Organic electroluminescent device

Abstract

The invention relates to an organic electroluminescent device. A light emitting device includes a first electrode, a first transport layer over the first electrode, a first emissive layer over the first transport layer, a second transport layer over the first emissive layer, and a second electrode over the second transport layer, wherein at least one of the first transport layer and the second transport layer includes nanoparticles.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 677,573, filed July 31, 2024, and U.S. Provisional Application No. 63 / 780,690, filed March 31, 2025, each of which is incorporated herein by reference in its entirety.

[0003] Statement as to Federally Sponsored Research or Development

[0004] This application was made with government support under DE-EE0009688 awarded by the U.S. Department of Energy. The government has certain rights in the application. TECHNICAL FIELD

[0005] The present application relates to emissive devices, including organic emissive devices that include nanoparticles in one or more transport layers. BACKGROUND

[0006] Opto-electronic devices that make use of organic materials are becoming increasingly important for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential to be lower cost than alternative devices that use expensive materials. In addition, the inherent properties of organic materials, such as their flexibility, can make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting diodes / devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic

[0007] OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in the design of flat panel displays, for use in the design of illumination areas, and for use in the design of devices such as small molecular weight organic light emitting diodes. 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.

[0008] One application for phosphorescent phosphor emitting molecules is full color displays. Industry standards for such displays require pixels suitable for emitting specific colors, referred to as "saturated" colors. Specifically, these standards require saturated red, green, and blue pixels. Alternatively, an OLED can be designed to emit white light. In conventional liquid crystal displays, absorbing filters are used to filter the emission from a white backlight to produce red, green, and blue emissions. The same technique can be used for OLEDs. A white OLED can be a single EML device or a stacked structure. Color can be measured using CIE coordinates, which are well known in the art.

[0009] As used herein, the term "organic" includes polymeric and small molecule organic materials, which can be used to fabricate organic light emitting devices. Small molecules can also be used to fabricate organic light emitting devices. Most

[0010] As used herein, "top" means furthest away from the substrate, and "bottom" means closest to the substrate. Where a first layer is described as "disposed on" a second layer, the first layer is disposed further from the substrate than is the second layer. Unless stated to the contrary, there can be intervening layers between the first and second layers. For example, a cathode can be described as "disposed on" an anode, even though various organic layers are between the cathode and the anode.

[0011] As used herein, "solution processible" means capable of being dissolved, dispersed, or transported in and / or deposited from a liquid medium, either in solution or suspension form.

[0012] A ligand can be referred to as "photosensitizing" when it is believed to contribute directly to the photoactive properties of an emissive material. A ligand can be referred to as "auxiliary" when it is believed not to contribute to the photoactive properties of an emissive material, although an auxiliary ligand can alter the properties of a photosensitizing ligand.

[0013] As used herein, and as will be generally understood by one of ordinary skill 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 ionization potential (IP) is measured as a negative energy with respect to the vacuum energy level, a higher HOMO energy level corresponds to a smaller absolute value of IP (a less negative IP). Similarly, a higher LUMO energy level corresponds to a smaller absolute value of electron affinity (EA) (a less negative EA). On a conventional energy level diagram with the vacuum energy level at the top, a LUMO energy level of a material is higher than a HOMO energy level of the same material. A "higher" HOMO or LUMO energy level is thus represented by a more positive number on such a diagram, as it is closer to the top of the diagram.

[0014] As used herein, and as will be generally understood by one of ordinary skill in the art, a first work function has a "greater than" or "higher than" a second work function if the first work function has a higher absolute value. Since work functions are typically measured as negative numbers relative to the vacuum energy level, this means that a "higher" work function is more negative. On a conventional energy level diagram with the vacuum energy level at the top, a "higher" work function is thus illustrated as being further away from the vacuum energy level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow different conventions than work functions.

[0015] Layers, materials, regions, and devices can be described herein with reference to the color of light emitted thereby. Generally, as used herein, an emissive region described as producing a particular color of light can include one or more emissive layers disposed in a stacked manner over one another.

[0016] 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 about 570-700 nm or that has the highest peak of its emission spectrum in that region. Similarly, a "green" layer, material, region, or device refers to a layer, material, region, or device that emits with a peak wavelength in the range of about 500-600 nm or that has an emission spectrum; a "blue" layer, material, or device refers to a layer, material, or device that emits with a peak wavelength in the range of about 400-500 nm or that has an emission spectrum; a "yellow" layer, material, region, or device refers to a layer, material, region, or device that has an emission spectrum with a peak wavelength in the range of about 540-600 nm; a "cyan" layer, material, or device refers to a layer, material, or device that emits with a peak wavelength in the range of about 490-520 nm or that has an emission spectrum; and an "orange" layer, material, or device refers to a layer, material, or device that emits with a peak wavelength in the range of about 570-620 nm or that has an emission spectrum. In some arrangements, separate regions, layers, materials, regions, or devices can provide separate "deep blue" and "light blue" light. As used herein, in arrangements that provide separate "light blue" and "deep blue" components, the "deep blue" component refers to a component with a peak emission wavelength that is at least about 4 nm less 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 about 465-500 nm, and the peak emission wavelength of the "deep blue" or "dark blue" component is in the range of about 400-470 nm, although these ranges can vary for some configurations. The peak emission wavelength of the "light green" component is in the range of about 520-560 nm, and the peak emission wavelength of the "deep green" or "dark green" component is in the range of about 500-520 nm, although these ranges can vary for some configurations. The peak emission wavelength of the near infrared ("NIR") component is in the range of about 700-1800 nm. Similarly, a color changing layer refers to a layer that converts or modifies light of another color to light with a wavelength specified for that color. For example, a "red" filter refers to a filter that forms light with a wavelength in the range of about 580-700 nm. In general, there are two classes of color changing layers: color filters that modify the spectrum by removing unwanted wavelengths of light, and color changing layers that convert higher energy photons to lower energy. A component of "color" refers to a component that, when activated or used, produces or otherwise emits light with a particular color as previously described. For example, "a first emission region of a first color" and "a second emission region of a second color different from the first color" describe two emission regions that emit two different colors as previously described when activated within a device.

[0017] As used herein, emission materials, layers, and regions can be distinguished from one another and from other structures based on the spectra of light that the materials, layers, or regions initially produce as distinct from the light ultimately emitted by the same or different structures. Initial light production is typically the result of energy level changes that lead to photon emission. For example, an organic emission material can initially produce blue light, which can be converted to red, green, or yellow light by color filters, quantum dots, or other structures, so that the complete emission stack or sub-pixel emits red, green, or yellow light. In this case, the initial emission material or layer can be referred to as a "blue" component, even though the sub-pixel is a "red," "green," or "yellow" component.

[0018] In some cases, it can be preferable to describe the color of a component, such as an emission region, sub-pixel, color conversion layer, etc., in terms of 1931 CIE coordinates. For example, a yellow emission material can have multiple peak emission wavelengths, one in or near the edge of the "green" region, and one within or near the edge of the "red" region, as previously described. Thus, as used herein, each color term also corresponds to a shape in the 1931 CIE coordinate color space. Shapes in the 1931 CIE color space are constructed by tracing the locus between two color points and any other interior point. For example, the interior shape parameters for red, green, blue, and yellow can be defined as follows:

[0019]

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

[0021] Some embodiments of the invention disclosed herein are set forth below, and any combination of these embodiments (or portions thereof) can be made to define another embodiment.

[0022] In one aspect, a light emitting device comprises a first electrode, a first transport layer over the first electrode, a first emission layer over the first transport layer, a second transport layer over the first emission layer, and a second electrode over the second transport layer, wherein at least one of the first transport layer and the second transport layer comprises nanoparticles.

[0023] In some embodiments, the nanoparticles comprise metal nanoparticles.

[0024] In some embodiments, the metal comprises Ag, Al, Au, Pt, or Ti.

[0025] In some embodiments, the nanoparticles are randomly dispersed throughout the layer.

[0026] In some embodiments, the nanoparticles are periodically dispersed throughout the layer.

[0027] In some embodiments, the nanoparticles have a spacing in at least one direction of 1 nm to 1000 nm.

[0028] In some embodiments, the nanoparticles are quasi-periodically dispersed throughout the layer.

[0029] In some embodiments, the device further comprises at least one second emitter stack between the first electrode and the first transport layer.

[0030] In some embodiments, the at least one second emitter stack comprises a third transport layer, a second emission layer over the third transport layer, a fourth transport layer over the second emission layer, and a charge generation layer over the fourth transport layer.

[0031] In some embodiments, at least one of the third transport layer and the fourth transport layer comprises nanoparticles.

[0032] In some embodiments, the absorption edge of the nanoparticles is adjusted such that the nanoparticles are strongly coupled to singlet exciton emission of the first transport layer or the second transport layer.

[0033] In some embodiments, the nanoparticles have a size of 10 nm to 1000 nm.

[0034] In some embodiments, the cube root of the concentration (C) of the nanoparticles is within the wavelength (λ) of light emitted from the device, as defined by .

[0035] In some embodiments, at least one of the first transport layer and the second transport layer comprising nanoparticles is located at an interface of at least one of the first electrode and the second electrode.

[0036] In some embodiments, the device comprises a tandem stack device.

[0037] In some embodiments, each of the first emission layer and the second emission layer is associated with one or more of the first transport layer, the second transport layer, the third transport layer, and the fourth transport layer comprising nanoparticles.

[0038] In some embodiments, each of the first emission layer and the second emission layer is adjacent to one or more of the first transport layer, the second transport layer, the third transport layer, and the fourth transport layer comprising nanoparticles.

[0039] In some embodiments, the spacing of the nanoparticles is in the range of 1 nm to 1000 nm.

[0040] In some embodiments, at least one of the first transport layer and the second transport layer comprises an organic transport layer.

[0041] In some embodiments, the consumer electronic device incorporating the device described above is at least one type selected from the group consisting of a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a signboard, a light for interior or exterior illumination and / or signaling, a heads-up display, a full or partial transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a cellular 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 micro display with a diagonal less than 2 inches, a 3D display, a virtual reality or augmented reality display, a vehicle, an automotive display, a video wall comprising multiple displays tiled together, a theater or stadium screen, and a signboard. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 An organic light emitting device is shown.

[0043] Figure 2 An inverted organic light emitting device without a separate electron transport layer is shown.

[0044] Figure 3 An example stack device structure incorporating a nanoparticle-enhanced transport layer is shown, including embodiments of the disclosed subject matter.

[0045] Figure 4 The electric field (V / m) intensity around a single 20 nm diameter Ag nanoparticle in a material with refractive index n = 1.7 is shown, assuming a periodic spacing of 40 nm in the x and y directions.

[0046] Figure 5A And 5B The absorbance variation of a) 20 nm diameter Ag particles with different spacing and b) 60 nm spaced Ag particles with different diameters is shown.

[0047] Figure 6 The localized Purcell factor is shown, calculated as the ratio of the average Poynting vector over a unit cell as a function of wavelength.

[0048] Figure 7 The Purcell factor as a function of wavelength for a full standard bottom emission device with and without a nanoparticle-enhanced transport layer in an Al-ITO cavity is shown.

[0049] Figures 8A to 8EDetails are shown regarding the use of the Purcell effect enhanced by plasmonic enhancement to enhance the stability of deep blue phosphor sensitized fluorescent OLEDs.

[0050] Figures 9A to 9F Simulated experimental results are depicted. DETAILED DESCRIPTION

[0051] In general, an OLED includes at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an "exciton," which is a localized electron-hole pair having an excited state, is formed. When the exciton relaxes through a photoemissive mechanism, light is emitted. In some cases, the exciton can localize on an excimer or an exciplex. Nonradiative mechanisms, such as thermal relaxation, can also occur, but are generally considered undesirable.

[0052] Initial OLEDs used emissive molecules which emitted light from singlet states ("fluorescence"), as disclosed, for example, in U.S. Patent No. 4,769,292, incorporated by reference in its entirety. Fluorescent emission generally occurs in a small percentage of instances relative to other mechanisms, which often result in light emission that is less than desirable.

[0053] More recently, OLEDs having 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, no. 3, pp. 4-6, 1999 ("Baldo-II"), which are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Patent No. 7,279,704 at cols. 5-6, incorporated by reference.

[0054] Figure 1An organic light emitting device 100 is shown. The figures are not necessarily drawn to scale. The device 100 can include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive 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 order. The properties and functions of these various layers, as well as example materials, are described in more detail in US 7,279,704 columns 6-10, which is incorporated by reference.

[0055] More examples of each of these layers can be found. For example, flexible and transparent substrate-anode combinations are disclosed in U.S. Patent No. 5,844,363, incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F4-TCNQ in a 50:1 molar ratio, as disclosed in U.S. Patent Application Publication No. 2003 / 0230980, incorporated by reference in its entirety. Examples of light emitting and host materials are disclosed in U.S. Patent No. 6,303,238 to Thompson et al., incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li in a 1:1 molar ratio, as disclosed in U.S. Patent Application Publication No. 2003 / 0230980, incorporated by reference in its entirety. U.S. Patent Nos. 5,703,436 and 5,707,745, incorporated by reference in their entirety, disclose examples of cathodes including composite cathodes with a thin layer of metal (such as Mg:Ag) having 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, incorporated by reference in their entirety. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004 / 0174116, incorporated by reference in its entirety. Barrier layer 170 can be a single layer or a multi-layer barrier layer and can cover or surround other layers of the device. Barrier layer 170 can also surround substrate 110, and / or it can be disposed between the substrate and other layers of the device. Barrier layers can also be referred to as encapsulants, encapsulation layers, protective layers, or permeation barriers, and generally provide protection from moisture, ambient air, and other like materials from permeating through other layers of the device. Examples of barrier layer materials and structures are provided in U.S. Patent Nos. 6,537,688, 6,597,111, 6,664,137, 6,835,950, 6,888,305, 6,888,307, 6,897,474, 7,187,119, and 7,683,534, each incorporated by reference in its entirety.

[0056] 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 fabricated by depositing the layers sequentially. Because the most commonly used OLED configuration has a cathode disposed over an anode, and device 200 has a cathode 215 disposed under anode 230, device 200 can be referred to as an "inverted" OLED. Similar materials as those described with respect to device 100 can be used in the corresponding layers of device 200. Figure 2Provide an example of how some layers can be omitted from the structure of device 100.

[0057] Figure 1 and 2 The simple layered structures illustrated herein are provided by way of non-limiting examples, and it should be understood that embodiments of the invention can be used in conjunction with a variety of 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 omitted entirely based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than 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, such as mixtures of host and dopant, or more generally, mixtures, can 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 can 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 the different organic materials mentioned above.

[0058] 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. By another example, OLEDs with a single organic layer can be used. OLEDs can be stacked, for example, as described in, U.S. Patent No. 5,707,745 to Forrest et al., which is incorporated herein by reference in its entirety. OLED structures can be deviated from... 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 described in U.S. Patent No. 6,091,195 to Forrest et al., and / or the recessed structure described in U.S. Patent No. 5,834,893 to Bulovic et al., which are incorporated herein by reference in their entirety.

[0059] In some embodiments disclosed herein, the emission layer or material, for example Figures 1-2The emissive layers 135 and 220 shown in FIGS. 1 and 2, respectively, can include quantum dots. The emissive layers can use different emissive display technologies. Such technologies can include inorganic and / or organic devices such as LEDs, submillimeter LEDs, micro-LEDs, electroluminescent thin films, organic light emitting devices, etc. Unless explicitly indicated to the contrary or as understood by one of skill in the art in light of the discussion, a "emissive layer" or "emissive material" as disclosed herein can include organic emissive materials and / or emissive materials containing quantum dots or equivalent structures. Generally, an emissive layer includes emissive materials within a host matrix. Such emissive layers can include only quantum dot materials that convert light emitted by separate emissive materials or other emitters, or they can also include separate emissive materials or other emitters, or they can themselves directly emit light by application of an electric current. Similarly, color changing layers, color filters, up- or down-conversion layers or structures can include materials containing quantum dots, but such layers can not be considered "emissive layers" as disclosed herein. Generally, an "emissive layer" or material is a material that emits initial light based on injected charge, where the initial light can be changed by another layer, such as a color filter or other color changing layer, that does not itself emit the initial light in the device, but can re-emit altered light with a different spectral content based on absorption and down-conversion of the initial light emitted by the emissive layer into lower energy light emission. In some embodiments disclosed herein, color changing layers, color filters, up- and / or down-conversion layers can be disposed externally to an OLED device, such as above or below an electrode of an OLED device.

[0060] Unless otherwise described, any of the layers of the various embodiments can be placed, disposed, or deposited by any suitable method. For organic layers, preferred methods include thermal evaporation, ink-jet (as described in U.S. Patent Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties), organic vapor phase deposition (OVPD) as described in U.S. Patent No. 6,337,102 to Fifer et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), as described in U.S. Patent No. 7,431,968, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably conducted in a nitrogen or 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. Patent Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties) and patterning associated with some of the deposition methods such as ink-jet and OVJD. Other methods can also be used. The materials to be deposited can be modified in order to impart desirable characteristics to the deposition process. For example, substituents can be used in small molecules to enhance their solution processability. Branched or unbranched, and preferably containing at least 3 carbons, substituents such as alkyls and aryls can be used. Substituents with 20 or more carbons can be used, and from 3 to 20 carbons are a preferred range. Materials with asymmetric structures can have better solution processability than those with symmetric structures, because the asymmetric materials can have lower recrystallization tendencies. Dendrimer substituents can be used to enhance solution processability of small molecules.

[0061] 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 an environment including moisture, vapor, and / or gases. The barrier layer may be deposited above, below, or adjacent to the substrate and electrodes, or above 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 and compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. Inorganic or organic compounds, or both, may be incorporated into the barrier layer. 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 process to be considered a "mixture," the aforementioned polymeric and non-polymeric materials constituting the barrier layer should be deposited and / or deposited simultaneously under the same reaction conditions. The weight ratio of polymeric to non-polymeric materials 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.

[0062] In some embodiments, at least one of the anode, the cathode, or a new layer disposed above the organic emissive layer acts as an enhancement layer. The enhancement layer comprises a plasmonic material that exhibits surface plasmon resonance, which non-radiatively couples to the emitter material and transfers excitation state energy from the emitter material to non-radiative modes of the surface plasmon polaritons. The enhancement layer is provided no more than a threshold distance from the organic emissive layer, where due to the presence of the enhancement layer, the emitter material has a total non-radiative decay rate constant and a total radiative decay rate constant, and the threshold distance is the distance at which the total non-radiative decay rate constant equals the total radiative decay rate constant. In some embodiments, the OLED further comprises an out-coupling layer. In some embodiments, the out-coupling layer is disposed above the enhancement layer on an opposite side of the organic emissive layer. In some embodiments, the out-coupling layer is disposed on a side of the emissive layer opposite the enhancement layer, but still enables out-coupling of energy from the surface plasmon modes of the enhancement layer. The out-coupling layer scatters energy from the surface plasmon polaritons. In some embodiments, this energy is scattered as photons into free space. In other embodiments, the energy is scattered from the surface plasmon modes of the device into other modes, such as but not limited to organic waveguide modes, substrate modes, or another waveguide mode. If the energy is scattered into non-free space modes of the OLED, other out-coupling schemes can be incorporated to extract the energy into free space. In some embodiments, one or more intervening layers can be disposed between the enhancement layer and the out-coupling layer. Examples of intervening layers can be dielectric materials, including organic, inorganic, perovskite, oxide, and can include stacks and / or mixtures of these materials.

[0063] The enhancement layer changes the effective properties of the medium in which the emitter material resides, resulting in any or all of the following: reduced emissivity, altered emission line shape, emission intensity variation with angle, altered stability of the emitter material, altered OLED efficiency, and reduced roll-off efficiency of the OLED device. Placing the enhancement layer on the cathode side, the anode side, or both, results in an OLED device that utilizes any of the effects described above. In addition to the specific functional layers mentioned herein and illustrated in the various OLED examples shown in the figures, the OLEDs according to the present disclosure can also include any other functional layers commonly found in OLEDs.

[0064] The enhancement layer can comprise a plasmonic material, an optically active metamaterial, or a hyperbolic metamaterial. As used herein, a plasmonic material is a material whose real part of the permittivity in the visible or ultraviolet region of the electromagnetic spectrum crosses zero. In some embodiments, the plasmonic material includes at least one metal. In such embodiments, the metal can include at least one of Ag, Al, Au, Ir, Pt, Ni, Cu, W, Ta, Fe, Cr, Mg, Ga, Rh, Ti, Ru, Pd, In, Bi, Ca, alloys or mixtures of these materials, and stacks of these materials. In general, a metamaterial is a medium composed of different materials, where the medium as a whole behaves differently than the sum of its material parts. In particular, we define an optically active metamaterial as a material that has both a negative permittivity and a negative permeability. On the other hand, a hyperbolic metamaterial is an anisotropic medium, where the permittivity or permeability has different signs for different spatial directions. Optically active metamaterials and hyperbolic metamaterials are strictly distinguished from many other photonic structures, such as Distributed Bragg Reflectors (“DBRs”), because the medium should exhibit a length scale of the order of the wavelength of light in the direction of propagation. Using terminology that will be understood by those skilled in the art: the permittivity of a metamaterial in the direction of propagation can be described using an effective medium approximation. Plasmonic materials and metamaterials provide a way to control light propagation that can enhance OLED performance in a variety of ways.

[0065] In some embodiments, the enhancement layer is provided as a planar layer. In other embodiments, the enhancement layer has wavelength-sized features arranged periodically, quasi-periodically, or randomly, or has subwavelength-sized features arranged periodically, quasi-periodically, or randomly. In some embodiments, the wavelength-sized features and the subwavelength-sized features have sharp edges.

[0066] In some embodiments, the outcoupling layer has wavelength-sized features arranged periodically, quasi-periodically, or randomly, or has sub-wavelength-sized features arranged periodically, quasi-periodically, or randomly. In some embodiments, the outcoupling layer can be composed of a plurality of nanoparticles, and in other embodiments, the outcoupling layer is composed of a plurality of nanoparticles disposed above a material. In these embodiments, the outcoupling can be adjusted by at least one of the following: changing the size of the plurality of nanoparticles, changing the shape of the plurality of nanoparticles, changing the material of the plurality of nanoparticles, adjusting the thickness of the material, changing the refractive index of the material, or an additional layer disposed on the plurality of nanoparticles, changing the thickness of the enhancement layer, and / or changing the material of the enhancement layer. The plurality of nanoparticles of the device can be formed of at least one of the following: a metal, a dielectric material, a semiconductor material, a metal alloy, a mixture of dielectric materials, a stack or a hierarchy of one or more materials, and / or a core of one type of material coated with a shell of another type of material. In some embodiments, the outcoupling layer is composed of at least metal nanoparticles, where the metal includes Ag, Al, Au, Ir, Pt, Ni, Cu, W, Ta, Fe, Cr, Mg, Ga, Rh, Ti, Ru, Pd, In, Bi, Ca, alloys or mixtures of these materials, and stacks of these materials. The plurality of nanoparticles can have an additional layer disposed above them. In some embodiments, the polarization of the emission can be tuned using the outcoupling layer. Changing the dimensions and periodicity of the outcoupling layer can select a class of polarizations that preferentially outcouple to air. In some embodiments, the outcoupling layer also serves as an electrode for the device.

[0067] In embodiments of the disclosed subject matter, a device can include an enhancement layer arranged over an emissive region of at least one sub-pixel configured to have Lambertian emission and / or at least one sub-pixel having a microcavity configured for direct emission, as described in detail below. In at least some such embodiments, the enhancement layer can include a plasmonic structure disposed at a predetermined threshold distance from the emissive region. The predetermined threshold distance can be a distance at which a total non-radiative decay rate constant is equal to a total radiative decay rate constant. In some such embodiments, the device can include an outcoupling layer disposed over the enhancement layer on opposite sides of the emissive region.

[0068] It is believed that the internal quantum efficiency (IQE) of fluorescent OLEDs can exceed the 25% spin-statistics limit through delayed fluorescence. As used herein, there are two types of delayed fluorescence, namely P-type delayed fluorescence and E-type delayed fluorescence. P-type delayed fluorescence results from triplet-triplet annihilation (TTA).

[0069] In some embodiments, the compounds in the emitting material and / or layer in an OLED can be used as a phosphorescent sensitizer, where one or more layers in the OLED can include an acceptor in the form of one or more fluorescent and / or delayed fluorescent emitters. In some embodiments, the compounds can be used as one component of an exciplex used as a sensitizer. As a phosphorescent sensitizer, the compound must be able to transfer energy to an acceptor and the acceptor can emit energy or further transfer energy to a final emitter. The acceptor concentration can range from 0.001% to 100%. The acceptor can be in the same layer as the phosphorescent sensitizer or in one or more different layers. In some embodiments, the acceptor can be a TADF emitter. In some embodiments, the acceptor can be a fluorescent emitter. In some embodiments, the emission can be produced by any or all of the sensitizer, acceptor, and / or final emitter.

[0070] On the other hand, the E-type delayed fluorescence described above does not rely on the collision of two triplets, but rather on the thermal population between a triplet and a singlet excited state. Compounds capable of producing E-type delayed fluorescence are needed in order to have a minimal singlet-triplet gap. Thermal energy can activate the triplet transition back to the singlet. This type of delayed fluorescence is also known as thermally activated delayed fluorescence (TADF). A notable feature of TADF is that the delayed component increases with temperature due to the thermal energy increase. If the rate of reverse intersystem crossing is fast enough to minimize non-radiative decay from the triplet state, then the fraction of singlet excited states that are refilled can reach 75%. The total singlet state fraction can be 100%, which is well above the spin statistical limit for electrically generated excitons.

[0071] The E-type delayed fluorescence characteristic can be found in exciplex systems or in single compounds. Without being bound by theory, it is believed that E-type delayed fluorescence requires that the light emitting material have a small singlet-triplet energy gap (ΔES-T). Organic, metal-free donor-acceptor light emitting materials can be able to achieve this. The emission of these materials is often characterized by donor-acceptor charge transfer (CT) type emission. The spatial separation of the HOMO and LUMO in these donor-acceptor type compounds often results in a small ΔES-T. These states can involve CT states. Typically, the donor-acceptor light emitting materials are constructed by linking an electron donor moiety (such as an amino or carbazole derivative) with an electron acceptor moiety (such as an N-containing six-membered aromatic ring).

[0072] Additionally, in some embodiments, the emissive region can have one or more emissive layers. In one embodiment, the number of layers in each emissive region of each device can be the same. In alternative embodiments, the number of layers in each emissive region of each device can be different. In yet alternative embodiments, the number of layers in some emissive regions of each device can be the same and the number of layers in some emissive regions of each device can be different. In some embodiments, an emissive layer of the one or more emissive layers of any emissive region can comprise a phosphorescent material, a fluorescent material, or any combination thereof. In some embodiments, the emissive region in a device can comprise a sensitizer and an acceptor having the various sensitized device properties disclosed in the present application.

[0073] Devices fabricated in accordance with embodiments of the application can be incorporated into a wide variety of electronic assemblies (or units) that can be incorporated into a wide variety of electronic products or intermediate assemblies. Examples of such electronic products or intermediate assemblies 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 assemblies can optionally include drive electronics and / or power supplies. Devices fabricated in accordance with embodiments of the application can be incorporated into a wide variety of consumer products having one or more electronic assemblies (or units) incorporated therein. A consumer product is disclosed that includes an OLED that includes a compound of the present disclosure in an organic layer in the OLED. The consumer product should include any kind of product that includes one or more of one or more light sources and / or some type of visual display. Some examples of the consumer product include flat panel displays, curved panel displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and / or signaling, heads-up displays, fully transparent or partially transparent displays, flexible displays, rollable displays, foldable displays, stretchable displays, laser printers, telephones, cellular phones, tablet computers, phablets, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, video cameras, viewfinders, micro-displays with a diagonal less than 2 inches, 3D displays, virtual reality or augmented reality displays, vehicles, automotive displays, video walls comprising multiple displays tiled together, theater or stadium screens, and signs. Devices fabricated in accordance with the application can be controlled using a variety of control mechanisms, including passive matrix and active matrix. It is intended that many of the devices be used in temperature ranges comfortable to humans, such as 18 °C to 30 °C, and more preferably at room temperature (20-25 °C), but can be used outside this temperature range (e.g., -40 °C to 80 °C).

[0074] The materials and structures described herein can be applied in 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.

[0075] In some embodiments, the OLED has one or more properties including flexible, rollable, foldable, stretchable, and curved. In some embodiments, the OLED is transparent or semi-transparent. In some embodiments, the OLED further includes a layer having carbon nanotubes.

[0076] In some embodiments, the OLED further includes a layer having a delayed fluorescence emitter. In some embodiments, the OLED includes 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 less than 10 inches or an area 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 an illumination panel.

[0077] In some embodiments of the emissive region, the emissive region further includes a host.

[0078] In some embodiments, the light-generating compound can be an emissive dopant. In some embodiments, the compound can generate emission via phosphorescence, fluorescence, thermally activated delayed fluorescence (i.e., TADF (also known as E-type delayed fluorescence)), triplet-triplet annihilation, or a combination of these processes, including phosphor-sensitized fluorescence.

[0079] The OLEDs disclosed herein can be incorporated into one or more of consumer products, electronic component modules, and illumination panels. In some embodiments, the organic layer can be an emissive layer and the compound can be an emissive dopant, while in other embodiments, the compound can be a non-emissive dopant.

[0080] The organic layer can also include a host. In some embodiments, two or more hosts are preferred. In some embodiments, the host used can be a) ambipolar, b) electron-transporting, c) hole-transporting, or d) a wide band gap material that plays little role in charge transport. In some embodiments, the host can include a metal complex. The host can be an inorganic compound.

[0081] Combinations with other materials

[0082] Materials described herein as useful for particular layers in an organic light emitting device can be used in combination with a wide variety of other materials present in devices. For example, the emissive dopants disclosed herein can be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that can be present. The materials described or referenced below are non-limiting examples from among the many materials that can be used in combination with the compounds disclosed herein, and one of skill can readily identify and adapt other materials for use in combination with the compounds disclosed herein.

[0083] A wide variety of materials can be used for the various emissive and non-emissive layers and arrangements disclosed herein. Examples of suitable materials are disclosed in U.S. Patent Application Publication No. 2017 / 0229663, which is incorporated by reference in its entirety.

[0084] Conducting dopants:

[0085] Charge transport layers can be doped with a conducting dopant to substantially alter its charge carrier density, which in turn will alter its conductivity. The conductivity is increased by generating charge carriers in the matrix material, and depending on the type of dopant, a shift of the Fermi level of a semiconductor can also be achieved. Hole transport layers can be doped with a p- type conducting dopant, and n-type conducting dopants are used in electron transport layers.

[0086] HIL / HTL:

[0087] The hole injection / transport material used in the present application is not particularly limited, and any compound can be used as long as the compound is generally used as a hole injection / transport material.

[0088] EBL:

[0089] An electron blocking layer (EBL) can be used to reduce the number of electrons and / or excitons that leave an emissive layer. The presence of such a blocking layer in a device can result in a device with greater efficiency and / or longer lifetime as compared to a similar device without the blocking layer. Further, the blocking layer can be used to confine the emission to a desired area 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 some aspects, the compounds used in the EBL contain the same molecule or the same functional group as used in one of the hosts described below.

[0090] Hosts:

[0091] The light-emitting layer of the organic EL device of the present application preferably contains at least a metal complex as a light-emitting material, and can contain a host material using a metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complex or organic compound can be used as long as the triplet energy of the host is greater than that of the dopant. Any host material can be used with any dopant as long as the triplet criterion is satisfied.

[0092] HBL:

[0093] A hole-blocking layer (HBL) can be used to reduce the number of holes and / or excitons leaving the emission layer. The presence of such a blocking layer in a device can result in substantially higher efficiency and / or longer lifetime compared to a similar device lacking the blocking layer. Furthermore, the blocking layer can be used to confine emission to a desired region 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.

[0094] ETL:

[0095] An electron transport layer (ETL) can include a material capable of transporting electrons. The electron transport layer can be intrinsic (undoped) or doped. Doping can be used to enhance the conductivity. Examples of ETL materials are not particularly limited and any metal complex or organic compound can be used as long as it is typically used to transport electrons.

[0096] Charge generation layer (CGL)

[0097] In a tandem or stacked OLED, the CGL plays an essential role in performance, which 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; subsequently, the ambipolar current gradually reaches a steady state. Typical CGL materials include n- and p-conductivity dopants used in the transport layers.

[0098] Previous work has demonstrated that the operational lifetime of blue organic light emitting diodes (OLEDs) can be improved by increasing the Purcell factor of the cavity and further by coupling excitons to plasmon-exciton-polaritons (PEPs) formed at the metal / organic interface through strong coupling. In the prior art, the OLED structure is designed such that PEPs are formed at the planar interface between the organic transport layer and the metal electrode. Further details can be found in U.S. Patent Application No. 17 / 666,664, U.S. Patent Application No. 17 / 932,475, U.S. Patent Application No. 18 / 157,308, U.S. Patent Application No. 18 / 413,235, and U.S. Patent Application No. 18 / 951,352, each of which is incorporated herein by reference in its entirety. This design is limited to at most two interfaces within the device and prescribes the choice of electrode materials. Disclosed herein is a design for increasing the local Purcell factor and creating plasmon-exciton-polaritons in a nanoparticle-enhanced organic transport layer.

[0099] In some embodiments, the nanoparticle-enhanced transport layer comprises an electron transport material and / or a hole transport material doped with nanoparticles. In some embodiments, the nanoparticles comprise metal nanoparticles. In some embodiments, the nanoparticle material (e.g., Ag, Al, Au, Pt, Ti, etc.), size, and concentration can be varied to achieve the proper absorption edge of the metal nanoparticles such that the nanoparticles can strongly couple to the transport layer singlet exciton emission. In some embodiments, the nanoparticles have a size in the range of 10 nm to 1000 nm, and the nanoparticles can have any suitable shape. In some embodiments, the nanoparticles are randomly dispersed throughout the layer. In some embodiments, the nanoparticles are periodically or quasi-periodically dispersed throughout the layer with a pitch of 1 nm to 1000 nm in at least one direction. In some embodiments, the cube root of the concentration (C) of the nanoparticles is within the wavelength (l) of the light emitted from the device, as defined by In some embodiments, the nanoparticle-enhanced transport layer can be included anywhere in the device. For example, in a single-emissive-layer (EML) device structure, one or more transport layers will be included at the electrode (anode and / or cathode) interface. In a tandem-stacked multi-EML device structure, for each EML, a nanoparticle-enhanced transport layer can be included throughout the device, as shown in Figure 3

[0100] ​In some embodiments, light emitting device 300 includes a substrate 301, a first (bottom) electrode 302 over substrate 301, a first transport layer 307 over first electrode 302, a first emission layer 308 over first transport layer 307, a second transport layer 309 over first emission layer 308, and a second (top) electrode 310 over second transport layer 309. In some embodiments, first transport layer 307 and / or second transport layer 309 is a nanoparticle-enhanced transport layer including nanoparticles. In some embodiments, either of first transport layer and / or second transport layer can include a hole transport layer (HTL) and / or an electron transport layer (ETL). In some embodiments, either of first electrode and / or second electrode can include an anode and / or a cathode. In some embodiments, at least one of first transport layer and / or second transport layer (307, 309, respectively) including nanoparticles is located at an interface of at least one of first electrode and / or second electrode (302, 310, respectively). In some embodiments, at least one of first transport layer and / or second transport layer (307, 309, respectively) includes an organic transport layer.

[0101] In some embodiments, the device 300 further comprises at least one second emitter stack 350 between the first electrode 302 and the first transport layer 307. In some embodiments, the one or more second emitter stacks 350 comprise a third transport layer 303 over the first electrode 302, a second emission layer 304 over the third transport layer 303, a fourth transport layer 305 over the second emission layer 304, and a charge generation layer 306 over the fourth transport layer 305. In some embodiments, the third transport layer 303 and / or the fourth transport layer 305 is a nanoparticle-enhanced transport layer comprising nanoparticles. In some embodiments, the device 300 comprises a tandem stacked device. In some embodiments, each of the first and second emission layers (308, 304, respectively) is associated with one or more of the first, second, third, and fourth transport layers (307, 309, 303, 305, respectively) comprising nanoparticles. In some embodiments, one or more of the first and / or second emission layers (308, 304, respectively) is adjacent to one or more of the first, second, third, and / or fourth transport layers (307, 309, 303, 305, respectively) comprising nanoparticles. In some embodiments, each of the first and second emission layers (308, 304, respectively) is adjacent to one or more of the first, second, third, and / or fourth transport layers (307, 309, 303, 305, respectively) comprising nanoparticles. In some embodiments, at least one of the first, second, third, and / or fourth transport layers (307, 309, 303, 305, respectively) comprises an organic transport layer.

[0102] In some embodiments, the nanoparticles comprise metal nanoparticles, such as Ag, Al, Au, Pt, Ti, or any other suitable metal, combinations thereof, or oxides thereof. In some embodiments, the absorption edge of the nanoparticles is adjusted such that the nanoparticles are strongly coupled to the singlet exciton emission of the first, second, third, and / or fourth transport layers 307, 309, 303, 305. In some embodiments, the nanoparticles have a size of 10 nm to 1000 nm. In some embodiments, the concentration of the nanoparticles is within the wavelength of the light emitted from the device. In some embodiments, the spacing of the nanoparticles is in the range of 1 nm to 1000 nm.

[0103] In some embodiments, the consumer electronics device incorporates the device 300 described above, wherein the consumer electronics device is a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior illumination and / or signaling, a heads-up display, a fully transparent or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a cellular phone, a tablet computer, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a video camera, a viewfinder, a microdisplay with a diagonal less than 2 inches, a 3D display, a virtual reality or augmented reality display, a vehicle, an automotive display, a video wall comprising multiple displays tiled together, a theater or stadium screen, and / or a sign.

[0104] Simulating device performance

[0105] COMSOL was used to simulate the electric field distribution around Ag nanoparticles in a square lattice with a background medium with n = 1.7, approximating the refractive index of an organic material, see Figure 4 . By varying the size and spacing of the nanoparticles, the absorbance of the nanoparticles can be tuned, as shown in Figures 5A-5B . For this example, Ag was chosen as the nanoparticle material because its absorbance couples well with blue emission. Other materials, such as gold, can be used for longer wavelength applications for red and green emission.

[0106] The local Purcell factor can be estimated by calculating the ratio of the Poynting vector calculated with 20 nm diameter Ag nanoparticles in a 60 nm unit cell to the Poynting vector calculated for the same size unit cell with index n = 1.7. The local Purcell factor as a function of wavelength is shown in Figure 6 . While the local Purcell factor will only affect excitons within the unit cell boundary, the Purcell factor for the entire device can be calculated using the Green's function method by using the calculated absorbance of one of the nanoparticle-enhanced transport layers. In this example, the device structure comprises: 700 pm glass / 70 nm ITO / 50 nm nanoparticle-enhanced transport layer / 50 mCBP / 30 nm transport layer, n = 1.7 / 120 nm Al. The Purcell factor for this device using the nanoparticle-enhanced transport layer as the bottom transport layer is compared to the Purcell factor for the same structure with the nanoparticle-enhanced layer replaced by a transport layer with n = 1.7, see Figure 7 . The nanoparticle-enhanced layer increases the Purcell factor around its absorption peak without any modification to the cathode / anode cavity structure.

[0107] In some embodiments, the device can include more than one emissive stack comprising at least one nanoparticle-enhanced transport layer. Additionally, a charge generation layer is located between each of the more than one emissive stack.

[0108] Figures 8A-8E Details are shown regarding the use of the Purcell effect enhanced by plasmonic polaritons to enhance the stability of deep blue phosphor sensitized fluorescent OLEDs. The Purcell effect enhanced by plasmonic polaritons can increase the stability of PHOLEDs by reducing the density of triplet emitters (see Zhao 2024). Phosphor sensitized fluorescent (PSF) OLEDs enable high efficiency OLEDs with saturated colors. However, long-lived, efficient, deep blue PSF-OLEDs are still rare. The Purcell effect increases the PSF-OELD stability because it enhances all radiative processes resonating with the cavity, reducing intrinsic degradation. Figure 8A Energy transfer processes in PDF-OLEDs are depicted.

[0109] The Purcell effect increases the radiative decay rates of triplets and singlets in phosphors and fluorophores. The low exciton density on the triplet state existing in both phosphors and fluorophores leads to low triplet annihilation and device degradation rates. The organic plasmon-exciton-plasmon between Ag and transport layers (ETL / HTL) greatly increases the Purcell factor (PF), which is equivalent to the ratio of radiative decay rates with and without cavities (see Zhao 2025). Figure 8B Energy transfer rates in PSF-OLEDs altered by the Purcell effect are depicted. Figures 8C-8D Simulated device structures and their components are depicted. The device structures have three optical cavities: Al-ITO control C (weak), Ag-ITO half-cavity H (moderate), Ag-ITO / Ag / ITO full-cavity F (strong).

[0110] Figures 9A-9F Simulated Figures 8A-8E Simulated experimental results for control (C), half-cavity (H), and full-cavity (F) device structures are detailed in the. Figure 9A Intensity versus wavelength is shown. Figure 9B EQE versus current density is shown. Figure 9C Luminance versus time is shown. Figure 9D EL intensity versus time is shown. Figure 9E Purcell factor versus distance to cathode is shown. Figure 9F Luminance versus time is shown. The full-cavity device has the greatest device lifetime (at J = 10 mA / cm 2The full cavity device has the largest color saturation, followed by the control device, and then the half cavity device. The cavity reduces the vibration peak and results in CIExy = [0.13, 0.09] from only PH [0.15, 0.21]. The full cavity device has the largest EQE roll-off, followed by the half cavity device, and then the control device. The full cavity reduces the EQE roll-off from 35% to 17%, achieving higher EQE at high brightness. The spatially dependent Purcell factor is scanned by the thin exciton-blocking emission layer in the half cavity device. Faster EL transients result in longer device lifetimes.

[0111] In summary, the disclosed devices demonstrate a plasmonic-enhanced Purcell effect that accelerates all radiative decay processes and increases PSF-OLED lifetimes. By employing a strong plasmonic full cavity (Ag electrode and plasmonic ETL / HTL), the PSF-OLED achieves a 3.1x direct lifetime increase, saturated color at CIExy = [0.13, 0.09], low EQE roll-off, and high EQE. The device lifetime increase and TrEL acceleration follow the PF quantitative increase.

[0112] 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 invention. For example, many of the materials and structures described herein can be substituted for one another without departing from the spirit of the invention. The present invention as claimed is thus intended to include, among other things, the various embodiments described herein, as well as equivalents and modifications thereof. It is intended that the scope of the invention be defined by the claims appended hereto.

[0113] References:

[0114] The following publications are each incorporated herein by reference in their entirety:

[0115] H. Zhao et al., Nature 2024, 626, 300.

[0116] H. Zhao et al., Nature Photonics 2025, accepted.

[0117] The disclosures of each patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. Although the present invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of these embodiments can be devised by others skilled in the art without departing from the true spirit and scope of the invention.

Claims

1. A light-emitting device, comprising: First electrode; The first transport layer above the first electrode; The first transmission layer above the first transmission layer; The second transmission layer above the first transmission layer; and The second electrode above the second transport layer; At least one of the first transport layer and the second transport layer contains nanoparticles.

2. The apparatus of claim 1, wherein the nanoparticles comprise metal nanoparticles.

3. The apparatus of claim 2, wherein the metal comprises Ag, Al, Au, Pt or Ti.

4. The apparatus of claim 2, wherein the nanoparticles are randomly dispersed throughout the layer.

5. The apparatus of claim 2, wherein the nanoparticles are periodically dispersed throughout the layer.

6. The apparatus of claim 5, wherein the nanoparticles have a spacing of 1 nm to 1000 nm in at least one direction.

7. The apparatus of claim 2, wherein the nanoparticles are quasi-periodicly dispersed throughout the layer.

8. The apparatus of claim 1, further comprising at least one second emitter stack between the first electrode and the first transmission layer.

9. The apparatus of claim 8, wherein the at least one second emitter stack comprises a third transport layer, a second emitter layer above the third transport layer, a fourth transport layer above the second emitter layer, and a charge generation layer above the fourth transport layer, wherein at least one of the third transport layer and the fourth transport layer comprises nanoparticles.

10. The apparatus of claim 1, wherein the nanoparticles have a size of 10 nm to 1000 nm.

11. The device according to claim 1, wherein the cube root of the concentration (C) of the nanoparticles is within the wavelength (λ) of the light emitted from the device, as determined by... Defined.

12. The apparatus of claim 1, wherein at least one of the first transport layer and the second transport layer comprising nanoparticles is located at the interface of at least one of the first electrode and the second electrode.

13. The apparatus of claim 9, wherein each of the first emission layer and the second emission layer is adjacent to one or more of the first transport layer, the second transport layer, the third transport layer, and the fourth transport layer containing nanoparticles.

14. The apparatus of claim 1, wherein the spacing between the nanoparticles is in the range of 1 nm to 1000 nm.

15. A consumer electronic device incorporating the apparatus of claim 1, wherein the consumer electronic device is at least one type selected from the group consisting of: flat panel displays, curved displays, computer monitors, medical monitors, televisions, billboards, lights for internal or external lighting and / or signaling, head-up displays, fully transparent or partially transparent displays, flexible displays, rollable displays, foldable displays, stretchable displays, laser printers, telephones, cellular phones, tablet computers, tablet phones, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, camcorders, viewfinders, microdisplays with a diagonal of less than 2 inches, 3D displays, virtual reality or augmented reality displays, vehicles, automotive displays, video walls comprising multiple displays tiled together, theater or stadium screens, and signs.

Images