Segmented printbar for large area organic vapor jet printing (OVJP) deposition

Abstract

This application relates to segmented print bars for large area OVJP deposition. An OVJP print bar is provided that includes a plurality of print head segments, each of the print head segments including a print head and being positionable relative to a substrate independently of each other print head segment. A more consistent print head to substrate distance can thereby be maintained even if the substrate has a non-uniform flatness.

Description

[0001] Information related to divisional application

[0002] This application is a divisional application of Chinese Patent Application No. 201810435695.4, filed on May 7, 2018, entitled "Segmented Printing Rod for Large-Area Organic Vapor Jet (OVJP) Deposition".

[0003] Cross-reference of related applications

[0004] This application is a non-provisional application and claims priority to U.S. Provisional Patent Application No. 62 / 501,905 (filed May 5, 2017) and No. 62 / 597,605 (filed December 12, 2017), the entire contents of which are incorporated herein by reference. Technical Field

[0005] This invention relates to apparatus and techniques for manufacturing relatively large-area devices including organic emitting layers; and to devices including such devices, such as organic light-emitting diodes and other devices. Background Technology

[0006] 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 instance, the wavelength of light emitted by an organic emitting layer can often be easily tuned using appropriate dopants.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] Further details regarding OLEDs and the definitions described above can be found in U.S. Patent No. 7,279,704, which is incorporated herein by reference in its entirety. Summary of the Invention

[0016] 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.

[0017] According to one embodiment, a printing bar for organic vapor jet (OVJP) deposition is provided, comprising a plurality of printing head segments, each including an OVJP printing head; a plurality of flight altitude distance sensors, each configured to measure the distance between a substrate disposed below the printing bar and a portion of at least one printing head segment; and a plurality of actuators, each configured to adjust the position and / or orientation of one or more of the plurality of printing head segments based on one or more distances between the substrate and the printing bar measured by one or more of the plurality of flight altitude distance sensors. When the printing bar is operated to deposit material onto the substrate, the printing head segments may be arranged in two rows in a direction substantially perpendicular to the direction of movement of the printing bar relative to the substrate. The printing head segments may be arranged in rows such that when the printing bar is operated to deposit material onto the substrate, the printing area corresponding to each row of OVJP printing heads forms a single printed column on the substrate. Each OVJP printing head may include an OVJP deposition nozzle in fluid communication with a carrier gas source and an organic material vapor source. Each actuator may be connected to at least two of the printing head segments and configured to control the position and / or orientation of at least two of the printing head segments. Alternatively or additionally, each actuator may control the position and / or orientation of at least two of the printheads based on distance measurements obtained from two or more of the flight altitude sensors. Alternatively or additionally, each actuator may control the position and / or orientation of at least two of the printheads based on distance measurements obtained from at least one of the flight altitude sensors. Each printhead is movable independently of each other of the plurality of printheads. Each printhead is movable independently of each other printhead in at least a direction substantially orthogonal to the substrate, such that the distance from each printhead to the substrate can be adjusted independently of the distance from each other printhead to the substrate. The printhead may include one or more gas channels arranged to transport organic material and / or carrier gas to the plurality of printheads, one or more vacuum channels arranged to remove material from the region between the printhead and the substrate when the printhead is operated to deposit material onto the substrate, or any combination thereof. The printhead and / or each printhead pad includes a cold plate disposed adjacent to the plurality of printheads.

[0018] In one embodiment, a method for manufacturing an apparatus using organic vapor jet (OVJP) deposition is provided. The method may include operating an OVJP printing bar as previously disclosed. For example, the method may include operating a plurality of printing heads to deposit material onto a substrate, each printing head including an OVJP printing head; receiving distance measurements from each of a plurality of flight altitude distance sensors, each distance sensor configured to measure the distance between a substrate disposed below the printing bar and a portion of at least one printing head; and activating one or more actuators of a plurality of actuators based on one or more distance measurements to adjust the position and / or orientation of one or more of the plurality of printing heads. The printing bar, printing heads, and their components may be arranged in any configuration as previously described and disclosed herein. For example, when operating the printing bar to deposit material onto a substrate, the printing heads may be arranged in two rows in a direction substantially perpendicular to the direction of movement of the printing bar relative to the substrate. The method may further include moving the substrate relative to the plurality of printing heads, moving the plurality of printing heads relative to the substrate, or a combination thereof, in the direction of movement. The printheads can be arranged in rows so that when the print head is operated to deposit material onto the substrate, the print area corresponding to each row of OVJP printheads forms a single print column on the substrate. Each actuator can be operated to control the position and / or orientation of at least two of the plurality of printheads. The method may include activating at least one actuator to control the position and / or orientation of at least two of the printheads based on distance measurements obtained from two or more of a plurality of flight altitude sensors. The method may also include activating at least one actuator to control the position and / or orientation of at least two of the printheads based on distance measurements obtained from at least one of the flight altitude sensors. The method may further include moving at least one of the printheads independently of each other printhead. For example, the method may include moving at least one of the printheads independently of each other printhead in a direction substantially orthogonal to the substrate, such that the distance from the printhead to the substrate is adjusted independently of the distance from each other printhead to the substrate. Attached Figure Description

[0019] Figure 1 An example of an organic light-emitting device that can be manufactured using the embodiments disclosed herein is described.

[0020] Figure 2 An example of an inverted organic light-emitting device that can be fabricated using the embodiments disclosed herein, without having a separate electron transport layer, is depicted.

[0021] Figure 3A and 3BA schematic diagram depicts a new generation of substrates and an exemplary single rigid printhead for printing across the entire substrate. The printhead and support structure are over 2.5 meters long.

[0022] Figure 4A and 4B A frontal schematic diagram of the printhead and substrate is depicted. Figure 4A The uniform gap between the printhead and the theoretically perfect flat substrate is depicted. Figure 4B The non-uniform gap between the printhead and the substrate with imperfect flatness is depicted.

[0023] Figure 5A A segmented printing bar according to an embodiment disclosed herein is depicted, wherein an articulated printhead disposed above a non-flat substrate is capable of maintaining a constant or nearly constant printhead-to-substrate distance.

[0024] Figure 5B An exemplary printing bar with two rows of printheads is depicted according to an embodiment disclosed herein, wherein the printheads in each row of printheads are arranged such that the entire row is printed without overlapping printheads and without gaps between staggered rows of printheads.

[0025] Figure 5C A schematic diagram depicts a rectangular printed bar, including, for example... Figure 5B The rectangular segment shown.

[0026] Figure 6 An example of a partial printing rod according to an embodiment disclosed herein is depicted, which has a “T”-shaped segment.

[0027] Figure 7 An example of a partial printing rod according to an embodiment disclosed herein is depicted, which has a triangular printing head segment.

[0028] Figure 8 An example of a printed bar having a rectangular segment, a front cold plate, and a rear cold plate according to an embodiment disclosed herein is depicted. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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 various other structures. The specific materials and structures described are exemplary in nature, and other materials and structures can be used. Functional OLEDs can be obtained by combining the various layers described in different ways, or the layers can be 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 can 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.

[0036] 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.

[0037] 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 OVJP. 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 materials 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.

[0038] 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.

[0039] 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 the compound of the present invention in an organic layer within the OLED. 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, computer monitors, medical monitors, televisions, billboards, lights for internal or external lighting and / or signaling, head-up displays, fully or partially transparent displays, flexible displays, laser printers, telephones, mobile phones, tablet computers, phablets, personal digital assistants (PDAs), wearable devices, laptops, 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 to 30 degrees Celsius, and more preferably at room temperature (20-25 degrees Celsius), but can be used outside this temperature range (e.g., -40 to +80 degrees Celsius).

[0040] 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.

[0041] 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.

[0042] 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.

[0043] In some embodiments of the launch region, the launch region further includes a body.

[0044] 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.

[0045] 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.

[0046] The organic layer may further include a host. In some embodiments, two or more hosts are preferred. In some embodiments, the host used may be a) bipolar, b) electron transport, c) hole transport, or d) wide bandgap material that plays a minimal role in charge transport. In some embodiments, the host may include a metal complex. The host may be an inorganic compound.

[0047] Combination with other materials

[0048] The materials described herein for use in specific layers of organic light-emitting devices can be used in combination with a wide 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 possible host layers, transport layers, blocking layers, injection layers, electrodes, and other 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.

[0049] 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.

[0050] Conductive dopants:

[0051] 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.

[0052] HIL / HTL:

[0053] 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.

[0054] EBL:

[0055] 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 the 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.

[0056] main body:

[0057] 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.

[0058] HBL:

[0059] 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.

[0060] ETL:

[0061] 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.

[0062] Charge generation layer (CGL)

[0063] 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.

[0064] As discussed earlier, OVJP is a maskless, solvent-free printing technology used for relatively large-area OLED devices (such as displays). In this technology, OLED material is heated to its evaporation or sublimation temperature and transported to a printhead via a carrier gas flow. A typical OVJP printhead contains multiple holes or nozzles to direct vapor to the substrate, thereby depositing OLED material onto the substrate. In display manufacturing technology, typically one row of display pixels is printed per hole. The printhead can be multiplexed to form printing "bars" that span the width of the substrate so that all pixel rows can be printed in parallel.

[0065] OVJP is currently primarily viewed as a research tool. However, OVJP technology has demonstrated the linewidth and full-pixel film thickness uniformity required for manufacturing OLED displays using a parallel RGB pixel format. In mass production systems, it is desirable to keep the time to complete each manufacturing step relatively low to maintain efficient overall production. The time between completed manufacturing steps is commonly referred to as the "TAKT" time. To achieve the desired TAKT time in OLED device production, mass production OVJP printers may need to print multiple pixels or pixel rows in parallel. For example, the optimal TAKT time is achieved if all pixel rows are printed simultaneously. As a specific example, current 4K displays require 3,840 rows of pixels to be printed simultaneously across the width of the display. Six 55-inch displays can be manufactured on a single 2,200m × 2,500m substrate in the next generation. In this case, the OVJP deposition system would span 2.2 meters across the substrate and be able to print two displays or 7,680 pixels simultaneously. Figure 3A and Figure 3B An example is depicted of a new generation (“Gen 8”) substrate 300, a printhead support structure 301, and a single monolithic printhead 302 spanning the width of the display glass.

[0066] However, the flatness of substrates used to manufacture devices such as large-panel displays is imperfect, and rigid printing rods cannot provide sufficient control over the spacing between the printhead and the substrate. Therefore, current OVJP-type technologies only allow for efficient and precise single-pass deposition on substrates with limited width. For example, the most conventional OVJP-type technologies are not suitable for deposition on large substrates, and sometimes unsuitable for substrates larger than approximately 0.5 square meters or equivalent without rasterization. To deposit on larger substrates, current technologies typically use a single OVJP nozzle array, which includes multiple deposition holes rasterized across the substrate. For example, some configurations in OVJP nozzle arrays include up to 100 or more deposition holes. The nozzle array may include sensors and motion actuators to maintain a generally precise gap between the substrate and the nozzle array assembly. Such technologies are much less sensitive to changes in flight altitude and thus much less sensitive to changes in substrate flatness. However, they require complex management systems and have relatively high TAKT times.

[0067] Therefore, to achieve the desired pixel width using an OVJP-type system, it is desirable to have strict control over the distance between the substrate and the printhead. To this end, the embodiments disclosed herein provide a “segmented printhead,” a device having multiple segments that can move independently of each other to maintain the desired distance between the printhead and the substrate, while accommodating variations in substrate flatness. Each segment may include one or more OVJP printheads. The embodiments disclosed herein also allow the printhead to move significantly only in the y-direction (in the substrate plane and perpendicular to the substrate movement direction), whereas conventional OVJP systems require significant movement in both the x and y directions for the nozzles to rasterize the substrate. The embodiments disclosed herein were developed prior to the consideration of the feasibility of printing large-scale substrates using OVJP-type techniques as disclosed herein. Therefore, existing and conventional systems exclude any consideration of adjusting the flight altitude during material deposition and do not include any mechanisms for generating such adjustments.

[0068] As a specific example, a 55-inch 4K display pixel has a width of approximately 50 μm. The linewidth obtained using an OVJP printhead is on the same order of magnitude as the width of the ejector orifice and the distance from the printhead to the substrate. Therefore, for OVJP technology to achieve a print width of approximately 50 μm, the flight height spacing between the printhead or the printhead and the substrate should be precisely maintained within + / - 5 μm of the target flight height, or better. That is, during material deposition from the printhead to the substrate, the distance between the edge of the printhead orifice and the nearest surface of the substrate should vary by no more than + / - 5 μm. A flight height deviation greater than + / - 5 μm in either direction may widen the deposited line to the point that it collides with adjacent pixels, or result in line thickness that does not conform to the pixel size specifications. To print a display on a next-generation glass substrate with dimensions of 2.2 x 2.5 m and a thickness of 0.5 mm, as previously disclosed, the printhead needs to be at least 2.2 m long, such as... Figure 3A As shown, the glass needs to have a flatness within + / -5μm to maintain an appropriate flight altitude.

[0069] However, as mentioned earlier, the new generation of glass substrates is expected to have some variations in surface flatness. For example, the new generation of display glass typically has a maximum deviation of approximately 40 μm relative to a flat surface. As a specific example, Corning cites the Lotus NXT... It has the specifications shown in Table 1.

[0070] Table 1

[0071]

[0072] As another example, Schott Glass provides “Moving Window Dimensions” as shown in Table 2, which is a measure of glass flatness.

[0073] Table 2

[0074]

[0075]

[0076] The specific values ​​in Tables 1 and 2 are provided for illustrative purposes only, and those skilled in the art will recognize that the flatness specifications in Table 1 are for older generation substrate glass, while the values ​​in Table 2 are for newer generation substrate glass.

[0077] A flat printing bar spanning the width of such a display or substrate has a maximum deviation in the printhead-to-substrate distance equal to at least half the maximum substrate deviation, i.e., 20 μm in this example. Therefore, conventional single-piece solid printing bars cannot maintain the desired pitch of + / - 5 μm during printing.

[0078] Figure 4A A cross-section of an exemplary 2.2m printhead and a perfectly flat glass panel substrate is depicted. The printhead assembly 400 spans the width of the substrate 401. The support structure 403 of the printhead 402 is wider than the substrate so that the printhead can span the entire width of the substrate. The flight height gap 405 between the substrate 401 and the printhead 402 is uniform across the entire width of the substrate. However, as previously described, a real substrate does not have perfect flatness and the gap is not uniform across the entire width of the substrate. Figure 4B A schematic example is depicted, such as the previously disclosed 2.2m long printing rod and glass panel 406 with a flatness deviation of up to 40μm. The resulting deviations relative to the ideal flight altitude are marked in 407 and 408. It was found that the variation in flight altitude is proportional to the flatness specifications in Table 1.

[0079] like Figure 4B It has been proposed that, in order to maintain an appropriate flight altitude, the printhead must be able to conform to the morphology of the substrate glass or otherwise adjust for the non-uniformity of the substrate flatness.

[0080] The embodiments disclosed herein provide a printing bar having multiple segments, each segment including a printing head capable of being translated (e.g., moved up and down relative to a substrate) and / or rotated (e.g., tilted relative to a substrate) individually and independently of each other. Figure 5AAn example of such a device is depicted, wherein segmenting the printing bar into smaller printheads capable of moving independently of each other allows the spacing between the substrate and each printhead to be maintained at a desired value. A side view schematic of an exemplary substrate is shown. Flatness deviations relative to the plane are magnified, and the schematic outline of the segmented printing bar depicts how the individual segments 502 / 503 / 504 are hinged to follow the contour of the substrate.

[0081] like Figure 5A As shown, each segment may include a printhead support structure 501, a hinged mounting bracket 502, a printhead 503, and one or more perforated plates 504. Each hinged support structure may include a movable element that responds to one or more sensors in each printhead, said sensors measuring the distance from the printhead to the substrate. Any suitable distance sensor can be used. For example, differential pressure, acoustic, capacitive, infrared, laser, ultrasonic, optical, and / or other sensor types can be used. As a particular example, a capacitive sensor, as disclosed in U.S. Application No. 2018 / 0323373 (file number UDC-1240US), the disclosure of which is incorporated herein by reference in its entirety, can be used. Data from each sensor can be provided to one or more of the printhead segments, and based on the measurements and the desired flight altitude, the printhead segments can be moved relative to the substrate to achieve a desired position and / or orientation of the printhead relative to the substrate. Alternatively or additionally, a single sensor array or device can be used to measure the distance from each printhead to the substrate. For example, a digital imaging or video system, in conjunction with image recognition software, can be used to identify and measure the position of each printhead segment and provide feedback to the corresponding support structure. Based on the distance measured by each sensor, a moving element moves the relevant printhead to maintain a constant distance 506 between the bottom of the printhead (e.g., bottom orifice plate 504) and the substrate 505. Additionally, each segment can also be tilted relative to the substrate, such as maintaining the deposition orifice parallel to the substrate or the spindle of the deposition nozzle perpendicular to the substrate. Generally, each printhead can be oriented independently of each other to maintain the desired orientation at a desired distance from the substrate.

[0082] Each printhead may include a fully functional OVJP nozzle or a similar deposition device. For example, each segment may include one or more print holes defined by a non-flexible rigid material to maintain its shape. For example, materials such as metal, ceramic, or silicon may be suitable. Each hole may be a rectangular gas outlet or may have any shape to produce the desired print profile. It may also be formed by multiple smaller holes configured according to a unique pattern to print each line.

[0083] Each printhead may also contain a vacuum port and orifice to remove carrier gas and excess organic material. The vacuum port may be made of the same material as the gas outlet orifice.

[0084] Each printhead segment may include a heater or may be kept in thermal contact with a heater to prevent organic materials from condensing.

[0085] Organic vapors, carrier gases, and vacuum ports can be connected to their respective sources or pumps via pipes suitable for transmission.

[0086] More generally, each printhead segment may include an OVJP printhead and any necessary components and connectors to operate as a fully functional printhead independent of each other printhead in the segmented printhead.

[0087] In some embodiments, some or all of the individual printheads may be in fluid communication with a common vacuum source, organic material source, etc., or each printhead may be in communication with a separate source.

[0088] In some embodiments, each printhead segment may include two or more sensors to measure the distance between each end of the printhead and the substrate, thereby enabling precise positioning and alignment of the segment relative to the substrate.

[0089] As disclosed herein, segmented printing bars may include gaps between adjacent segments. In some embodiments, the gaps between segments may be filled by a second row of printhead segments offset relative to the first row to fill the gaps. Figure 5B The illustration shows two rows of printing bars with printing sections of equal length. Individual print heads 551, each integrating a height sensor 552, are configured in two rows 553 and 554, such that the printing sections in each row print pixel lines without overlap or gaps. The supply of organic material and / or vacuum to the print heads can be provided by a shared source, individual sources, or a combination thereof, as previously disclosed. Figure 5B The sequential arrangement of the printing rods shown also provides additional space for the vertical actuator and allows for fine adjustments to the distance between the print heads to accommodate manufacturing tolerances of the substrate backplane or thermal expansion of the substrate. A staggered arrangement also allows space for manifolds to mount the printing dies in the section. Manifolds are typically wider than the dies they carry, so they cannot be placed too close together to avoid leaving one or more pixel rows unprinted. By staggering the two rows of printing dies, the entire display can be printed in a single pass without leaving any pixel rows unprinted.

[0090] In some embodiments, the width of the printhead segment can be determined based on the flatness of a local area of ​​the substrate, for example, based on the movement window dimensions as shown in Table 2 and / or the fluctuation values ​​as shown in Table 1. Such dimensions can be used to determine the minimum, optimal, or acceptable dimensions of individual printheads in the segmentation apparatus disclosed herein. More generally, the maximum width of the print segment is typically only as long as the distance by which the height variation on the substrate equals the flight altitude tolerance. For example, using the values ​​in Table 2 as an example, a printhead with a 150 mm print segment is within a + / - 5 μm tolerance with a thickness variation of a specified 9 μm (maximum).

[0091] More generally, in the embodiments disclosed herein, the die length can be determined based on the flight altitude requirements of the printhead design, the resolution required by the display design, and the local flatness of the glass substrate. For the next-generation Gen8 glass, a typical die length can be in the range of 75 to 100 mm.

[0092] like Figure 5B and 5C The embodiments shown include rectangular printhead segments. Each rectangular printhead segment may include one or more distance sensors, such as those previously disclosed for measuring the gap between the printhead and the substrate, one or more actuators for adjusting the gap between the segment and the substrate based on feedback from the sensors, and one or more other sensors, such as vision sensors, which can be used to align the printhead with features on the substrate.

[0093] For example, Figure 5C A schematic diagram of a segmented printed bar 560 as disclosed herein is depicted, viewed from the printhead toward the substrate (not shown), or viewed from the surface of the substrate along a line orthogonal to the substrate toward the printhead 560. The segmented printed bar 560 may include one or more segments 561 as previously disclosed, each of which may be rectangular in shape. Adjacent substrate surfaces of each printed bar segment may be thermally insulated from the printhead and can be cooled to act as heat shields 564, thereby preventing the heated elements of the printed bar from overheating the substrate. In the exemplary arrangement shown, each segment includes two altitude sensors 562, two altitude actuators 563 (which may be positioned above the surface of the printed segment relative to the substrate and therefore may not be visible when viewed from the substrate), and a printing mold 565. As used herein, the printing mold (such as printing mold 565) may include deposition, venting, confinement, and other gas holes. Such molds may be fabricated in silicon, for example, using MEMS microfabrication techniques. The segments and printing mold can be arranged such that there are no gaps in the printing area when the substrate moves relative to the printing rod in direction 566. Except for small gaps between the segments, the cooling surface is continuous.

[0094] In some embodiments, fewer sensors and actuators and / or smaller sections can be used. Additionally, the movement of the front and rear printhead sections can be coupled. Such an arrangement can reduce the space, complexity, and cost of large-scale OVJP systems.

[0095] For example, in some embodiments, the printhead can take different shapes and / or be arranged in different configurations, using the same methods as previously shown and referenced. Figure 5B and 5C The same staggered design allows for the use of a single sensor in two segments (one in front and one behind). The segment surfaces form cooling surfaces that limit heat radiation from the thermal die and other heated parts of the printhead to the substrate. Any large gaps between segments could cause excessive thermal damage to the substrate, and minimizing such gaps is desirable. Therefore, during system operation, the surfaces of the disclosed segmented printhead can act as continuously cooled surfaces while still providing sufficient movement to follow the substrate surface and maintain a constant or substantially constant flight altitude, as previously disclosed.

[0096] Figure 6 An exemplary segmented printing bar according to one embodiment disclosed herein is depicted, wherein each segment 601 has a “T” shape. Segments 601 are configured such that each flight altitude sensor 602 and actuator pair 603 acts as two printing molds 605 in a staggered arrangement—one as a front mold and one as a rear mold—where the direction of movement 620 relative to the substrate defines which mold is considered “front” and “rear” relative to the other mold. That is, during operation of the OVJP deposition system, each flight altitude sensor can provide distance information between the two segments, and / or each actuator 603 can be used to adjust the distance and / or orientation of the two segments relative to the substrate. As a particular example, flight altitude sensor 602a can provide altitude information, which can be used to adjust actuator 603a to control… Figure 6 The distance and / or tilt angle of the two sections 601a and 601b shown are illustrated. Aligning the flight altitude distance sensor, actuator, and mold edge allows for more precise and accurate control of the mold's position relative to the substrate than other configurations. For example, by aligning two flight altitude sensors with the ends of the mold and positioning the actuator in a similar position on the other side of the mold, the positioning of each end of the mold can be precisely controlled based on distance measurements that accurately represent the distance of each end of the mold from the substrate. As previously mentioned, the cooling surface 604 can limit the thermal radiation of the mold.

[0097] Figure 7 Another example of a segmented printing bar 700 according to an embodiment disclosed herein is depicted. This example uses a triangular printing head segment 701. Similar to... Figure 5A -C and Figure 6In the configuration shown, the printhead 700 may include one or more height sensors 702, actuators 703, and print molds 705. As previously disclosed, the height sensors and / or actuators may be “shared” between adjacent segments. In operation, the segmented printhead 700 may move relative to the substrate in direction 710, i.e., such that the top / bottom edges of the print molds 705 and the triangular printhead segments 701 are perpendicular to or substantially perpendicular to the direction of movement. In some designs and applications, such as Figure 7 The configuration shown can be desirable due to the potentially greater compactness of the segmented printing bars. However, while the triangular segments are potentially more compact than the rectangular segments previously disclosed herein, they offer less tilting capability than the "T"-shaped segments and, as referenced... Figure 6 There are so many similar designs.

[0098] Figure 8 Another arrangement of the segmented printing head according to the embodiments disclosed herein is depicted. In this arrangement, rectangular printing heads 801 can be arranged in multiple rows, with front heads 802 and rear heads 803 arranged in an overlapping manner such that individual printing heads partially overlap in the direction of movement 830 relative to the substrate. As previously disclosed, actuators 804 and distance sensors 807, 808 can be used to adjust the distance and tilt angle of individual printing head segments relative to the substrate. For example, in Figure 8 In the illustrated arrangement, each actuator 804 can transfer vertical movement to the rear corner 805 of the front printhead 820 and the front corner 806 of the rear printhead 825. As in other arrangements disclosed herein, each actuator and the hinge connecting it to the two printheads it serves can be positioned according to the printing direction. Additionally, the flight altitude sensors of the front printhead 820 can each be associated with different actuators, as previously disclosed in other arrangements, and synchronized with the associated actuators along the printing direction. A second set of flight altitude sensors 808 can be mounted on the rear printhead. This second set of flight altitude sensors 808 can improve the performance of the segmented printhead rod in bidirectional operation because it allows the printhead to respond to changes in substrate height (relative to the depositor) as it moves backward and forward relative to the substrate. The printhead segment can be surrounded by a fixed cold plate 809 positioned in front of and / or behind the segmented printhead. The cold plate may include extensions 810 (“finger”) located at the front and / or rear edges, which intersect with the staggered lines of the printhead, as shown. This arrangement covers the area between the cold plates associated with each individual printhead segment and can further protect the substrate from heat generated by the OVJP mechanism. The cold plate finger may be spaced apart from the printhead by a small gap 811 to allow segmented printhead movement, as previously disclosed.

[0099] As used herein, when a print bar or other OVJP deposition apparatus and substrate are described as moving in a direction relative to each other or in a relative direction (such as directions 620, 710, 830, etc.), it should be understood that such movement can be achieved by: moving the print bar or apparatus while keeping the substrate stable; moving the substrate while keeping the deposition apparatus stable; or moving both components to achieve the desired relative movement.

[0100] The embodiments disclosed herein provide a segmented OVJP-type print head comprising multiple independent print heads that can be suspended from a rigid support structure. The print head segments provide the full functionality of a large print head while addressing the inability of a single, monolithic print head to maintain a constant print head-to-substrate distance. Segmenting the print head into multiple discrete print heads (each with a range of movement toward the substrate) as disclosed herein allows the printing system to compensate for unevenness in substrates suitable for OVJP.

[0101] Furthermore, compared to conventional printheads or single printhead bars used for deposition on the same surface area, segmented printhead bars, as disclosed herein, can also have more relaxed tolerances required by the printhead bar itself. For example, if it were not impossible to produce extremely large printhead bars (e.g., 1-2 m long or longer) with flatness tolerances of + / -5 μm or less using conventional techniques, and similarly tight end-to-end depositor positioning tolerances would be extremely difficult. In contrast, using segmented printhead bars, as disclosed herein, allows individual segments to be sized to meet the required tolerances. For example, components with dimensions of 150 mm and smaller can be fabricated using well-understood semiconductor manufacturing techniques. Individual segments can be directly aligned based on features on the substrate, allowing for greater tolerance to printhead-substrate overlap tolerances in the process.

[0102] The segmented printing bar disclosed herein can outperform a single linear printing bar because it can maintain the printhead-to-substrate spacing on substrates with imperfect flatness. As disclosed herein, when the printhead-to-substrate distance cannot be maintained at a constant desired value, linewidth and deposition thickness may vary, and deposition may not proceed as specified, even if the tolerances are sufficient to provide acceptable or even poor performance. Generally, if the spacing is too large, the deposited line becomes too wide, and if the spacing is too small, the thickness becomes too large. Therefore, maintaining an appropriate spacing is likely essential for producing printed lines with the desired width and thickness to achieve large-scale OLED manufacturing.

[0103] 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 vapor jet printing (OVJP) deposition system comprising one or more printing bars, each of the plurality of printing bars comprising: Multiple printhead segments, each of which includes an OVJP printhead; A plurality of flight altitude distance sensors, each configured to measure the distance between a substrate disposed below the printing rod and a portion of at least one of the printing head segments; and A plurality of actuators configured to adjust the position and / or orientation of one or more of the plurality of printhead segments based on one or more distances between the substrate and the printhead, the distances being measured by one or more of the plurality of flight altitude distance sensors.

2. The OVJP deposition system according to claim 1, further comprising: One or more gas distribution channels connect each printhead to one or more organic vapor source units located remotely from the printhead.

3. The OVJP deposition system of claim 1, wherein the print head section of each print bar is in fluid communication with a single vapor source or multiple vapor sources.

4. The OVJP deposition system according to claim 1, wherein the printing head sections of the plurality of printing rods are in fluid communication with a common vapor source or a plurality of vapor sources.

5. The OVJP deposition system of claim 1, wherein when the printing bar is operated to deposit material on the substrate, the plurality of printing head segments of at least one of the plurality of printing bars are arranged in two rows in a direction substantially perpendicular to the direction of movement of the at least one printing bar relative to the substrate.

6. The OVJP deposition system of claim 5, wherein the plurality of print head segments of the at least one print bar are disposed in the row such that when the print bar is operated to deposit material on the substrate, the printing area of ​​the OVJP print head corresponding to each row forms a single print column on the substrate.

7. The OVJP deposition system of claim 1, wherein each OVJP printhead comprises an OVJP deposition nozzle in fluid communication with a carrier gas source and an organic material vapor source.

8. The OVJP deposition system according to claim 7, wherein the carrier gas source and the organic material vapor source are shared by the plurality of printheads of the plurality of printheads.

9. The OVJP deposition system of claim 1, wherein each of the plurality of actuators is connected to at least two of the plurality of printhead segments and configured to control the position and / or orientation of at least two of the plurality of printhead segments.

10. The OVJP deposition system of claim 9, wherein each of the plurality of actuators controls the position and / or orientation of at least two of the plurality of printhead segments based on distance measurements obtained from two or more of the plurality of flight altitude sensors.

11. The OVJP deposition system of claim 9, wherein each of the plurality of actuators controls the position and / or orientation of the at least two of the plurality of printhead segments based on a distance measurement obtained from at least one of the at least one flight altitude sensor.

12. The OVJP deposition system according to claim 1, wherein, In each of the plurality of printing rods, each of the plurality of printing head segments is movable independently of each of the other printing head segments.

13. The OVJP deposition system of claim 12, wherein each printhead segment is movable independently of each other printhead segment in at least a direction substantially orthogonal to the substrate, such that the distance of each printhead segment from the substrate can be adjusted independently of the distance of each other printhead segment from the substrate.

14. The OVJP deposition system of claim 1, further comprising one or more vacuum channels arranged to remove material from the region between one or more of the plurality of printing bars and the respective substrate when each printing bar is operated to deposit material on the substrate.

15. The OVJP deposition system of claim 1, further comprising a cold plate disposed adjacent to a plurality of printhead segments of at least one of the plurality of printheads.

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