide white light emission, blue and red and green to produce white light emission, or blue, red, green and / or yellow to provide white light emission. Similarly, each emission stack may include multiple independent emission layers to achieve the same effect. Each emission material can be a fluorescent, phosphorescent or thermally activated delayed fluorescence (TADF) material or a combination of these types of materials. Similarly, each emission stack in each device disclosed herein can use any combination of fluorescent, phosphorescent and / or TADF materials.

[0067] Each OLED and each OLED stack including multiple OLEDs can be a bottom emitting, top emitting, or double-sided device. A bottom emitting device is a device that emits through the substrate on which the device is stacked, while a top emitting device emits light primarily through the opposite side of the device. A double-sided device emits through both surfaces of the OLED or device. These devices can be used in any combination within any individual device. For example, the topmost emitting stack can be top emitting, while the stacks lower in the device (i.e., closer to the substrate) can have double-sided emission. As understood in the art with respect to conventional OLED structures, a variety of reflective and transmissive materials and layers can be used to achieve any desired type of emission. In some cases, the arrangement of the emitting stacks and devices can be varied from Figure 3 -5. For example, for a bottom emitting device, the plasma OLED may be arranged closer to the substrate, with one or more non-plasma OLEDs stacked above it, and any outcoupling layers or components may be arranged below the anode rather than above it, with the anode acting as an enhancement layer for the plasma OLED. Alternatively or additionally, in some configurations, the electrodes may be reversed from the example shown, such that the cathode is below the emitting stack and the anode is the uppermost conductive layer.

[0068] Each down-conversion layer or component as disclosed herein may include one or more materials, including fluorescent emitters, inorganic phosphors, organic phosphors, and / or quantum dots. More generally, a down-conversion layer or component may include any material that absorbs photons and re-emits photons at an energy lower than the energy absorbed by the material. A down-conversion layer may be a blanket layer that extends unbroken across multiple sub-pixels, or it may be patterned only on one or more sub-pixels within a device.

[0069] Plasmonic outcoupling layers such as layer 305, layer 571, layer 572, and layer 573 as disclosed herein may include a variety of structures. Examples of suitable outcoupling structures include, but are not limited to, grids or corrugations, nanopatch antennas or other nanoparticle-based outcoupling schemes, and through-hole arrays. Alternatively or in addition, the outcoupling layer may include a voltage-tunable refractive index material that may be used in conjunction with another electrode that allows tuning of the outcoupling color based on an external voltage. Alternatively or in addition to these outcoupling structures, some devices may include conventional outcoupling structures such as microlens sheets, outcoupling grids or lenses, etc.

[0070] Each charge generation layer disclosed herein may include metallic materials and any other materials or structures known in the art for charge generation in conventional OLEDs. Alternatively or in addition, the charge generation layer may include other components such as, but not limited to, spin-coated nanoparticles, nanoparticles prepared by slowly growing a metal so that it dewets, or by laminating metal films. Laminated CGL structures may include arrays of particles, pseudo-periodic and randomly oriented nanoparticles, and arrays of through holes of metals or metal alloys. The CGL may consist of a single component, or it may include a mixed layer of organic material with dielectric or metal nanoparticles embedded therein, or it may include sublayers in any combination of these materials.

[0071] The radiation pattern changing element as disclosed herein can convert the radiation pattern from non-Lambertian to Lambertian, or from Lambertian to non-Lambertian (such as for applications where a certain angular dependence is desired), or more generally change the angular dependence of the properties of the light emitted by the device. Examples of components that can be used to provide the radiation pattern changing element include nanopatch antennas and components including equivalent nanopatch structures, semi-transparent metals, and distributed Bragg reflectors.

[0072] Each stacked device including multiple emission stacks and each individual emission stack can emit light of any desired color. For example, a plasma or non-plasma OLED can emit red, green, blue, yellow, white, or any other desired color. The light emitted by the emission stack within the stacked device can be emitted by an unchanged device, or it can be changed by using color filters, down-conversion layers, up-conversion layers, and other structures as disclosed herein to achieve the desired emission spectrum of the device. The stacked device can provide a single sub-pixel within the pixel structure of the display panel, or a single stacked device structure can provide multiple sub-pixels, as disclosed in various examples herein and as generally known in the art for conventional stacked devices. In some cases, a plasma OLED as disclosed herein may preferably emit blue light and / or include a blue emission material in the emission layer, because a blue emission device is generally a limiting factor in the lifetime of the device. A display panel using the device structure disclosed herein may include any desired combination of colors of sub-pixels, including 3- and 4-sub-pixel arrangements, white sub-pixels, red-green-blue (RGB) side-by-side arrangements, arrangements including two blue sub-pixels (RGB1B2 type devices). The device may include a limited number of colors of emissive materials, such as where only two or three colors of emissive materials are used, and color shifting layers and components are used to provide the other colors in a full-color pixel.

[0073] have Figure 3 Specific examples of arrangements of the basic structures shown in FIG. 4-5 will now be described with respect to FIG. 4-5. Any of the specific means, components, and layers shown in FIG. 4-5 may be used in combination with any other means, components, and layers unless specifically indicated to the contrary, or unless such combination is physically prohibited based on the description and requirements of each. In addition, other layers and components may be used in any of the devices shown in FIG. 4-5, including but not limited to one or more other layers disposed on the side of the substrate opposite to the one or more emission stacks, as described with respect to FIG. Figure 3 described.

[0074] Figure 4A A schematic illustration of a plasma OLED stacked in series with one or more non-plasma OLEDs as disclosed herein is shown. As shown, a device as provided herein may include a non-plasma OLED structure 360 ​​including external electrodes 330, 340 with one or more layers 335 disposed therebetween. The non-plasma OLED may be a stacked structure including multiple OLED structures therein. For example, Figure 4AThe non-plasma OLED structure shown in FIG. 1 includes two non-plasma OLEDs arranged in a stacked manner. The first electrode is defined by external electrodes 330, 340, with an emission layer 335 disposed therebetween. The second non-plasma OLED is defined by external conductive layers 320, 330, with an emission layer 322 disposed therebetween. Each non-plasma OLED may include about Figure 1 and 2 Any or all of the other layers disclosed, or more generally, any layer or structure suitable for use in an OLED as known in the art. Figure 4A As shown in , the plasma and non-plasma OLEDs disclosed herein may use electrodes 310, 340 to provide external electrical connections, or they may use charge generation layers 320, 330 to provide electrode-like functionality as known in the art. Plasma OLED 350 may include one or more electrodes or equivalent layers 310, 320 with one or more emissive layers 315 disposed therebetween. Plasma and non-plasma OLEDs may be arranged in a stacked manner on a substrate (not shown). As used herein, two devices, layers, or other components may be arranged "in a stack" or in a "stacked" configuration, wherein one is at least partially disposed on the other relative to a substrate or other common layer. In contrast to a stacked configuration, two components may be described as being arranged in a plane or in a side-by-side configuration, wherein there is no overlap of the components along any and all vertical lines drawn through one of the components.

[0075] More generally, the arrangements disclosed herein may include one or more plasma OLEDs and zero or more non-plasma OLEDs incorporated into a common display architecture. As previously disclosed, the plasma OLED includes an enhancement layer. Figure 4A In the example structure shown in , cathode 310 serves as both an electrical contact and an enhancement layer for plasma OLED 350. As described in further detail herein, light emitted by emissive layers (such as EML 322, 335) in one or more non-plasma OLEDs 360 can be transmitted by plasma OLED 360 and outcoupling structure 305 (if present).

[0076] The devices disclosed herein may include additional structures that operate in conjunction with plasma and / or non-plasma OLEDs. For example, Figure 4B Display and Figure 4A The same device, with a down conversion layer 365 and red, green and blue color filters 370. The down conversion layer may include fluorescent emitters, inorganic phosphors, organic phosphors, quantum dots or any other element that absorbs photons and re-emits them at lower energy. Figure 4BThe device shown in may include a down-conversion layer uniformly deposited over all sub-pixels as shown, or it may be patterned over one or more sub-pixels. For example, where one or more of the OLEDs emit blue light, red and green down-conversion and / or color filter layers may be placed over the red and green sub-pixels, while the blue sub-pixel uses only unfiltered light provided by the blue emitting device. When this layer is patterned over one or more sub-pixels, its composition may vary between sub-pixels. In addition to the down-conversion layer, various configurations may use any number of color filters, or the down-conversion layer may be used without an associated color filter. Each sub-pixel may have a different configuration, so that each may include a down-conversion layer and / or color filter in any combination, regardless of the structure used for other sub-pixels.

[0077] As another example, an apparatus disclosed herein may include a radiation pattern changing element. Figure 4C Display and Figure 4B , the angular dependence of the display is modified by adding a radiation pattern changing element. As with the down-conversion and color filter components, the radiation pattern changing element 375 can be deposited uniformly on the display or patterned individually or simultaneously on one or more sub-pixels. The radiation pattern changing element composition does not have to be the same on all sub-pixels and can vary between pixels within a single display panel or between stacked OLED devices. In addition, the radiation pattern changing element can be used to convert the radiation pattern from non-Lambertian to Lambertian, or from Lambertian to non-Lambertian for applications requiring a certain angular dependence. For example, element 375 may include a nanopatch antenna outcoupling mechanism to convert plasma energy into photons, which produces a near-Lambertian emission curve. In certain mobile display applications that require a certain angular dependence, the radiation pattern changing element can be used to form a cavity atop the plasma outcoupling mechanism. The element may include, for example, a semi-transparent metal or a distributed Bragg reflector to achieve the desired cavity effect. Element 375 can be used alone or in combination with Figure 4B One or more of the described components may be used in conjunction with any combination.

[0078] As previously disclosed, one or more plasma OLEDs may be arranged in a stacked fashion with zero or more non-plasma OLEDs. Figure 4D A schematic depiction of a device is shown that includes two plasma OLED devices 350, 380 arranged in a stack with a non-plasma OLED 360. As shown, the device can include electrodes and charge generation layers that define the boundaries of each OLED in the stack. In this example, the cathode 310 acts as an enhancement layer for the emissive layer 410 in the first plasma OLED 350, and the charge generation layer 420 acts as an enhancement layer and outcoupling layer for the emissive layer 430 in the second plasma OLED 380 and the CGL for the device stack. Figure 4DThe examples shown in include down-conversion layers and color filters as previously disclosed as examples, but more generally zero or more down-conversion layers, color filters, outcoupling components and / or radiation pattern changing elements may be used as previously disclosed.

[0079] In some cases, the plasma OLED 380 may have lower efficiency than other plasma OLEDs in different stacking structures. This may occur when light outcoupled from the non-plasma OLED 360 needs to pass through the charge generation layer 440 and the anode 460 for a bottom-emitting device or through the cathode 310 for a top-emitting device. The transmission of these layers may be less than 100%, thus reducing the efficiency of the plasma OLED 380 formed with the EML2 430.

[0080] In some cases, it may be desirable to use a plasma OLED with an emission spectrum having a larger spectral width. Such a device can directly display a display having multiple sub-pixels. An example of a device including a structure having a combination of a plasma OLED and a non-plasma OLED that can display multiple sub-pixels is described in Figures 5A-5C Schematically shown in .

[0081] Figure 5A An exemplary device structure including one plasma OLED and two non-plasma OLEDs is shown, and Figures 4A-4C The structures described are particularly similar. The plasma OLDD may include a phosphorescent or other emissive layer 315, which may include one or more emissive materials that emit colored light. The light emitted by the plasma EML 315 in the OLED 350 may be converted to provide two or more sub-pixels, such as by using one or more layers of color filters 370. As previously disclosed, although Figure 5A Two non-plasma OLEDs 360 are shown for illustration purposes, more typically as Figure 5A The device shown in may include zero or more non-plasma OLEDs. Conversion of light from a plasmonic OLED having a relatively large spectral width may be achieved, for example, by a broadband outcoupling structure, where the outcoupled emission is then converted into a spectrally pure color by one or more color filters, down-conversion layers, or a combination, as previously disclosed and described in Figures 5A-5C For example, Figure 5B An arrangement is shown in which a single outcoupling layer 305 is used to decouple light generated in the plasma OLED 350, but individual down conversion layers 565 are used to generate red, green and blue light from corresponding sub-pixels. Figure 5CThe same device is shown where individual subpixels include a combined color filter and down conversion component 566. Such components may be provided in a single layer where the components are arranged side by side, or they may be provided in two or more separate layers. In some embodiments, the color filter or down conversion layer may include additional coatings, or additional layers or components may be used to alter the radiation pattern as previously disclosed.

[0082] In some configurations, subpixel colors can be visualized by outcoupling specific spectral regions. For example, a white emitting plasma OLED can be outcoupled into red, green, and blue subpixels by using a fixed pitch grating by changing the refractive index of the material coating the grating so that the dispersion relationship preferentially scatters red, green, or blue light perpendicular to the substrate. A schematic depiction of this embodiment is shown in Figure 5D . In this arrangement, the composition of the outcoupling layer 567 may be different for each subpixel, such that the red, green, and blue subpixels are defined by corresponding outcoupling layers 571, 572, 573, respectively. In some embodiments, the differences between the outcoupling components and / or materials may be smaller. For example, all outcoupling layers may have a 300nm pitch grating, with the blue subpixel outcoupling layer 573 having no coating, and the red outcoupling layer 571 may have a 1 micron thick coating of a material having a refractive index of 1.7. Other example outcoupling mechanisms for selecting a specific wavelength range include, but are not limited to, nanopatch antennas or other nanoparticle-based outcoupling schemes and through-hole arrays.

[0083] In some configurations, it may be desirable to use specific materials or combinations of materials to achieve specific effects. For example, it may be desirable to balance charge distribution and injection within a plasma OLED, and particularly for phosphorescent plasma OLEDs. One way to avoid a large charge increase when switching the plasma enhanced layer from Al to Ag or other more plasma active materials is to use an electron injection layer, such as Yb or its alloys or oxides, which works with common plasma active materials such as Mg and Ag. Alternatively or in addition, adhesion layers that also act as charge injection layers, such as Mg, Al, Ni, and Ti layers, may be used. As a specific example, a 10 angstrom Al layer combined with an Ag layer may be used. The thickness for the adhesion layer may preferably be between 2 and 60 angstroms; more preferably between 5 and 30 angstroms, or more preferably between 5 and 20 angstroms.

[0084] It may also be necessary to balance the charge within the device because even in a device stabilized by coupling to a plasma mode of a metal, the lifetime of the device may be reduced if charge balance is lost. Various techniques can be used to maintain the desired charge balance, including the use of a lower electron mobility electron transport layer, such as AlQ3. As another example, the thickness of the hole blocking layer can be increased to reduce the electron injection rate from the electron transport layer to the emission layer. As another example, a hole blocking material with a relatively high LUMO can be used to add an electron injection barrier or within the emission layer to reduce electron injection and / or mobility in the emission layer. Alternatively or in addition, a high HOMO electron blocking material can be used to reduce the hole injection barrier into the emission layer. As another example, the proportion of e-type hosts within the emission layer can be reduced to a lower electron mobility within the emission layer. As another example, a relatively thin hole transport layer can be used, and / or the percentage of emission material in the doped EML can be increased to increase the hole mobility within the device. It may also be necessary to maintain a high quality enhancement layer to improve the performance of the plasma OLED. Specific examples include growth rates of 0.1 to More preferably, 0.5 to Any or all of these methods can be used individually or in combination with any other method to obtain stable, efficient plasma OLEDs.

[0085] It should be understood that the various embodiments described herein are by way of example only, and are not intended to limit the scope of the present invention. For example, other materials and structures may be used to replace many materials and structures described herein without departing from the spirit of the present invention. The present invention as required may therefore include variations of specific examples and preferred embodiments described herein, as will be apparent to those skilled in the art. It should be understood that the various theories about why the present invention works are not intended to be restrictive.

Claims

1. A device comprising: A first organic light emitting diode (OLED) stack, the first OLED stack comprising: a first electrode; a first charge generating layer; and a first organic emission layer disposed between the first electrode and the first charge generation layer and within a first threshold distance of the first electrode or the first charge generation layer, the first organic emission layer comprising a first organic emission material, wherein the first threshold distance is a distance from the first organic emission material at which a total non-radiative decay rate constant is equal to a total radiative decay rate constant of the first organic emission material; A second OLED stack, the second OLED stack comprising: the first charge generating layer; a second electrode; and a second organic emission layer disposed between the first charge generation layer and the second electrode; and The first organic emission layer is disposed above the second organic emission layer.

2. The device of claim 1, further comprising at least one component selected from the group consisting of: a color filter, a down-conversion layer, an up-conversion layer, and a radiation pattern modifying element. The device of claim 1 , wherein the first organic emissive material comprises a blue emissive material.

4. A device according to claim 1, wherein the second organic emission layer is within a second threshold distance of the first charge generating layer or the second electrode, and the second organic emission layer comprises a second organic emission material, wherein the second threshold distance is a distance from the second organic emission material at which a total non-radiative decay rate constant is equal to a total radiative decay rate constant of the second organic emission material. The device of claim 4 , wherein the second organic emissive material comprises a blue emissive material. 6 . The device of claim 1 , further comprising a first outcoupling layer disposed in stack with the first electrode and the second electrode. 7 . The device of claim 6 , further comprising a second outcoupling layer disposed in stack with the first electrode and the second electrode.

8. The device of claim 7, wherein at least one of the first outcoupling layer and the second outcoupling layer comprises a structure selected from the group consisting of: a mesh; a corrugated layer; a nanopatch antenna; a nanoparticle outcoupling structure; and a through-hole array. 9 . The device of claim 1 , wherein at least one of the first organic emission layer and the second organic emission layer comprises a plurality of emission materials.

10. The device of claim 1 or 4, wherein at least one of the first organic emission material and the second organic emission material is selected from the group consisting of: a phosphorescent emission material, a fluorescent emission material, a delayed fluorescent emission material, or a thermally activated delayed fluorescent (TADF) emission material.

11. The device of claim 1, further comprising a plurality of color filters, each having a different color.

12. The device of claim 1, further comprising a substrate, wherein the first and second plasma OLEDs are disposed over a first side of the substrate, and wherein at least one of the following two conditions (a) and (b) is true: (a) further comprising at least one component selected from the group consisting of: a color filter, a down-conversion layer, an up-conversion layer, and a radiation pattern modifying element, wherein the at least one component is disposed on a side of the substrate opposite to the first side, (b) wherein the device is configured to emit light primarily through the substrate.

13. The device of claim 1, further comprising a radiation pattern modifying element disposed with the first plasma OLED stack.

14. The device of claim 13, wherein the device comprises a plurality of sub-pixels, and radiation pattern modifying elements of different types are disposed over sub-pixels of different colors.

15. The device of claim 1, wherein the device is at least one category selected from the group consisting of: a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior lighting and / or signaling, a head-up display, a fully or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a phone, a cell phone, a tablet computer, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a microdisplay having a diagonal of less than 2 inches, a 3-D display, a virtual reality or augmented reality display, a vehicle, a video wall comprising multiple displays tiled together, a theater or stadium screen, and a sign.

Images