CN117529129A

CN117529129A - Organic electroluminescent device

Info

Publication number: CN117529129A
Application number: CN202310715686.1A
Authority: CN
Inventors: H·蒙多尔; N·J·汤普森; V·M·梅农
Original assignee: Universal Display Corp
Current assignee: Universal Display Corp
Priority date: 2022-06-17
Filing date: 2023-06-16
Publication date: 2024-02-06

Abstract

This application relates to organic electroluminescent devices. Embodiments of the disclosed subject matter provide a device that may include an organic light emitting device OLED having a substrate, a first electrode disposed on the substrate, and an OLED disposed on the first electrode. a second electrode and an organic emissive layer disposed between the first electrode and the second electrode, the organic emissive layer having a first surface positioned on a second surface. A nanoparticle layer can be disposed on the organic emissive layer and have a first surface positioned on a second surface. The nanoparticle layer may include a first plurality of nanoparticles including a dielectric material and a surrounding medium. The distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer may be no more than 50 nm, and there is at least 1.0 between the refractive index of the dielectric material and the surrounding medium difference.

Description

Organic electroluminescent device

Cross reference to related applications

The present application claims priority from U.S. patent application Ser. No. 63/396,320, filed on 8/9 of 2022, and U.S. patent application Ser. No. 63/353,392, filed on 17 of 2022, 6/6, each of which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to devices and techniques for fabricating organic emission devices, such as organic light emitting diodes, for low-loss OLEDs that utilize Mie scattering (Mie scattering) of nanoparticles and that increase the efficiency of OLED devices, as well as devices and techniques including the same.

Background

Optoelectronic devices utilizing organic materials are becoming increasingly popular for a number of reasons. Many of the materials used to fabricate the devices are relatively inexpensive, so organic photovoltaic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials (e.g., their flexibility) may make them more suitable for specific applications, such as fabrication on flexible substrates. Examples of organic optoelectronic devices include organic light emitting diodes/devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, organic materials can have performance advantages over conventional materials. For example, the wavelength at which the organic emissive layer emits light can generally be readily tuned with appropriate dopants.

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

One application of phosphorescent emissive molecules is in full color displays. Industry standards for such displays require pixels adapted to emit a particular color (referred to as a "saturated" color). In particular, these standards require saturated red, green and blue pixels. Alternatively, the OLED may be designed to emit white light. In conventional liquid crystal displays, the emission from a white backlight is filtered using an absorbing filter to produce red, green and blue emissions. The same technique can also be used for OLEDs. The white OLED may be a single EML device or a stacked structure. The color may be measured using CIE coordinates well known in the art.

As used herein, the term "organic" includes polymeric materials and small molecule organic materials that can be used to fabricate organic optoelectronic devices. "Small molecule" refers to any organic material that is not a polymer, and may be substantial in nature. In some cases, the small molecule may include repeat units. For example, the use of long chain alkyl groups as substituents does not remove the molecule from the "small molecule" class. Small molecules may also be incorporated into the polymer, for example as side groups on the polymer backbone or as part of the backbone. Small molecules can also serve as the core of a dendrimer, which consists of a series of chemical shells built on the core. The core moiety of the dendrimer may be a fluorescent or phosphorescent small molecule emitter. Dendrimers may be "small molecules" and all dendrimers currently used in the OLED field are considered small molecules.

As used herein, "top" means furthest from the substrate, and "bottom" means closest to the substrate. Where a first layer is described as being "disposed" over "a second layer, the first layer is disposed farther from the substrate. Unless a first layer is "in contact with" a second layer, other layers may be present between the first and second layers. For example, a cathode may be described as "disposed over" an anode even though various organic layers are present between the cathode and the anode.

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

A ligand may be referred to as "photosensitive" when it is believed that the ligand contributes directly to the photosensitive properties of the emissive material. When the ligand is considered not to contribute to the photosensitive properties of the emissive material, the ligand may be referred to as "ancillary", but the ancillary ligand may alter the properties of the photosensitive ligand.

As used herein, and as will be generally understood by those of skill in the art, if the first energy level is closer to the vacuum energy level, then the first "highest occupied molecular orbital" (Highest Occupied Molecular Orbital, HOMO) or "lowest unoccupied molecular orbital" (Lowest Unoccupied Molecular Orbital, LUMO) energy level is "greater than" or "higher than" the second HOMO or LUMO energy level. Since Ionization Potential (IP) is measured as a negative energy relative to the vacuum level, a higher HOMO level corresponds to an IP with a smaller absolute value (less negative). Similarly, a higher LUMO energy level corresponds to an Electron Affinity (EA) with a smaller absolute value (less negative EA). On a conventional energy level diagram with vacuum energy level on top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. The "higher" HOMO or LUMO energy level appears closer to the top of this figure than the "lower" HOMO or LUMO energy level.

As used herein, and as will be generally understood by those of skill in the art, a first work function is "greater than" or "higher than" a second work function if the first work function has a higher absolute value. Since work function is typically measured as a negative number relative to the vacuum level, this means that the "higher" work function is more negative (more negative). On a conventional energy level diagram with the vacuum energy level on top, a "higher" work function is illustrated as being farther from the vacuum energy level in a downward direction. Thus, the definition of HOMO and LUMO energy levels follows a different rule than work function.

Layers, materials, regions and colors of light emitted by devices may be described herein with reference to them. In general, as used herein, an emissive region described as producing a particular color of light may include one or more emissive layers disposed on top of each other in a stacked fashion.

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 580-700nm or whose emission spectrum has the highest peak in that region. Similarly, a "green" layer, material, region or device refers to a layer, material, region or device that emits or has an emission spectrum with a peak wavelength in the range of about 500-600 nm; "blue" layer, material or device refers to a layer, material or device that emits or has an emission spectrum with a peak wavelength in the range of about 400-500 nm; and a "yellow" layer, material, region or device refers to a layer, material, region or device having an emission spectrum with a peak wavelength in the range of about 540-600 nm. In some arrangements, individual regions, layers, materials, regions, or devices may provide individual "deep blue" and "light blue" light. As used herein, in an arrangement that provides separate "light blue" and "dark blue" components, a "dark blue" component refers to a component having a peak emission wavelength that is at least about 4nm 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 465nm to 500nm, and the peak emission wavelength of the "deep blue" component is in the range of about 400nm to 470nm, although these ranges may vary for some configurations. Similarly, a color changing layer refers to a layer that converts or modifies light of another color into light having a wavelength specified for that color. For example, a "red" color filter refers to a color filter that forms light having a wavelength in the range of about 580-700 nm. In general, there are two types of color changing layers: a color filter to modify the spectrum by removing unwanted wavelengths of light, and a color changing layer to convert higher energy photons to lower energy. "color" component refers to a component that, when activated or in use, generates or otherwise emits light having 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.

As used herein, emissive materials, layers, and regions may be distinguished from one another and from other structures based on light originally generated by the materials, layers, or regions, rather than light ultimately emitted by the same or different structures. Initial light generation is typically the result of a change in energy level that results in photon emission. For example, an organic emissive material may initially produce blue light, which may be converted to red or green light by a color filter, quantum dot, or other structure, such that the complete emissive stack or subpixel emits red or green light. In this case, the initial emissive material or layer may be referred to as the "blue" component, even though the subpixels are of the "red" or "green" components.

In some cases, it may be preferable to describe the color of components, such as the color of the emission area, sub-pixels, color changing layers, etc., according to 1931CIE coordinates. For example, the yellow emissive material may 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 item also corresponds to a shape in the 1931CIE coordinate color space. The shape in the 1931CIE color space is constructed by following a trajectory between two color points and any other internal points. For example, the internal shape parameters of red, green, blue, and yellow may be defined as follows:

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

Disclosure of Invention

According to one embodiment, an organic light emitting diode/device (OLED) is also provided. An 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 consumer products, electronic component modules, and/or lighting panels.

According to one embodiment, a device may include an Organic Light Emitting Device (OLED) having a substrate, a first electrode disposed on the substrate, a second electrode disposed on the first electrode, and an organic emissive layer disposed between the first electrode and the second electrode, wherein the organic emissive layer may have a first surface positioned on a second surface. The nanoparticle layer may be disposed on the organic emissive layer, and the nanoparticle layer may have a first surface positioned on a second surface. The nanoparticle layer may include a first plurality of nanoparticles comprising a dielectric material and a surrounding medium. The distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer may be no more than 50nm and there is a difference of at least 1.0 between the refractive indices of the dielectric material and the surrounding medium.

The first plurality of nanoparticles may be disposed in an outcoupling layer disposed on the second electrode.

At least some of the first plurality of nanoparticles may be integrated with a second electrode.

The arrangement of the first plurality of nanoparticles may cause an External Quantum Efficiency (EQE) of at least 15%.

The first plurality of nanoparticles may include at least one nanoparticle having a mie scattering efficiency (Mie scattering efficiency) of 2-8 based on a size of the nanoparticle, a shape of the nanoparticle, and/or a material refractive index of the nanoparticle.

The refractive index of the first plurality of nanoparticles may be at least 1.9, at least 2.1, at least 2.5, and/or less than 3.5.

The first plurality of nanoparticles may include silicon, silicon nitride, boron nitride, silicon carbide, carbon, diamond, zinc sulfide, zinc selenide, germanium, zinc telluride, potassium niobate, titanium trioxide, antimony oxide, niobium pentoxide, tantalum pentoxide, vanadium oxide, vanadium pentoxide, gallium phosphate, bismuth oxide, gallium arsenide, and/or aluminum gallium.

The first plurality of nanoparticles may have a single configuration or may have a multiparticulate configuration.

The first plurality of nanoparticles of the device may comprise two or more materials, each of the two or more materials having a different refractive index being uniformly or non-uniformly distributed within the outcoupling layer, wherein at least one of the two or more materials causes a difference between the refractive index of the surrounding medium and the at least one of the two or more materials of at least 1.0.

The shape of the nanoparticle may be at least one of a cube, cylinder, sphere, spheroid, parallelepiped, bar, star, cone, amorphous, and/or polyhedral three-dimensional object.

The differences between at least two of the first plurality of nanoparticles include size, shape, and/or refractive index.

The first plurality of nanoparticles may be configured in a periodic array. The scattering wavelength and efficiency of the first plurality of nanoparticles in the periodic array may be based on the array periodicity, particle shape, particle size, and/or symmetry of the array. The at least two nanoparticles in the periodic array may have the same shape, different shapes, the same size, different sizes, the same refractive index value, and/or different refractive index values. The lattice periodicity of the periodic array may be configured to output non-lambertian emissions (non-Lambertian emission) from the device. In some embodiments, the first plurality of nanoparticles in the periodic array may have the following shape: conical, square pyramidal, shapes with square bases and curved surfaces, and/or parabolic pyramidal. The shape of the first plurality of nanoparticles may have a tapered end facing away from the OLED, and the first plurality of nanoparticles may be integrated with the first electrode or the second electrode. The largest in-plane dimension of the first plurality of nanoparticles may be at least 100nm, at least 200nm, at least 300nm, and/or at least 500nm, wherein the in-plane dimension is in a plane horizontal to the substrate. The out-of-plane dimensions of the first plurality of nanoparticles may be at least 150nm, at least 300nm, at least 600nm, and/or at least 1 μm, wherein the out-of-plane dimensions are in a plane perpendicular to the substrate. The shortest edge-to-edge spacing between the first plurality of nanoparticles may be less than 100nm, less than 50nm, less than 25nm, and/or may be less than 10nm. In some embodiments, the first plurality of nanoparticles in the periodic array may be cubic, cylindrical, cubical, or spherical. The center-to-center inter-particle spacing of the first plurality of nanoparticles in any ordered direction may be less than 300nm, less than 400nm, less than 500nm, and/or less than 600nm. The in-plane dimensions of the first plurality of nanoparticles may be at least 100nm, at least 200nm, at least 300nm, and/or at least 500nm. The out-of-plane dimensions of the first plurality of nanoparticles may be at least 50nm, at least 150nm, at least 300nm, and/or at least 500nm.

The device may include a transparent dielectric layer having a thickness of at least 2nm but no more than 50nm minus the electrode thickness, wherein the transparent dielectric layer is disposed between the second electrode and the nanoparticle layer. The refractive index of the dielectric material may be less than 1.2, less than 1.5, less than 2, and/or less than 2.5.

The device may include a transparent layer disposed over the first plurality of nanoparticles. The transparent layer may include a dielectric material having a refractive index of less than 1.2, less than 1.5, less than 2, less than 2.5, and/or less than 3. The light transmission of a 50nm thick dielectric material through the transparent layer may be at least 30% for any wavelength in the visible region of the electromagnetic spectrum that exceeds 400 nm.

The device may include a second plurality of nanoparticles comprising a dielectric material disposed on a first plurality of nanoparticles disposed on a second electrode. The first layer may be disposed on the first plurality of nanoparticles and the second layer disposed on the second plurality of nanoparticles.

The device may have a first side and a second side. The first electrode may comprise a reflective metal layer for reflecting light to the first side of the device. The second electrode may be a transparent layer and the nanoparticle layer is disposed over the transparent layer. The organic emissive layer may be disposed at a distance of at least 75nm from the reflective metal layer. The thickness of the reflective metal layer may be at least 50nm, at least 100nm, at least 150nm, at least 200nm, and/or less than 300nm.

The device may have a first side and a second side, and light is emitted from the first side and the second side.

The device may comprise a reflective layer arranged on the second side for guiding the emitted light to the first side of the device.

The apparatus may include a distributed bragg reflector (distributed Bragg reflector, DBR) stack disposed to reflect light from the second side of the apparatus. The substrate has a first side and a second side, and the DBR stack is disposed on the second side of the substrate. The OLED stack may be disposed on the first side of the substrate. In some embodiments, the DBR may be disposed on the first side of the substrate, and the OLED may be disposed on the DBR. The DBR stack may include at least 2 pairs of layers, at least three pairs of layers, at least 5 pairs of layers, at least 10 pairs of layers, and/or no more than 20 pairs of layers. The number of layer pairs may be based on a refractive index difference between the first refractive index material layer and the second refractive index material layer. The first refractive index material and the second refractive index material may form a pairing. The first refractive index material may be made of one material type having a specific refractive index value, and the second refractive index material will be made of a different material having a different refractive index value than the first refractive index material.

The first electrode and/or the second electrode may be transparent electrodes, wherein the first plurality of nanoparticles may be disposed on the second electrode. The in-plane dimensions of the nanoparticles may be between 200-400nm, 400-600nm and/or 600-800nm, wherein the in-plane dimensions are in a plane horizontal to the substrate. The distance of the out-of-plane dimension between the nanoparticles may be between 25-75nm, 75-200nm, 200-400nm, and/or 400-600nm, wherein the out-of-plane dimension may be in a plane perpendicular to the substrate.

The in-plane dimensions of the nanoparticles may be 200-400nm, 400-600nm and/or 600-800nm, wherein the in-plane dimensions are in a plane horizontal to the substrate. The distance in the out-of-plane dimension between the nanoparticles may be 25-75nm, 75-200nm, 200-400nm, and/or 400-600nm, with the out-of-plane dimension in a plane perpendicular to the substrate.

The OLED may be a stack with multiple layers and the thickness of the stack is 50-600nm.

The organic emissive layer may have a thickness of at least 0.2nm, but not more than 75 nm.

The organic emissive layer of the device is disposed at a distance of at least 10nm, at least 100nm, at least 300nm, and/or at least 600nm from the second electrode.

The arrangement of the first plurality of nanoparticles may cause the External Quantum Efficiency (EQE) to be at least 30%.

The first plurality of nanoparticles of the device may be arranged to have an External Quantum Efficiency (EQE) of at least 50%.

The first and/or second electrodes of the device may comprise indium tin oxide, fluorine doped tin oxide, indium doped zinc oxide, aluminum zinc oxide, indium doped cadmium oxide, barium stannate, carbon nanotubes, graphene, multi-layer graphene, single layer graphene, graphene oxide, metal nanoparticle or nanowire impregnated materials, and conductive polymers such as polyacetylene, polypyrrole, polybenzazole, polyaniline, poly (p-phenylene vinylene) and/or poly (3-alkylthiophene), (poly (3, 4-ethylenedioxythiophene)).

The first electrode and/or the second electrode of the device may comprise a polymer, an oxide material, nano-sized metal nanoparticles and/or metal nanowires.

The first electrode and/or the second electrode may comprise a plurality of layers of indium tin oxide, fluorine doped tin oxide, indium doped zinc oxide, aluminum zinc oxide, indium doped cadmium oxide, barium stannate, carbon nanotubes, graphene, multi-layer graphene, single layer graphene, graphene oxide, metal nanoparticle or nanowire impregnated material, polyacetylene, polypyrrole, polybenzazole, polyaniline, poly (p-phenylene vinylene) and/or poly (3-alkylthiophene), (poly (3, 4-ethylenedioxythiophene)). The first electrode and/or the second electrode may comprise a metal layer having a thickness of 2-5nm and/or 6-10 nm. The organic emissive layer may be disposed at a distance of at least 75nm from the metal layer.

The second electrode of the device may be a metal electrode and the nanoparticle layer may be disposed on the metal electrode. The first plurality of nanoparticles of the nanoparticle layer may be configured as dimers, trimers, and/or as multiple levels of units configured to output non-lambertian emissions. The organic emissive layer of the device may be a first surface positioned on a second surface, the metal electrode of the device may have a first surface positioned on the second surface, and the distance from the first surface of the organic emissive layer to the second surface of the metal electrode is at least one distance selected from the group consisting of: less than 10nm, less than 15nm, less than 20nm, less than 30nm, and less than 40nm. The metal electrodes of the device may have one or more layers of metallic silver, one or more layers of metallic aluminum, and/or one or more layers of metallic gold. The distance between the first surface and the second surface of the metal electrode may be less than 20nm, less than 30nm and/or less than 50nm. The thickness of the organic emissive layer may be less than 1nm, less than 2nm, less than 5nm, and/or less than 10nm. The organic emissive layer of the device may have a first surface positioned on a second surface, the metal electrode of the device may have a first surface positioned on the second surface, and the distance from the first surface of the organic emissive layer to the second surface of the nanoparticle layer may be at least 20nm, at least 30nm, at least 40nm, and/or at least 50nm. A dielectric layer may be disposed between the metal electrode and the nanoparticle layer having a thickness of less than 10nm, less than 5nm, and/or at least 2 nm. The refractive index of the dielectric layer may be at least 1.5, at least 1.75, at least 2, at least 2.5, and/or greater than 2.5.

The thickness of the second electrode may be 10-20nm, 20-50nm and/or 50-100nm.

The substrate of the device may be a transparent material.

The device may have a first side and a second side, wherein the substrate comprises a reflective material for reflecting light to the second side of the device.

The dielectric material of the first plurality of nanoparticles may absorb no more than 50% of the light energy in the coupled spectral range.

The dielectric material of the first plurality of nanoparticles may absorb no more than 20% of the light energy in the coupled spectral range.

According to one embodiment, a consumer electronic device may include an Organic Light Emitting Device (OLED) having a substrate, a first electrode disposed on the substrate, a second electrode disposed on the first electrode, and an organic emissive layer disposed between the first electrode and the second electrode, wherein the organic emissive layer may have a first surface positioned on a second surface. The nanoparticle layer may be disposed on the organic emissive layer, and the nanoparticle layer may have a first surface positioned on a second surface. The nanoparticle layer may include a plurality of nanoparticles comprising a dielectric material and a surrounding medium. The distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer may be no more than 50nm and there is a difference of at least 1.0 between the refractive indices of the dielectric material and the surrounding medium.

The device may be a flat panel display, curved display, computer monitor, medical monitor, television, billboards, lights for interior or exterior illumination and/or signaling, heads-up display, fully or partially transparent display, flexible display, rollable display, foldable display, stretchable display, laser printer, telephone, cellular telephone, tablet, personal Digital Assistant (PDA), wearable device, laptop computer, digital camera, video camera, viewfinder, micro-display with a diagonal less than 2 inches, 3-D display, virtual or augmented reality display, vehicle, on-board display, video wall comprising a plurality of tiled displays, theatre or gym screen, and sign.

According to one embodiment, a device may include an Organic Light Emitting Device (OLED) having a substrate, a first electrode disposed on the substrate, a second electrode disposed on the first electrode, and an organic emissive layer disposed between the first electrode and the second electrode, wherein the organic emissive layer may have a first surface positioned on a second surface. The nanoparticle layer may be disposed on the organic emissive layer, wherein the nanoparticle layer may have a first surface positioned on a second surface. The nanoparticle layer may include a plurality of nanoparticles comprising a dielectric material and a surrounding medium. The organic emissive layer may be directly coupled with the mie scattering mode of the plurality of nanoparticles. The distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer may not exceed 1/5, not more than 1/8, and/or not more than 1/10 of the peak emission wavelength capable of being emitted by the organic emissive layer.

Drawings

Fig. 1 shows an organic light emitting device.

Fig. 2 illustrates an inverted organic light emitting device without a separate electron transport layer.

Fig. 3A-3H show schematic diagrams of proposed OLED designs with transparent electrodes and spheres (fig. 3A-3B), cylinders (fig. 3C), hemispheres (fig. 3D), dimers of spheres (fig. 3E), trimers of spheres (fig. 3G) and random arrays of randomly shaped (fig. 3H) dielectric particles as outcoupling layers, according to embodiments of the disclosed subject matter.

Fig. 4A and 4C show schematic diagrams of OLED structures used in FDTD simulations showing a single isotropic dipole emitter and dielectric spheres (fig. 4A) and cylinders (fig. 4C) with refractive index 2.5 on the transparent electrode, according to embodiments of the disclosed subject matter. In both simulations, the electrode was ITO (indium tin oxide). FIG. 4B shows simulated Top Emission (TE) EQE curves for spheres of diameters 300nm, 350nm, and 400nm placed on a transparent electrode for the OLED design shown in FIG. 4A, in accordance with an embodiment of the disclosed subject matter. Fig. 4D shows simulated Top Emission (TE) EQE curves for OLED devices with dielectric cylinders of diameters 400nm, 500nm, and 600nm for the structure shown in fig. 4C, in accordance with an embodiment of the disclosed subject matter. The solid curves in fig. 4B and 4D represent simulated TE EQE curves for devices without any dielectric particles, in accordance with embodiments of the disclosed subject matter.

Fig. 5A shows a schematic diagram of an OLED structure with asymmetric dimers formed from spheres having diameters of 300nm and 200nm, in accordance with an embodiment of the disclosed subject matter. Fig. 5B shows a symmetrical dimer formed from two spheres 300nm in diameter, according to an embodiment of the disclosed subject matter. Fig. 5C shows a trimer for outcoupling formed by one sphere with a diameter of 300nm and two spheres with a diameter of 200nm on a transparent electrode, according to an embodiment of the disclosed subject matter. 5D-5E show simulated TE EQE (FIG. 5D) and TE/BE (FIG. 5E) curves for the OLED structure shown in FIGS. 5A-5C, according to an embodiment of the disclosed subject matter.

Fig. 6A shows a schematic diagram of an OLED structure with asymmetric dimers formed from cylinders of 400nm and 200nm diameter, in accordance with an embodiment of the disclosed subject matter. Fig. 6B shows a symmetrical structure formed by a cylinder of 400nm diameter, and fig. 6C shows a trimer for outcoupling formed by one cylinder of 400nm diameter and two cylinders of 200nm diameter on a transparent electrode, according to an embodiment of the disclosed subject matter. According to an embodiment of the disclosed subject matter, the height of the cylinders shown in fig. 6A-6C is 100nm. FIGS. 6D-6E show simulated TE EQE (FIG. 6D) and TE/BE (FIG. 6E) curves for the OLED structure shown in FIGS. 6A-6C, according to an embodiment of the disclosed subject matter.

Fig. 7 shows estimated peltier enhancement (Purcell enhancement) of a single isotropic emitter caused by the following placed on an OLED device, according to an embodiment of the disclosed subject matter: a single cylinder with a diameter of 400nm (solid line curve), an asymmetric dimer formed by cylinders with diameters of 400nm and 200nm (dotted line curve), a symmetric dimer formed by a cylinder with a diameter of 400nm (short dotted line), and a trimer formed by one cylinder with a diameter of 400nm and two cylinders with diameters of 200nm (dot curve).

Fig. 8A-8B show schematic diagrams of several embodiments of square arrays with transparent electrodes and dielectric cylinders as outcoupling layers, according to embodiments of the disclosed subject matter. Fig. 8C shows a structured electrode as an electrode and outcoupling layer, according to an embodiment of the disclosed subject matter.

Fig. 9A-9D show schematic diagrams of several embodiments of square arrays with transparent electrodes and the following as outcoupling layers, according to embodiments of the disclosed subject matter: conical (fig. 9A), square pyramidal (fig. 9B) dielectric particles with tapered ends, square bottom and curved edges (fig. 9C) and parabolic pyramidal (fig. 9D) particles.

Fig. 10A-10B show a spacing arrangement of nanoparticles according to an embodiment of the disclosed subject matter.

Detailed Description

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. The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and a hole are localized on the same molecule, an "exciton" is formed, which is a localized electron-hole pair having an excited energy state. Light is emitted when the exciton relaxes through a light emission mechanism. In some cases, excitons may be localized on an excimer or exciplex. Non-radiative mechanisms (such as thermal relaxation) may also occur, but are generally considered undesirable.

Initial OLEDs used emissive molecules that emitted light ("fluorescence") from a singlet state, as disclosed, for example, in U.S. patent No. 4,769,292, which is incorporated by reference in its entirety. Fluorescence emission typically occurs in time frames less than 10 nanoseconds.

Recently, OLEDs have been demonstrated that have emissive materials that emit light from a triplet state ("phosphorescence"). Baldo et al, "efficient phosphorescent emission from organic electroluminescent devices (Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices)", nature, vol.395, 151-154,1998 ("Baldo-I"); and Bardo et al, "Very efficient green organic light emitting device based on electrophosphorescence (Very high-efficiency green organic light-emitting devices based on electrophosphorescence)", applied physical fast report (appl. Phys. Lett.), vol.75, stages 3,4-6 (1999) ("Bardo-II"), incorporated by reference in its entirety. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704, columns 5-6, which is incorporated by reference.

Fig. 1 shows an organic light emitting device 100. The figures are 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 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. Cathode 160 is a composite cathode having a first conductive layer 162 and a second conductive layer 164. The device 100 may be fabricated by depositing the layers in sequence. The nature and function of these different layers and example materials are described in more detail in U.S. Pat. No. 7,279,704 at columns 6-10, which is incorporated by reference.

Further 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 doped with F in a 50:1 molar ratio ₄ M of TCNQMTDATA, as disclosed in U.S. patent application publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. 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 in 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. Examples of cathodes are disclosed in U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entirety, that include composite cathodes having a thin layer of metal (e.g., mg: ag) containing an overlying transparent, electrically conductive, sputter-deposited ITO layer. The theory and use of barrier layers is 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 implanted 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. The barrier layer 170 may be a single or multiple layer barrier layer and may cover or surround other layers of the device. The barrier layer 170 may also surround the substrate 110 and/or it may be disposed between the substrate and other layers of the device. The barrier layer may also be referred to as an encapsulant, encapsulation layer, protective layer, or permeation barrier, and generally provides protection against moisture, ambient air, and other similar materials from penetrating other layers of the device. Examples of barrier 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 of which is incorporated by reference in its entirety.

Fig. 2 shows an inverted OLED 200. The device includes a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. The device 200 may be fabricated by depositing the layers in sequence. Because the most common OLED configuration has a cathode disposed above an anode, and the device 200 has a cathode 215 disposed below an anode 230, the device 200 may be referred to as an "inverted" OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layers of device 200. Fig. 2 provides one example of how some layers may be omitted from the structure of the apparatus 100.

The simple layered structure illustrated in fig. 1 and 2 is provided by way of non-limiting example, and it should be understood that embodiments of the present invention may 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 may be used. Functional OLEDs may be obtained by combining the various layers described in different ways, or the layers may 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 of the examples provided herein describe the various layers as comprising a single material, it should be understood that combinations of materials may be used, such as mixtures of host and dopant, or more generally, mixtures. Further, 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, 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 multiple layers of different organic materials as described, for example, with respect to fig. 1 and 2.

Structures and materials not specifically described, such as OLEDs (PLEDs) comprising polymeric materials, such as disclosed in frank (Friend) et al, U.S. patent No. 5,247,190, which is incorporated by reference in its entirety, may also be used. By way of another example, an OLED with a single organic layer may be used. The OLEDs can be stacked, for example, as described in U.S. patent No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in fig. 1 and 2. For example, the substrate may include an angled reflective surface to improve out-coupling, such as a mesa structure as described in U.S. Pat. No. 6,091,195 to Furster et al, and/or a pit structure as described in U.S. Pat. No. 5,834,893 to Boolean et al, which are incorporated by reference in their entirety.

In some embodiments disclosed herein, emissive layers or materials, such as emissive layer 135 and emissive layer 220 shown in fig. 1-2, respectively, may comprise quantum dots. Unless specifically indicated to the contrary or otherwise indicated as appropriate to the understanding of those skilled in the art, an "emissive layer" or "emissive material" as disclosed herein may include organic emissive materials and/or emissive materials comprising quantum dots or equivalent structures. In general, the emissive layer comprises an emissive material within a host matrix. Such an emissive layer may comprise only quantum dot materials that convert light emitted by the individual emissive material or other emitter, or it may also comprise individual emissive materials or other emitters, or it may itself emit light directly by application of an electrical current. Similarly, a color changing layer, color filter, up-conversion or down-conversion layer or structure may include a material containing quantum dots, but such layers may not be considered "emissive layers" as disclosed herein. In general, an "emissive layer" or material is a material that emits an initial light based on injected charge, where the initial light may be altered by another layer, such as a color filter or other color altering layer, that does not itself emit the initial light within the device, but may re-emit altered light having a different spectral content based on absorption and down-conversion of the initial light emitted by the emissive layer to a lower energy light emission. In some embodiments disclosed herein, the color changing layer, color filter, up-conversion and/or down-conversion layer may be disposed external to the OLED device, such as above or below an electrode of the OLED device.

Any of the layers of the various embodiments may be deposited by any suitable method unless otherwise specified. Preferred methods for the organic layer include thermal evaporation, ink jet (as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, incorporated by reference in their entirety), organic vapor deposition (OVPD) (as described in U.S. Pat. No. 6,337,102, incorporated by reference in its entirety), and deposition by Organic Vapor Jet Printing (OVJP) (as described in U.S. Pat. No. 7,431,968, incorporated by reference in its entirety). Other suitable deposition methods include spin-coating and other solution-based processes. The solution-based process is preferably carried out under nitrogen or an inert atmosphere. For other layers, the preferred method includes 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, incorporated by reference in their entirety), and patterning associated with some of the deposition methods, such as inkjet and OVJD. Other methods may also be used. The material to be deposited may be modified to suit the particular deposition method. For example, substituents such as alkyl and aryl groups that are branched or unbranched and preferably contain at least 3 carbons can be used in small molecules to enhance their ability to withstand solution processing. Substituents having 20 carbons or more may be used, and 3 to 20 carbons are a preferred range. A material with an asymmetric structure may have better solution processibility than a material with a symmetric structure because an asymmetric material may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.

Devices fabricated according to embodiments of the present invention may further optionally include a barrier layer. One purpose of the barrier layer is to protect the electrodes and organic layers from harmful substances exposed to the environment including moisture, vapors and/or gases, etc. The barrier layer may be deposited on the substrate, electrode, under or beside the substrate, electrode, or on any other portion of the device, including the edge. The barrier layer may comprise 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 combination of materials may be used for the barrier layer. The barrier layer may incorporate inorganic compounds or organic compounds or both. Preferred barrier layers comprise a mixture of polymeric and non-polymeric materials, as described in U.S. patent No. 7,968,146, PCT patent application No. PCT/US2007/023098, and PCT/US2009/042829, which are incorporated herein by reference in their entirety. To be considered as a "mixture", the aforementioned polymeric and non-polymeric materials that make up the barrier layer should be deposited under the same reaction conditions and/or simultaneously. The weight ratio of polymeric material to non-polymeric material may be in the range of 95:5 to 5:95. The polymeric material and the non-polymeric material may be produced from the same precursor material. In one example, the mixture of polymeric and non-polymeric materials consists essentially of polymeric silicon and inorganic silicon.

In some embodiments, at least one of the anode, cathode, or new layer disposed over the organic emissive layer is used as the enhancement layer. The enhancement layer includes a plasmonic material exhibiting surface plasmon resonance, the plasmonic material non-radiatively coupled to the emitter material and transferring excited state energy from the emitter material to a non-radiative mode of surface plasmon polaritons. The enhancement layer is provided at a threshold distance from the organic emissive layer that is no more than a total non-radiative decay rate constant and a total radiative decay rate constant due to the presence of the enhancement layer, and the threshold distance is a distance where the total non-radiative decay rate constant is equal to the total radiative decay rate constant. In some embodiments, the OLED further comprises an outcoupling layer. In some embodiments, the outcoupling layer is disposed over the enhancement layer on an opposite side of the organic emissive layer. In some embodiments, the outcoupling layer is disposed on the opposite side of the emissive layer from the enhancement layer, but still allows energy to be outcoupled from the surface plasmon mode of the enhancement layer. The outcoupling layer scatters energy from the surface plasmon polaritons. In some embodiments, this energy is scattered into free space in the form of photons. In other embodiments, energy is scattered from surface plasmon modes of the device into other modes, such as, but not limited to, an organic waveguide mode, a substrate mode, or another waveguide mode. If the energy is scattered into the non-free space mode of the OLED, other outcoupling schemes may be incorporated to extract the energy into free space. In some embodiments, one or more intervening layers may be disposed between the enhancement layer and the outcoupling layer. Examples of intervening layers may be dielectric materials, including organic, inorganic, perovskite, oxide, and may include stacks and/or mixtures of these materials.

The enhancement layer modifies the effective properties of the medium in which the emitter material resides, causing any or all of the following: reduced emissivity, modification of emission line shape, variation of emission intensity and angle, variation of stability of the emitter material, variation of efficiency of the OLED, and reduction of efficiency decay of the OLED device. Placing the enhancement layer on the cathode side, the anode side, or both sides creates an OLED device that takes advantage of 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, an OLED according to the present invention may also include any of the other functional layers that are typically found in an OLED.

The enhancement layer may be composed of a plasmonic material, an optically active metamaterial or a hyperbolic metamaterial. As used herein, plasmonic materials are materials in which the real part of the dielectric constant crosses zero in the visible or ultraviolet region of the electromagnetic spectrum. In some embodiments, the plasmonic material comprises at least one metal. In such embodiments, the metal may 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, metamaterials are media composed of different materials, where the media as a whole acts differently than the sum of its material portions. Specifically, we define an optically active metamaterial as a material having both negative permittivity and negative permeability. On the other hand, hyperbolic metamaterials are anisotropic media in which 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 uniformity in the direction of propagation over the length scale of the wavelength of light. Using terms that will be understood by those skilled in the art: the dielectric constant of a metamaterial in the direction of propagation can be approximately described by an effective medium. Plasmonic materials and metamaterials provide a means of controlling light propagation that can enhance OLED performance in a variety of ways.

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

In some embodiments, the outcoupling layer has a periodically, quasi-periodically, or randomly arranged wavelength-sized feature, or has a periodically, quasi-periodically, or randomly arranged sub-wavelength-sized feature. In some embodiments, the outcoupling layer may be composed of a first plurality of nanoparticles, and in other embodiments, the outcoupling layer is composed of a plurality of nanoparticles disposed on a material. In these embodiments, the outcoupling may be tuned by at least one of: changing the size of the first plurality of nanoparticles, changing the shape of the first plurality of nanoparticles, changing the material of the first plurality of nanoparticles, adjusting the thickness of material, changing the refractive index of material or an additional layer disposed on the first plurality of nanoparticles, changing the thickness of the enhancement layer, and/or changing the material of the enhancement layer. The first plurality of nanoparticles of the device may be formed from at least one of: a metal, a dielectric material, a semiconductor material, a metal alloy, a mixture of dielectric materials, a stack or layering of one or more materials, and/or a core of one type of material, and the core is coated with a shell of a different type of material. In some embodiments, the outcoupling layer is composed of at least metal nanoparticles, wherein the metal is selected from the group consisting 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. The first plurality of nanoparticles may have an additional layer disposed over them. In some embodiments, the polarization of the emission may be tuned using an outcoupling layer. Changing the dimensions and periodicity of the outcoupling layer may select a class of polarizations that preferentially outcouple to air. In some embodiments, the outcoupling layer also serves as an electrode of the device.

It is believed that the Internal Quantum Efficiency (IQE) of fluorescent OLEDs can be limited by spin statistics that delay fluorescence by more than 25%. As used herein, there are two types of delayed fluorescence, namely P-type delayed fluorescence and E-type delayed fluorescence. The P-type delayed fluorescence is generated by triplet-triplet annihilation (TTA).

On the other hand, the E-type delayed fluorescence does not depend on the collision of two triplet states, but on the number of thermal population between triplet and singlet excited states. Compounds capable of generating E-type delayed fluorescence are needed to have very small singlet-triplet gaps. The thermal energy may activate a transition from the triplet state back to the singlet state. This type of delayed fluorescence is also known as Thermally Activated Delayed Fluorescence (TADF). One significant feature of TADF is that the delay component increases with increasing temperature due to increasing thermal energy. The fraction of backfill singlet excited states may reach 75% if the rate of intersystem crossing is sufficiently fast to minimize non-radiative decay from the triplet states. The total singlet fraction may be 100%, well beyond the spin statistical limit of the electrically generated excitons.

Type E delayed fluorescence features can be found in excitation complex systems or in single compounds. Without being bound by theory, it is believed that the E-delayed fluorescence requires that the luminescent material have a small singlet-triplet energy gap (Δes-T). Organic, metal-free donor-acceptor luminescent materials may be able to achieve this. The emission of these materials is generally characterized by a donor-acceptor Charge Transfer (CT) type emission. The spatial separation of HOMO from LUMO in these donor-acceptor type compounds generally results in a small Δes-T. These states may relate to CT states. Typically, donor-acceptor luminescent materials are constructed by linking an electron donor moiety (e.g., an amino or carbazole derivative) to an electron acceptor moiety (e.g., containing an N six-membered aromatic ring).

Devices manufactured in accordance with embodiments of the present invention may be incorporated into a wide variety of electronic component modules (or units), which may be incorporated into a wide variety of electronic products or intermediate components. Examples of such electronic products or intermediate components include display screens, lighting devices (e.g., discrete light source devices or lighting panels), etc., that may be utilized by end user product manufacturers. The electronics assembly module may optionally include drive electronics and/or a power source. Devices manufactured in accordance with embodiments of the present invention may be incorporated into a wide variety of consumer products having one or more electronic component modules (or units) incorporated therein. Disclosed is a consumer product comprising an OLED comprising a compound of the present disclosure in an organic layer in the OLED. The consumer product should include any kind of product that contains one or more light sources and/or one or more of some type of visual display. Some examples of such consumer products include flat panel displays, curved displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads-up displays, fully or partially transparent displays, flexible displays, rollable displays, foldable displays, stretchable displays, laser printers, telephones, cellular telephones, tablet computers, tablet phones, personal Digital Assistants (PDAs), wearable devices, laptop computers, digital cameras, video cameras, viewfinders, micro-displays with a diagonal of less than 2 inches, 3-D displays, virtual or augmented reality displays, vehicles, video walls including a plurality of tiled displays, theatre or gym screens, and signs. Various control mechanisms may be used to control devices made in accordance with the present invention, including passive matrices and active matrices. Many of the devices are intended to be used in a temperature range that is comfortable for humans, such as 18 ℃ to 30 ℃, and more preferably at room temperature (20-25 ℃), but can be used outside this temperature range (e.g., -40 ℃ to 80 ℃).

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

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

In some embodiments, the OLED further comprises a layer comprising a delayed fluorescent 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 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 an illumination panel.

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

In some embodiments, the compound may be an emissive dopant. In some embodiments, the compound may produce emission via phosphorescence, fluorescence, thermally activated delayed fluorescence (i.e., TADF, also known as delayed fluorescence of type E), triplet-triplet annihilation, or a combination of these processes.

The OLEDs disclosed herein can be incorporated into one or more of consumer products, electronics assembly modules, and lighting panels. The organic layer may be an emissive layer, and the compound may be an emissive dopant in some embodiments, and the compound may be a non-emissive dopant in other embodiments.

The organic layer may further include a host. In some embodiments, two or more bodies are preferred. In some embodiments, the host used may be a) bipolar, b) electron transport, c) hole transport, or d) a wide bandgap material that plays a small role in charge transport. In some embodiments, the host may include a metal complex. The host may be an inorganic compound.

In combination with other materials

Materials described herein as suitable for use in particular layers in an organic light emitting device may 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, implant layers, electrodes, and other layers that may be present. The materials described or mentioned below are non-limiting examples of materials that may be used in combination with the compounds disclosed herein, and one of ordinary skill in the art may readily review the literature to identify other materials that may be used in combination.

The various 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 disclosure is incorporated by reference in its entirety.

Conductive dopants:

the charge transport layer may be doped with a conductive dopant to substantially change its charge carrier density, which in turn will change its conductivity. Conductivity is increased by the generation of charge carriers in the host material and, depending on the type of dopant, a change in Fermi level (Fermi level) of the semiconductor can also be achieved. The hole transport layer may be doped with a p-type conductivity dopant, and an n-type conductivity dopant is used in the electron transport layer.

HIL/HTL：

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.

EBL：

An Electron Blocking Layer (EBL) may be used to reduce the number of electrons and/or excitons that leave the emissive layer. The presence of such a barrier layer in a device may result in substantially higher efficiency and/or longer lifetime than a similar device lacking such a barrier layer. Furthermore, a blocking layer may be used to limit 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 higher triplet energy than the emitter closest to the EBL interface. In some embodiments, the EBL material has a higher LUMO (closer to vacuum level) and/or 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.

A main body:

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 that of the dopant. Any host material may be used with any dopant so long as the triplet criteria are met.

EML：

The EML may comprise phosphorescent or fluorescent emitters. Phosphorescence generally refers to photon emission with a change in electron spin, i.e., the initial and final states of the emission have different diversity, such as from the T1 to the S0 state. Ir and Pt complexes currently widely used in OLEDs belong to the phosphorescent emitters. In some embodiments, if exciplex formation involves triplet emitters, such exciplex may also emit phosphorescence. Fluorescent emitters, on the other hand, generally refer to photon emission without changing the spin of electrons, such as from the S1 to S0 state. The fluorescent emitter may be a delayed fluorescent or non-delayed fluorescent emitter. Depending on the spin state, the fluorescent emitter may be a singlet emitter or a doublet emitter or other multiple state emitter. It is believed that the Internal Quantum Efficiency (IQE) of fluorescent OLEDs can be limited by spin statistics that delay fluorescence by more than 25%. There are two types of delayed fluorescence, namely P-type and E-type delayed fluorescence. The P-type delayed fluorescence is generated by triplet-triplet annihilation (TTA). On the other hand, the E-type delayed fluorescence does not depend on the collision of two triplet states, but on the thermal population between triplet and singlet excited states (thermal population). Thermal energy may activate triplet state transfer back to singlet state. This type of delayed fluorescence is also known as Thermally Activated Delayed Fluorescence (TADF). Type E delayed fluorescence features can be found in excitation complex systems or in single compounds. Without being bound by theory, it is believed that TADF requires a compound or exciplex having a small singlet-triplet energy gap (Δes-T) of less than or equal to 300, 250, 200, 150, 100, or 50 meV. There are two main types of TADF emitters, one is known as donor-acceptor TADF and the other is known as Multiple Resonance (MR) TADF. Typically, a donor-acceptor single compound is constructed by linking an electron donor moiety (e.g., an amino or carbazole derivative) and an electron acceptor moiety (e.g., containing an N six-membered aromatic ring). A donor-acceptor excitation complex may be formed between the hole transporting compound and the electron transporting compound. Examples of MR-TADF include highly conjugated boron-containing compounds. In some embodiments, the reverse intersystem crossing (cross) time from T1 to S1 of the delayed fluorescence emission at 293K is less than or equal to 10 microseconds. In some embodiments, such times may be greater than 10 microseconds and less than 100 microseconds.

In some embodiments, the emissive dopant may be a phosphorescent or fluorescent material. In some embodiments, the non-emissive dopant may also be a phosphorescent or fluorescent material. In some embodiments, the OLED may comprise additional compounds selected from the group consisting of fluorescent materials, delayed fluorescent materials, phosphorescent materials, and combinations thereof.

In some embodiments, the phosphorescent material is an emitter that emits light within the OLED. In some embodiments, the phosphorescent material does not emit light within the OLED. In some embodiments, the phosphorescent material energy transfers its excited state to another material within the OLED. In some embodiments, the phosphorescent material participates in charge transport within the OLED. In some embodiments, the phosphorescent material is a sensitizer, and the OLED further comprises an acceptor. In some embodiments, both the phosphorescent emitter and the acceptor emit light within the OLED.

In some embodiments, the fluorescent material or delayed fluorescent material is an emitter that emits light within the OLED. In some embodiments, the fluorescent material or delayed fluorescent material does not emit light within the OLED. In some embodiments, the fluorescent material or another material whose excited state is transferred into the OLED by delayed fluorescent material energy. In some embodiments, the fluorescent material or delayed fluorescent material participates in charge transport within the OLED. In some embodiments, the fluorescent material or delayed fluorescent material is a sensitizer and the OLED further comprises an acceptor.

HBL：

A Hole Blocking Layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a barrier layer in a device may result in substantially higher efficiency and/or longer lifetime than a similar device lacking the barrier layer. Furthermore, a blocking layer may be used to limit the emission to a desired area of the OLED. In some embodiments, the HBL material has a lower HOMO (farther from the vacuum level) and/or higher triplet energy than the emitter closest to the HBL interface. In some embodiments, the HBL material has a lower HOMO (farther from the vacuum level) and/or higher triplet energy than one or more of the hosts closest to the HBL interface.

ETL：

An 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 the ETL material are not particularly limited, and any metal complex or organic compound may be used as long as it is generally used to transport electrons.

Charge Generation Layer (CGL)

In tandem or stacked OLEDs, CGL plays a fundamental role in performance, consisting of n-doped and p-doped layers for injecting electrons and holes, respectively. Electrons and holes are supplied by the CGL and the electrode. Electrons and holes consumed in the CGL are refilled with electrons and holes injected from the cathode and anode, respectively; subsequently, the bipolar current gradually reaches a steady state. Typical CGL materials include n and p conductivity dopants used in the transport layer.

Organic Light Emitting Devices (OLEDs) are becoming widely used in displays and other light emitting applications. However, the device faces several challenges primarily, including maximizing the number of photons coupled into free space, and enhancing the stability and efficiency of the light emitting device, especially a blue light emitting device. A top or bottom emitting type typical OLED device utilizes at least one electrode that also acts as a mirror. This electrode reflects light so that the device emits from only one side, maximizing the efficiency of the light that can be collected. However, because the electrodes are metallic, emitters in the emissive layer of the OLED may couple to the electrodes and generate surface plasmons. These surface plasmons have a large in-plane momentum and cannot be directly recovered as photons in free space, resulting in reduced efficiency of the OLED. Embodiments of the disclosed subject matter can include low-loss OLEDs that utilize mie scattering of nanoparticles to outcouple light from non-metallic electrodes to avoid losses associated with metallic electrodes. In some embodiments, these devices have improved efficiency compared to typical devices having metal-based electrodes. In some embodiments, the overall efficiency of the device may be similar to or lower than a metal-based OLED when compared to an OLED containing metal electrodes, but the angular dependence and/or emission shape may be improved.

Embodiments of the disclosed subject matter provide low-loss OLEDs that utilize high refractive index dielectric particles to couple EL (electroluminescent) emissions from the OLED. Low-loss OLEDs can provide enhanced External Quantum Efficiency (EQE) for horizontally and vertically aligned dipoles. In some embodiments, the OLED may have minimal peltier enhancement. However, the device can be driven at lower currents and thus improve overall device stability, even without the presence of a peltier increase. In some embodiments, to reduce ohmic losses caused by metallic electrodes, non-metallic electrodes or multi-layer stacks with thin metallic and non-metallic conductive layers may be used for the electrodes. An array of high refractive index, low loss dielectric particles disposed on one or both transparent conductive electrodes may be used to decouple the emissive layer of the OLED from the device.

In some embodiments, the electrode may be a thin layer of: indium Tin Oxide (ITO), fluorine doped tin oxide (FTO), indium doped zinc oxide (IZO), aluminum Zinc Oxide (AZO), indium doped cadmium oxide, barium stannate, carbon nanotubes, graphene, multi-layer graphene, single layer graphene, graphene oxide, metal nanoparticle or nanowire impregnated materials, and conductive polymers such as polyacetylene, polypyrrole, polybenzazole, polyaniline, poly (p-phenylene vinylene), poly (3-alkylthiophene), (poly (3, 4-ethylenedioxythiophene)), and the like.

In some embodiments, a composite material may be used as an electrode, which may include one or more polymers, oxide materials, carbon-based compounds, and the like, as well as nano-sized metal particles or nanowires. In some embodiments, the electrode may include multiple layers of conductive material (e.g., the materials described above) or have no thin metal layers. In some embodiments, when a metal layer is used for the electrode, the EML layer is placed at a distance of at least 75nm from the metal layer to minimize plasmon losses caused by excitation of plasmon modes. In some embodiments, the thickness of the metal layer may be at least 2nm, but not more than 10nm, to ensure light transmission through the electrode. The total thickness of the transparent conductive electrode may be between 10 and 200nm, and more preferably between 30nm and less than 50 nm.

Fig. 10A-10B show a spacing arrangement of nanoparticles according to an embodiment of the disclosed subject matter. As shown in fig. 10A-10B, the layers 102, 202 may be nanoparticle layers, which may be part of the outcoupling layers shown in fig. 3A-3H and/or 9A-9D and described in detail below, and/or may be part of the nanoparticle layers shown in fig. 4A, 4C, 5A-5C and/or 6A-6C as described in detail below. The layers 101, 201 may be any number of layers disposed over a nanoparticle layer. The layers 103, 203 are any number of layers disposed below the nanoparticle layer.

As used throughout, "in-plane" may be defined as a plane "horizontal" to the substrate, and/or any other layer disposed horizontally on the substrate. As used throughout, "out-of-plane" may be defined as a plane "perpendicular" to the substrate, and/or any other layer disposed horizontally on the substrate.

In one embodiment, where there is an array in the vertical direction, there may be a dielectric layer between the multiple nanoparticle layers. A dielectric layer may not be required in the arrangement shown in fig. 10A, and thus is not shown in fig. 10A. However, the embodiment illustrated in fig. 10B may include a dielectric layer 204. In an alternative embodiment, there may be no dielectric layer between the stacked arrays of nanoparticle layers, and the nanoparticles may be located almost directly on the underlying nanoparticle layer.

In one embodiment, no more than 50nm is present from the bottom of the nanoparticle layer to the top of the emissive layer. In one embodiment, the 50nm distance may include a dielectric gap directly below the nanoparticle layer. In one embodiment, the nanoparticles in the nanoparticle layer may be located almost directly on top of the layer below the nanoparticle layer, e.g., on top of the emissive layer. In one embodiment, as described above, the nanoparticles in the nanoparticle layer may be located on top of the dielectric gap.

Fig. 10A shows random placement of nanoparticles according to an embodiment of the disclosed subject matter. The individual nanoparticles may be at least 100nm, at least 200nm, at least 300nm, and/or at least 500nm apart in the largest in-plane direction. In fig. 10A, this may be the X and Z distances. Further, the in-plane direction may enter and leave the sheet (i.e., a third dimension not shown in the two-dimensional diagram of fig. 10A).

The individual nanoparticles may be at least 50nm, at least 150nm, at least 300nm, and/or at least 500nm apart in the largest out-of-plane direction. As shown in fig. 10A, this may be the distance of X 'and Z'.

In a first embodiment, the shortest edge-to-edge spacing may be the horizontal in-plane distance between any adjacent nanoparticles. In a first embodiment, this distance (i.e., distance B shown in fig. 10A) may be less than 100nm, less than 50nm, less than 25nm, and/or may be less than 10nm.

In a second embodiment, the shortest edge-to-edge spacing may be the distance of any adjacent nanoparticle in any plane. In a second embodiment, this distance (i.e., distance a shown in fig. 10A) may be less than 100nm, less than 50nm, less than 25nm, and/or may be less than 10nm.

Fig. 10B shows an array placement of nanoparticles according to an embodiment of the disclosed subject matter. The individual nanoparticles may be at least 100nm, at least 200nm, at least 300nm, and/or at least 500nm apart in the largest in-plane direction. As shown in fig. 10B, this may be the X distance of each circle.

The individual nanoparticles may be at least 50nm, at least 150nm, at least 300nm, and/or at least 500nm apart in the largest out-of-plane direction. As shown in fig. 10B, this may be the X' distance of each circle.

The center-to-center inter-particle spacing of the first plurality of nanoparticles in any ordered direction may be less than 300nm, less than 400nm, less than 500nm, and/or less than 600nm. As shown in fig. 10B, this may be the a distance and is the direction parallel to the substrate. Similar to above, it should be noted that the center-to-center inter-particle spacing also enters and exits the paper (i.e., the third dimension not shown in this two-dimensional view of FIG. 10B).

When manufacturing nanoparticles, it is well known and understood that the individual nanoparticles are not identical and that there are manufacturing differences between the individual nanoparticles. For example, nanoparticle spheres having an average diameter of 100nm and standard deviation of + -5 nm may be prepared. In this example, the coefficient of variation is 5%. In another example, nanoparticle cubes can be prepared having an average length of 100nm on each side and a standard deviation of + -5 nm. In this example, the coefficient of variation is 5%. In one embodiment, any distance of the nanoparticles may be used to define the nanoparticles. For example, a radius or diameter of a sphere, a height of a cone, sides of a cube, a length of a rectangle, a width of a rectangle, etc. are used.

In one embodiment, the first nanoparticle is different in size from the second nanoparticle when the average size of the first particle differs from the average size of the second particle by a standard deviation. In an alternative embodiment, the first nanoparticle is of a different size than the second nanoparticle when the average size of the first particle differs from the average size of the second particle by a factor of two standard deviation. In another alternative embodiment, the size of the first nanoparticle is different from the second nanoparticle when the average size of the first particle differs from the average size of the second particle by any number of standard deviations.

In one embodiment, the first nanoparticle is different in size from the second nanoparticle when the average size of the first particle differs from the average size of the second particle by a factor of one. In an alternative embodiment, the first nanoparticle is of a different size than the second nanoparticle when the average size of the first particle differs from the average size of the second particle by a factor of two. In another alternative embodiment, the first nanoparticle is different in size from the second nanoparticle when the average size of the first particle differs from the average size of the second particle by any number of coefficients of variation.

Similarly, when nanoparticles are manufactured, it is well known and understood that the individual nanoparticles are not identical in shape and that there are manufacturing differences between the individual nanoparticles. Thus, while all nanoparticles may be spheres, for example, they are not all the same spheres, and there may be a sphericity difference between one or more nanoparticles. Similarly, while all nanoparticles may be cones, for example, they are not all the same cone, and there may be a taper difference between one or more tapered nanoparticles. There may be one or residual and/or waste particles that may be distributed in the nanoparticle layer caused by the formation of the nanoparticles. For example, there may be residual and/or waste particles of different sizes and/or shapes distributed in layers, matrices, and/or other arrangements of spherical nanoparticles. In one embodiment, when the devices disclosed herein are implemented differently with respect to a second nanoparticle using a first nanoparticle, the first nanoparticle is a nanoparticle that is shaped differently than the second nanoparticle.

In one embodiment, the layers may be stacked such that at least a portion of the nanoparticles in the top layer overlie corresponding nanoparticles in the bottom layer. In one embodiment, the layers may be stacked such that the nanoparticles in the top layer are offset from the corresponding nanoparticles in the bottom layer (i.e., there is no overlap).

Fig. 3A-3H schematically illustrate several embodiments of an OLED design of the disclosed subject matter that use a random array of dielectric particles as an outcoupling layer. Fig. 3A-3B show random arrays of spheres as outcoupling layers, fig. 3C shows cylinders, fig. 3D shows hemispheres, fig. 3E shows dimers of spheres, fig. 3F shows spheroids, fig. 3G shows trimers of spheres, and fig. 3H shows shaped dielectric particles, according to embodiments of the disclosed subject matter.

EQE enhancement may depend on the scattering efficiency of the dielectric particles. Unlike metallic particles which excite predominantly electrical resonance, dielectric particles can excite both electrical and magnetic mode resonances. This may provide an effective control of the light scattering and may optimize the intensity in the forward or backward direction and/or direct the light beam in any direction. Since the radiation of the dipole emitters may be affected by the surrounding medium, it is expected that the peltier factor may be enhanced with the dielectric nanoparticles as outcoupling layers.

The scattering efficiency of the dielectric particles may depend on the particle size, shape and/or refractive index of the material. For particle sizes similar to the wavelength of light, scattering efficiency can be estimated based on Mie's theory. Enhanced light outcoupling may be achieved by direct coupling of the EL emission (i.e., emission by the Emissive Layer (EL)) with the mie scattering mode of the nanoparticle. To achieve strong coupling of the EL emission to the mie scattering mode of the nanoparticle, the EML layer may be positioned closer to the outcoupling layer such that the distance from the top of the EML layer to the bottom of the outcoupling layer is within 1/10 of the peak emission wavelength of the emitter. In some embodiments, the coupling between the mie scattering mode and at least some of the EML layers may occur at longer distances (up to 1/2 of the peak emission wavelength of the emitter). One difference between at least some embodiments of the disclosed subject matter and other OLEDs containing dielectric nanoparticles is the direct coupling of emitters in the EML to the mie mode of the dielectric particles. In OLEDs using dielectric nanoparticles that are not directly coupled to the mie mode, the emitter first generates or emits photons, which are subsequently scattered by the mie mode of the dielectric nanoparticle. In contrast, in embodiments of the disclosed subject matter, the emission event of a photon from an emitter directly relates to the mie mode of the particle. For this reason, it is preferable that the distance between the EML and the dielectric nanoparticle is relatively close. Since scattering efficiency increases with refractive index, a material having a high refractive index is preferable. In addition, a material having low light absorption in the visible light region may be used. Some high refractive index materials that may be used to prepare the nano-sized particles may include silicon, silicon nitride, boron nitride, silicon carbide, carbon, diamond, zinc sulfide, zinc selenide, germanium, zinc telluride, potassium niobate, titanium trioxide, antimony oxide, niobium pentoxide, tantalum pentoxide, vanadium oxide, vanadium pentoxide, gallium phosphate, bismuth oxide, gallium arsenide, and/or aluminum gallium.

Arbitrarily shaped particles with preferred spectral characteristics, in the form of single or multiparticulate arrangements (such as dimers, trimers, etc.), as shown in fig. 3A-3H, can be used to control the scattering wavelength and efficiency of the outcoupling layer. In some embodiments, the dielectric particles may be prepared using two or more materials having different refractive indices, uniformly or non-uniformly distributed within the structure, wherein at least one of the two or more materials causes a difference of at least 1.0 between the refractive index of the surrounding medium and at least one of the two or more materials.

To demonstrate the enhancement of the outcoupling efficiency of the proposed low-loss OLED, the EQE of the OLED device was simulated using single or multiple dielectric particles with different shapes and sizes for outcoupling. Using Ansys Lumerical by time domain finite difference (FDTD) method ^TM The FDTD solution was simulated. The different layers of the OLED device were rendered at their refractive index values into a calculated volume of 4 μm x 1 μm and enclosed within a Perfect Matching Layer (PML) in all directions to match the open boundary conditions. The single dipole emitter in either vertical or horizontal orientation has a broad emission spectrum covering the entire visible region (450-750 nm), and is placed 20nm from the 50nm thick ITO electrode to act as an emissive layer. That is, the simulation was performed with a distance of 70nm between the emissive layer and the nanoparticles. We modeled the host medium with a 75nm thick non-absorbing dielectric layer with a refractive index of 1.7. Simulations were performed with and without the presence of high refractive index particles on the ITO layer. Luminescence in the far field was recorded using two power monitors placed 300nm above the particles and 250nm below the bottom of the OLED stack, which were used to calculate the Top Emission (TE) and Bottom Emission (BE) EQEs of the device, respectively. The calculated volume was discretized using a rectangular grid of non-uniform refractive index adjustment, with a resolution of 34 grid cells per wavelength. Furthermore, a grid coverage area with a resolution of 1nm is used for the high refractive index dielectric particles to minimize calculation errors. The peltier increase is estimated by calculating the power emitter by dipole using the box of the monitor around the emitter normalized to the free space emitted power.

Fig. 4A and 4C show schematic diagrams of OLED structures used in FDTD simulations showing a single isotropic dipole emitter and dielectric spheres (fig. 4A) and cylinders (fig. 4C) with refractive index 2.5 on the transparent electrode, according to embodiments of the disclosed subject matter. The outcoupling shown in fig. 4A and 4C illustrates the spectral tunability as well as the size and shape of the dielectric particles. In both such simulations, the electrodes were ITO. FIG. 4B shows simulated Top Emission (TE) EQE curves for spheres of diameters 300nm, 350nm, and 400nm placed on a transparent electrode for the OLED design shown in FIG. 4A, in accordance with an embodiment of the disclosed subject matter. Fig. 4D shows simulated Top Emission (TE) EQE curves for OLED devices with dielectric cylinders of diameters 400nm, 500nm, and 600nm for the structure shown in fig. 4C, in accordance with an embodiment of the disclosed subject matter. The solid curves in fig. 4B and 4D represent simulated TE EQE curves for devices without any dielectric particles, in accordance with embodiments of the disclosed subject matter. The enhancement of the EQE value is evident compared to OLED devices without any dielectric particles. Particles positioned above the transparent electrode achieve outcoupling of light with the far field by light scattering while minimizing waveguide effects in the OLED stack, resulting in enhanced EQE.

Furthermore, the scattering properties may be further modified by assembling the plurality of particles in the form of dimers, trimers, etc., as illustrated in fig. 5A-5E and fig. 6A-6E. The particle assembly may be tuned to achieve directional emission of the OLED device.

That is, the curves in FIGS. 5D-5E show simulated TE EQE and TE/BE curves for an OLED device with: asymmetric dimers formed from spheres with different sizes (dot curve), symmetric dimers formed from spheres with the same size (dashed curve), and trimer assemblies formed from one large sphere and two smaller spheres with the same size (solid curve), which indicate enhanced TE EQE. Furthermore, the TE/BE curves shown in fig. 5E indicate that the emissions of these devices are primarily toward the top side of the device.

Fig. 6A shows a schematic diagram of an OLED structure with asymmetric dimers formed from cylinders of 400nm and 200nm diameter, in accordance with an embodiment of the disclosed subject matter. Fig. 6B shows a symmetrical structure formed by a cylinder of 400nm diameter, and fig. 6C shows a trimer for outcoupling formed by one cylinder of 400nm diameter and two cylinders of 200nm diameter on a transparent electrode, according to an embodiment of the disclosed subject matter. According to an embodiment of the disclosed subject matter, the height of the cylinders shown in fig. 6A-6C is 100nm.

FIGS. 6D-6E show simulated TE EQE (FIG. 6D) and TE/BE (FIG. 6E) curves for the OLED structure shown in FIGS. 6A-6C, according to an embodiment of the disclosed subject matter. That is, fig. 6D-6E show simulated results of dimers and trimers formed from dielectric cylinders, showing enhanced TE EQEs of asymmetric dimers (dot curves) formed from cylinders with different diameters, symmetric dimers (dotted curves) formed from cylinders with the same diameter, and trimers (realization curves) formed from one cylinder with a larger diameter and two cylinders with a smaller diameter. The curve in fig. 6E indicates the emission anisotropy of the dimer and trimer assembly formed by the cylinders, exhibiting a significantly higher TE EQE compared to BE EQE.

The simulation results shown in fig. 5D-5E and fig. 6D-6E indicate that an assembly of multiple dielectric particles on a transparent electrode in a low-loss OLED device can be used to control and direct light emission without using any other optical elements in the display panel. In some embodiments, a random array of such particle assemblies may be formed from particles having the same and/or different shapes, sizes, and/or refractive indices as outcoupling layers on transparent electrodes.

Fig. 7 shows estimated peltier enhancements caused by single cylinders of 400nm diameter and symmetrical and asymmetrical dimer and trimer combinations of cylinders formed from 200nm diameter cylinders, exhibiting moderate peltier enhancements at peak EQE values. That is, fig. 7 shows estimated peltier enhancement of a single isotropic emitter caused by: a single cylinder with a diameter of 400nm (solid line curve), an asymmetric dimer formed by cylinders with diameters of 400nm and 200nm (dotted line curve), a symmetric dimer formed by a cylinder with a diameter of 400nm (short dotted line), and a trimer formed by one cylinder with a diameter of 400nm and two cylinders with diameters of 200nm (dot curve).

In some embodiments, a periodic array of high refractive index dielectric particles may be used as the outcoupling layer, as shown in fig. 8A-8C. The scattering wavelength and efficiency may be adjusted by controlling the array periodicity, particle shape, size, and/or array symmetry. In this case, the or each dielectric particle may be regarded as a Huygen's source. The transmission efficiency of such ordered arrays may depend on the spectral overlap between the electrical and magnetic dipole resonances, which may enhance the peltier factor. Although in several embodiments, the simulation indicates a medium peltier enhancement for a low loss OLED device, device stability and lifetime similar to a plasmonic OLED device can be achieved by driving at lower current densities without significant loss of brightness caused by EQE value enhancement.

In some embodiments, the periodic structure of dielectric material will be fabricated on the electrode layer (example of fig. 8A) or will be directly part of the electrode (as shown in fig. 8C). In some embodiments, individual particles in the periodic array may be replaced by an assembly of multiple particles having the same and/or different shape, size, and/or refractive index values. In some embodiments, the lattice periodicity will be changed in different ordering directions to control the directional emission of the device. The center-to-center inter-particle spacing of the particles in any ordered direction may be less than 300nm, less than 400nm, less than 500nm, or less than 600nm. In some embodiments, the first plurality of nanoparticles in the periodic array may be cubic, cylindrical, cubical, or spherical. The in-plane dimensions of the first plurality of nanoparticles may be at least 100nm, at least 200nm, at least 300nm, and/or at least 500nm. The out-of-plane dimensions of the first plurality of nanoparticles may be at least 50nm, at least 150nm, at least 300nm, and/or at least 500nm. In some embodiments, the emission is coupled to a grating mode of the array and the emission direction can be adjusted by controlling the nanoparticle periodicity. In some embodiments, coupling of the emission to the grating pattern may cause luminescence directed primarily perpendicular to the device.

In some embodiments, a periodic array of dielectric particles having tapered ends may be used, as shown in fig. 9A-9D. The particles may have shapes such as cones, square pyramids, etc., and particles with square bottoms and curved surfaces, parabolic cones, etc., and tapered ends facing away from the OLED may be fabricated on the electrode layer. Particles can be manufactured at the highest possible density to achieve a high packing fraction near the electrode layer. The shortest edge-to-edge spacing between particles may be less than 100nm, less than 50nm, less than 25nm, or more preferably less than 10nm. The edge-to-edge spacing between particles may vary in an out-of-plane direction. Based on the particle shape, the effective packing fraction of particles can be reduced in a plane away from the electrode, which can create a refractive index gradient that can effectively enhance light transmission of the OLED structure. Particle heights about equal to the wavelength of light may be used. The particle layer may act as an anti-reflective coating, which may reduce ambient light reflection from the OLED. The maximum in-plane dimension of the particles may be at least 100nm, at least 200nm, at least 300nm, or at least 500nm. The out-of-plane dimensions of the particles may be at least 150nm, at least 300nm, at least 600nm or at least 1 μm.

The high refractive index particle array on the electrode can be prepared by various top-down and bottom-up methods such as lithography-based techniques, multiphoton absorption photopolymerization of resins with focused laser beams in the presence or absence of nanoparticle inclusions, nanosphere lithography, guided self-assembly-based methods using particles prepared by chemical synthesis or photopolymerization, and the like.

In some embodiments, a thin layer of high refractive index material may be placed on the electrode layer. In some embodiments, the device may have a thin transparent layer on top of the nanoparticle layer. In some embodiments, an array of dielectric particles may be fabricated on the second electrode. In some embodiments, a first or second layer may be disposed on top of the nanoparticle outcoupling layer. The nanoparticle outcoupling layer may be formed by first forming a thin film and then forming nanoparticles using a subtractive etching method. In other embodiments, the nanoparticles may be formed by another synthetic method and then deposited on a substrate. In some embodiments, the nanoparticles are formed on the OLED substrate by physical vapor deposition.

In some embodiments, the device may have a first side and a second side, and light may be emitted from the first side of the device. In some embodiments, a highly reflective layer may be placed on the second side of the device to direct the emission to the first side of the device. According to embodiments of the disclosed subject matter, the first electrode may be replaced by a thick metal layer to reflect light to the first side of the device, and the emissive layer is at least 75nm from the metal electrode to minimize metal losses. The thickness of the metal layer may be at least 50nm, and preferably about 200nm, to ensure near-unit reflectivity from the layer. In some embodiments, a Distributed Bragg Reflector (DBR) may be used to reflect light from the second side of the device. The DBR stack may have at least 2-3 pairs of layers, more preferably 10 pairs of layers, and preferably no more than 20 pairs of layers due to the time required to fabricate the DBR. The number of layer pairs may depend on the refractive index difference between the layers of high and low refractive index material. In some embodiments, a transparent electrode layer may be deposited directly to the emissive layer to enhance the peltier parameter or efficiency of the device.

In some embodiments, the refractive index of the nanofeature responsible for outcoupling is at least 1.9, more preferably at least 2.1, and most preferably exceeds 2.5. In some embodiments, the nanoparticles may be composed of a material having minimal absorption in the outcoupled spectral range. This can prevent any loss due to absorption when the nanoparticle scatters energy out of the OLED. In some embodiments, the absorption of the nanoparticle may be tuned to specific values at various emission wavelengths, which modify the electrical and magnetic dipole resonances and change their relationship.

In some embodiments, the high dielectric nanoparticle outcoupling layer may be adjacent to the metal electrode. In some embodiments, the high dielectric nanoparticle outcoupling layer may be adjacent to the electrode, and the nanoparticles are arranged as dimers, trimers or higher order units. For all of the above embodiments, the total thickness of the OLED stack with multiple layers may be in the range between 50-600 nm. The thickness of the emissive layer may be at least 0.2nm and not more than 75nm, and preferably not more than 500nm from the transparent electrode on which the nanoparticles for forming the outcoupling layer will be fabricated. The nanoparticles may be disposed on a second electrode, which may be a transparent electrode. More preferably, the emissive layer may be within 10-200nm from the transparent electrode on which the nanoparticles for forming the outcoupling layer will be fabricated. The size of the particles in the plane of the transparent electrode may be in the range between 200-800nm, and more preferably in the range 400-600 nm. The out-of-plane size of the particles may be in the range between 25-600nm, and more preferably in the range 75-200 nm.

In some embodiments described above with respect to fig. 3A-9D, a device may include an Organic Light Emitting Device (OLED) having a substrate, a first electrode disposed on the substrate, a second electrode disposed on the first electrode, and an organic emissive layer disposed between the first electrode and the second electrode, wherein the organic emissive layer may have a first surface positioned on a second surface. The nanoparticle layer may be disposed on the organic emissive layer, and the nanoparticle layer may have a first surface positioned on a second surface. The nanoparticle layer may include a first plurality of nanoparticles comprising a dielectric material and a surrounding medium. The distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer may be no more than 50nm and there is a difference of at least 1.0 between the refractive indices of the dielectric material and the surrounding medium. The distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer may be, for example, 1-10nm, 10-20nm, 20-30nm, 30-40nm, or 40-50nm.

The organic emissive layer of the device may have a thickness of at least 0.2nm, but not more than 75 nm. In some embodiments, the organic emissive layer of the device is disposed at least 10nm, at least 100nm, at least 300nm, and/or at least 600nm from the second electrode. The OLED may be a stack with multiple layers and the thickness of the stack is 50-600nm.

The first plurality of nanoparticles of the nanoparticle layer of the device may be disposed in an outcoupling layer disposed on the second electrode. In some embodiments, at least some of the nanoparticles of the device may be integrated with the second electrode. The arrangement of nanoparticles in the nanoparticle layer of the device may cause the External Quantum Efficiency (EQE) to be at least 15%. The nanoparticles of the nanoparticle layer may include at least one nanoparticle having a mie scattering efficiency of 2-8. The mie scattering efficiency value may be based on a size of the nanoparticle, a shape of the nanoparticle, and/or a material refractive index of the nanoparticle. For example, the refractive index of the first plurality of nanoparticles may be at least 1.9, at least 2.1, at least 2.5, and/or less than 3.5. The arrangement of the first plurality of nanoparticles may cause an External Quantum Efficiency (EQE) of at least 30%, at least 50%, etc.

The nanoparticles of the nanoparticle layer may include silicon, silicon nitride, boron nitride, silicon carbide, carbon, diamond, zinc sulfide, zinc selenide, germanium, zinc telluride, potassium niobate, titanium trioxide, antimony oxide, niobium pentoxide, tantalum pentoxide, vanadium oxide, vanadium pentoxide, gallium phosphate, bismuth oxide, gallium arsenide, and/or aluminum gallium. The dielectric material of the first plurality of nanoparticles may absorb no more than 50% of the light energy in the coupled spectral range. In some embodiments, the dielectric material of the first plurality of nanoparticles may absorb no more than 20% of the light energy in the coupled spectral range.

The first plurality of nanoparticles may have a single configuration or may have a multiparticulate configuration. For example, a multiparticulate configuration may include dimers, trimers, and/or higher level units (e.g., units comprising multiple levels). The nanoparticles in these arrangements may be configured to output non-lambertian emissions. The device may be configured to emit at least 60%, at least 70% and/or at least 80% of the light through the side of the device on which the nanoparticles are disposed.

The nanoparticles of the device may comprise two or more materials each having a different refractive index uniformly or non-uniformly distributed within the outcoupling layer, wherein at least one of the two or more materials causes a difference between the refractive index of the surrounding medium and at least one of the two or more materials of at least 1.0. The shape of the nanoparticle may be cubic, cylindrical, spherical, spheroid, parallelepiped, bar, star, cone, amorphous, and/or polyhedral three-dimensional objects. There may be a difference between at least two of the first plurality of nanoparticles. These differences may include size, shape, and/or refractive index.

The nanoparticles of the device may be configured in a periodic array, such as shown in fig. 8A. The scattering wavelength and efficiency of the nanoparticles in the periodic array may be based on the array periodicity, particle shape, particle size, and/or symmetry of the array. The at least two nanoparticles in the periodic array may have the same shape, different shapes, the same size, different sizes, the same refractive index value, and/or different refractive index values. The lattice periodicity of the periodic array may be configured to output non-lambertian emissions from the device. The shape of the periodic array of nanoparticles may be conical, square pyramidal, shapes with square bases and curved surfaces, and/or parabolic pyramids, such as shown in fig. 9A-9D. The shape of the nanoparticles, such as shown in fig. 9A-9D, may have a tapered end facing away from the OLED, and the first plurality of nanoparticles may be integrated with the first electrode or the second electrode.

The device may include a second plurality of nanoparticles having a dielectric material disposed on a first plurality of nanoparticles disposed on a second electrode. The first layer may be disposed on the first plurality of nanoparticles and the second layer disposed on the second plurality of nanoparticles.

The device may include a transparent layer disposed over the first plurality of nanoparticles. The transparent layer may be a layer that allows at least 50%, at least 70%, at least 80% and/or at least 90% of the light emitted by the emissive layer of the OLED to pass through. The transparent layer may include a dielectric material having a refractive index of less than 1.2, less than 1.5, less than 2, less than 2.5, and/or less than 3. The effective refractive index of the transparent layer may be less than the ranges detailed herein, as the layer thickness may be less than the particle height, and in the case of particle materials, a refractive index difference of 1 may still be met.

The device may include a transparent dielectric layer that may have a thickness of at least 2nm but no more than 50nm minus the thickness of the electrode. A transparent dielectric layer may be disposed between the second electrode and the nanoparticle layer. The refractive index of the dielectric material may be less than 1.2, less than 1.5, less than 2, and/or less than 2.5.

The device may have a first side and a second side. The first electrode may comprise a reflective metal layer for reflecting light to the first side of the device. The second electrode may be a transparent layer and the nanoparticle layer is disposed over the transparent layer. The organic emissive layer may be disposed at a distance of at least 75nm from the reflective metal layer. The thickness of the reflective metal layer may be at least 50nm, at least 100nm, at least 150nm, at least 200nm, and/or less than 300nm. In some embodiments, light may be emitted from the first side and the second side. The thickness of the second electrode may be 10-20nm, 20-50nm and/or 50-100nm.

The device may comprise a reflective layer and/or a partially reflective layer disposed on the first side or the second side of the device to direct light emitted from the device. The partially reflective or reflective layer may have a reflectivity of at least 40%, at least 50%, at least 70%, and/or at least 90%.

The apparatus may include a Distributed Bragg Reflector (DBR) stack positioned to reflect light from the second side of the apparatus. The substrate may have a first side and a second side, and the DBR stack may be disposed on the first side and/or the second side of the substrate. The OLED stack may be disposed on the first side of the substrate. In some embodiments, the DBR may be disposed on the first side of the substrate, and the OLED may be disposed on the DBR. The DBR stack may include at least 2 pairs of layers, at least three pairs of layers, at least 5 pairs of layers, at least 10 pairs of layers, and/or no more than 20 pairs of layers. The number of layer pairs may be based on a refractive index difference between the first refractive index material layer and the second refractive index material layer. The first refractive index material and the second refractive index material may form a pairing. The first refractive index material may be made of one material type having a specific refractive index value, and the second refractive index material will be made of a different material having a different refractive index value than the first refractive index material. The first layer of refractive index material may have a high refractive index of at least 1.6, at least 2, at least 2.3, and/or less than 3.5, and the second layer of refractive index material may have a low refractive index of less than 1.2 and/or less than 1.6.

The first electrode and/or the second electrode may be transparent electrodes, wherein the nanoparticles may be disposed on the second electrode. The in-plane dimensions of the nanoparticles may be 200-400nm, 400-600nm and/or 600-800nm, wherein the in-plane dimensions are in a plane horizontal to the substrate. The distance in the out-of-plane dimension between the nanoparticles may be 25-75nm, 75-200nm, 200-400nm, and/or 400-600nm, with the out-of-plane dimension in a plane perpendicular to the substrate.

The in-plane dimensions of the nanoparticles may be between 200-400nm, 400-600nm and/or 600-800nm, wherein the in-plane dimensions are in a plane horizontal to the substrate. The distance of the out-of-plane dimension between the nanoparticles may be 25-75nm, 75-200nm, 200-400nm, and/or 400-600nm, with the out-of-plane dimension in a plane perpendicular to the substrate.

The first electrode and/or the second electrode of the device may comprise a polymer, an oxide material, nano-sized metal nanoparticles and/or metal nanowires. The first electrode and/or the second electrode may comprise a plurality of layers of indium tin oxide, fluorine doped tin oxide, indium doped zinc oxide, aluminum zinc oxide, indium doped cadmium oxide, barium stannate, carbon nanotubes, graphene, multi-layer graphene, single layer graphene, graphene oxide, metal nanoparticle or nanowire impregnated material, polyacetylene, polypyrrole, polybenzazole, polyaniline, poly (p-phenylene vinylene) and/or poly (3-alkylthiophene), (poly (3, 4-ethylenedioxythiophene)). The first electrode and/or the second electrode may comprise a metal layer having a thickness of 2-5nm and/or 6-10 nm. The organic emissive layer may be disposed at a distance of at least 75nm from the metal layer.

In this light outcoupling mode, the emitter may be coupled with a surface plasmon mode of the metal electrode and light may be outcoupled through a hybrid plasmon dielectric mode. With respect to efficient coupling of the Emissive Layer (EL) to the surface plasmon modes of the electrode, the emissive layer may be disposed closer to the metal electrode. The distance from the top of the emissive layer (e.g., the first surface of the emissive layer) to the bottom of the metal electrode may be less than 10nm, less than 15nm, less than 20nm, less than 30nm, and/or less than 40nm. A metal layer of silver, aluminum or gold having a thickness of less than 20nm, less than 30nm or less than 50nm may be used as the metal electrode. The emissive layer may have a thickness of less than 1nm, less than 2nm, less than 5nm, and/or less than 10 nm. The distance from the top of the emissive layer (e.g., the first surface of the emissive layer) to the bottom of the nanoparticle layer (e.g., the second surface of the nanoparticle layer) may be at least 20nm, at least 30nm, at least 40nm, or at least 50nm. In some embodiments, a dielectric layer having a thickness of less than 10nm, less than 5nm, or at least 2nm may be disposed between the metal electrode and the nanoparticle layer. The refractive index of the dielectric layer may be at least 1.5, at least 1.75, at least 2, at least 2.5, or greater than 2.5.

The substrate of the device may be a transparent material. The device may have a first side and a second side, wherein the first and second electrodes are transparent and light is output from the first and second sides of the device.

In some embodiments, a device may include an Organic Light Emitting Device (OLED) having a substrate, a first electrode disposed on the substrate, a second electrode disposed on the first electrode, and an organic emissive layer disposed between the first electrode and the second electrode. The organic emissive layer may have a first surface positioned on the second surface, and the nanoparticle layer may have a first surface positioned on the second surface. The nanoparticle layer may be disposed on the organic emissive layer. The nanoparticle layer may include a plurality of nanoparticles comprising a dielectric material and a surrounding medium. The organic emissive layer may be directly coupled with the mie scattering mode of the plurality of nanoparticles. The distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer may not exceed 1/5, not more than 1/8, and/or not more than 1/10 of the peak emission wavelength capable of being emitted by the organic emissive layer. Direct coupling may include coupling with a grating pattern or the like of a nanoparticle lattice of an ordered nanoparticle array.

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 may be substituted with other materials and structures without departing from the spirit of the invention. The invention as claimed may thus include variations of the specific examples and preferred embodiments described herein, as will be apparent to those skilled in the art. It is to be understood that the various theories as to why the present invention works are not intended to be limiting.

Claims

1. A device comprising:

Organic light-emitting device OLED, which includes:

substrate;

a first electrode disposed on the substrate;

a second electrode disposed on the first electrode; and

an organic emissive layer disposed between the first electrode and the second electrode, the organic emissive layer having a first surface positioned on a second surface; and

A nanoparticle layer disposed on the organic emissive layer, the nanoparticle layer having a first surface positioned on a second surface, the nanoparticle layer comprising:

a first plurality of nanoparticles comprising a dielectric material; and

surround medium;

wherein the distance from the bottom of the nanoparticle layer to the top of the organic emissive layer does not exceed 50 nm, and

Wherein there is a difference in refractive index of at least 1.0 between the dielectric material and the surrounding medium.

2. The device of claim 1, wherein the plurality of nanoparticles are disposed in an outcoupling layer disposed on the second electrode.

3. The device of claim 1, wherein at least some of the plurality of nanoparticles are integrated with the second electrode.

4. The device of claim 1, wherein the plurality of nanoparticles includes at least one nanoparticle having a Mie scattering efficiency of 2-8 based on at least one selected from the group consisting of: the nanoparticles The size of the particles, the shape of the nanoparticles and the material refractive index of the nanoparticles.

5. The device of claim 1, wherein the plurality of nanoparticles are configured to be at least one selected from the group consisting of dimers, trimers, and configured to output non-Lambertian emissions. Multiple levels of units.

6. The device of claim 5, wherein the device is configured to emit at least one selected from the group consisting of: at least 60%, At least 70% and at least 80% light.

7. The device of claim 1, further comprising:

A transparent dielectric layer having a thickness of at least 2 nm but not more than 50 nm minus the thickness of the electrode, wherein the transparent dielectric layer is disposed between the second electrode and the nanoparticle layer.

8. The device of claim 1, wherein the device has a first side and a second side,

wherein the first electrode includes a reflective metal layer for reflecting light to the first side of the device, wherein the second electrode is a transparent layer, and

wherein said nanoparticle layer is disposed over said transparent layer, and

wherein the organic emission layer is disposed at least 75 nm away from the reflective metal layer.

9. The device of claim 1, wherein the device has a first side and a second side, and the device further comprising:

A stack of distributed Bragg reflectors DBR positioned to reflect light from the second side of the device.

10. The device of claim 1, wherein at least one selected from the group consisting of the first electrode and the second electrode is a transparent electrode.

11. The device of claim 10, wherein the second electrode is the transparent electrode, and the transparent electrode is disposed on the organic emissive layer.

12. The device of claim 11,

wherein the in-plane dimension of the nanoparticle is at least one selected from the group consisting of: 200-400 nm, 400-600 nm, and 600-800 nm, wherein the in-plane dimension is in a plane horizontal to the substrate ,and

wherein the distance in the out-of-plane dimension between the nanoparticles is at least one selected from the group consisting of: 25-75nm, 75-200nm, 200-400nm and 400-600nm, wherein the out-of-plane dimension is in in a plane perpendicular to the substrate.

13. The device of claim 1,

14. The device of claim 1, wherein the device 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 billboard, a user device Lamps for internal or external lighting and/or signaling, heads-up displays, fully 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, microdisplays less than 2 inches diagonally, 3-D displays, virtual reality or augmented reality displays, vehicles , vehicle mounted displays, video walls containing multiple displays tiled together, theater or stadium screens and signage.

15. A device comprising:

Organic light-emitting device OLED, which includes:

substrate;

a first electrode disposed on the substrate;

a second electrode disposed on the first electrode; and

a plurality of nanoparticles comprising a dielectric material; and

surround medium;

wherein the organic emissive layer is directly coupled to the Mie scattering mode of the plurality of nanoparticles, and

wherein the distance from the second surface of the nanoparticle layer to the first surface of the organic emissive layer is at least one selected from the group consisting of: no more than the organic emissive layer is capable of emitting 1/5, no more than 1/8 and no more than 1/10 of the peak emission wavelength.