Inkjet printing systems and techniques for light-emitting devices with enhanced light outcoupling

Abstract

The present teachings relate to various embodiments of ink compositions, which once printed and cured on a substrate form a continuous composite film layer that includes a first pattern of polymeric areas having a first refractive index (RI) interspersed within a second pattern of polymeric areas having an RI that is higher in comparison to the RI of the first pattern of polymeric areas. Various embodiments of composite thin films so formed on a substrate can be tuned so as to enhance light outcoupling or extraction for various light-emitting devices of the present teachings, such as, but not limited by, an OLED display or lighting device.

Description

[Technical Field]

[0001] This invention relates to an inkjet printing system and technology for a light-emitting device having enhanced external light coupling. [Previous Technology]

[0002] Various light-emitting devices, such as various organic light-emitting diode (OLED) display devices or OLED lighting devices, have an architecture comprising multiple functional layers surrounding a light-emitting layer. These functional layers may have different refractive indices, and they generate waveguides due to internal reflections in the discrete layers defining the device architecture, thereby reducing the light emitted from the light-emitting device.

[0003] The inventors have realized that inkjet printing technology can be used to provide a light-emitting device that enhances the external coupling of light from the device, thereby enhancing the device's performance. [Summary of the Invention]

[0004] One embodiment of the present invention is a method for forming a film on a substrate, the method comprising: forming a composite polymeric film on the substrate by: depositing a first ink on the substrate with a first defining pattern; depositing a second ink on the substrate with a second defining pattern; drying or curing the first ink to form a first polymeric region pattern; drying or curing the second ink to form a second polymeric region pattern; and depositing at least one thin film layer on the composite polymeric film, wherein the refractive index of the first polymeric region pattern is closer to the refractive index of the substrate and less close to the refractive index of the at least one thin film, and further wherein the refractive index of the second polymeric region pattern is closer to the refractive index of the at least one thin film layer and less close to the refractive index of the substrate.

[0005] Another embodiment of the present invention is a photoelectric device, comprising: a photoelectric device substrate; a composite polymer film on the photoelectric device substrate, the composite polymer film including a first polymer region pattern and a second polymer region pattern; and at least one thin film layer on the composite polymer film, wherein the refractive index of the first polymer region pattern is closer to the refractive index of the photoelectric device substrate and less close to the refractive index of the at least one thin film, and further wherein the refractive index of the second polymer region pattern is closer to the refractive index of the at least one thin film layer and less close to the refractive index of the photoelectric device substrate.

Implementation Method

[0014] This teaching relates to various specific forms of ink compositions that, once printed and cured on a substrate, can form a continuous composite film layer comprising a first polymeric region pattern having a first refractive index (RI) dispersed in a second polymeric region pattern having a higher RI than the first polymeric region pattern. Various specific forms of the composite film thus formed on the substrate can be adapted to, for example, enhance external light coupling or light extraction for bottom-emitting display devices, various OLED lighting devices, and related light-emitting devices, in a non-limiting manner.

[0015] According to this teaching, the effective refractive index of the first polymeric region pattern in the composite film layer deposited on the substrate can be adjusted to match or closely match the refractive index of the device substrate through which light emitted from the device light-emitting layer passes. Incidentally, the effective refractive index of the second polymeric region pattern in the composite film layer deposited on the substrate can be adjusted to match or closely match the higher refractive index of the stacked layers of the display device that exhibit waveguide characteristics due to internal reflection. This enhances light emitted toward the substrate and then passing through it by adjusting the first polymeric region pattern to match or closely match the substrate's refractive index. Thus, by providing discrete regions with variable RI on the composite polymeric layer on the substrate, external coupling of light passing through the substrate in the viewing direction can be enhanced. Various specific configurations of the composite film layer of this teaching can provide, for example, effective external light coupling from the display device and various light-emitting devices. The composite film layer can be fabricated such that the refractive index of the first region is closer to the refractive index of the substrate and less closer to the refractive index of the overlay device layer, while the refractive index of the second region is closer to the refractive index of the overlay device layer and less closer to the refractive index of the substrate.

[0016] The various specific forms of inks described in this teaching can be printed using an industrial inkjet printing system that can be encapsulated in a gas envelope, the interior of which is a controlled environment that maintains an inert and substantially low-particle process environment. The composite film layer of this teaching, patterned and printed on a substrate (for example, but not limited to, OLED device substrates) under such a controlled environment, can ensure high-volume, high-yield processes for a wide variety of light-emitting devices.

[0017] Figure 1 generally illustrates a bottom-emitting light-emitting device. During the manufacture of such a device (e.g., an OLED display or OLED light-emitting device), an OLED film stack can be formed on a substrate 1, which can emit emission light 2 with a specific peak wavelength when a voltage is applied. As shown in Figure 1, the OLED film stack structure between the anode 3 and the cathode 4 may include a hole injection layer (HIL) 5, a hole transport layer (HTL) 6, an emissive layer (EML) 7, an electron transport layer (ETL) 8, and an electron injection layer (EIL) 9. As shown in Figure 1, in some specific configurations of the OLED film stack structure, the electron transport layer (ETL) can be combined with the electron injection layer (EIL) to form an ETL / EIL layer. As will be discussed in more detail later, for bottom-emitting devices, such as those shown in Figure 1, the anode material can be a transparent film material, such as indium tin oxide (ITO) or a patterned metal nanowire structure.

[0018] The inventors have realized that inkjet printing can achieve patterned printing to form various specific forms of the composite film layer of this teaching. The composite film layer of this teaching can be printed on various device substrates, such as glass substrates or various polymer substrates, for example, substrates formed of polymers such as polyimide, polyethylene terephthalate, cyclic olefin copolymers and the like.

[0019] Various inks used to prepare the composite layer of this teaching may include polymers or polymeric components, such as, but not limited to, various glycol monomer materials, acrylic acid (e.g., mono- or poly-methyl acrylic acid), methacrylic acid (e.g., mono- or poly-methyl methacrylic acid), or other materials, and copolymers and mixtures thereof. Various ink formulations used to prepare the composite film layer of this teaching may include nanoparticles intended to enhance light emitted from an emitting layer in a device stack and to emit light extracted through a substrate via the composite film layer. Nanoparticles are typically characterized by having one or more dimensions less than 1000 nanometers. Various ink compositions of this teaching may be cured using heat treatment (e.g., baking), ultraviolet (UV) exposure, and combinations thereof. As used herein, polymers and copolymers may include any form of polymeric component that can be incorporated into inks and cured on a substrate to form a composite film layer. Such polymeric components may include polymers and copolymers and their precursors, such as, but not limited to, monomers, oligomers, and resins.

[0020] According to this teaching, inkjet printing offers several advantages. First, extensive vacuum processing operations can be eliminated because this inkjet-based fabrication can be performed under atmospheric pressure. Incidentally, during the inkjet printing process, composite film layers can be easily fabricated using inkjet printing, which may include a first region formed by a first ink and a second region formed by a second ink; and various specific forms of the composite film of this teaching can be achieved. Targeted patterning using inkjet printing eliminates material waste and the additional processing typically required to achieve the patterning of the composite layer of this teaching, such as the processing involving the use of multiple masks to create complex area patterns with variable RI.

[0021] To selectively adjust the refractive index of various regions of the composite film of this teaching, nanoparticles (NPs) may be included in various ink compositions. When NPs are incorporated into various regions of the composite film layer of this teaching, they can adjust the refractive index (RI) of the formed region to the desired effective RI to provide enhanced light extraction. As a non-limiting example, some exemplary NPs may include inorganic nanoparticles, including metal oxide NPs, such as NPs of zirconium oxide (i.e., zirconium oxide), titanium oxide (i.e., titanium oxide), and aluminum oxide (i.e., aluminum oxide). Various NPs may be included in ink compositions and deposited by inkjet printing, incorporating them into the composite film regions formed on the substrate of the light-emitting device. Effective nanoparticle sizes between about 10 nanometers and about 100 nanometers may be selected for jettable inks. As will be discussed in more detail herein, various specific forms of ink compositions for printing NP-containing regions of the composite film layer formed on the substrate of the light-emitting device may have NP filling concentrations ranging from about 1% by weight to about 60% by weight.

[0022] FIG2 includes a series of cross-sectional views, which generally illustrate the process and apparatus 100A of various specific forms according to the techniques and apparatus of this teaching. As shown in stage I of FIG2, droplets 120 of the first ink can be deposited on the substrate 110 to generate a defined pattern of deposited ink, which, when cured, can, for example, form a polymer structure pattern 132 of a dome or a small lens, as shown in stage II of FIG2. By using inkjet printing, any polymer structure pattern 132 can be formed on the substrate 110; whether the pattern is regular or random, it is to be deposited on the surface of the substrate 110. As shown in stage III of FIG2, droplets 125 of the second ink can be deposited on the substrate 110 on which the structure 132 has been formed, and when cured, can form a composite film layer 130, which includes: a polymer structure 132 having a first refractive index that matches or closely matches the refractive index of the substrate 110; and a polymer matrix 134 having a refractive index that matches or closely matches the refractive index of the transparent electrode layer 140. Once the composite film 130 is formed on the substrate 110, it can present a planarized surface for deposition of an anode layer (see FIG. 1), such as film layer 140. As discussed previously, film layer 140 can be a transparent electrode material, such as ITO. Incidentally, metal nanowire patterning structures can also be used to generate anodes of various specific forms for the light-emitting devices of this teaching. Accordingly, as shown in FIG. 2, various specific forms of the composite film layer of this teaching (e.g., composite film layer 130) can have: a region having a first refractive index in contact with the substrate 110, which is the result of depositing a first ink; and a region having a second refractive index in contact with the substrate 110, which is the result of depositing a second ink.

[0023] According to this teaching, the first ink may be a composition comprising a polymer or polymeric component, for example, but not limited to, various polyethylene glycol monomer materials, acrylic acid (e.g., mono- or poly-monomeric acrylic acid), methacrylic acid (e.g., mono- or poly-monomeric methacrylic acid), or other materials, and copolymers and mixtures thereof. This polymeric ink may form a polymer structure 132 having a refractive index between about 1.45 and about 1.50, thus having a refractive index matching or closely matching the refractive index of the substrate 110, which may be glass or various polymeric materials, such as polymers of polyimide, polyethylene terephthalate, cyclic olefin copolymers, and the like. According to this teaching, the second ink may include a polymer matrix, as described in various specific embodiments of the first ink, but its effective refractive index may be adjusted to between about 1.6 and about 1.9 using a specific selection and filling of NP as part of the ink composition.

[0024] While not limited to theory or explanation, Figure 3 generally illustrates how various specific forms of the composite film layers of this teaching can function to enhance the external coupling of light from the display device. Various specific forms of the ITO layer can have a refractive index between approximately 1.6 and 1.9. Incidentally, as shown in Figure 1, various stacked layers of the display device, including the anode, HIL, HTL, and EML, can also have a refractive index in the range of 1.6 to 1.9. In contrast, various specific forms of the substrate 110 in Figure 3 (for example, a glass substrate or various polymer substrates, such as substrates formed from polymers like polyimide, polyethylene terephthalate, cyclic olefin copolymers, and the like) can have a refractive index in the range of 1.45 to 1.5. Inconsistencies in refractive index can lead to internal reflections through film layers with a higher refractive index compared to the substrate 110. However, for various specific forms of the composite film of this teaching, such as the composite film 130 of FIG. 3, light initially refracted from the ITO layer 140 and passing through the organic film layer 10 (e.g., HIL, HTL, EML layers, see FIG. 1) (represented by the dashed lines in the figure) can penetrate the polymer matrix 134, including the NP, to make its refractive index match or closely match the refractive index of the transparent electrode layer 140. When the light interacts with the polymer structure 132 having a refractive index that matches or closely matches the substrate 110, the light can be coupled outwards in the viewing direction of the display device and pass through the substrate. By way of example only, if the RI difference between the two materials is not greater than 10%, then the RI of one material can be considered to closely match the RI of the other material. This includes specific forms where the RI difference between the two materials is not greater than 5%, and further includes specific forms where the RI difference between the two materials is not greater than 1%.

[0025] Figure 4 includes a series of cross-sectional views, which generally illustrate various specific forms of the process and apparatus 100B according to the technology and apparatus of this teaching. As with the process and apparatus according to Figure 2, in stage I of Figure 4, droplets 120 of the first ink can be deposited on the substrate 110 to generate a pattern of deposited ink. However, in various specific forms of the process and apparatus of Figure 4, the droplets of the first ink are not cured during the sequential printing process before the deposition of the second ink, and as shown in stage II of Figure 4, droplets 125 of the second ink can be deposited on the substrate 110 on which droplets 120 of the first ink have been deposited, thus forming a composite ink layer 127 to form a first pattern of the first ink and a second pattern of the second ink, as generally illustrated in stage III of Figure 4. Although some diffusion may occur between the deposition and curing of the composite ink layer 127, the ink and process can generate such that the composite ink layer 127 can form a composite film layer 135 when cured. In this specific embodiment of the method, the first and second inks are sufficiently immiscible to avoid complete or substantially complete mixing of the two inks over a time scale during the ink deposition process. The inks, for example, can become immiscible by selecting solvents and / or monomers. The composite film 135 may include: a polymeric region 132 having a first refractive index that matches or closely matches the refractive index of the substrate 110; and a polymeric region 134 having a refractive index that matches or closely matches the refractive index of the transparent electrode layer 140. As previously discussed with respect to the device 100A of FIG. 2, once the composite film 135 is formed on the substrate 110, it can present a planarized surface for deposition of an anode layer (see FIG. 1), such as film 140. As previously discussed, film 140 may be a transparent electrode material, such as ITO. Incidentally, metal nanowire patterning structures may also be used to generate anodes of various specific embodiments for the display devices of this teaching. Accordingly, as shown in FIG4, various specific forms of the composite film layer of this teaching (e.g., composite film layer 135) may have: a region having a first refractive index in contact with the substrate 110, which is the result of depositing a first ink; and a region having a second refractive index in contact with the substrate 110, which is the result of depositing a second ink. According to this teaching, the various specific forms of the composite film layer of FIG4 can generally function as demonstrated in FIG3.

[0026] In a specific embodiment of a method for forming a composite film with different refractive index regions, the film is formed on a substrate by: depositing a first ink on the substrate with a first defining pattern, the first defining pattern forming a second defining pattern on the substrate, wherein the first ink forms a first patterned film having a refractive index substantially the same as that of the substrate; depositing a second ink on the substrate with a second defining pattern, wherein the second ink forms a second patterned film having a refractive index greater than that of the substrate; and depositing at least one thin film layer on the substrate, wherein the at least one thin film layer has a refractive index substantially the same as that of the second patterned film. <Ink Composition>

[0027] The following teachings pertain to various specific forms of ink compositions that, once printed and dried or cured, form a thin polymeric layer on a substrate of an optoelectronic device (e.g., but not limited to, light-emitting devices, such as OLED displays or lighting devices). These various forms of ink compositions can be printed using an industrial inkjet printing system that can be enclosed in a gas encapsulation, the interior of which is a controlled environment maintained as an inert and substantially low-particle process environment. Patterning composite films onto a substrate during the fabrication of light-emitting devices in this controlled environment ensures high-volume, high-yield processes for a wide variety of light-emitting devices (e.g., but not limited to OLED displays or lighting devices). According to these teachings, various ink compositions for light-emitting devices can be inkjet printed using a variety of ink compositions designed to form patterned printing with low-RI regions dispersed within higher-RI regions (the higher-RI regions may include NP).

[0028] The ink composition includes polymeric components, such as, but not limited to, various acrylic monomers (e.g., mono- or poly-acrylic acid), various methacrylic acid monomers (e.g., mono- or poly-acrylic methacrylic acid), and copolymers and mixtures thereof. The inks used to form the first and second patterned regions on the substrate may include the same monomers, such as when the first ink is dried or cured prior to the deposition of the second ink. Alternatively, the inks may include different monomers, such as when both inks are deposited prior to drying or curing. The polymeric components may be cured using heat treatment (e.g., baking), ultraviolet (UV) exposure, and combinations thereof. As used herein, polymers and copolymers may include any form of polymeric component that can be incorporated into the ink and cured on the substrate to form a composite film. Such polymeric components may include polymers, copolymers, and their precursors, such as, but not limited to, monomers, oligomers, and resins. As discussed previously, various specific forms of the ink composition of this teaching further include nanoparticles (NPs) to adjust the RI of various regions of the composite film of this teaching.

[0029] According to this teaching, inkjet printing offers several advantages. First, extensive vacuum processing operations can be eliminated because this inkjet-based fabrication can be performed under atmospheric pressure. Additionally, during the inkjet printing process, the printed layer can be precisely localized and patterned on the substrate. Furthermore, inkjet printing can be used to vary the particle density, film thickness, or both, along the length of the printed layer, as illustrated in Figures 3-7. <Composition and Method of Composite Film Ink>

[0030] Various specific forms of the ink composition of this teaching can be inkjet printed on target printing areas on, for example but not limited to, light-emitting devices (e.g., OLED display devices or lighting devices) to form composite polymer film layers, which can enhance the external light coupling from various light-emitting devices of this teaching.

[0031] In addition to the multifunctional crosslinking agent, the thin-layer ink composition also includes one or more mono(meth)acrylate monomers, one or more di(meth)acrylate monomers, or a combination of mono(meth)acrylate and di(meth)acrylate monomers. As used herein, "(meth)acrylate monomer" means that the monomer can be acrylic acid or methacrylic acid. Certain specific forms of the ink composition further include curing initiators, such as photoinitiators, thermal initiators, or electron beam initiators. Such inkjetable ink compositions, which can be used to print one or more ink compositions to form composite films of the present teaching, are described in U.S. Patent Publication No. 2016 / 0024322, filed July 22, 2015; U.S. Patent Publication No. 2017 / 0062762, filed July 19, 2016; U.S. Patent Publication No. 2017 / 0358775, filed June 10, 2016; and U.S. Patent Application No. 15 / 727,551, filed October 6, 2017, the entire contents of which are incorporated herein by reference.

[0032] The properties of mono(meth)acrylic acid and di(meth)acrylic acid monomers make them suitable for inkjet printing applications. In terms of ink composition, these monomers can provide compositions that are jettable over a wide range of inkjet printing temperatures (including room temperature). Generally, for ink compositions suitable for inkjet printing applications, the surface tension, viscosity, and wetting properties of the ink composition should be designed to allow the composition to be delivered through the inkjet nozzle at printing temperatures (e.g., room temperature of about 22°C, or, for example, higher temperatures up to about 50°C) without drying on or clogging the nozzle. Once formulated, the various specific forms of the ink composition can have a viscosity between about 2 centipoise and about 30 centipoise in the temperature range of 22°C to 50°C (for example, between about 10 centipoise and about 27 centipoise, and between about 14 centipoise and about 25 centipoise), and a surface tension between about 25 dynes per centimeter and about 45 dynes per centimeter in the temperature range of 22°C to 50°C (for example, between about 30 dynes per centimeter and about 42 dynes per centimeter, and between about 28 dynes per centimeter and about 38 dynes per centimeter). The viscosity and surface tension of the individual monomers suitable for use in the ink composition will depend on the viscosity and surface tension of the other components present in the given ink composition and the relative amount of each component in the ink composition. However, generally speaking, mono(meth)acrylic acid monomers and di(meth)acrylic acid monomers will have a viscosity range of about 4 centipoise to about 22 centipoise in the temperature range of 22°C to 50°C, including a range of about 4 centipoise to about 18 centipoise in the temperature range of 22°C to 50°C, and a surface tension range of about 30 dynes per centimeter to 41 dynes per centimeter in the temperature range of 22°C to 50°C, including a range of about 32 dynes per centimeter to 41 dynes per centimeter in the temperature range of 22°C to 50°C. Methods for measuring viscosity and surface tension are well known and include the use of commercially available rheometers (such as the DV-I Prime Brookfield rheometer) and tensiometers (such as the SITA bubble pressure tensiometer).

[0033] For certain specific forms of ink compositions filled with high nanoparticles, if the viscosity and / or surface tension of the ink composition fall outside these ranges without an organic solvent, an organic solvent may be added to adjust the viscosity and / or surface tension of the ink composition. Suitable organic solvents include esters and ethers. Examples of organic solvents that may be included in the ink composition include high-boiling-point organic solvents, including organic solvents with a boiling point of at least 200°C. This includes organic solvents with a boiling point of at least 230°C, at least 250°C, or even at least 280°C. Diols and glycols (e.g., propylene glycol, pentanediol, diethylene glycol, triethylene glycol) are examples of high-boiling-point organic solvents that may be used. High-boiling-point aprotic solvents, including aprotic solvents with a boiling point of at least 240°C, may also be used. Cyclobutane (1,1-dioxo-2,3,4,5-tetrahydrothiophene, also known as tetramethylphenidate) is an example of a relatively high-boiling-point aprotic solvent. Other non-limiting exemplary organic solvents may include toluene, xylene, [grass(above) + rice], propylene glycol methyl ether, methylnaphthalene, methyl benzoate, tetrahydronaphthalene, dimethylformamide, terpineol, phenoxyethanol, and butylbenzene.

[0034] Mono(meth)acrylic acid monomers and di(meth)acrylic acid monomers may, for example, be linear aliphatic mono(meth)acrylic acid and di(meth)acrylic acid, or may include cyclo and / or aryl groups. In various specific forms of inkjet-printable ink compositions, the mono(meth)acrylic acid monomers and / or di(meth)acrylic acid monomers are polyethers. In various specific forms of inkjet-printable ink compositions, the di(meth)acrylic acid monomer is an alkyl-oxidized aliphatic di(meth)acrylic acid monomer. These include 1,6-hexanediol diacrylate, 1,12-dodecyl di(meth)acrylic acid, and di(meth)acrylic acid containing neopentyl glycol groups (including alkyl-oxidized neopentyl glycol diacrylate, such as neopentyl glycol propoxydi(meth)acrylic acid and neopentyl glycol ethoxydi(meth)acrylic acid). Various specific forms of di(meth)acrylic acid containing neopentyl glycol groups have a number average molecular weight ranging from about 200 grams per mole to about 400 grams per mole. This includes neopentyl glycol-containing di(meth)acrylic acid with a number average molecular weight ranging from about 280 g / mol to about 350 g / mol, and further includes neopentyl glycol-containing di(meth)acrylic acid with a number average molecular weight ranging from about 300 g / mol to about 330 g / mol. Various neopentyl glycol-containing di(meth)acrylic acid monomers are commercially available. For example, neopentyl glycol propylene oxide diacrylic acid can be purchased from Sartomer under the trademark SR9003B, or from Sigma Aldrich under the trademark Aldrich-412147 (about 330 g / mol; viscosity at 24°C about 18 centipoise; surface tension at 24°C about 34 dynes per centimeter). Neopentyl glycol diacrylate can also be purchased from Sigma Aldrich under the trademark Aldrich-408255 (approximately 212 grams per mole; viscosity approximately 7 centipoise; surface tension approximately 33 dynes per centimeter).

[0035] Other suitable (meth)acrylic acid monomers include, but are not limited to: alkyl (meth)acrylic acids, such as meth (meth)acrylic acid and ethyl (meth)acrylic acid; cyclic trimethylolpropanedimethylformaldehyde (meth)acrylic acid; alkyltetrahydrofuran meth (meth)acrylic acid; phenoxyalkyl (meth)acrylic acids, such as 2-phenoxyethyl (meth)acrylic acid and phenoxymethyl (meth)acrylic acid; and 2(2-ethoxyethoxy)ethyl (meth)acrylic acid. The structure, room temperature viscosity, and room temperature surface tension of these specific (meth)acrylic acid monomers are provided in Figure 5. Other suitable mono- and di(meth)acrylic acid monomers include polyethylene glycol di(meth)acrylic acid monomers, including those with a number average molecular weight ranging from about 230 grams per mole to about 440 grams per mole. For example, ink compositions may include polyethylene glycol 200 dimethacrylic acid and / or polyethylene glycol 200 diacrylate, having a number average molecular weight of about 330 grams per mole. Other mono- and di(meth)acrylic monomers that may be included, alone or in combination, in various specific forms of the ink composition include dicyclopentenoxyethyl acrylate (DCPOEA), isocamphenic acid (ISOBA), dicyclopentenoxyethyl methacrylate (DCPOEMA), isocamphenic acid (ISOBMA), and N-octadecyl methacrylate (OctaM). Homologues of ISOBA and ISOBMA (collectively referred to as the "ISOB(M)A" homologues) may also be used, wherein one or more methyl groups on the ring are replaced by hydrogen.

[0036] Multifunctional (meth)acrylic acid crosslinking agents are desirable to have at least three reactive crosslinkable groups, such as (meth)acrylic acid groups or vinyl groups. Therefore, multifunctional (meth)acrylic acid crosslinking agents can, for example, be tri(meth)acrylic acid, tetra(meth)acrylic acid, and / or more functional (meth)acrylic acid. Pentargytol tetraacrylate or pentargytol tetramethacrylic acid, di(trimethylolpropane)tetraacrylate, di(trimethylolpropane)tetramethacrylic acid are examples of multifunctional (meth)acrylic acids that can be used as primary crosslinking agents. The term "primary" is used here to indicate that other components of the ink composition may also participate in crosslinking, although that is not their primary functional purpose. Photoinitiators may optionally be included in the ink composition to initiate the polymerization process.

[0037] In certain specific forms of ink compositions, mono(meth)acrylic acid and di(meth)acrylic acid monomers are the main components of the ink composition by weight. These various specific forms of ink compositions have mono(meth)acrylic acid and / or di(meth)acrylic acid monomer contents ranging from about 70% by weight to about 96% by weight. That is, the combined weight of mono(meth)acrylic acid and di(meth)acrylic acid monomers accounts for about 70% by weight to about 96% by weight of the ink composition. This includes specific forms of ink compositions with mono(meth)acrylic acid and di(meth)acrylic acid monomer contents ranging from about 75% by weight to 95% by weight, and further includes specific forms of ink compositions with mono(meth)acrylic acid and di(meth)acrylic acid monomer contents ranging from about 80% by weight to 90% by weight. Some specific forms of ink compositions include only a single mono(meth)acrylic acid monomer or a single di(meth)acrylic acid monomer, while others include mixtures of two or more mono(meth)acrylic acid monomers and / or two or more di(meth)acrylic acid monomers. For example, various specific forms of ink compositions include two mono(meth)acrylic acid monomers, two di(meth)acrylic acid monomers, or a combination of mono(meth)acrylic acid monomers and di(meth)acrylic acid monomers. The weight ratio of the two monomers can be significantly varied to design the viscosity, surface tension, and film-forming properties of the ink composition. For example, some specific forms of ink compositions including either mono(meth)acrylic acid or di(meth)acrylic acid monomers include a first mono(meth)acrylic acid or di(meth)acrylic acid monomer and a second mono(meth)acrylic acid or di(meth)acrylic acid monomer, with a weight ratio ranging from 95:1 to 1.2, including a weight ratio ranging from 12:5 to 1:2. This includes specific examples of ink compositions in which the weight ratio of a first mono(meth)acrylic or di(meth)acrylic acid monomer to a second mono(meth)acrylic or di(meth)acrylic acid monomer ranges from 12:5 to 4:5; further includes specific examples of ink compositions in which the weight ratio of a first mono(meth)acrylic or di(meth)acrylic acid monomer to a second mono(meth)acrylic or di(meth)acrylic acid monomer ranges from 5:4 to 1:2; and even further includes specific examples of ink compositions in which the weight ratio of a first mono(meth)acrylic or di(meth)acrylic acid monomer to a second mono(meth)acrylic or di(meth)acrylic acid monomer ranges from 5:1 to 5:4. For the purposes of the weight percentages and weight ratios described in this paragraph, any crosslinking ligands present in the ink composition are not considered mono(meth)acrylic or di(meth)acrylic acid monomers.

[0038] If one or more crosslinking agents are included in the ink composition according to the present teaching, they typically account for about 1% to about 10% by weight of the ink composition, including about 2% to about 8% by weight of the ink composition.

[0039] According to this teaching, as discussed previously, ink compositions containing NPs may include more than one type of NP, wherein different types of NPs may differ in nominal particle size, particle shape, particle material, or combination thereof. As a non-limiting example, some exemplary NPs may include metal oxide NPs, such as zirconium oxide (i.e., zirconium oxide), titanium oxide (i.e., titanium oxide), and aluminum oxide (i.e., aluminum oxide) NPs. Specific forms of ink compositions for printing NP-containing regions on composite films formed on light-emitting device substrates may have NP filling concentrations ranging from about 1 wt% to about 60 wt% for NPs between about 10 nanometers and about 100 nanometers. As a result, the content of mono(meth)acrylic acid and di(meth)acrylic acid monomers in these ink compositions may be lower than discussed above. For example, various specific forms of NP-containing ink compositions for forming composite films on light-emitting device substrates may have mono(meth)acrylic acid and di(meth)acrylic acid monomer contents ranging from about 50 wt% to about 90 wt%. This includes specific examples of ink compositions with a monomer content of mono(meth)acrylic acid and di(meth)acrylic acid ranging from about 60% to 80% by weight, and further includes specific examples of ink compositions with a monomer content of mono(meth)acrylic acid and di(meth)acrylic acid ranging from about 65% to 75% by weight.

[0040] As discussed previously, organic solvents can be added to these ink compositions to provide them with viscosity and / or surface tension suitable for inkjet printing, as discussed above. Suitable organic solvents include esters and ethers. Examples of organic solvents that can be included in ink compositions include high-boiling organic solvents, including organic solvents with a boiling point of at least 200°C. This includes organic solvents with a boiling point of at least 230°C, at least 250°C, or even at least 280°C. Diols and glycols (e.g., propylene glycol, pentane glycol, diethylene glycol, triethylene glycol) are examples of high-boiling organic solvents that can be used. High-boiling aprotic solvents can also be used, including aprotic solvents with a boiling point of at least 240°C. Cyclobutane (1,1-dioxo-2,3,4,5-tetrahydrothiophene, also known as tetramethyl sulfide) is an example of a relatively high-boiling aprotic solvent. Other non-limiting exemplary organic solvents may include toluene, xylene, [grass (above) + rice], propylene glycol methyl ether, methylnaphthalene, methyl benzoate, tetrahydronaphthalene, dimethylformamide, terpineol, phenoxyethanol, and butylbenzene. If the organic solvent is included in the ink composition, the above-mentioned NP and monomer concentrations are based on the solids content of the ink composition.

[0041] For various specific forms of the ink composition of this teaching, the polyfunctional (meth)acrylic acid crosslinking agent may account for about 4% to about 10% by weight of the ink composition. Generally, the curing initiator (e.g., photoinitiator) will be included in a range of about 0.1% to about 10% by weight, including a range of about 0.1% to about 8% by weight. This includes specific forms in which the photoinitiator is present in a range of about 1% to about 6% by weight, further includes specific forms in which the photoinitiator is present in a range of about 3% to about 6% by weight, and even further includes specific forms in which the photoinitiator is present in a range of about 3.75% to about 4.25% by weight.

[0042] Specific photoinitiators used for a given ink composition are desired to be selected such that they are activated at wavelengths that do not damage the materials used to manufacture the device (e.g., materials used to manufacture light-emitting devices [e.g., but not limited to OLED displays or lighting devices]). The photoinitiators can be selected such that polymerization initiation is induced at wavelengths in the UV region of the electromagnetic spectrum, the blue region of the visible spectrum, or both. For example, various ink compositions of this teaching can use photoinitiators that trigger polymerization at wavelengths in the blue region of the electromagnetic spectrum. Therefore, complete curing of the composite film layer of this teaching can be achieved using a light source emitting blue light. For example, an LED light source with a peak intensity of around 395 nanometers may be used.

[0043] While it is understood that a wide variety of photoinitiators can be used, phosphine oxide photoinitiators can be used. For example, but not limited to, photoinitiators from the α-hydroxyketone, phenylglyoxylic acid, and α-aminoketone types can also be considered. For free radical-based polymerization, various types of photoinitiators can have absorption profiles between about 200 nanometers and about 400 nanometers. For the various specific forms of ink compositions and printing methods disclosed herein, 2,4,6-trimethylbenzyl-diphenylphosphine oxide (TPO) and 2,4,6-trimethylbenzyl-diphenylphosphine acid possess the desired properties. Examples of phosphonic photoinitiators include: Irgacure® TPO initiator for UV curing (formerly also available under the trade name Lucirin® TPO), sold under the trade name Irgacure® TPO, a type I hemolytic initiator with absorption at 380 nm; Irgacure® TPO-L, a type I photoinitiator with absorption at 380 nm; and Irgacure® 819 with absorption at 370 nm. For example, light sources with a nominal emission wavelength range from 350 nm to 395 nm and a radiant energy density up to 1.5 joules per square centimeter can be used to cure ink compositions including TPO photoinitiators. With appropriate energy, a high degree of curing can be achieved. For example, certain specific samples of the cured composite films of this teaching can have a curing degree of 90% or greater, as measured, for example, by Fourier Transform Infrared (FTIR) spectroscopy.

[0044] If the polymerization initiation can be induced by light, the ink composition can be prepared to avoid exposure. Regarding the preparation of the various compositions of this teaching, in order to ensure the stability of the various compositions, the compositions can be prepared in a darkroom or a room with very low lighting or a facility with controlled lighting to exclude wavelengths that would induce polymerization. Such wavelengths generally include wavelengths below about 500 nanometers.

[0045] A flowchart of the method for formulating an ink composition according to this teaching is provided in FIG6. To formulate the ink composition, a mixture 2202 of mono(meth)acrylic acid monomers, di(meth)acrylic acid monomers and combinations thereof, and a polyfunctional (meth)acrylic acid crosslinking agent is mixed with a photoinitiator 2203 to form an initially curable monomeric blend 2206. If the ink composition will include crosslinking ligands 2204, they may also be added to the curable monomeric blend 2206. NP 2008 may be dispersed in the curable monomeric blend 2206 to form a dispersion 2209. Various NPs may be added in the form of aqueous or non-aqueous, organic solvent-based dispersions. If so, water or organic solvent may be removed from the dispersion 2209 to form a second dispersion 2210. The ink composition is then ready for use and should be stored away from light. Once the ink compositions are prepared, they can be mixed for a day or longer in the presence of molecular sieve beads to dehydrate them, and then stored in a dry, inert atmosphere (such as a compressed dry air atmosphere).

[0046] The ink composition can be printed using a printing system, as described herein and also in U.S. Patent Nos. 9,343,678 and 9,579,905, the entirety of which is incorporated herein. The film can be cured in an inert nitrogen environment using UV radiation. The ink composition is designed to be applied by inkjet printing and is therefore characterized by jettability, wherein the jettability of the ink composition, when continuously jetted via the nozzles of the printhead, exhibits a constant or substantially constant droplet velocity, droplet volume, and droplet trajectory over time. Incidentally, an advantageous feature of the ink composition is good latency, wherein latency refers to the time during which the nozzle can remain uncovered and idle before a significant reduction in performance (e.g., a reduction in droplet velocity or volume and / or a change in trajectory, which would significantly affect image quality).

[0047] Various specific forms of this ink composition can be deposited on a substrate, such as a glass substrate or various polymeric substrates, such as substrates formed of polymers like polyimide, polyethylene terephthalate, cyclic olefin copolymers, and the like, and various specific forms of the composite film layer of this teaching can be formed by printing patterned areas of the ink. <Printing System>

[0048] Figure 7 generally illustrates an encapsulated inkjet printing system 1000A that integrates and controls sources of non-reactive gases and clean dry air (CDA), which can, for example, be used to establish a controlled environment as referred to in other examples described herein, and may include, for example, a pressurized gas supply for use in manufacturing the inkjet printing system 2000 shown inside the encapsulated object 100. Incidentally, the encapsulated inkjet printing system 1000A of Figure 7 may include a CDA supply, thus establishing a CDA environment in the manufacturing of the encapsulated object 100, for example, during various maintenance procedures.

[0049] As shown in FIG. 7, the encapsulated inkjet printing system 1000A may include an inkjet printing system 2000, which is housed within the encapsulation 100. The inkjet printing system 2000 may be supported by a printing system base 2150, which may be a granite pedestal. The printing system base 2150 may support a substrate support device, such as a chuck, for example, but not limited to, a vacuum chuck, a substrate floating chuck with pressure ports, or a substrate floating chuck with both vacuum and pressure ports. In various specific embodiments of this teaching, the substrate support device may be a substrate floating table, such as the substrate floating table 2250 indicated in FIG. 7. The substrate floating table 2250 may be used for frictionless support of the substrate. In addition to a floating table that produces low-particle emissions, the inkjet printing system 2000 may also have a Y-axis motion system utilizing an air bushing to enable frictionless Y-axis transport of the substrate. Incidentally, the printing system 2000 may have an X,Z axis carrier assembly 2310, which can be mounted on the printing system bridge 2130. The X,Z axis carrier assembly 2310 may have motion control provided by an X-axis air bearing assembly that generates low-particle emissions. Various components of the motion system that generates low-particle emissions, such as the X-axis air bearing assembly, can be used, for example, to replace various linear mechanical bearing systems that generate particles. For various specific embodiments of the gas encapsulation and system of this teaching, the use of various pneumatically operated devices and equipment can provide low-particle emission efficiency and low maintenance.

[0050] Regarding the supply and control of process gases, as shown in Figure 7, various embodiments of the encapsulated inkjet printing system 1000A may have an external gas loop 3200 that integrates and controls the non-reactive gas source 3201 and the clean dry air (CDA) source 3203 for various aspects of the operation of the encapsulated inkjet printing system 1000A. The encapsulated inkjet printing system 1000A may also include various embodiments of internal particle filtration and gas circulation systems as well as various embodiments of external gas purification systems, as previously described. Some commonly used, non-limiting gas examples of the non-reactive gas source 3201 may include nitrogen, any inert gas, and any combination thereof. According to various specific configurations of the gas purification system described in this teaching, each of the various reactive species in the manufactured encapsulated material 100 (including various reactive atmospheric gases [e.g., water vapor, oxygen, ozone] and organic solvent gases) can be maintained at a level of 100 ppm or lower, for example, at 10 ppm or lower, at 1.0 ppm or lower, or at 0.1 ppm or lower. In addition to the non-reactive gas supply, the substrate floating table 2250 of the inkjet printing system 2000 (which can utilize air bearing technology) can also utilize the vacuum system 3270, which is connected to the manufacturing encapsulation system 1000A via line 3272 when valve 3274 is in the open position.

[0051] Regarding the control of the internal pressure of the manufactured encapsulation 100, as generally illustrated in Figure 7, the gas pressure within the manufactured encapsulation 100 can be maintained within a desired or specific range, for example, using a valve coupled to a pressure monitor P. The valve uses information obtained from the pressure monitor to allow gas to be discharged to another encapsulation, system, or area surrounding the internal manufactured encapsulation 100. This gas can be recovered and reprocessed. As discussed previously, this regulation can help maintain a slightly positive internal pressure within the internal manufactured encapsulation 100 during the printing process. Furthermore, the varying requirements of various pneumatic devices and equipment can generate irregular pressure profiles for the various manufacturing encapsulation systems and methods of this teaching, requiring constant control and regulation. Accordingly, as shown in Figure 7, for the manufactured encapsulation 100, the pressure control system is configured to maintain a dynamic pressure balance in the manufacturing encapsulation system 1000A, so that it can maintain a slightly positive pressure relative to the environment surrounding the encapsulation during the printing process.

[0052] This teaching is intended to be exemplary and not restrictive. An abstract is provided to comply with Section 1.72(b) of Title 37 of the Federal Regulations, allowing the reader to quickly ascertain the nature of the technical disclosure. It is understood and presented that this abstract will not be used to interpret or limit the scope or meaning of the claims. Moreover, in the above [Implementing the Embodiments], multiple features may be grouped together to make the disclosure flow smoothly. This should not be construed as making any unclaimed disclosed feature essential to any claim. The subject matter of the invention may, on the contrary, have fewer features than those of the particular disclosed embodiment. Therefore, the following claims are incorporated herein by reference to the [Implementing the Embodiments] as examples or embodiments, and each claim is a separate embodiment, and it is contemplated that such embodiments may be combined with each other in various combinations or arrangements. The scope of the invention should be determined with reference to the appended claims, together with the full scope of their equivalents.

[0053] Those skilled in the art will understand that the apparatus, method, and system disclosed herein can be modified and varied in many ways without departing from the scope of this disclosure and the appended claims. Other specific forms of this disclosure will become apparent to those skilled in the art from considering the specification and implementing the contents disclosed herein. The specification and examples are intended to be considered merely exemplary. [Simplified Explanation of the Diagram]

[0006] Referring to the accompanying diagrams will provide a better understanding of the features and advantages of this disclosure, wherein the diagrams are intended to demonstrate rather than limit this teaching. In diagrams that are not necessarily drawn to scale, similar numbers may describe similar components in different diagrams. Similar numbers ending with different letters may represent different examples of similar components.

[0007] [Figure 1] A schematic diagram of a display device that roughly demonstrates various specific forms of the technology and apparatus according to this teaching.

[0008] [Figure 2] A general demonstration of various specific forms of processes and devices based on the techniques and devices taught in this teaching.

[0009] [Figure 3] shows an enlarged view of the device in Figure 2, with an example of enhanced external optical coupling according to this teaching.

[0010] [Figure 4] A general demonstration of various specific forms of processes and devices based on the techniques and devices of this teaching.

[0011] [Figure 5] is a table that roughly illustrates various specific forms of monomers that can be used to prepare the inks of this teaching.

[0012] [Figure 6] shows a flowchart of a method for preparing various ink compositions according to this teaching.

[0013] [Figure 7] A general demonstration of exemplary printing systems of various specific forms based on the systems and methods of this teaching.

Claims

1. A method for forming a film on a substrate, the method comprising: A composite polymer film is formed on the substrate by the following steps: depositing a plurality of droplets of a first ink on the substrate in a first pattern; A plurality of droplets of a second ink are deposited on the substrate in a second pattern, wherein the material of the plurality of droplets of the second ink is not mixed with the material of the plurality of droplets of the first ink, wherein the plurality of droplets of the second ink are in contact with the substrate; the plurality of droplets of the first ink are dried or cured to form a first patterned polymeric material; and the plurality of droplets of the second ink are dried or cured to form a second patterned polymeric material, wherein a first contact area of ​​the composite polymeric film in contact with the substrate has a first refractive index and a second contact area of ​​the composite polymeric film in contact with the substrate has a second refractive index, the second refractive index being different from the first refractive index; and a layer is deposited on the composite polymeric film, wherein the refractive index of the first patterned polymeric material is closer to the refractive index of the substrate and less close to the refractive index of the layer, and the refractive index of the second patterned polymeric material is closer to the refractive index of the layer and less close to the refractive index of the substrate.

2. The method of claim 1, wherein the refractive index of the substrate ranges from 1.45 to 1.

5.

3. The method of claim 2, wherein the refractive index of the first patterned polymeric material ranges from 1.45 to 1.

5.

4. The method of claim 1, wherein the refractive index of the layer ranges from 1.6 to 1.

9.

5. The method of claim 4, wherein the refractive index of the second patterned polymeric material ranges from 1.6 to 1.

9.

6. The method of claim 1, wherein the first ink, the second ink, or both the first ink and the second ink comprise acrylic monomers and nanoparticles.

7. The method of claim 1, wherein the first ink is dried or cured before the second ink is deposited.

8. The method of claim 1, wherein the substrate is a substrate of an optoelectronic device and the layer is an electrode.

9. The method of claim 8, wherein the photoelectric device is an organic light-emitting diode.

10. A photoelectric device comprising: Optoelectronic device substrate; A composite polymer film is disposed on a substrate of an optoelectronic device. The composite polymer film includes a first patterned polymeric material and a second patterned polymeric material in the shape of a small lens. The composite polymer film has a first region having a first refractive index in contact with the optoelectronic substrate and a second region having a second refractive index in contact with the optoelectronic substrate. The second region and the first region are arranged in an alternating droplet pattern. The second refractive index is different from the first refractive index. A layer is disposed on the composite polymer film. The difference between the first refractive index and the refractive index of the optoelectronic device substrate is not greater than 10%, and the second refractive index is closer to the refractive index of the layer and less closer to the refractive index of the optoelectronic device substrate.

11. The apparatus of claim 10, wherein the refractive index of the photoelectric device substrate ranges from 1.45 to 1.

5.

12. The apparatus of claim 11, wherein the first refractive index ranges from 1.45 to 1.

5.

13. The apparatus of claim 10, wherein the refractive index of the layer ranges from 1.6 to 1.

9.

14. The apparatus of claim 13, wherein the second refractive index ranges from 1.6 to 1.

9.

15. The apparatus of claim 10, wherein the first patterned polymeric material, the second patterned polymeric material, or both the first patterned polymeric material and the second patterned polymeric material comprise a polymer of acrylic monomers and nanoparticles.

16. The apparatus of claim 10, wherein the layer is an electrode.

17. The device of claim 16, wherein the photoelectric device comprises an organic light-emitting diode.

18. A method for forming a film on a substrate, the method comprising: A composite polymer film is formed on the substrate by the following steps: depositing a plurality of droplets of a first ink on the substrate in a first pattern; A plurality of droplets of a second ink are deposited on the substrate in a second pattern between the plurality of droplets of a first ink that have already been deposited, wherein the material of the plurality of droplets of the second ink does not mix with the material of the plurality of droplets of the first ink, wherein the plurality of droplets of the second ink are in contact with the substrate; the plurality of droplets of the first ink are dried or cured to form a first patterned polymeric material; and the plurality of droplets of the second ink are dried or cured to form a second patterned polymeric material, wherein a first contact area of ​​the composite polymeric film in contact with the substrate has a first refractive index and a second contact area of ​​the composite polymeric film in contact with the substrate has a second refractive index, the second refractive index being different from the first refractive index; and a layer is deposited on the composite polymeric film, wherein the refractive index of the first patterned polymeric material is closer to the refractive index of the substrate and less close to the refractive index of the layer, and the refractive index of the second patterned polymeric material is closer to the refractive index of the layer and less close to the refractive index of the substrate.

19. The method of claim 18, wherein the refractive index of the substrate ranges from 1.45 to 1.

5.

20. The method of claim 18, wherein the first ink, the second ink, or both the first ink and the second ink comprise acrylic monomers and nanoparticles.

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