阅读说明：本技术 用于热激发oled材料的连续材料源 (Continuous material source for thermally excited OLED materials ) 是由 W·E·奎因 J·J·布朗 G·麦格劳 G·科塔斯 W·T·麦韦瑟 于 2019-06-18 设计创作，主要内容包括：本申请涉及用于热激发OLED材料的连续材料源。本发明提供用于沉积的系统和技术,如经由使用多个源安瓿的OVJP。所述源安瓿经布置和控制以使得载气可通过每个源安瓿依序馈入,由此允许更连续地操作和使用原本将经受热降解的材料。(The present application relates to a continuous material source for thermally exciting OLED material. The present invention provides systems and techniques for deposition, such as via OVJP using multiple source ampoules. The source ampoules are arranged and controlled such that a carrier gas may be fed through each source ampoule in sequence, thereby allowing for more continuous operation and use of materials that would otherwise be subject to thermal degradation.)

1. An Organic Vapor Jet Printing (OVJP) deposition system comprising:

a plurality of source ampoules in fluid communication with a source of carrier gas via a control manifold, the control manifold including a plurality of valves, each of which controls a fluid connection between the source of carrier gas and at least one of the source ampoules;

a plurality of heaters, each heater of the plurality of heaters thermally coupled to one of the plurality of source ampoules such that a temperature of each source ampoule is controllable independently of each other source ampoule via the heater thermally coupled to the source ampoule;

a mixing chamber in fluid communication with each of the plurality of source ampoules; and

an OVJP print head in fluid communication with the mixing chamber.

2. The OVJP deposition system according to claim 1, wherein each source ampoule contains the same material.

3. The OVJP deposition system according to claim 2, wherein each source ampoule is refillable.

4. The OVJP deposition system according to claim 2, wherein each source ampoule is removably connected to the control manifold such that the source ampoule in the system can be replaced when the system is in operation.

5. The OVJP deposition system according to claim 1, wherein the control manifold allows a gas flow to flow through each of the plurality of source ampoules in sequence.

6. The OVJP deposition system according to claim 5, further comprising an additional plurality of source ampoules different from the plurality of source ampoules, wherein the control manifold allows gas flow through the plurality of source ampoules or the additional plurality of source ampoules in sequence.

7. The OVJP deposition system according to claim 1, wherein the manifold allows gas to be delivered from the carrier gas source to exactly one of the first plurality of source ampoules at a time.

8. The OVJP deposition system according to claim 1, further comprising one or more valves, each of the one or more valves controlling a flow of material between one or more of the source ampoules and the mixing chamber.

9. The OVJP deposition system according to claim 8, further comprising a purge gas source in fluid communication with one or more of the source ampoules via a dedicated gas line.

10. The OVJP deposition system according to claim 1, further comprising a balancing manifold in fluid communication with one or more of the source ampoule, the carrier gas storage chamber, or both.

11. The OVJP deposition system according to claim 1, wherein at least two of the plurality of source ampoules comprise sources of the same material.

12. The OVJP deposition system according to claim 1, wherein the control manifold is configured to automatically direct gas through at least one of the plurality of source ampoules at a time.

13. The OVJP deposition system according to claim 12, wherein the system automatically heats and directs a carrier gas through exactly one source ampoule at a time.

14. An Organic Vapor Jet Printing (OVJP) deposition system comprising:

a plurality of source ampoules in fluid communication with a source of carrier gas via a control manifold, each source ampoule of the plurality of source ampoules containing a first source material, wherein the control manifold includes a plurality of valves, each of which controls a fluid connection between the source of carrier gas and at least one of the source ampoules;

a mixing chamber in fluid communication with each of the plurality of source ampoules; and

an OVJP print head in fluid communication with the mixing chamber.

15. The OVJP deposition system according to claim 14, further comprising:

a plurality of heaters, each heater of the plurality of heaters thermally coupled to one of the plurality of source ampoules such that a temperature of each source ampoule may be controlled independently of each other source ampoule.

Technical Field

The present invention relates to systems and techniques for fabricating devices, such as organic light emitting diodes, and other devices including the same.

Background

Photovoltaic devices utilizing organic materials are becoming increasingly popular for a variety of reasons. Many of the materials used to make such devices are relatively inexpensive, and therefore organic photovoltaic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials (e.g., their flexibility) may make them more suitable for particular 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 may have performance advantages over conventional materials. For example, the wavelength of light emitted by the organic emissive layer can generally be readily tuned with appropriate dopants.

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

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

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

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

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

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

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

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

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

Disclosure of Invention

According to one embodiment, an Organic Vapor Jet Printing (OVJP) deposition system is provided that includes a plurality of source ampoules in fluid communication with a source of carrier gas via a control manifold containing a plurality of valves, each of which controls a fluid connection between the source of carrier gas and at least one of the source ampoules; a plurality of heaters, each heater of the plurality of heaters thermally coupled to one of the plurality of source ampoules such that a temperature of each source ampoule is controllable independently of each other source ampoule via the heater thermally coupled to the source ampoule; a mixing chamber in fluid communication with each of the plurality of source ampoules; and an OVJP print head in fluid communication with the mixing chamber.

In one embodiment, an Organic Vapor Jet Printing (OVJP) deposition system is provided that includes a plurality of source ampoules in fluid communication with a source of a carrier gas via a control manifold, each of the plurality of source ampoules containing a first source material, wherein the control manifold includes a plurality of valves, each of which controls a fluid connection between the source of the carrier gas and at least one of the source ampoules; a mixing chamber in fluid communication with each of the plurality of source ampoules; and an OVJP print head in fluid communication with the mixing chamber.

Each source ampoule may contain the same material and may be refillable and/or removably connected to the control manifold so that the source ampoules in the system may be replaced when the system is in operation. The control manifold may allow a flow of gas to pass through each of the source ampoules in sequence. One or more additional source ampoules may be used that are different from the plurality of source ampoules, in which case the control manifold may allow for sequential flow of gas through either the initial source ampoule or the additional source ampoule. The gas-bearing chamber and control manifold may be external to the deposition chamber in which the source ampoule is disposed. Some or all of the source ampoules may be connected to the mixing chamber via a single delivery line. The manifold may allow gas to be delivered from the carrier gas source to exactly one of the first plurality of source ampoules at a time. Each source ampoule may contain the same source material. The system may also contain additional source ampoules, which may contain the same or different materials than the plurality of source ampoules. The flush gas source may be in fluid communication with one or more of the source ampoules via a dedicated gas line. The balancing manifold may be used to balance the pressure and/or flow in the system. The control manifold and other components may be configured to automatically direct gas through at least one of the plurality of source ampoules at a time to heat components of the system as needed, and to otherwise automatically engage the source ampoules for use in the system in sequence.

In one embodiment, a method of operating an OVJP deposition system having a plurality of source ampoules in fluid communication with a carrier gas source and a mixing chamber is provided. The method may include heating a first source ampoule of a plurality of source ampoules to a deposition temperature, the first source ampoule containing a first source material; depositing a first source material via a mixing chamber and an OVJP nozzle; after depositing at least a portion of the first material; heating a second source ampoule of the plurality of source ampoules to a deposition temperature; closing a valve between the first source ampoule and the mixing chamber; opening a valve between the second source ampoule and the mixing chamber; and depositing a second material via the mixing chamber and the OVJP nozzle. The first and second materials may comprise the same material. The method may further comprise separating one or more of the plurality of source ampoules from the deposition chamber and other ampoules using one or more valves; and purging and evacuating the process gas from the one or more source ampoules while the one or more source ampoules are separated from the deposition chamber and other ampoules. The method may further include heating at least a portion of each valve in fluid communication with the first source ampoule to at least the same temperature as the first source ampoule.

Drawings

Fig. 1 shows an organic light emitting device.

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

FIG. 3 shows a conventional OVJP deposition system.

Figure 4A shows a process flow diagram for a conventional OVJP deposition system including a body and a dopant source.

Fig. 4B shows a plot of dopant concentration and growth rate as a function of deposition flow fraction of the total flow rate in a conventional OVJP deposition system.

FIG. 5 shows an example process flow diagram of embodiments disclosed herein, wherein a showerhead is fed with organic vapor species through a series of individual sources connected in parallel thereto, which may be sequentially heated and vented.

FIG. 6 shows an example process flow diagram of embodiments disclosed herein that includes a shut-off valve downstream of each of the series of individual sources.

FIG. 7 shows an example process flow diagram of embodiments disclosed herein, including a source having a downstream shut-off valve connected in parallel with a series of source ampoules, which may be filled with a different source material than the series of sources.

FIG. 8 shows an example process flow diagram of embodiments disclosed herein, including a pressure/flow balancer.

Detailed Description

Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When current is applied, the anode injects holes and the cathode injects electrons into the organic layer. The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and a hole are located on the same molecule, an "exciton," which is a localized electron-hole pair with an excited energy state, is formed. When the exciton relaxes by a light emission mechanism, light is emitted. In some cases, the exciton may be localized on an excimer (eximer) or an exciplex. Non-radiative mechanisms (such as thermal relaxation) may also occur, but are generally considered undesirable.

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

More recently, OLEDs having emissive materials that emit light from the triplet state ("phosphorescence") have been demonstrated. Baldo (Baldo), et al, "high efficiency phosphorescent Emission from Organic Electroluminescent Devices," Nature, 395, 151-154,1998 ("Baldo-I"); and baldo et al, "Very high-efficiency green organic light-emitting devices based on electrophosphorescence (Very high-efficiency green organic light-emitting devices-based on electrophosphorescence)", applied physical promissory (appl. phys. lett.), volume 75, stages 3,4-6 (1999) ("baldo-II"), which are incorporated by reference in their entirety. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704, columns 5-6, which is incorporated by reference.

Fig. 1 shows an organic light emitting device 100. The figures are not necessarily to scale. Device 100 can include substrate 110, anode 115, hole injection layer 120, hole transport layer 125, electron blocking layer 130, emissive layer 135, hole blocking layer 140, electron transport layer 145, electron injection layer 150, protective layer 155, cathode 160, and blocking layer 170. Cathode 160 is a composite cathode having a first conductive layer 162 and a second conductive layer 164. The device 100 may be fabricated by depositing the layers in sequence. The nature and function of these various layers and example materials are described in more detail in U.S. Pat. No. 7,279,704, columns 6-10, which is incorporated by reference.

More instances of each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is doped with F at a molar ratio of 50:1₄TCNQ m-MTDATA as disclosed in U.S. patent application publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of luminescent and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al, which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. patent application publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entirety, disclose examples of cathodes comprising composite cathodes having a thin layer of a metal (e.g., Mg: Ag) with an overlying transparent, conductive, sputter-deposited ITO layer. The theory and use of barrier layers is described in more detail in U.S. patent No. 6,097,147 and U.S. patent application publication No. 2003/0230980, which are incorporated by reference in their entirety. Examples of injection layers are provided in U.S. patent application publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of the protective layer may be found in U.S. patent application publication No. 2004/0174116, which is incorporated by reference in its entirety.

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

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

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

Any of the layers of the various embodiments may be deposited by any suitable method, unless otherwise specified. For organic layers, preferred methods include thermal evaporation, ink jetting (as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, both incorporated by reference in their entirety), organic vapor deposition (OVPD) (as described in U.S. Pat. No. 6,337,102 to Foster et al, both incorporated by reference in their entirety), and deposition by Organic Vapor Jet Printing (OVJP) (as described in U.S. Pat. No. 7,431,968, incorporated by reference in its entirety). Other suitable deposition methods include spin coating and other solution-based processes. The solution-based process is preferably carried out in a nitrogen or inert atmosphere. For other layers, a preferred method includes thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding (as described in U.S. patent nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entirety), and patterning associated with some of the deposition methods, such as inkjet and OVJD. Other methods may also be used. The material to be deposited may be modified to suit the particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3 to 20 carbons is a preferred range. A material with an asymmetric structure may have better solution processibility than a material with a symmetric structure because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.

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

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

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

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

In some embodiments, the OLED further comprises a layer comprising a delayed fluorescence emitter. In some embodiments, the OLED comprises an RGB pixel arrangement or a white plus color filter pixel arrangement. In some embodiments, the OLED is a mobile device, a handheld device, or a wearable device. In some embodiments, the OLED is a display panel having a diagonal of less than 10 inches or an area of less than 50 square inches. In some embodiments, the OLED is a display panel having a diagonal of at least 10 inches or an area of at least 50 square inches. In some embodiments, the OLED is a lighting panel.

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

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

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

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

In combination with other materials

Materials described herein as suitable for use in a particular layer in an organic light emitting device can be used in combination with a variety of other materials present in the device. For example, the emissive dopants disclosed herein may be used in conjunction with a wide variety of host, transport, barrier, implant, electrode, and other layers that may be present. The materials described or referenced below are non-limiting examples of materials that can be used in combination with the compounds disclosed herein, and one of ordinary skill in the art can readily review the literature to identify other materials that can be used in combination.

The different emissive and non-emissive layers and arrangements disclosed herein may use different materials. Examples of suitable materials are disclosed in U.S. patent application publication No. 2017/0229663, which is incorporated by reference in its entirety.

Conductive dopant:

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

HIL/HTL：

The hole injecting/transporting material used in the present invention is not particularly limited, and any compound may be used as long as the compound is generally used as a hole injecting/transporting material.

EBL：

An Electron Blocking Layer (EBL) may be used to reduce the number of electrons and/or excitons that leave the emissive layer. The presence of such a barrier layer in a device may result in substantially higher efficiency and/or longer lifetime compared to a similar device lacking a barrier layer. In addition, blocking layers can be used to limit the emission to the desired area of the OLED. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and/or higher triplet energy than the emitter closest to the EBL interface. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and or higher triplet energy than one or more of the bodies closest to the EBL interface. In one aspect, the compound used in the EBL contains the same molecule or the same functional group as used in one of the hosts described below.

A main body:

the light-emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as a light-emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complex or organic compound may be used as long as the triplet energy of the host is larger than that of the dopant. Any host material may be used with any dopant so long as the triplet criteria are met.

HBL：

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

ETL：

The Electron Transport Layer (ETL) may include a material capable of transporting electrons. The electron transport layer may be intrinsic (undoped) or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complex or organic compound may be used as long as it is generally used to transport electrons.

Charge Generation Layer (CGL)

In tandem or stacked OLEDs, CGL plays a fundamental role in performance, consisting of an n-doped layer and a p-doped layer for injecting electrons and holes, respectively. 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 conductivity dopants used in the transport layer.

As previously disclosed, various systems and techniques are used to fabricate OLEDs and other similar devices. For example, OVJP as disclosed previously is a maskless, solventless printing technique for large area OLED displays. In general, the OLED material is heated to an evaporation temperature in a source chamber and the vapor is transported with a carrier gas to a showerhead assembly where the material condenses on the substrate. OVJP techniques and systems are disclosed in at least U.S. patent nos. 7,744,957, 7,897,210, 7,879,401, 8,293,329, 8,535,759, 8,574,934, 8,613,496, 8,728,858, 8,801,856, 8,931,431, 8,944,309, 8,939,555, 9,178,184, 9,583,707, 9,653,709, 9,700,901, 9,873,939, 8,940,568 and 9,252,397 and U.S. publication nos. 2011/0097495, 2013/0273239, 2015/0376787, 2015/0380648, 2017/0101711, 2017/0104159 and 2017/0306486, the disclosures of each of which are incorporated by reference in their entirety. In conventional OVJP techniques, vapor streams from multiple sources are mixed before being ejected onto a substrate. One or more sources are operated simultaneously, non-sequentially, and the bulk-dopant ratio can be varied over a limited range by changing the gas flow ratio through two independent sources. The system is a batch type system in which the source is operated to exhaustion and the chamber is vented to refill the source. Conventional OLED display manufacturing techniques typically use linear evaporation sources and fine metal shadow masks to define individual pixels. In this system, a linear evaporation source heats the OLED material to a temperature sufficient to evaporate the material at high flux to rapidly deposit the desired thickness. A large amount of OLED material is loaded into the evaporation source to extend the duration of the deposition event. However, some OLED source materials may begin to decompose upon prolonged exposure to high temperatures (e.g., during long-term deposition activities) and thereby impair the quality of the deposited material.

To address these problems, it has been found that the architecture of the OVJP system can be used to prevent or reduce long-term thermal degradation of the OLED material if the OVJP sources can be operated sequentially. Thermal degradation can be reduced or avoided altogether by heating a small portion of the OLED material and consuming it before degradation becomes a problem. Furthermore, the use of multiple sequentially usable OLED sources may enable long-term deposition campaigns, and more specifically deposition campaigns that are much longer than required or possible using conventional techniques. The present disclosure describes systems and techniques for OVJP deposition that sequentially use heated OLED sources to prevent thermal degradation of the OLED material and enable long-term activity.

Fig. 3 shows a conventional OVJP system. In this system 300, the OLED material 302 is contained in a heated, sealed enclosure 304 containing a gas inlet 305 and a gas outlet 306. The organic material is heated to a vaporization temperature to form a vapor 303 of the OLED material in the headspace of the enclosure. An inert carrier gas 301 flows through the heated enclosure and becomes saturated with organic material. The material is transported through heated transfer line 307 to jet engine 308. The jet head motor contains a series of printing holes 309 that print the OLED material onto the moving substrate 310.

The emissive layer of an OLED device typically includes two or more components, a carrier transporting host and one or more light emitting dopants. Fig. 4A shows a schematic illustration of components typically used to print host and dopant materials by OVJP. Similar to the system 300 shown in fig. 3, in the system 400, a carrier gas 401 flows through a heated, sealed enclosure containing organic matter, commonly referred to as a material source. The carrier gas becomes saturated with organic vapor and the gas streams from the body source 403 and dopant source 404 are mixed at 405, such as in a mixing chamber or equivalent component, and then enter the injector head at 406. The organic flux from the source is regulated by varying the source temperature and carrier gas flow rate. The source may have a relatively large thermal mass and the temperature cannot be changed quickly, so the temperature is adjusted to obtain the required flux at a certain gas flow. The total airflow used may be determined by the requirements of the particular jetting head used in the system 400. The ratio of dopant to host in the printed film can be varied by changing the ratio of gas flows through the dopant and host sources while keeping the total flow constant.

Fig. 4B shows a plot of dopant concentration 1001 and growth rate 1002 as a function of deposition flow rate (which is plotted on horizontal axis 1003) of the total flow rate in a conventional OVJP system for a fixed body and dopant source temperature. The total carrier gas flow was 12 sccm. Dopant concentration is plotted in volume percent on the right vertical axis 1004 and feature thickness is plotted in angstroms on the left vertical axis 1005. Typically, the fraction of dopant in the deposited film ranges from 10% to 60% for gas flow fractions of 8% to 92%. Gas flow modulation works well for compositional variations in the mid-range (5% to 95%) of the composition, but is generally not useful for completely shutting off the organic flux because the organic material has sufficient vapor pressure to travel from the source to the injector head in the absence of a carrier gas. To completely shut off the sources, the temperature must be lowered to a point where the vapor pressure is negligible, or valves must be added between the sources and before the gas streams mix.

In a high volume production system, it is often desirable to have the process equipment produce as much product as possible, i.e., with as few interruptions and interruptions in production as possible. This factor of the production equipment is called uptime (uptime). Typical semiconductor processing equipment operates at greater than 85% uptime. OLED displays are currently manufactured using conventional vacuum thermal evaporation sources and shadow masks (fine metal masks). The evaporation source is a large linear source loaded with material and maintained until the material is consumed after heating to the evaporation temperature. Evaporation occurs under a high vacuum (approximately 10-7 torr) with the mean free path of ambient gas molecules being much larger than the distance between the source and the substrate. The vaporized material travels from the source to the substrate through a gap between the source and the substrate; the vaporized material condenses on all surfaces in the chamber. The vaporization system must be vented to load another batch of material into the source. To achieve the desired level of uptime, the batch deposition system must be loaded with a large amount of OLED material to extend the time between source material reloads. Unfortunately, some OLED materials begin to degrade after being held at the deposition temperature for an extended period of time. Degradation products can reduce the performance of the deposited film. To maintain high device performance, the amount of loadable source material must be reduced, which shortens the time between source reloads. Using smaller source loads generally reduces uptime and increases production costs. Furthermore, recharging the source in the vacuum chamber may require a long soak time to return it to a high vacuum, after which growth may resume.

In contrast to conventional systems, embodiments disclosed herein use multiple sources of material that are remote from the jetting head. Multiple sources can be loaded with a small amount of material to be deposited and can be used sequentially and thus heated only at the time of use. This may minimize or eliminate thermal degradation and provide a greater total amount of material to be loaded into the deposition system. It may also be particularly suitable for thermally unstable materials or other materials that may be particularly susceptible to thermal degradation.

Fig. 5 shows a schematic illustration of such a system according to one embodiment disclosed herein. The system may include a plurality of source ampoules 503a-503d and 504 in fluid communication with a source of carrier gas 501. Carrier gas 501 (e.g. H)₂He, Ar, or the like) may be connected to a gas control manifold 502, which contains valvesAnd flow controllers to regulate the flow to each source ampoule 503, 504. That is, each valve in the control manifold 502 may control a fluid connection between the carrier gas source 501 and one or more source ampoules 503, 504. The carrier gas and control manifold may be external to the deposition chamber 500. Some or all of the sources 503, 504, mixing chamber or other volume 505, and ejection head 506 may be disposed within a common deposition chamber 500. The material to be deposited by the jetting system, which may comprise a thermally brittle material, may be loaded into a plurality of source ampoules 503a, 503b, 503c, 503 d. In some arrangements, more thermally stable materials may be loaded into the larger source ampoule 504. For example, some organic emissive materials may be more resistant to thermal degradation than others, in which case a larger source ampoule 504 may be used without causing undesirable degradation of the material, while still obtaining the benefit of using a larger amount of source material than may be used for more thermally sensitive or brittle materials.

Source ampoules 503a-503d and 504 may each include or be thermally coupled to a heater such that the temperature of each source ampoule may be controlled independently of each other source ampoule. For example, each source ampoule 503a-503d may be thermally coupled to a respective heater, which may be used to set the temperature of the source ampoule without changing the temperature of the other source ampoules. As detailed further herein, such an arrangement may allow each source ampoule to be "opened" or "closed," i.e., heated to a deposition temperature and placed in fluid communication with a carrier gas source, such that the source ampoule provides source material to the injector head 506.

At the beginning of a deposition event, sources 503a and 504 may be heated to deposition temperature and the valves supplying carrier gas to those sources may be opened to supply material to be deposited on the substrate to ejection head 506. The jetting head 506 may be, for example, an OVJP printhead. The control manifold may allow a gas flow to pass through each of the small source ampoules 503a, 503b, 503c, 503d in sequence. When the first small source 503a is near completion, the second source 503b may be heated to the deposition temperature, the carrier gas supply valve of 503a may be closed, and the supply valve of the next source 503b may be opened. Once first source 503a is no longer in use, it may be actively cooled or allowed to cool to ambient temperature. Similarly, when source 503b is near completion, source 503c may be heated to the deposition temperature, the supply valve of 503b may be closed, and the supply valve of 503c may be opened. The source 503b is then cooled to ambient temperature. This process is repeated for the remainder of the small source. When all small sources are exhausted, the sources are cooled and refilled. Each valve and/or gas line may be thermally coupled to a heater, as previously disclosed with respect to the source ampoule, such that the temperature of each valve may be controlled independently of each other valve and each source ampoule to prevent condensation and other undesirable effects within the system. In some embodiments, one or more valves may be controlled by the same heater that controls the temperature of the source ampoule, wherein the valve controls gas entry. Alternatively or additionally, individual heaters may be used for valves, gas lines, or other components of the systems disclosed herein.

Thermal degradation is minimized by using small sources that are heated sequentially. In some cases, the same material may be placed in each small source ampoule 503a, 503b, 503c, 503 d. This may be particularly advantageous for source materials that are susceptible to thermal degradation as disclosed herein, as each source ampoule may not be maintained at the deposition temperature for a long time sufficient to cause material degradation of the ampoule before severing the ampoule and switching to the next source ampoule process. Furthermore, the system may operate for a longer overall period of time, as each source ampoule may be removed, cleaned, and/or refilled with the same or different source materials while other source ampoules are used. The control manifold may also allow the gas flow to pass sequentially through additional source ampoules, such as ampoule 504, in addition to each of the small source ampoules 503a-503d, either sequentially or simultaneously with the small source ampoule 503. One or more additional source ampoules 504 may contain the same source material as the ampoule 503, or they may contain a different source material.

In some embodiments, a series of source ampoules may be used. For example, a second series of source ampoules similar to 503a-503d may be connected in parallel with the initial series 503a-503d such that any series of source ampoules may be used to provide source material in the system. That is, multiple sets of source ampoules in series may be connected in parallel within the system such that each series may be operated such that the source ampoules in the series operate in series, as described with respect to 503a-503 d. For example, when a first series is depleted, a second series may be used while replenishing the source ampoules in the first series.

In fig. 5 and other figures provided herein, source ampoules, such as 503, 504, may be referred to as individual "sources" or "source ampoules. In some embodiments, each source ampoule may be removed, cleaned, refilled, and/or replaced in the system without stopping operation, as disclosed herein. Unless otherwise specifically indicated, it is understood that a "source" of material as described herein may be provided by, or considered equivalent to, a "source ampoule" containing the source material.

Fig. 6 shows an embodiment as disclosed herein incorporating high temperature values with a continuous source arrangement as described with respect to fig. 5. Similar to the system described with respect to fig. 5, a plurality of source ampoules 603a, 603b, 603c, 603d and 604 may be used. The carrier gas 601 is connected to the gas manifold 502 as previously described. The carrier gas and control manifold may be located outside the deposition chamber 500. Some or all of the sources 603, 604, mixing chamber or other volume 606, and spray head 607 may be disposed within the deposition chamber 500. Material to be deposited by the jetting system (which may include a thermally brittle material) may be loaded into source ampoules 603a, 603b, 603c, 603d, and/or a more thermally stable material may be loaded into larger source ampoule 604, as previously described. In general, the system shown in fig. 6 may operate in much the same manner as fig. 5, with the additional option of using one or more high temperature valves 605 disposed between the sources 603a-d, 604 and the mixing volume 606 and which may be used to control the flow of material therebetween. Using a high temperature valve may be advantageous because the source 603 has a positive shut off. In designs that omit such valves after the source, a small amount of material may leave the source due to the vapor pressure of the organic material when the source is at the deposition temperature. This material would then be transferred to the jetting head 607 in the absence of a control valve 605 or similar arrangement. The amount of material is small and may not have any detrimental effect on the deposited material quality when the sources that are switched on and off contain the same material. However, where the sources contain different materials (examples of which are provided and described with respect to fig. 7), the likelihood of cross-contamination and related undesirable effects may increase.

The addition of the positive shutoff valve 605 reduces or minimizes the possibility of cross-contamination. If the source is around and outside the deposition chamber, as shown in fig. 6 by the isolation valve, it is possible to remove, refill, and replace the source ampoule without suspending the operation of the deposition tool. Once separated, the source may be cooled to a safe processing temperature and then repaired or replaced while the rest of the tool is still hot and separated from the outside environment. The source may then be flushed with an ultra-pure carrier gas pump through dedicated line 608 with its own shut-off valve 609 and then warmed up if necessary. Other small sources in the source train 603 may similarly refill, permitting the tool to operate indefinitely.

Fig. 7 shows a deposition system as disclosed herein, including an additional source ampoule compared to the arrangement shown in fig. 5 and 6. The system includes a plurality of successive small sources 703a, 703b, 703c, which operate similarly to the previously disclosed sources 503, 603. The system also includes a small source ampoule 708 that may contain a different source material and a larger source ampoule 704 containing a third source material, similar to the source ampoules 504, 604 as previously disclosed. In this example, all source ampoules in the system have a positive shutoff valve 705, but this may not be required in some embodiments. In general, the system of fig. 7 operates similarly to the system of fig. 5 and 6, with carrier gas 701 being transported through one or more of source ampoules 703, 704, 708 to mixing chamber 706, after which it is deposited by spray head 707. When operation of the system of fig. 7 begins first, the source materials in source ampoules 703a, 704 and 708 may be heated to their respective deposition temperatures, which may be the same or different. The upstream 702 and downstream 705 valves associated with the sources may be opened, in which case the final material deposited by the spray head 707 will include source materials 703a, 704, and 708. By closing the upstream and downstream valves 705b for the source 708, the deposition material will contain only the materials 703b and 704. In this way, binary and ternary material mixtures can be deposited using the same system. This process can be extended to more than 3 materials by adding more sources and control valves. The temperature sensitive material 703 may be used in sequentially heated sources 703a, 703b, and 703c as previously described.

In some embodiments disclosed herein, turning on or off individual source ampoules as disclosed herein may create pressure or flow disruptions at the injector head that may affect deposition quality. To reduce or minimize flow and pressure variations when switching sources, a balancing manifold may be used that controls and balances pressure and/or flow within the system. Fig. 8 shows an example of a deposition system according to embodiments disclosed herein, where such a manifold may be used in OVJP. As previously disclosed, carrier gas 801 may flow through source ampoules 803a-803c, 804 and/or 808 to a mixing chamber 806. As previously disclosed, one or more source materials may be deposited via an ejection head 807. Downstream valves 805a and 805b (disposed after the source ampoule) may be, for example, three-way valves that switch flow from the source to a spray head or flow and pressure balancing manifold 808. The balancing manifold matches the back pressure and flow rate of the jetting head 807 such that there is little or no resulting change in pressure or flow rate in the mixing volume 806 and/or jetting head 807 as the sources 803, 804, 808 are turned on and off. To maintain equilibrium, the balancing network may be connected to the carrier gas 801 (to match the gas flow) and/or the exhaust vacuum system 809 (to maintain the pressure). The equalization manifold may also add a carrier gas to the mixing volume to maintain flow equilibrium.

Unless indicated to the contrary, similar components in fig. 5-8 as disclosed herein operate in the same or similar manner as each other. For example, each jetting head 506, 607, 707, 807 may be an OVJP printhead and may operate in a similar manner (except for the particular mixture of source materials received from the various source ampoules described and shown in each figure). Similarly, each source ampoule in each of the example systems shown may include the same or different source materials than other source ampoules of the same arrangement, depending on the application for each system. As another example, each of the systems disclosed herein may include one or more heaters thermally coupled to the source ampoule, valves, gas lines, and other components of the system in any suitable combination to allow for control of the temperature of each component.

The source ampoule as described herein may be removable, refillable and/or replaceable within each of the described systems. That is, each source ampoule may be removed, refilled, and replaced within the system, or refilled while it is still in place in the system, without stopping operation of the entire system.

In some embodiments, the systems disclosed herein may be configured to operate automatically or semi-automatically. For example, a deposition system as disclosed herein may automatically heat and direct a carrier gas through one source ampoule of a plurality of source ampoules containing the same source material at a time, automatically switching from one source ampoule to the next as the source material in each source ampoule is depleted. As a specific example, referring to fig. 8, the deposition system may automatically heat and open the source ampoule 803b by controlling the appropriate valves to allow the source material 803b to deposit as the source material in the earlier ampoule 803a is depleted. Similarly, the system may automatically open source ampoule 803c and close source ampoule 803b when the source material in ampoule 803b is depleted.

It should be understood that the various embodiments described herein are by way of example only and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted with other materials and structures without departing from the spirit of the invention. The invention as claimed may thus comprise 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 as to why the invention works are not intended to be limiting.