Energy levels and device structures for plasmonic oleds

Abstract

The present invention relates to energy levels and device structures for plasmonic OLEDs. The present invention provides organic emissive devices that include a host structure with electron and / or hole transport components having specific energy levels that promote good charge balance and enhanced charge trapping. The disclosed energy level structures provide host systems that reduce excited complex formation and thereby promote improved internal quantum efficiency and stability of the device, or that include excited complex formation in order to tune the average orientation of the dipoles.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 093,987, filed October 20, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to organic emission devices, such as organic light-emitting diodes having a plasmonic enhancement layer and related structures, as well as devices and techniques including the thereof. Background Technology

[0004] Optoelectronic devices utilizing organic materials are becoming increasingly popular for a variety of reasons. Many of the materials used to manufacture these devices are relatively inexpensive, thus organic optoelectronic devices have the potential to offer a cost advantage over inorganic devices. Furthermore, the inherent properties of organic materials, such as their flexibility, 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 offer performance advantages over conventional materials. For example, the wavelength of light emitted by an organic emitting layer can often be easily tuned using appropriate dopants.

[0005] OLEDs utilize organic thin films that emit light when a voltage is applied to the device. OLEDs are becoming an increasingly popular technology for applications such as flat panel displays, lighting, and backlighting. Several OLED materials and configurations are described in U.S. Patents 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

[0006] One application of phosphorescent emitting molecules is in full-color displays. Industry standards for such displays require pixels suited to emitting specific colors (called "saturated" colors). Specifically, these standards require pixels saturated with red, green, and blue light. Alternatively, OLEDs can be designed to emit white light. In conventional liquid crystal displays, absorption filters are used to filter the emission from a white backlight to produce red, green, and blue emission. The same technology can be used for OLEDs. White OLEDs can be single EML devices or stacked structures. Color can be measured using CIE coordinates, well-known in the field.

[0007] As used herein, the term "organic" includes both polymeric materials and small-molecule organic materials that can be used to manufacture organic optoelectronic devices. "Small molecule" refers to any organic material that is not a polymer, and "small molecule" can actually be quite large. In some cases, small molecules can include repeating units. For example, using long-chain alkyl groups as substituents does not remove a molecule from the "small molecule" category. Small molecules can also be incorporated into polymers, for example, as side groups on the polymer backbone or as part of the backbone. Small molecules can also act as the core portion of dendritic polymers, which consist of a series of chemical shells built on the core portion. The core portion of a dendritic polymer can be a fluorescent or phosphorescent small-molecule emitter. Dendritic polymers can be "small molecules," and all dendritic polymers currently used in the OLED field are considered small molecules.

[0008] As used herein, "top" means furthest from the substrate, and "bottom" means closest to the substrate. When the first layer is described as being "placed" "above" the second layer, the first layer is placed further away from the substrate. Unless specified that the first layer "contacts" the second layer, other layers may exist between the first and second layers. For example, even if various organic layers exist between the cathode and anode, the cathode may still be described as being "placed" "above" the anode.

[0009] As used herein, “solution-handleable” means capable of dissolving, dispersing or transporting in and / or depositing from a liquid medium in the form of a solution or suspension.

[0010] When a ligand is considered to directly contribute to the photosensitivity of the emissive material, the ligand may be referred to as "photosensitive." When a ligand is considered not to contribute to the photosensitivity of the emissive material, the ligand may be referred to as "auxiliary," but auxiliary ligands can alter the properties of photosensitizing ligands.

[0011] As used herein, and as will generally be understood by those skilled in the art, if the first energy level is closer to the vacuum level, then the first "Highest Occupied Molecular Orbital" (HOMO) or "Lowest Unoccupied Molecular Orbital" (LUMO) level is "greater than" or "higher than" the second HOMO or LUMO level. Since the ionization potential (IP) is measured as a negative energy relative to the vacuum level, a higher HOMO level corresponds to an IP with a smaller absolute value (less negative IP). Similarly, a higher LUMO level corresponds to an electron affinity (EA) with a smaller absolute value (less negative EA). On a conventional energy level diagram with the vacuum level at the top, the LUMO levels of a material are higher than the HOMO levels of the same material. "Higher" HOMO or LUMO levels appear to be closer to the top of this diagram than "lower" HOMO or LUMO levels.

[0012] As used herein, and as will generally be understood by those skilled in the art, if the first work function has a higher absolute value, then the first work function is “greater” or “higher” than the second work function. This is because the work function is typically measured as a negative number relative to the vacuum level, meaning that the “higher” work function is more negative. On a conventional energy level diagram with the vacuum level at the top, the “higher” work function is illustrated as being farther from the vacuum level in the downward direction. Therefore, the definitions of HOMO and LUMO levels follow different rules than those for the work function.

[0013] Further details regarding OLEDs and the above definition can be found in U.S. Patent No. 7,279,704, which is incorporated herein by reference in its entirety. Summary of the Invention

[0014] According to one embodiment, an organic light-emitting diode / device (OLED) is also provided. The OLED may include an anode; a cathode; and an organic layer disposed between the anode and the cathode. According to one embodiment, the organic light-emitting device is incorporated into one or more devices selected from consumer products, electronic component modules, and / or lighting panels.

[0015] An organic emission device is provided, comprising: a substrate; a first electrode disposed on the substrate; an emission stack disposed on the first electrode, the emission stack including: a first organic emission layer (EML) comprising one or more host materials and organic emission materials, and a hole blocking layer (HBL), an electron blocking layer (EBL), or both; a second electrode disposed on the emission stack; and a first reinforcement layer comprising a plasmonic material exhibiting surface plasmon resonance, the plasmonic material being nonradiatively coupled to the organic emission material in the organic emission layer and transferring excited state energy from the organic emission material to the nonradiative mode of surface plasmon polaritons in the reinforcement layer.

[0016] Emission stacks can have various energy level relationships and other characteristics. Emission stacks may include EBLs with the highest occupied molecular orbital (HOMO) energy level within 0.4 eV of the HOMO energy level of the organic emission material and / or EBLs with triplet energy not greater than the triplet energy of at least one of the host materials.

[0017] The emission stack may include a lowest unoccupied molecular orbital (LUMO) energy level within 0.3 eV of at least one of the host materials.

[0018] At least one host material can form an excitation complex with an organic emissive material.

[0019] The emission stack may include HOMO energy levels in at least one of the host materials with an HTL not exceeding 0.5 eV.

[0020] The launch stack can satisfy the condition: E ET ≤|HOMO 发射体 -LUMO EML |+δ, where E ET It is the lowest triplet energy level of all materials in EML, LUMO EML It is the deepest LUMO of all materials in EML, and δ is at least 0.01 eV. Attached Figure Description

[0021] Figure 1 An organic light-emitting device is shown.

[0022] Figure 2 An inverted organic light-emitting device without a separate electron transport layer is shown.

[0023] Figure 3 An example device architecture applicable to the embodiments disclosed herein is shown, wherein the emission layer is located within a threshold distance of the enhancement layer.

[0024] Figure 4An example of an energy level diagram of a body and emitter system according to embodiments disclosed herein is shown, wherein the lowest triplet energy level E ET Below the charge-transfer state energy ΔE. This arrangement represents any multi-component host and emitter system where any material in the system with the highest HOMO and any other material in the system with the lowest LUMO satisfy the condition ΔE > E. ET E ET This represents the triplet energy of the emitter. The energy level difference is not plotted to emphasize the difference.

[0025] Figure 5A , 5B Figures 5 and 5C show examples of energy level diagrams for a single-component host and emitter system according to embodiments disclosed herein.

[0026] Figure 6A-11F Together, examples of energy level diagrams of a two-component host and emitter system according to embodiments disclosed herein are shown.

[0027] Figure 12A-17F Together, examples of energy level diagrams of a three-component host and emitter system according to embodiments disclosed herein are shown.

[0028] Figure 18 Energy level diagrams of a three-component host and emitter system according to embodiments disclosed herein are shown.

[0029] Figure 19 The chemical structures of various compounds used in the embodiments disclosed herein are shown. Detailed Implementation

[0030] Generally, an OLED comprises at least one organic layer disposed between and electrically connected to both the anode and cathode. When a current is applied, holes are injected into the anode and electrons into the organic layer from the cathode. The injected holes and electrons migrate toward their respective oppositely charged electrodes. When electrons and holes are localized on the same molecule, an "exciton" is formed, which is a localized electron-hole pair with an excited energy state. When the exciton relaxes through a photoemission mechanism, light is emitted. In some cases, excitons may be localized on excimers or excited-state complexes. Non-radiative mechanisms (such as thermal relaxation) may also occur, but are generally considered undesirable.

[0031] Early OLEDs used emitting molecules that emitted light from a single state (“fluorescence”), as disclosed, for example, in U.S. Patent No. 4,769,292, which is incorporated herein by reference in its entirety. Fluorescence emission typically occurs within timeframes of less than 10 nanoseconds.

[0032] Recently, OLEDs with emitting materials that emit light from the triplet state (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, Vol. 395, 151-154, 1998 (“Baldo-I”); and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Applied Physics Letters, Vol. 75, 3, 4-6 (1999) (“Baldo-II”), are incorporated herein by reference in their entirety. Phosphorescence is described in more detail in columns 5-6 of U.S. Patent No. 7,279,704, which is incorporated herein by reference.

[0033] Figure 1 An organic light-emitting device 100 is shown. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emission layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, a cathode 160, and a blocking layer 170. The cathode 160 is a composite cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 can be fabricated by sequentially depositing the layers. The properties and functions of these various layers and example materials are described in more detail in columns 6-10 of US 7,279,704, which is incorporated herein by reference.

[0034] Further examples of each of these layers are available. For instance, a flexible and transparent substrate-anode combination is disclosed in U.S. Patent No. 5,844,363, which is incorporated herein by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F4-TCNQ in a 50:1 molar ratio, as disclosed in U.S. Patent Application Publication No. 2003 / 0230980, which is incorporated herein by reference in its entirety. Examples of luminescent and host materials are disclosed in U.S. Patent No. 6,303,238 to Thompson et al., which is incorporated herein by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li in a 1:1 molar ratio, as disclosed in U.S. Patent Application Publication No. 2003 / 0230980, which is incorporated herein by reference in its entirety. Examples of cathodes, comprising composite cathodes having a thin layer of metal (e.g., Mg:Ag) having an overlying transparent, conductive, sputtered ITO layer, are disclosed in their entirety in U.S. Patent Nos. 5,703,436 and 5,707,745, which are incorporated herein by reference in their entirety. Theories and uses of barrier layers are described in more detail in U.S. Patent No. 6,097,147 and U.S. Patent Application Publication No. 2003 / 0230980, which are incorporated herein by reference in their entirety. Examples of implantation layers are provided in U.S. Patent Application Publication No. 2004 / 0174116, which is incorporated herein by reference in its entirety. Descriptions of protective layers can be found in U.S. Patent Application Publication No. 2004 / 0174116, which is incorporated herein by reference in its entirety.

[0035] Figure 2 An inverted OLED 200 is shown. The device includes a substrate 210, a cathode 215, an emitter layer 220, a hole transport layer 225, and an anode 230. The device 200 can be fabricated by sequentially depositing these layers. Because the most common OLED configuration has a cathode disposed above the anode, and the device 200 has a cathode 215 disposed below the anode 230, the device 200 can be referred to as an "inverted" OLED. Materials similar to those described with respect to device 100 can be used in the corresponding layers of the device 200. Figure 2 Provide an example of how some layers can be omitted from the structure of device 100.

[0036] Figure 1 and 2The simple layered structures illustrated herein are provided by way of non-limiting examples, and it should be understood that embodiments of the invention can be used in conjunction with a variety of other structures. The specific materials and structures described are exemplary in nature, and other materials and structures can be used. Functional OLEDs can be obtained by combining the various layers described in different ways, or the layers can be omitted entirely based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than those specifically described may be used. Although many examples provided herein describe various layers as comprising a single material, it should be understood that combinations of materials, such as mixtures of host and dopant, or more generally, mixtures, can be used. Furthermore, the layers may have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. For example, in device 200, hole transport layer 225 transports holes and injects holes into emitter layer 220, and can be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED may be described as having an “organic layer” disposed between a cathode and an anode. This organic layer may comprise a single layer, or may further comprise, for example, regarding Figure 1 and 2 Multiple layers of the different organic materials mentioned above.

[0037] Structures and materials not specifically described can also be used, such as OLEDs (PLEDs) containing polymeric materials, as disclosed in, for example, U.S. Patent No. 5,247,190 to Friend et al., which is incorporated herein by reference in its entirety. By another example, OLEDs with a single organic layer can be used. OLEDs can be stacked, for example, as described in, U.S. Patent No. 5,707,745 to Forrest et al., which is incorporated herein by reference in its entirety. OLED structures can be deviated from... Figure 1 and 2 The simple layered structure described herein. For example, the substrate may include angled reflective surfaces to improve out-coupling, such as the tabletop structure described in U.S. Patent No. 6,091,195 to Forrest et al., and / or the recessed structure described in U.S. Patent No. 5,834,893 to Bulovic et al., which are incorporated herein by reference in their entirety.

[0038] In some embodiments disclosed herein, the emission layer or material, for example Figure 1-2The emitting layers 135 and 220 shown herein may include quantum dots. Unless explicitly stated otherwise or indicated by a person skilled in the art as such, the term "emitting layer" or "emitting material" as disclosed herein may include organic emitting materials and / or emitting materials containing quantum dots or equivalent structures. Such emitting layers may consist only of quantum dot materials that convert light emitted by a single emitting material or other emitting body, or may also include a single emitting material or other emitting body, or may emit light directly by applying an electric current. Similarly, color-changing layers, filters, up-conversion or down-conversion layers or structures may include materials containing quantum dots, but such layers may not be considered "emitting layers" as disclosed herein. Generally, an "emitting layer" or material is an "emitting layer" or material that emits initial light, which may be altered by another layer (e.g., a filter or other color-changing layer) that itself does not emit the initial light within the device, but may re-emit altered light with different spectral content based on the initial light emitted by the emitting layer.

[0039] Unless otherwise specified, any of the layers in the various embodiments may be deposited by any suitable method. For organic layers, preferred methods include thermal evaporation, inkjet printing (as described in U.S. Patent Nos. 6,013,982 and 6,087,196, which are incorporated herein by reference in their entirety), organic vapor deposition (OVPD) (as described in U.S. Patent No. 6,337,102 by Forrest et al., which are incorporated herein by reference in their entirety), and deposition by organic vapor jet printing (OVJP) (as described in U.S. Patent No. 7,431,968, which is incorporated herein by reference in its entirety). Other suitable deposition methods include spin coating and other solution-based processes. Solution-based processes are preferably performed in a nitrogen or inert atmosphere. For other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition via a mask, cold soldering (as described in U.S. Patents 6,294,398 and 6,468,819, which are incorporated herein by reference in their entirety), and patterning associated with some of the deposition methods such as inkjet and OVJD. Other methods may also be used. The material to be deposited may be modified to suit a particular deposition method. For example, branched or unbranched substituents, preferably containing at least three carbons, such as alkyl and aryl groups, may be used in small molecules to enhance their solution handling ability. Substituents having 20 or more carbons may be used, with 3 to 20 carbons being a preferred range. Materials with asymmetric structures may have better solution handleability than those with symmetric structures because asymmetric materials may have a lower tendency to recrystallize. Dendritic polymer substituents may be used to enhance the solution handling ability of small molecules.

[0040] Devices manufactured according to embodiments of the present invention may optionally further include a barrier layer. One use of the barrier layer is to protect the electrodes and organic layers from damage caused by exposure to harmful substances in an environment including moisture, vapor, and / or gases. The barrier layer may be deposited on, under, or beside a substrate or electrode, or on any other part of the device, including edges. The barrier layer may comprise a single layer or multiple layers. The barrier layer can be formed using various known chemical vapor deposition techniques and may comprise compositions having a single phase and compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may contain inorganic or organic compounds, or both. Preferred barrier layers comprise a mixture of polymeric and non-polymeric materials, as described in U.S. Patent No. 7,968,146, PCT Patent Application Nos. PCT / US2007 / 023098 and PCT / US2009 / 042829, which are incorporated herein by reference in their entirety. For the process to be considered a "mixture," the aforementioned polymeric and non-polymeric materials constituting the barrier layer should be deposited and / or deposited simultaneously under the same reaction conditions. The weight ratio of polymeric to non-polymeric materials can range from 95:5 to 5:95. The polymeric and non-polymeric materials can be produced from the same precursor material. In one example, the mixture of polymeric and non-polymeric materials is essentially composed of polymeric silicon and inorganic silicon.

[0041] In some embodiments, at least one of an anode, cathode, or new layer disposed above the organic emitting layer serves as a reinforcement layer. The reinforcement layer comprises a plasmonic material exhibiting surface plasmon resonance, which is nonradiatively coupled to the emitter material and transfers excited-state energy from the emitter material to the nonradiative mode of the surface plasmon polariton. The reinforcement layer is positioned at a distance from the organic emitting layer not exceeding a threshold distance, wherein, due to the presence of the reinforcement layer, the emitter material has a total nonradiative decay rate constant and a total radiative decay rate constant, and the threshold distance is the position where the total nonradiative decay rate constant equals the total radiative decay rate constant. In some embodiments, the OLED further comprises an external coupling layer. In some embodiments, the external coupling layer is disposed on the reinforcement layer on the opposite side of the organic emitting layer. In some embodiments, the external coupling layer is disposed on the emitting layer on the side opposite to the reinforcement layer, but still externally couples energy from the surface plasmon polariton modes of the reinforcement layer. The external coupling layer scatters energy from the surface plasmon polaritons. In some embodiments, this energy is scattered as photons into free space. In other embodiments, energy is scattered from the surface plasmon modes of the device into other modes, such as, but not limited to, organic waveguide modes, substrate modes, or another waveguide mode. If energy is scattered into the non-free-space modes of the OLED, other external coupling schemes can be combined to extract the energy into free space. In some embodiments, one or more intermediary layers may be disposed between the enhancement layer and the external coupling layer. Examples of intermediary layers may be dielectric materials, including organic, inorganic, perovskite, and oxide materials, and may comprise stacks and / or mixtures of these materials.

[0042] The enhancement layer alters the effective properties of the medium in which the emitter material resides, thereby causing any or all of the following: reduced emissivity, altered emission profile, emission intensity varying with angle, altered emitter material stability, altered OLED efficiency, and reduced roll-off efficiency of the OLED device. Placing the enhancement layer on the cathode side, anode side, or both sides produces an OLED device that utilizes any of the aforementioned effects. In addition to the specific functional layers mentioned herein and illustrated in the various OLED examples shown in the figures, the OLED according to this disclosure may also include any other functional layers commonly found in OLEDs.

[0043] The reinforcing layer may comprise a plasmonic material, an optically active metamaterial, or a hyperbolic metamaterial. As used herein, a plasmonic material is a material 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 the following: 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. Typically, metamaterials are media composed of different materials, wherein the overall effect of the medium differs from the sum of its material components. Specifically, we define an optically active metamaterial as a material that simultaneously possesses negative permittivity and negative permeability. On the other hand, a hyperbolic metamaterial is an anisotropic medium in which the permittivity or permeability has different signs for different spatial orientations. Optically active metamaterials and hyperbolic metamaterials differ significantly from many other photonic structures, such as distributed Bragg reflectors (DBRs), because the medium should exhibit uniformity along the propagation direction over the long scale of the light wavelength. Using terminology understandable to those skilled in the art, the dielectric constant of the metamaterial along the propagation direction can be described by an effective dielectric approximation. Plasmon materials and metamaterials offer methods for controlling light propagation, which can enhance OLED performance in a variety of ways.

[0044] In some embodiments, the enhancement layer is configured as a planar layer. In other embodiments, the enhancement layer has wavelength-sized features arranged periodically, quasi-periodicly, or randomly, or subwavelength-sized features arranged periodically, quasi-periodicly, or randomly. In some embodiments, the wavelength-sized features and subwavelength-sized features have sharp edges.

[0045] In some embodiments, the outer coupling layer is characterized by a wavelength size arranged periodically, quasi-periodicly, or randomly, or by a subwavelength size arranged periodically, quasi-periodicly, or randomly. In some embodiments, the outer coupling layer may be composed of a plurality of nanoparticles, and in other embodiments, the outer coupling layer is composed of a plurality of nanoparticles disposed on a material. In these embodiments, the outer coupling can be adjusted by at least one of the following: changing the size of the plurality of nanoparticles, changing the shape of the plurality of nanoparticles, changing the material of the plurality of nanoparticles, adjusting the thickness of the material, changing the refractive index of the material or an additional layer disposed on the plurality of nanoparticles, changing the thickness of the reinforcing layer, and / or changing the material of the reinforcing layer. The plurality of nanoparticles of the device may be formed from at least one of the following: metal, dielectric material, semiconductor material, metal alloy, mixture of dielectric materials, stack or layering of one or more materials, and / or a core of one type of material coated with a shell of another type of material. In some embodiments, the outer coupling 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. Multiple nanoparticles may have additional layers disposed on them. In some embodiments, the outer coupling layer can be used to tune the polarization of the emission. Changing the size and periodicity of the outer coupling layer can select the polarization type preferentially coupled to air. In some embodiments, the outer coupling layer also functions as an electrode of the device.

[0046] It is believed that the internal quantum efficiency (IQE) of fluorescent OLEDs can exceed the 25% spin statistical limit through delayed fluorescence. As used in this paper, there are two types of delayed fluorescence: P-type delayed fluorescence and E-type delayed fluorescence. P-type delayed fluorescence is generated by triplet-triplet annihilation (TTA).

[0047] On the other hand, E-type delayed fluorescence does not depend on the collision of two triplet states, but rather on the number of thermal particles between the triplet and singlet excited states. Compounds capable of producing E-type delayed fluorescence must possess an extremely small singlet-triple state gap. Thermal energy can activate the triplet state transition back to the singlet state. This type of delayed fluorescence is also known as thermally activated delayed fluorescence (TADF). A unique characteristic of TADF is that the delayed component increases with increasing temperature due to the increased thermal energy. If the reverse intersystem crossing rate is fast enough to minimize the nonradiative decay originating in the triplet state, the fraction of the backfilled singlet excited state can potentially reach 75%. The total singlet fraction can be 100%, far exceeding the spin statistical limit of electrically generated excitons.

[0048] E-type delayed fluorescence can be detected in excited complex systems or single compounds. Unbound by theory, it is believed that E-type delayed fluorescence requires the luminescent material to have a small singlet-triplet band gap (ΔES-T). Organic donor-acceptor luminescent materials containing nonmetals can achieve this requirement. The emission of these materials is typically characterized by donor-acceptor charge transfer (CT) emission. The spatial spacing between the HOMO and LUMO of these donor-acceptor compounds usually causes a small ΔES-T. These states can include CT states. Typically, donor-acceptor luminescent materials are constructed by linking an electron donor moiety (e.g., an amino or carbazole derivative) with an electron acceptor moiety (e.g., an N-containing six-membered aromatic ring).

[0049] Devices manufactured according to embodiments of the present invention can be incorporated into a wide variety of electronic component modules (or units), which can be incorporated into a variety of electronic products or intermediate components. Examples of such electronic products or intermediate components include displays, lighting devices (such as discrete light source devices or lighting panels), etc., which can be utilized by end-user product manufacturers. The electronic component module may optionally include driving electronics and / or a power supply. Devices manufactured according to embodiments of the present invention can be incorporated into a wide variety of consumer products having one or more electronic component modules (or units) incorporated therein. A consumer product incorporating an OLED is disclosed, wherein the OLED comprises compounds of the present disclosure in its organic layer. The consumer product should include any type of product containing one or more light sources and / or one or more of some type of visual display. Examples of the consumer products described include flat panel displays, curved displays, computer monitors, medical monitors, televisions, billboards, lights for internal or external lighting and / or signaling, head-up displays, fully transparent or partially transparent displays, flexible displays, rollable displays, foldable displays, stretchable displays, laser printers, telephones, cellular phones, tablet computers, phablets, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, camcorders, viewfinders, microdisplays (displays with a diagonal of less than 2 inches), 3D displays, virtual reality or augmented reality displays, vehicles, video walls comprising multiple tiled displays, theater or stadium screens, and signage. Various control mechanisms, including passive and active matrices, can be used to control the devices manufactured according to the invention. Many of the devices are intended for use in temperature ranges comfortable for humans, such as 18°C ​​to 30°C, and more preferably at room temperature (20-25°C), but can be used outside this temperature range (e.g., -40°C to +80°C).

[0050] The materials and structures described herein can be applied to devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors can utilize the materials and structures described herein. More generally, organic devices such as organic transistors can utilize the materials and structures described herein.

[0051] In some embodiments, the OLED has one or more features selected from the group consisting of: flexible, rollable, foldable, stretchable, and bendable. In some embodiments, the OLED is transparent or translucent. In some embodiments, the OLED further comprises a layer including carbon nanotubes.

[0052] In some embodiments, the OLED further comprises a layer including a delayed phosphor emitter. In some embodiments, the OLED comprises an RGB pixel arrangement or a white pixel arrangement with a color filter. 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 with 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 with a diagonal of at least 10 inches or an area of ​​at least 50 square inches. In some embodiments, the OLED is a lighting panel.

[0053] In some embodiments of the launch area, the launch area further includes a body.

[0054] In some embodiments, the compound may be an emission dopant. In some embodiments, the compound may generate emission via phosphorescence, fluorescence, thermally activated delayed fluorescence (TADF, also known as E-type delayed fluorescence), triplet-triplet annihilation, or a combination of these processes.

[0055] The OLEDs disclosed herein can be incorporated into one or more consumer products, electronic component modules, and lighting panels. The organic layer can be an emission layer, and the compound can be an emission dopant in some embodiments, while in other embodiments it can be a non-emission dopant.

[0056] The organic layer may also include a host. In some embodiments, two or more hosts are preferred. In some embodiments, the host used may be a) bipolar, b) electron transport, c) hole transport, or d) wide bandgap material that plays a minor role in charge transport. In some embodiments, the host may include a metal complex. The host may be an inorganic compound.

[0057] Combination with other materials

[0058] The materials described herein for use in specific layers of organic light-emitting devices can be used in combination with a variety of other materials present in the device. For example, the emission dopants disclosed herein can be used in combination with a wide variety of host layers, transport layers, blocking layers, injection layers, electrodes, and other possible layers. The materials described or mentioned below are non-limiting examples of materials that can be used in combination with the compounds disclosed herein, and those skilled in the art can readily consult the literature to identify other materials that can be used in combination.

[0059] The different emitting and non-emitting layers and arrangements disclosed herein may use different materials. Examples of suitable materials are disclosed in U.S. Patent Application Publication No. 2017 / 0229663, which is incorporated herein by reference in its entirety.

[0060] Conductive dopants:

[0061] Charge transport layers can be doped with conductive dopants to substantially alter their charge carrier density, which in turn changes their conductivity. Conductivity is increased by creating charge carriers in the matrix material and, depending on the type of dopant, can also achieve changes in the Fermi level of the semiconductor. Hole transport layers can be doped with p-type conductive dopants, while n-type conductive dopants are used in electron transport layers.

[0062] HIL / HTL:

[0063] The hole injection / transport materials used in this invention are not particularly limited, and any compound can be used, as long as the compound is commonly used as a hole injection / transport material.

[0064] EBL:

[0065] An electron blocking layer (EBL) can be used to reduce the number of electrons and / or excitons leaving the emitter layer. The presence of such a blocking layer in a device can result in generally higher efficiency and / or longer lifetime compared to similar devices lacking a blocking layer. Furthermore, the blocking layer can be used to confine emission to a desired area of ​​the OLED. In some embodiments, the EBL material has a higher LUMO (closer to vacuum level) and / or higher triplet energy compared to the emitter closest to the EBL interface. In some embodiments, the EBL material has a higher LUMO and / or higher triplet energy compared to one or more of the bodies closest to the EBL interface. In one aspect, the compound used in the EBL contains the same molecules or the same functional groups as those used in one of the bodies described below.

[0066] main body:

[0067] The light-emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as the light-emitting material, and may contain a host material using a metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complex or organic compound can be used, as long as the triplet energy of the host is greater than that of the dopant. Any host material can be used with any dopant, as long as the triplet criterion is satisfied.

[0068] HBL:

[0069] Hole blocking layers (HBLs) can be used to reduce the number of holes and / or excitons leaving the emitter layer. The presence of such blocking layers in a device can result in generally higher efficiency and / or longer lifetime compared to similar devices lacking a blocking layer. Furthermore, blocking layers can be used to confine emission to a desired area of ​​the OLED. In some embodiments, the HBL material has a lower HOMO (farthest from vacuum level) and / or higher triplet energy compared to the emitter closest to the HBL interface. In some embodiments, the HBL material has a lower HOMO and / or higher triplet energy compared to one or more of the bodies closest to the HBL interface.

[0070] ETL:

[0071] An electron transport layer (ETL) may comprise a material capable of transporting electrons. The ETL may be intrinsic (undoped) or doped. Doping can be used to enhance conductivity. Examples of ETL materials are not particularly limited, and any metal complex or organic compound may be used, provided it is typically used for electron transport.

[0072] Charge generation layer (CGL)

[0073] In tandem or stacked OLEDs, the conduction layer (CGL) plays a fundamental role in performance. It consists of an n-doped layer and a p-doped layer, respectively, for injecting electrons and holes. Electrons and holes are supplied by the CGL and the electrodes. Electrons and holes consumed in the CGL are refilled by 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-conductive dopants used in the transport layer.

[0074] It has been found that designing OLEDs to couple most or all of the excited-state energies to surface plasmon modes can make the device more stable. This can be achieved by positioning the emitter layer (EML) within a threshold distance of the enhancement layer, for example, as shown below. Figure 3 As shown in the figure. The “threshold distance” is defined as the distance at which the total nonradiative decay rate constant is equal to the total radiative decay rate constant, as further detailed in U.S. Patent No. 9,960,386, which is incorporated herein by reference in its entirety.

[0075] Typically, this method may also involve thinning the emitter layer (EML), thereby confining excitons to a small volume, making them more likely to interact with excited states. Therefore, charge balance and charge trapping can be particularly important in these types of devices.

[0076] The embodiments disclosed herein provide a variety of host structures having electron and / or hole transport components with specific energy levels that promote good charge balance and enhanced charge trapping. In some embodiments, the host system may reduce excited complex formation, thereby promoting improved quantum efficiency and stability within the device. Other embodiments may intentionally include excited complex formation to modulate the average orientation of dipoles.

[0077] In these embodiments, it is preferable that the emitter and its host components do not form excitation complexes or charge-transfer (CT) states in the device as the lowest energy state. The energy of the CT state (if formed) is required to be higher than the triplet energy of the emitter, ensuring that the emission spectrum of the device will be the emission spectrum of the emitter, not the CT state, and that the loss of emitter quantum yield in the host system is minimized due to excitation complex formation. The CT state energy (ΔE) can be considered as the energy difference between the HOMO energy level of the material with the highest HOMO energy in the organic emitter layer and the LUMO energy level of the material with the lowest LUMO energy in the organic emitter layer, such as... Figure 4 As shown in the figure. At 77 K, the triplet energy of the emitter was measured using the peak wavelength of photoluminescence. As used herein, E ET It is defined as the lowest triplet (T1) energy in all materials of the emitter layer.

[0078] Alternatively, the energy levels of the host component can be selected to promote good charge balance in plasmonic phosphorescent OLED devices. For a single-component host (i.e., first emitter + first host, such as...) Figures 5A-5C As shown, the HOMO level of the host can be tuned to control the hole mobility of the hole transport material. Correspondingly, for electron transport materials, the LUMO level of the host can be tuned to control the electron mobility. For example, when the host plays a major role in the conduction path, deepening the HOMO level of the host will slow down hole transport in the device, while making the LUMO level of the host shallower will slow down electron transport. More generally, when the host level deviates further from the emitter level, the host is unlikely to play a significant role in charge conduction.

[0079] Even with uniform charge recombination, asymmetric hole and electron transport mobilities can negatively impact device stability due to holes or electrons becoming trapped at interfaces, or lead to exciton recombination patterns preferentially localized at one interface of the EML. For example, in devices with relatively high electron mobility but relatively low hole mobility, electrons will accumulate on the hole transport side of the EML adjacent to the electron blocking layer, thereby increasing the likelihood of excited-state interactions, such as triplet-triplet annihilation and triplet-polaron annihilation, which is believed to reduce device stability. In this example, making the bulk LUMO level shallower will slow down electron transport and allow excited states to diffuse across the entire EML over a larger volume, thereby improving device stability.

[0080] If the HOMO level of the emitter is at the same energy level as the HOMO level of the host, the hole mobility of the system can be enhanced; correspondingly, if the LUMO level of the emitter is at the same energy level as the LUMO level of the host, the electron mobility of the system can be enhanced. This effect can be minimized if the dopant mobility is higher than the hole mobility on the host. When the HOMO level of the host becomes deeper than the HOMO level of the dopant, the dopant begins to become a strong hole trap. If the hole mobility on the dopant is lower than the hole mobility on the host, especially if the host, which plays a role in hole transport, is at the same energy level on both the host and dopant HOMO levels, this strong hole trap will hinder hole transport. Therefore, in some embodiments, it is preferable that the HOMO energy difference between the host and emitter is greater than 150 meV, or greater than 250 meV, or greater than 350 meV. Similarly, when the LUMO energy level of the host becomes shallower than that of the dopant, the dopant begins to act as a strong electron trap. If the electron mobility on the dopant is lower than that on the host, especially if the host, which acts as the electron transporter, has the same energy level at both the host and dopant LUMO levels, this strong electron trap will hinder electron transport. Therefore, in some embodiments, it is preferable that the LUMO energy difference between the host and the emitter is greater than 150 meV, or greater than 250 meV, or greater than 350 meV.

[0081] In the example shown in Figure 6-11, introducing a second host can further modulate the mobility of electrons and holes. For example, deepening the HOMO level of a host component below that of the emitter will introduce a hole transport barrier and slow down hole transport, and / or may also introduce a hole injection barrier in the EML. Therefore, in some embodiments, it is preferable that the HOMO energy difference between the host and emitter is greater than 150 meV, or greater than 250 meV, or greater than 350 meV. Conversely, making the LUMO of a host material shallower than that of the emitter will have the effect of slowing down electron transport and / or introducing an electron injection barrier. Therefore, in some embodiments, it is preferable that the LUMO energy difference between the host and emitter is greater than 150 meV, or greater than 250 meV, or greater than 350 meV. These energy level shifts can be used to finely tune the EML transport characteristics and thus adjust the charge balance in the device.

[0082] Introducing a third host, such as the examples shown in Figures 12-17 and 18, can further modulate transport characteristics. To modulate hole transport characteristics, another hole transport host can be included, and to modulate electron transport characteristics, another electron transport host can be included. Since the host triplet state is non-emitting, a wide-bandgap inert third host component can play a particularly important role in reducing or eliminating triplet quenching in the host material, thereby increasing the quantum efficiency within the device. In some embodiments where the third host has a wide bandgap, it can be used to dilute the concentrations of the other two hosts while maintaining the concentration of the emitter, thus allowing for further tuning of charge transport. Figures 12-17 and 18 show examples of such energy levels, but other configurations are more commonly possible. The third host HOMO can be energy-deep between the first and second host HOMOs, between the first emitter and the first host HOMO, deeper than or shallower than all other HOMOs in the EML. Similarly, the third-body LUMO can be energy-wise between the first and second-body LUMOs, between the first emitter and the first-body LUMO, deeper than all other LUMOs in the EML, while still being deeper than E... ET Shallower, or shallower than all other LUMOs in the EML. In all cases, to avoid quenching of the excited-state energy in the body, the LUMO-HOMO energy difference of the third body should be greater than the E0 of the first emitter. ET Energy difference with HOMO

[0083] Regardless of the number of hosts used, one or more hosts can be bipolar and / or mixed with electron transport host materials (e-hosts) and / or hole transport host materials (h-hosts). In the case of multi-component hosts, one or more bipolar hosts can be diluted with wide-bandgap host materials to further modulate charge transport. As used herein, e-host materials are typically the host components with the deepest (lowest) LUMO level, while h-host materials are typically the host components with the shallowest (highest) HOMO level. Notably, e-host and / or h-host materials can include emitters with the deepest LUMO or the shallowest HOMO in the emitter layer.

[0084] Figure 18 An example of a preferred embodiment of a three-component main body structure particularly suitable for blue applications in phosphorescent devices is shown, wherein E ET Below ΔE, as defined above. In this type of arrangement, a high triplet h-type body is used, along with an h-type body, to achieve better hole mobility (which typically has a lower triplet energy). In this way, the overall efficiency of the device is higher than that of a body using only high mobility and a lower triplet energy.

[0085] In some embodiments, some or all of the materials in the organic emitting layer may be in the form of a mixture. The mixture may be a homogeneous mixture, or the components of the organic emitting layer may have a gradually varying concentration throughout the entire thickness of the emitting layer. The concentration gradient may be linear, non-linear, sinusoidal, or any other suitable form. The emitter may be a phosphorescent metal complex, a delayed fluorescence emitter, or any other suitable type of emitting material and / or structure.

[0086] Some embodiments may include an injection layer and / or a transport layer to facilitate or delay charge injection into the EML. Generally, the hole injection and / or transport material has a HOMO level similar to the shallowest HOMO composition of the EML. However, in some embodiments, the hole injection layer and / or transport layer may have a HOMO level equal to or even slightly shallower than the highest HOMO composition of the EML, while still facilitating good hole injection / transport. If the HOMO level of the hole injection layer and / or transport layer is significantly shallower than the shallowest HOMO composition of the EML, then hole injection / transport can be delayed.

[0087] In other embodiments, hole transport materials can be aligned to achieve a good hole injection EML, but a blocking layer can be included to further delay hole injection. In some embodiments, the blocking layer may have a HOMO level deeper than the shallowest HOMO level material in the EML. In some embodiments, the blocking layer can enhance the hole injection EML by having HOMO levels between the HOMO of the hole transport layer and the HOMO of the highest HOMO level material in the EML. In other embodiments, the hole mobility of the hole transport material can be significantly reduced, even if the HOMO levels are aligned to achieve a good hole injection EML. Such an arrangement can be used, for example, to modulate charge recombination within the EML. In other embodiments, the HTL mobility can be reduced or increased to modulate charge recombination within the EML.

[0088] Similarly, generally, the LUMO level of the electron-injected and / or transport material is shallower than the shallowest LUMO composition of the EML. However, in some embodiments, the LUMO level of the electron-injected and / or transport layer can be at the same energy level as or even deeper than the shallowest LUMO composition of the EML and still promote good electron injection and / or transport. If the LUMO level of the electron-injected and / or transport layer is significantly deeper than the shallowest LUMO composition of the EML, then electron injection / transport can be delayed. In another embodiment, the injection layer and / or transport layer can be doped with another material to further promote or delay charge injection and / or transport. In another embodiment, a barrier layer can be inserted between the EML and the ETL to promote or delay electron injection into the EML. In another embodiment, the mobility of the ETL layer can be reduced or increased to modulate charge recombination within the EML.

[0089] use Figure 19 The compounds shown are constructed as described below to have Figure 4-1 Example of a device with the structure shown in 7. The specific device structure being tested is selected to provide data based on a range of available materials and common energy level structures and / or relationships (to allow comparisons of the most common and likely-to-be-used combinations) and can differ significantly from other device and energy level structures. More generally, other than... Figure 19 Compounds other than those shown in the diagram, without departing from the results or scope disclosed herein using materials having the same energy level relationships as described.

[0090] As shown in the experimental data disclosed below, it has been found that using emission layers and other layers with specific energy level relationships can improve the effect of using enhancement layers as disclosed herein. For example, the test device is constructed such that top emission (TE) is dominated by plasmon energy converted into light, while bottom emission (BE) is dominated by residual emission of energy not coupled to plasmon modes. Therefore, the ratio of top emission to bottom emission, TE / BE, and similar ratios or calculations can be used to determine the relative emission portion resulting from plasmon conversion and thereby determine the effectiveness of the enhancement layer in the device. It has been found that reducing the fraction of excitons further away from the enhancement layer by using an EBL with a triplet energy level lower than the bulk triplet energy level increases the ratio of top emission to bottom emission (thus avoiding plasmon coupling), making it more likely that excitons further away from the enhancement layer will be emitted and reach the bottom side of the device. Conversely, an EBL with a triplet energy level higher than the bulk exhibits a relatively low TE / BE emission ratio. As another example, when the HOMO level of a single host is within 0.2 eV of the emitter doped in the emitter layer along with the host, the ratio of top emission EQE to bottom emission EQE (TE EQE / BE EQE) decreases. Therefore, to maximize TE / BE EQE, an EBL triplet level that is as low as or even slightly lower than the emitter triplet can be used.

[0091] As another example, it has been found that using an emitter material (“emitter”) that forms an excitation complex and an emitter layer host (with emitters doped in the EML) can improve lifetime and device stability. This is believed to be because the energy of the excitation complex state is lower than the minimum energy emission state of the emitter. Generally, the lower the excitation state energy in an OLED device, the more stable the OLED device.

[0092] As another example, it has been found that when the e-body (electron transport host) LUMO level is at the same energy level as the HBL LUMO level, there is an enhanced stability; however, this enhancement decreases when an e-body barrier is introduced. To take advantage of this and improve device stability, the HBL can be chosen so that the LUMO level is within approximately 0.3 eV of the e-body LUMO level.

[0093] Other similar energy level relationships between materials in OLEDs have been found to improve device performance, such as efficiency, stability, and / or lifetime. As specific examples, the following relationships have been found to have beneficial effects: the HOMO level of the EBL is within 0.4 eV of the HOMO level of the organic emitter material (emitter); the triplet energy of the EBL is no greater than the triplet energy of at least one host material in the EML; the LUMO level of the HBL is within 0.3 eV of at least one host material in the EML; at least one host material in the EML forms an excitation complex with the organic emitter material in the EML; the HOMO level of the HTL is within 0.5 eV of at least one host material in the EML; and

[0094] E ET ≤|HOMO emitter -LUMO EML |+δ,

[0095] Where E ET It is the lowest triplet energy level in all materials in EML, LUMO EML It is the deepest LUMO of all materials in the EML, and δ is at least 0.01 eV, at least 0.11 eV, or at least 0.21 eV. Generally, these and similar relationships indicated in this disclosure include the following data, including... Figure 4-18 Any of the appropriate energy level relationships shown (if the selected inequality or other relationship allows) can be used in conjunction with any emitter structure having a relevant layer.

[0096] experiment

[0097] The fabrication apparatus described below illustrates the various energy level relationships and benefits disclosed herein. In the example apparatus, various host materials (e-host, h-host, or combinations thereof), electron blocking layers, and hole blocking layers (HBLs) are considered. The apparatus incorporates an EML within a threshold distance of the reinforcement layer as defined herein and utilizes a nanoparticle decoupling scheme (e.g., a nanoparticle layer or monolayer separated from the reinforcement layer) to convert the energy stored in the plasmonic modes into light. Examples of suitable nanoparticle decoupling structures are provided in U.S. Patent Publication No. 2021 / 0265584, the disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0098] In these devices, top emission (TE) is primarily the conversion of plasmon energy into light, while bottom emission (BE) is primarily the residual emission of energy not coupled to plasmon modes. As the data provided herein show, a high TE / BE ratio (e.g., TE / BE greater than 1, more preferably greater than 2, and even more preferably greater than 3) indicates that plasmon energy extraction is the dominant source of the output light from the device and also indicates that coupled plasmons are dominant (i.e., most of the excited state energy enters the plasmon mode). Therefore, it is preferable that the devices disclosed herein have a relatively high TE / BE ratio. Table 7 shows the HOMO and LUMO energy levels of the various compounds used in the examples.

[0099] Table 1-4 outlines how EBL affects device performance, such as external quantum efficiency (EQE). For all EBL materials used in the example devices, the LUMO of EBL is higher than that of compounds 8 and 6, thus confining electrons to the emitter layer. However, the HOMO levels of the EBL materials differ, with compound 3 having the shallowest HOMO level and compound 5 having the deepest. The triplet energies of the EBL materials also differ, with compound 3 having a lower triplet energy than either compound 5 or compound 4. All these factors affect the final efficiency of the device.

[0100] For example, when compound 3 or 4 is used as the EBL and compound 8 is used as the emitter (Table 1), the top emission EQE (TE EQE) of the device is significantly higher than that of compound 5. This indicates that for this system, a HOMO level similar to that of the emitter is beneficial for achieving a good EQE. More generally, when compound 8 is used as the emitter, the HOMO level of the EBL achieves a relatively high EQE within approximately 0.4 eV of the emitter's HOMO level, as shown in Table 1. The host / emitter combinations shown in Table 1 have been found to provide such performance. We also found that compound 4 as the EBL achieves the highest EQE, indicating that quenching may exist at the EBL interface, which limits the EQE of the device with compound 3 as the EBL. More generally, this data indicates that when compound 8 is used as the emitter, the EBL achieves a relatively high EQE within 0.4 eV of the emitter's HOMO level. Compounds 4 and 5 have the same LUMO level, but the EBL of compound 4 outperforms that of compound 5, indicating that there is no similar tendency in LUMO levels. The energy level arrangements of the compounds shown in Table 1 correspond to Figure 8F Those shown.

[0101] The lower half of Table 1 shows that using compound 4 as the hole transport host in the EML reduced the EQE difference between using compound 4 or compound 3 as the EBL and compound 5. This is due to the fact that the host participates more actively in hole transport, and therefore, exciton quenching at the EBL interface is reduced as the recombination region moves further away from the EBL interface.

[0102] Table 1: Overview of device performance of hybrid host plasmon devices using various EBL materials and compound 8 as emitters.

[0103] Compound 5: Compound 6 Compound 5 Compound 6 2.7 Compound 5: Compound 6 Compound 3 Compound 6 3.5 Compound 5: Compound 6 Compound 4 Compound 6 4.9 Compound 4: Compound 6 Compound 5 Compound 6 3.0 Compound 4: Compound 6 Compound 3 Compound 6 3.5 Compound 4: Compound 6 Compound 4 Compound 6 4.9

[0104] The host material can also determine which EBL results in the highest TE EQE for a given device. For example, considering the emitter of compound 8 again, we find that compound 4 EBL has the highest TE EQE when used with compound 7 HBL as a single host compound 6, as shown in Table 2, but compound 3 EBL has the highest TE EQE when host compound 4 is used with compound 7 HBL. This is because the e-host compound 6 relies on the emitter to transport holes, resulting in slower hole transport and a rebinding region close to the EBL interface. When using compound 3 EBL, hole transport is faster than with compound 4 EBL, causing the rebinding region to move away from the EBL interface, thereby enabling more plasmon coupling and potentially higher TE EQE; however, the quenching induced by compound 3 EBL overcomes these gains. When using the h-host compound 4, hole transport is faster and the rebinding region is positioned closer to the HBL interface. Since the rebinding region is adjacent to the cathode, this enhances plasmon coupling, thereby increasing TE EQE.

[0105] Enhanced plasmon coupling can be measured by examining the ratio of top-emission EQE to bottom-emission EQE (i.e., TE EQE / BE EQE), which is higher for large amounts of plasmon coupling and lower for small amounts. Since plasmon coupling is a near-field coupling process, the closer an exciton is to the enhancement layer, the more likely it is to couple to a plasmon mode. In other words, excitons located at the EML / HBL interface are more likely to couple to a plasmon mode than those located at the EBL / EML interface. Similarly, a shorter distance between the EML and the enhancement layer will increase the TE EQE / BE EQE ratio. Furthermore, emitter molecules or emitter layers with higher vertically aligned transition dipole moments (TDMs) will have higher TE EQE / BE EQE ratios because the enhanced coupling to plasmon modes suppresses residual emission leaving the device cavity. The surface roughness of the reinforcement layer, especially at the organic interface, also affects the ratio. Generally, a greater surface roughness leads to better plasmon coupling and thus a higher TE EQE / BEEQE ratio.

[0106] Interestingly, since excitons are primarily located near the HBL interface (due to faster hole transport), the EBL (compound 3) providing the highest EQE also exhibits the highest TE EQE / BE EQE ratio. Furthermore, the exciton quenching introduced at the EBL interface by compound 3 reduces the fraction of excitons farther from the enhancement layer, making excitons further away from the enhancement layer more likely to be emitted from the bottom side of the device (i.e., avoiding plasmon inversion).

[0107] Table 2: Overview of device performance of single-host plasmon devices using various EBL materials and compound 8 as emitters.

[0108] Compound 6 Compound 4 Compound 7 4.6 0.74 Compound 6 Compound 5 Compound 7 2.0 0.71 Compound 6 Compound 3 Compound 7 3.3 0.83 Compound 4 Compound 4 Compound 7 3.3 0.70 Compound 4 Compound 5 Compound 7 0.8 0.53 Compound 4 Compound 3 Compound 7 3.6 0.78

[0109] The energy level structure of the compound 6 host device using compound 8 emitter corresponds to... Figure 5A The structure shown is equivalent to that of compound 4, which has compound 8 as the emitter. Figure 5CThe structure is shown in the figures. These results indicate that for a single-host system using a compound-8 type emitter, an EBL triplet energy equal to the emitter triplet energy will cause exciton quenching at the EBL interface, leading to a decrease in exciton density further away from the reinforcement layer, thereby increasing TE EQE and TE / BE (plasmon induction). Therefore, to maximize TE EQE, the EBL triplet energy may need to be higher than the emitter triplet energy. When the HOMO energy of the single-host compound is within 0.2 eV of the emitter, the TE EQE / BE EQE decreases. To maximize the TE EQE / BE EQE ratio of such devices, triplet energy levels that are as low as or slightly lower than the emitter triplet energy level can be used.

[0110] The effects of the host and emitter compound 8 combinations were also investigated using the structures shown in Table 3. In terms of device stability, the host combinations of compound 5:compound 6 and compound 4:compound 6 exhibited the longest LT values. 90 The value, while the single-entity EML of compound 4 or compound 5 has the shortest LT. 90 Values. That is, the devices shown in the first two rows containing e-host compound 6 are more stable than those in the other rows of Table 3. An enhanced stability exists when the e-host LUMO is isoenergetic with the HBL LUMO; this enhanced stability no longer exists when a barrier is introduced using compound 7 as the e-host. These devices have... Figure 8F The energy level structure is shown in the figure. More generally, to achieve this effect, the HBL LUMO may need to be within 0.3 eV of the e-body LUMO to improve device stability.

[0111] When compound 11 was used as the emitter, a hybrid host was found to improve device stability compared to a single host. This enhanced stability in the hybrid host case is believed to be due to an improved charge balance, which increases the volume occupied by the formed excitons, thereby reducing the likelihood of instability in triplet-triplet and triplet-polaron interactions.

[0112] It is noteworthy that the compound 4:compound 6 host using compound 11 as the emitter exhibits an unexpectedly high LT90 lifetime. This is likely due to the formation of an excitation complex between compounds 11 and 6, or between compounds 11 and 7 (which is much less likely). Such effects can be utilized to improve device stability by selecting materials that will form an excitation complex between the emitter material and at least one component of the host.

[0113] Table 3: Overview of device stability of plasmon devices using various host materials and compound 8 or compound 11 as emitters.

[0114]

[0115] When optimizing the device's EQE and using materials such as compound 11 as the emitter, the energy levels of the device materials can be equally important. For the hybrid host case, it was found that compounds 3 or 4, despite having different triplet energies, have the same EQE as EBLs, as shown in Table 4. This is because the hybrid host provides effective charge transport for holes and electrons, resulting in the recombination region being dispersed throughout the EML, thus making quenching at the barrier layer interface less important. The compound 5 and compound 7 host devices exhibit similar EQEs due to the isoenergetic co-host HOMO levels. Figure 10C and 11C The energy level structure shown; Compound 4: Compound 7 device has Figure 10C The energy level structure shown is shown.

[0116] When compound 5 is used as the EBL, the mixed host system prevents effective hole injection into the EML, disrupting the charge balance and resulting in a lower EQE, as shown in the lower TE EQE in row 2 of Table 4. It is noteworthy that the difference between the HOMO level of compound 5 and the HTL is 0.5 eV, while the HOMO levels of compounds 3 and 4 are closer to the HTL HOMO level than 0.5 eV. Therefore, to improve device performance, it is preferable that the HOMO level difference between the HTL and the EBL is no greater than 0.5 eV.

[0117] Table 4: Overview of device performance of hybrid host plasmon devices using various EBL materials and compound 11 as emitters.

[0118]

[0119]

[0120] For the single-subject case, when using compound 5 as the subject, it was found that compounds 4 and 3EBL had a greater impact on TEEQE than when compound 7 was used as the subject, as shown in Table 5. This is because the compound 7 subject makes CIE... y,BE The increase in redshift leads to better alignment of the emission spectrum with the nanoparticle resonant decoupling scheme, resulting in a higher TEEQE / BE EQE ratio. This redshift dominates the TE EQE trend (note that the BE EQE of the compound 5 host is actually the highest), making the effect of EBL on TE EQE less significant. We also note that the total (TE+BE) EQE of the compound 7 host is the highest due to more efficient decoupling of the plasmon energy caused by the improved spectral overlap. The compound 5:11 and 7:11 host:emitter combinations shown in Table 5 have corresponding... Figure 5A The energy level structure.

[0121] Table 5: Overview of device performance of single-host plasmon devices using various EBL materials and compound 11 as emitters.

[0122]

[0123] Generally, due to the redshift NPA resonance of the emission of compound 11, material combinations that enhance CIEy will produce better plasmon decoupling performance (i.e., higher TE EQE). In the devices shown in Table 5, compound 7 as the host achieves this goal, as do compounds 3 and 4 as EBLs, with their HOMO levels within 0.3 eV of the host HOMO energy. The decrease in BE EQE combined with the increase in TE EQE (and therefore the increase in TE / BE) indicates that the rebinding region shifts towards the enhancement layer when using the compound 7 host compared to the compound 5 host. Devices using compounds 5 or 3 as EBLs exhibit increased TE EQE due to the increased hole injection caused by their HOMO energy levels. More generally, this suggests that setting the HOMO energy level of the EBL within 0.3 eV of the host will be able to improve the EQE. The same results are obtained using the devices shown in Table 1, which use Pt-based emitters instead of the Ir-based emitters used in Table 5.

[0124] The choice of materials also influences which HBL material is preferred for a given device structure, as shown in the results in Table 6. When using compound 11 as the emitter, we found that when h-host compound 4 was mixed with e-host compound 7, the TE EQE produced by compound 7 HBL was higher than that when HBL used compound 6. This is because, unlike compound 6 HBL, compound 7 HBL does not provide an electron injection barrier to the host, thereby providing a better charge balance in the host and offering higher recombination efficiency.

[0125] An apparatus in which a hybrid host system forms an excitation complex with an emitter was also constructed. The results are shown in Table 6. When the hybrid host compound 4:compound 6 is used in conjunction with compound 11, an excitation complex is formed between compound 6 and compound 11, as per CIE... yThe increase in the excitation complex demonstrates this. The quantum yield of this excitation complex can be lower than that of the emitter itself, resulting in a lower TE EQE for these devices. However, the TE EQE / BE EQE of these devices is higher than that of devices without the excitation complex. This indicates that there is more energy coupled into the plasmonic mode or more energy decoupling in these devices. The excitation complex formed in the emitter layer can increase the vertical dipole ratio, thereby coupling more energy into the plasmonic mode and thus resulting in a higher TE / BE EQE ratio. The spectral re-shift also results in better spectral overlap between the emission spectrum and the spectral response of the Ag nanocube-based decoupling scheme. The increased overlap between the emission spectrum and the decoupling will increase the fraction of decouplingable energy in the plasmonic mode, resulting in a higher TE EQE / BE EQE ratio. The devices in Table 6 have Figure 10C The energy level structure shown is shown.

[0126] Table 6: Overview of device performance of hybrid host plasmon devices using compound 11 emitter and various HBL materials.

[0127]

[0128] In the compound 4:compound 7 device, the LUMO of the compound 7 co-host is within 0.5 eV of the LUMO of the host compound 4. This results in a large EQE enhancement, compared to the device using the compound 6 co-host, which has a LUMO 0.8 eV difference from the host compound 4. However, the formation of low PLQY excitation complexes compounds 6 and 11 may dominate the performance of these devices. It is believed that the inefficient formation of excitation complexes between compounds 6 and 11 results in a lower EQE, thus this type of structure can be used to avoid the formation of inefficient excitation complexes. The EQE behavior can also be explained by the fact that the LUMO level alignment between compounds 7 and 4 is better than that between compounds 6 and 4, and the large LUMO level difference between compounds 6 and 4 adversely affects the charge balance and / or transport within the EML, thereby reducing EQE.

[0129] More generally, to avoid exciting the formation of the complex with potentially low quantum yield, it is preferable that the device has the following energy level structure: where E ET The sum of the absolute value of the difference between the deepest LUMO of all materials in the emitter HOMO and the EML, and another δ of at least 0.01 eV, more preferably at least 0.11 eV, more preferably at least 0.21 eV. That is:

[0130] E ET ≤|HOMO 发射体 -LUMO EML |+δ

[0131] Where EET As previously defined, LUMO EML It is the deepest LUMO of all materials in the emitter layer, and δ is at least 0.01 eV, 0.11 eV, or 0.21 eV.

[0132] Table 7: Energy levels of EBL, HBL, host and emitter materials.

[0133] Compound 7 -5.7 -2.5 3.0 Compound 5 -5.7 -2.0 3.5 Compound 3 -5.4 -1.8 2.7 Compound 4 -5.5 -2.0 3.0 Compound 6 --- -2.8 3.0 Compound 8 -5.3 -2.1 2.7 Compound 11 -4.9 -1.9 2.7

[0134] In some embodiments, it can be applied to selecting and / or constructing materials having specific desired HOMO, LUMO, or other energy level structures, for example, to satisfy energy level relationships previously disclosed for host materials, barrier materials, or other materials in an emitter stack or device. For example, chemical components can be selected and combined to form a specific host material, barrier layer, or the like.

[0135] Table 8 shows examples of organic portions that can be used to construct the body and barrier layers used in some embodiments, as previously disclosed. Those skilled in the art will understand that the list in Table 8 is not exhaustive, but is intended to provide examples of portions and associated energy levels and typical energy ranges for the body or transport layer constituted by such portions.

[0136] Multiple fragments can be used in some materials. To determine the energy level estimates of the final compound, the shallowest HOMO level (i.e., the largest positive energy level) and the deepest LUMO level (i.e., the smallest negative energy level) are used as the HOMO and LUMO estimates for the final compound. However, in some cases, the exact values ​​may fall outside these estimates. For example, compound 7, consisting of two carbazoles linked to an aryl group (similar to fragments #1 and #14), has a HOMO level estimate of -5.7 eV and a LUMO level estimate of -2.45 eV, consistent with the actual measured HOMO of -5.7 eV and LUMO of -2.5 eV. Similarly, compound 5, consisting of fragments #1, #26, and #13, has a HOMO level estimate of -5.7 eV and a LUMO level estimate of -2.1 eV, consistent with the measured HOMO of -5.7 eV and LUMO of -2.0 eV.

[0137] Table 8: Examples of components and related energy levels used to construct the host material and transport layer

[0138]

[0139]

[0140]

[0141]

[0142] The fragments shown in Table 8, together with each other and / or other organic molecular fragments, can be used to construct phosphorescent, thermally activated delayed fluorescence, and fluorescent emitter molecules.

[0143] In some cases, emitter molecules may also include heavy metals such as Ir, Os, Pt, Pd, Au, Rh, Ru, Cu, or Ag. Table 9 provides some examples of basic emitter molecule structures with energy levels within the estimated range.

[0144] Table 9: Basic structure and estimated energy levels of example emitter molecules.

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152] experiment

[0153] The OLED is grown on a glass substrate pre-coated with an indium tin oxide (ITO) layer with a sheet resistivity of 15 Ω / sq. Before any organic layer is deposited or coated, the substrate is degreased with a solvent, then treated with oxygen plasma at 100 mTorr and 50 W for 1.5 minutes and with UV ozone for 5 minutes.

[0154] In high vacuum (<10) -6 The device is used to manufacture the product via thermal evaporation. The anode electrode is... Indium tin oxide (ITO).

[0155] The device example containing compound 8 has an organic layer, which, from the ITO surface, is composed of the following in sequence: Thickness of compound 1 (HIL) Compound 2-layer (HTL) Compounds [3, 4, 5] (EBL), [Compound 4; Compound 5; Compound 6; Compound 7; Compound 5 doped with 40% Compound 6; Compound 5 doped with 40% Compound 7; Compound 4 doped with 40% Compound 7; Compound 4 doped with 40% Compound 6; Compound 5 doped with 30% Compound 4 and 10% Compound 3] and doped with 12% Compound 8 (EML), Compounds [6, 7] (BL), Compound 9 (ETL) doped with 35% of Compound 10 Compound 10 (EIL) Ca, followed by Ag (cathode) Compound 2 (interstitial layer) was spin-coated onto the top of 75nm Ag nanocubes using a 5mg / ml concentration solution.

[0156] The device example containing compound 11 has an organic layer, which, from the ITO surface, is composed of the following in sequence: Thickness of compound 1 (HIL) Compound 2-layer (HTL) Compounds [3, 4, 5] (EBL), [Compound 4; Compound 5; Compound 7; Compound 5 doped with 40% Compound 7; Compound 4 doped with 40% Compound 7; Compound 4 doped with 40% Compound 6; Compound 5 doped with 30% Compound 7 and 10% Compound 3] and doped with 12% Compound 11 (EML), Compounds [6, 7] (BL), Compound 9 (ETL) doped with 35% of Compound 10 Compound 10 (EIL) Ca, followed by Ag (cathode) Compound 2 (interstitial layer) was spin-coated onto the top of 75nm Ag nanocubes using a 5mg / ml concentration solution.

[0157] All devices, immediately after fabrication, were sealed with glass lids in a nitrogen glove box (H2O and O2 < 1 ppm) and then sealed with epoxy resin, with a desiccant incorporated inside the enclosure. Doping percentage is by volume.

[0158] To obtain the energy levels in Table 8, a CH Instruments 6201B potentiostat was used, with anhydrous dimethylformamide solvent and tetrabutylammonium hexafluorophosphate as the supporting electrolyte, for solution cyclic voltammetry and differential pulse voltammetry. Glassy carbon and platinum and silver wires were used as the working electrode, counter electrode, and reference electrode, respectively. The internal ferrocene-ferrocene redox pair (Fc+ / Fc) was used as an internal standard, and the electrochemical potential was measured by measuring the peak potential difference using differential pulse voltammetry. EHOMO=-[(E ox1 Eox1 is the first oxidation potential, and Ered1 is the first reduction potential.

[0159] It should be understood that the various embodiments described herein are merely examples and are not intended to limit the scope of the invention. For instance, many of the materials and structures described herein can be substituted with other materials and structures without departing from the spirit of the invention. The claimed invention may therefore include variations of the specific examples and preferred embodiments described herein, as will be apparent to those skilled in the art. It should be understood that various theories regarding why the invention works are not intended to be limiting.

Claims

1. An organic emission device comprising: Substrate; A first electrode is disposed on the substrate; An emission stack, disposed on the first electrode, comprises: A first organic emission layer (EML) comprising one or more host materials and organic emission materials; as well as Hole blocking layer (HBL), electron blocking layer (EBL), or both; The second electrode is disposed on the emission stack; as well as A first enhancement layer comprising a plasmonic material exhibiting surface plasmon resonance, the plasmonic material being nonradiatively coupled to an organic emission material in the organic emission layer and transferring excited-state energy from the organic emission material to the nonradiative mode of the surface plasmon polaritons in the first enhancement layer, the first enhancement layer being configured to be located at a distance from the first organic emission layer not exceeding a threshold distance, wherein the threshold distance is the position where the total nonradiative attenuation rate constant is equal to the total radiative attenuation rate constant; The emission stack comprises an EBL with a triplet energy lower than that of at least one of the host materials; The triplet energy of the EBL is the same as or lower than the triplet energy of the organic emissive material; and The EBL therein has a HOMO energy level within 0.3 eV of the HOMO energy level of the body.

2. An organic emission device comprising: Substrate; A first electrode is disposed on the substrate; An emission stack, disposed on the first electrode, comprises: A first organic emission layer (EML) comprising one or more host materials and organic emission materials; as well as Hole blocking layer (HBL), electron blocking layer (EBL), or both; The second electrode is disposed on the emission stack; as well as A first enhancement layer comprising a plasmonic material exhibiting surface plasmon resonance, the plasmonic material being nonradiatively coupled to an organic emission material in the organic emission layer and transferring excited-state energy from the organic emission material to the nonradiative mode of the surface plasmon polaritons in the first enhancement layer, the first enhancement layer being configured to be located at a distance from the first organic emission layer not exceeding a threshold distance, wherein the threshold distance is the position where the total nonradiative attenuation rate constant is equal to the total radiative attenuation rate constant; The emission stack comprises an EBL with a triplet energy lower than that of at least one of the host materials; The triplet energy of the EBL is the same as or lower than the triplet energy of the organic emissive material; and Where E ET ≤ |HOMO 有机发射材料 - LUMO EML | + δ, where E ET It is the lowest triplet energy level in all materials of the EML, LUMO. EML It is the deepest LUMO of all materials in the EML, and δ is at least 0.01 eV.

3. The apparatus according to claim 1 or 2, wherein the one or more body materials comprise an electron transport material.

4. The apparatus according to claim 1 or 2, wherein the one or more body materials comprise a hole transport material.

5. The apparatus of claim 4, wherein the one or more body materials comprise an electron transport material.

6. The apparatus of claim 1, wherein the emission stack comprises an EBL with the highest occupied molecular orbital (HOMO) energy level within 0.4 eV of the HOMO energy level of the organic emission material.

7. The apparatus of claim 1, wherein the emission stack comprises an HBL with a minimum unoccupied molecular orbital (LUMO) level within 0.3 eV of at least one of the host materials.

8. The apparatus of claim 1, wherein the emission stack comprises an HTL of HOMO energy level within 0.5 eV of at least one of the one or more host materials.

9. The apparatus according to claim 1, wherein E ET ≤ |HOMO 有机发射材料 - LUMO EML | + δ, where E ET It is the lowest triplet energy level in all materials of the EML, LUMO. EML It is the deepest LUMO among all materials in the EML, and δ is at least 0.01 eV.

10. The apparatus according to claim 2 or 9, wherein δ is at least 0.11 eV.

11. The apparatus of claim 10, wherein δ is at least 0.21 eV.

12. The apparatus of claim 2, wherein the organic emissive material in the EML has the lightest HOMO.

13. The apparatus of claim 2, wherein in the EML, one of the one or more host materials has the lightest HOMO.

14. The apparatus according to claim 1 or 2, further comprising a hole transport layer between the electron blocking layer and the first or second electrode.

15. The apparatus of claim 14, wherein the electron blocking layer is adjacent to the first organic emitting layer, and the hole transport layer is not adjacent to the organic emitting material.

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