JP7123967B2 - Printing method for organic light emitting diodes (OLEDs) - Google Patents

Description

Field of Invention

The present invention relates to a method of printing organic light emitting diodes (OLEDs), OLEDs printed by this method, and printing devices adapted to carry out this method.

technical level

OLEDs are light-emitting diodes whose light-emitting electroluminescent layers are films of organic compounds that emit light in response to an electric current. This layer of organic semiconductor is located between two electrodes. A typical OLED comprises a layer of organic material located between two electrodes, an anode and a cathode, both disposed on a substrate. Organic molecules are electrically semiconducting. Most basic polymer OLEDs contain a single organic layer, but multilayer OLEDs are common today. These layers are usually printed with suitable printing devices filled with suitable inks.

When preparing OLED devices, the active layers are typically applied using printing techniques. Suitable and preferred deposition methods include liquid coating and printing techniques. Preferred deposition methods include dip coating, spin coating, spray coating, aerosol jetting, inkjet printing, nozzle printing, gravure printing, doctor blade coating, roller printing, reverse roller printing, flexographic printing, web printing, screen printing, stencil printing, Spray coating, dip coating, curtain coating, kiss coating, Meyer bar coating, 2 roll nip fed coating, anilox coater, knife coating, or slot die coating include, but are not limited to. Preferably, the OSC layer is applied using gravure printing, doctor blade coating, roller printing, reverse roller printing, flexographic printing, web printing, anilox coater, or inkjet printing, more preferably using inkjet printing. Gravure and flexographic printing and variants of these printing methods are preferred. It includes, but is not limited to, micro gravure, reverse gravure, offset gravure, reverse roll, and the like. Both roll-to-roll and sheet-fed can be used in both flatbed and more traditional "on the round" configurations.

Due to the low solubility of most of the current organic compounds useful as emissive and/or charge transport materials, these techniques require the use of large amounts of solvents.

For example, WO2011/076325A1 discloses compositions comprising emissive and/or charge transport materials and polymeric binders and their use as inks for preparing OLED devices.

EP 1 883 124 A1 describes formulations of luminescent materials particularly suitable for forming displays and lamps by printing techniques, comprising an organic luminescent material housed in a protective porous matrix material, a binder and a solvent. However, OLED materials also include polymeric materials.

US2007/0103059 discloses a composition comprising an OLED material and a polymer with very specific repeating units. Polymers with special repeating units are added to improve the luminous efficiency of OLEDs. Polymeric OLED materials can also be utilized.

US 5,952,778 relates to an encapsulated organic light emitting device with an improved protective cover comprising a first layer of passivating metal, a second layer of inorganic dielectric material and a third layer of polymer . Organic light emitting materials can be of high or low molecular weight.

Thus, the printing of OLEDs and the inks used for each are known in the art. To print the OLED onto the substrate, a common inkjet printer is used and supplied with the appropriate inks as described above.

Nonetheless, all inks have certain properties that can affect the shape, image and appearance of printed OLEDs, so printers should be calibrated for the inks used. is important. It is very important that any ink not be misplaced in adjacent pixels, as this will result in color mixing which is detrimental to the electrical properties.

Thus, the formation of multiple droplets (of radically different sizes, commonly referred to as satellites) means that these smaller droplets can become trapped in air currents within the printer and land in undesirable locations. is generally undesirable because During the ejection process, a filament of ink is created and the leading edge of the filament slows down so that the "tail" catches up and forms a single drop. Poor formulation and/or corrugation often results in the formation of single droplets with very low velocity very small droplets (satellites) formed behind the initial droplets. In particular, the detached droplets usually vary in size, typically less than 3 μm in diameter, and are misaligned on the substrate, thus degrading the printed image. For example, piezoelectric printers used for printing OLEDs prevent the formation of multiple droplets through a combination of actuation waveforms, the size of a single droplet ejected by the printhead, and the properties of the ink used. adjusted to Figure 2 shows these waveforms for a 10 pl droplet on a Fujifilm Dimatix SQ printhead used with an ink having a viscosity of 0.975 cP at 20°C.

Another possibility for avoiding the occurrence of separated droplets is described in US 2006/0028497 A1. This document relates to an ink jet recording method using relatively high viscosity inks which are cured by UV light. In particular, this method is capable of outputting high-definition images and suppressing ink mist, i.e., satellites or separate droplets that can be displaced by air currents. According to US 2006/0028497 A1, it is preferred that there be no satellite development at all. For this, it is proposed to use an ink with a viscosity of 5-20 cP and that the jetted droplets have a velocity of 5 m/s at a distance of 1 mm from the nozzle. Thus, satellites stay closer than 500 μm from the main droplet and are not misplaced.

In the OLED industry, there is an ever-increasing demand for printing at higher resolution, ie, printing more droplets (pixels per inch (ppi)) in a given area. However, the size or volume of the ejected droplets is determined by the printhead used to eject the droplets. Therefore, reducing the size or volume of droplets requires construction of printheads capable of ejecting smaller droplets. One of the smallest droplets currently available is produced by 1 picoliter (pl) printheads and high ink densities. A high concentration is desirable to reduce the thickness of the film within the pixel to avoid spillover to adjacent pixels. This is more ideally suited for small molecule OLEDs due to both rheological and solubility considerations. Additionally, when printing within a pixel, it is important that the drop size of the ink droplets does not exceed the dimensions of the pixel.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method of printing OLEDs by using commonly known printers, but improving the resulting resolution. This object is solved by a method comprising the features of claim 1 and a piezoelectric printing device according to claim 12 . Further preferred embodiments are described in the dependent claims.

Surprisingly, it has been discovered that using inks with viscosities less than 5 cP results in the formation of two smaller droplets of essentially the same size. This requires that the operating waveforms of the piezoelectric printer be adjusted accordingly.

Thus, the method according to the invention consists in producing one or more layers of an OLED containing at least one organic semiconductor material, printing the solution onto a substrate using a piezoelectric printing device, , said solution contains at least one organic solvent and at least one organic semiconductor material; and drying the printed solution, wherein the solution is less than 5 cP, preferably less than 4 cP, more preferably It has a viscosity of less than 2 cP, most preferably less than 1 cP, and the electrical impulse for actuating the piezoelectric printing device is appropriately controlled corresponding to the print head used, in particular at least two smaller but essentially is controlled so that droplets of the same size are formed in the Preferably 2, 3, 4, 5, 6, 7, 8, 9 or 10 droplets, more preferably 2, 3, 4, 5, 6 or 7 droplets are formed.

The expression "droplets of essentially the same size" as used in the present application means that the diameter difference between the droplets having the largest diameter and the droplet having the smallest diameter is 20% or less, preferably 10% or less, more preferably means 5% or less.

Using this method has had the surprising effect of significantly increasing the resolution of the printed OLEDs. This is because at least two droplets of essentially the same size are formed. In particular, the two resulting droplets have a smaller diameter compared to a single ejected droplet. For example, if an ejected droplet has a volume of 10 pl (printhead dependent) that is typically about 26.7 μm (micrometers) in diameter, it will shrink to two droplets of approximately 21 μm in diameter. Similarly, for a 1 pl droplet with a diameter of about 12.4 μm, two droplets of about 9.8 μm are formed. Similarly, as more droplets are formed, the droplet size becomes smaller and smaller. Therefore, it is possible to realize a printing method capable of printing with improved resolution by simply adjusting the waveform of the printing device and the viscosity of the ink using a general printer. As a result of improved printing methods, OLEDs with better resolution can also be produced with smaller droplet diameters than printheads normally produce. These OLEDs can be distinguished from conventionally printed OLEDs because the droplet diameter can only be achieved with the method of the invention.

Printing is preferably carried out with a printhead that produces droplets of size 30 pl or less, more preferably 10 pl or less, most preferably 3 pl or less. The use of such printheads improves general resolution. This effect can be enhanced by combining with the method of the present invention.

In one aspect, the solution comprises a small molecule organic semiconductor material (small molecule OLED (SMOLED)) at a concentration of at least 1.0%, preferably at least 2.5%, more preferably at least 5%. This can include hole-injection layers, hole-transport layers, light-emitting layers and electron-transport layers. Even higher resolutions can be obtained by using SMOLEDs.

In another aspect, the solution comprises polymeric organic semiconductor material (polymeric OLED (POLED)) at a concentration of 2.5% or less, preferably 1.5% or less, more preferably 0.5% or less. Again, this can include a hole-injection layer, a hole-transport layer, a light-emitting layer and an electron-transport layer. The added polymer is advantageous because it does not affect device performance but enhances film forming ability. Additionally, a binder may be added to aid film formation.

Preferably, the solution comprises at least two organic solvents resulting in a viscosity of less than 5 cP, preferably less than 4 cP, more preferably less than 2 cP, most preferably less than 1 cP. By using at least two organic solvents, the drying and fluid properties of the solution can be better controlled. In particular, the second and subsequent solvents used in the solution are expected to provide good solubility for the emissive layer. These solvents will also preferably have different boiling points within a minimum range of 10°C, preferably at least 30°C, more preferably at least 50°C. Such a minimal difference in the boiling points of the at least two solvents facilitates tailoring the desired properties of the resulting solution/ink. Further, the boiling points of the at least two solvents are expected to be preferably in the range of 150°C to 300°C, more preferably in the range of 200°C to 300°C, and most preferably in the range of 250°C to 290°C. Within this range the most preferred solvents for the invention are found.

In general, similar properties of different solvents lead to good solubility. Thus, the use of two solvents with similar properties promotes the formation of homogeneous films and avoids crystallization of various organic semiconductor materials.

Drying the solution can include a vacuum drying process after printing the OLED. A drying process is performed after printing each layer of the OLED device. Of course, the vacuum drying process can be applied to each drying process of the various layers. However, it is also possible to carry out the vacuum drying process only for certain layers. The vacuum drying process is preferably carried out at a temperature of 20°C or higher. Since the pressure during the vacuum drying process is very low, the solvent evaporates quickly, improving drying.

Another aspect of the invention is an OLED manufactured using the method according to the invention. Since the diameter of the resulting discrete droplets is distinguishable by size from normal printed droplets, a specified resolution cannot be achieved with printheads alone and the method of the present invention is used. It can only be achieved by using

A further aspect of the invention relates to a piezoelectric printing device having a printhead of 30 pl or less, wherein the piezoelectric printing device is fed with a printing solution comprising at least one organic solvent and at least one organic semiconductor material. be done. Such a printer is ideally suited for implementing the method according to the invention. Because the columns of droplets produced have a smaller size, a common printhead structure is sufficient to achieve better resolution, but it is also preferable to adjust the angle of the printhead. This makes it possible to reduce the pitch between the nozzles. In this way, small voids between the liquid droplet arrays can be avoided. However, such adjustment of the nozzles is readily performed as suggested to those skilled in the art.

FIG. 1 shows the concept of using multiple droplets (single droplet, two droplets and multiple droplets) in a channel. FIG. 2 shows the waveforms used in the prior art for printing with inks having low viscosities and the corresponding printing results. FIG. 3 shows the waveforms used in the prior art for printing with inks having low viscosities and the corresponding printing results. FIG. 4 shows waveforms according to the invention for the two drop approach and the corresponding printed results. FIG. 5 shows waveforms according to the invention for the two drop approach and corresponding printed results. FIG. 6 shows the waveforms according to the invention for the multi-drop approach and the corresponding printed results. FIG. 7 shows waveforms according to the invention for the multi-drop approach and the corresponding printed results.

Detailed description of the preferred embodiment

In the following the terms "solution" and "solvent" are used. "Solution" means in the following an ink ready for printing on a substrate for OLEDs, whereas "solvent" means a chemical or liquid. Thus, several solvents can be mixed and combined into a solution, ie a solution can contain more than one solvent. The solution can further contain various additives.

Furthermore, viscosity is usually measured at a temperature of 25° C. and can be measured by common methods and equipment such as rotary viscometers, vibratory viscometers or capillary viscometers.

The present invention can be practiced with common inks that meet the required properties described below and can be printed using common printers that are adjusted accordingly. In principle, usable solutions are disclosed in the prior art documents mentioned in the introduction. However, in general there are some properties that the solution used in the present invention should have. Most importantly, the solution has a viscosity of less than 5 cP, preferably less than 4 cP, more preferably less than 2 cP, most preferably less than 1 cP. Other properties relate to solution surface tension and density, but for commonly used inks/solutions the general range of these properties is not critical as long as the viscosity is within the scope of the present invention.

In addition to the viscosity of the solution, the printhead for the piezoelectric printing device and the waveform for operating the piezoelectric printing device are important. By tailoring the waveform of the actuation signal to the printhead and combining it with the appropriate solution as described above, three parameters are defined which serve as the basic features of the present invention. The actuation waveform is expected to be adjusted so that the ejection process forms at least two droplets, which droplets have essentially the same size to avoid different flight characteristics of different droplets. . In addition, having the same size ensures that droplets do not exceed the dimensions of the pixel due to offset.

The waveform is controlled by adjusting the rise, fall, maximum voltage and/or maximum voltage hold time depending on the printhead used; ) can be created. This can be done by a simple test of different waveforms on a given solution with a particular printhead.

A general printer can be used as the printer. As an example, a Pixdro LP-50 printer with a Fujifilm Dimatix SQ printhead with a drop volume of 10 pl is used. The printer is a piezoelectric printing device that is actuated by electrical signals modulated in correspondence with respective waveforms. The Pixdro LP-50 has very limited waveform generation, with a single rise time, peak hold at a particular voltage, and one fall time (only these three segments are achievable with this printer). ) can only be used in Other printers can add more segments, thus providing more flexibility in controlling the waveform. Therefore, the same effect can be achieved by using different parameters. FIG. 2 shows waveforms for a 10 pl Fujifilm Dimatix SQ printhead mounted on the Pixdro LP50 printer referred to in the introduction to this application, in accordance with the present invention. For this impulse waveform for actuating the piezoelectric printing device, a voltage of 52V was chosen. It takes 7 μs (microseconds) to rise to the maximum voltage. The maximum voltage of the actuation waveform is maintained for 10 μs. The impulse fall time is 17 μs. Under this waveform, the ink described in Example 1 produces a single droplet.

In this example, in FIG. 4, the waveform is optimized for the Fujifilm Dimatix SQ 10 pl printhead mentioned above and two drops are printed instead of just one. A maximum voltage of 40 V is maintained for 9 μs and the ramp up and down is performed within 2 μs. This ensures that two smaller droplets of essentially the same size are produced.

For FIG. 6, the maximum voltage of 35V is maintained for 2.5 μs and the rise and fall take 2 μs. As a result, seven individual droplets are formed, and the size of each droplet is even smaller, improving the resolution.

This is achieved by using a particular print head with a particular droplet size, with a solution viscosity of 5 cP or less, and adjusting the piezoelectric print head actuation waveforms accordingly to produce essentially the same size droplets. means that two or more droplets of can be formed. Since droplets of different sizes can degrade the resulting image on the printed OLED layer, discrete droplets are inherently Having the same size is important. FIG. 1 shows a simple comparison of one droplet (FIG. 1A) printed with ink having a typical wavy shape and/or viscosity greater than 5 cP and two droplets according to the invention. As can be seen, the two droplets in FIG. 1B have a smaller size, thus resulting in a higher number of smaller droplets, resulting in improved resolution. The printed droplet in FIG. 1 corresponds to a 10 pl printhead ejecting a single droplet of approximately 27 μm in diameter, which reduces to approximately 20 μm upon separation.

In a printing device, a plurality of print nozzles are usually arranged adjacent to each other in single or multiple rows. When printing on a pixelated substrate, it is important to align the center of the nozzle (or droplet) along the pixel pattern. This can be achieved by tilting the printhead if the nozzle pitch (the spacing between nozzles) is different than the native resolution of the pixellated substrate.

After thus printing the layers of the OLED, the printed layers are dried, especially in a vacuum drying process which may or may not involve heat during drying. Alternatively or additionally, however, drying by radiation can also be carried out. Further layers can then be printed until the OLED is manufactured and completed.

As for the ink, the solution contains at least one organic solvent and at least one organic semiconductor material. The at least one organic semiconductor material can be either a small molecule organic semiconductor material or a polymeric organic semiconductor material.

Organic semiconductor materials include fluorescent emitters, phosphorescent emitters, host materials, matrix materials, exciton-blocking materials, electron-transporting materials, electron-injecting materials, hole-conducting materials, hole-injecting materials, n-dopants, p-dopants, wide It is selected from the group consisting of bandgap materials, electron blocking materials, and hole blocking materials.

Preferred aspects of organic semiconductor materials are disclosed in detail in WO2011/076314A1, which document is hereby incorporated by reference into the present application.

In preferred embodiments, the organic semiconductor material is an organic semiconductor selected from the group consisting of hole-injecting, hole-transporting, luminescent, electron-transporting and electron-injecting materials.

More preferably, the organic semiconductor material is an organic semiconductor selected from the group consisting of hole-injecting and hole-transporting materials.

The organic semiconducting material can be a compound, polymer, oligomer or dendrimer with a low molecular weight, wherein the organic functional material can also be in the form of a mixture. Thus, formulations according to the invention may comprise two different compounds with low molecular weight, one compound and one polymer with low molecular weight, or two polymers (blends).

Organic semiconductor materials are often described by the property of frontier orbitals, which are described in more detail below. The molecular orbitals, in particular the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), their energy levels and the energy of the lowest triplet state T ₁ or lowest excited singlet state S ₁ of a material are defined by quantum chemistry. It can be determined by calculation. To calculate the metal-free organic material, first a geometry optimization is performed using the "ground state/semi-empirical/default spin/AM1/zero charge/spin singlet" method. An energy calculation is then performed based on the optimized structure. The 'TD-SCF/DFT/default spin/B3PW91' method with the '6-31G(d)' basis set (zero charge, spin singlet) is used here. For metal-containing compounds, the structure is optimized by the "ground state/Hartley Fock/default spin/LanL2MB/zero charge/spin singlet" method. Energy calculations are performed in the same manner as for organic substances described above, but for metal atoms the 'LanL2DZ' basis set is used and for ligands the '6-31G(d)' basis set is used. There is a difference that Energy calculations yield the HOMO energy level HEh or the LUMO energy level LEh in Hartree units. The HOMO and LUMO energy levels in electron volts, calibrated with reference to cyclic voltammetry measurements, are then determined as follows:
HOMO (eV) = ((HEh ^* 27.212)-0.9899)/1.1206 LUMO (eV) = ((LEh ^* 27.212)-2.0041)/1.385
For the purposes of this application, we will consider these values to be the HOMO and LUMO energy levels of the material, respectively.

_The lowest triplet state T1 is defined as the energy of the triplet state with the lowest energy resulting from the described quantum chemical calculations.

_The lowest excited singlet state S1 is defined as the energy of the excited singlet state with the lowest energy resulting from the described quantum chemical calculations.

The method described here is independent of the software package used and always gives the same result. Examples of programs frequently used for this purpose are "Gaussian09W" (Gaussian Inc.) and Q-Chem 4.1 (Q-Chem, Inc.).

Compounds with hole-injecting properties, also referred to herein as hole-injecting materials, simplify or facilitate the movement of holes, ie positive charges, from the anode to the organic layer. A hole-injecting material has a HOMO level that is above the region of the anode level, ie, typically at least −5.3 eV.

A compound with hole-transporting properties, also referred to herein as a hole-transporting material, is generally capable of transporting holes, ie positive charges, injected from the anode or an adjacent layer, such as a hole-injecting layer. Hole-transporting materials generally have a high HOMO level, preferably at least -5.4 eV. Depending on the structure of the electronic device, it may also be possible to utilize the hole-transporting material as the hole-injecting material.

Preferred compounds with hole-injecting and/or hole-transporting properties include, for example, triarylamines, benzidines, tetraaryl-para-phenylenediamines, triarylphosphines, phenothiazines, phenoxazines, dihydrophenazines, thianthrene, dibenzo-para - dioxin, phenoxathiin, carbazole, azulene, thiophene, pyrrole and furan derivatives and further O, S or N containing heterocyclic compounds with high HOMO (HOMO=highest occupied molecular orbital).

As compounds with hole-injecting and/or hole-transporting properties, phenylenediamine derivatives (US3615404), arylamine derivatives (US3567450), amino-substituted chalcone derivatives (US3526501), styrylanthracene derivatives (JP-A-56-46234), Polycyclic aromatic compounds (EP1009041), polyarylalkane derivatives (US3615402), fluorenone derivatives (JP-A-54-110837), hydrazone derivatives (US3717462), acylhydrazones, stilbene derivatives (JP-A-61-210363) , silazane derivative (US4950950), polysilane (JP-A-2-204996), aniline copolymer (JP-A-2-282263), thiophene oligomer (JP-A-1 (1989)-211399), polythiophene, poly(N- vinylcarbazole) (PVK), polypyrrole, polyaniline, and other conductive polymers, porphyrin compounds (JP-A-63-2956965, US4720432), aromatic dimethylidene-type compounds, carbazole compounds such as CDBP, CBP, mCP, etc. Particular mention may be made of aromatic tertiary amine and styrylamine compounds (US Pat. No. 4,127,412), such as the benzidine type of triphenylamine, the styrylamine type of triphenylamine, and the diamine type of triphenylamine. Arylamine dendrimers (JP-A-8 (1996)-193191), monomeric triarylamines (US3180730), triarylamines containing one or more vinyl radicals and/or at least one functional group containing active hydrogen ( US 3,567,450 and US 3,658,520), or tetraaryldiamines (two tertiary amine units linked via an aryl group) can also be used. More triarylamino groups may be present in the molecule. Also suitable are phthalocyanine derivatives, naphthalocyanine derivatives, butadiene derivatives, and quinoline derivatives such as dipyrazino[2,3-f:2',3'-h]quinoxaline hexacarbonitrile.

Aromatic tertiary amines containing at least two tertiary amine units (US2008/0102311A1, US4720432 and US5061569) such as NPD (α-NPD = 4,4'-bis[N-(1-naphthyl)-N -phenyl-amino]biphenyl) (US5061569), TPD232 (=N,N'-bis-(N,N'-diphenyl-4-aminophenyl)-N,N-diphenyl-4,4'-diamino-1, 1′-biphenyl) or MTDATA (MTDATA or m-MTDATA=4,4′,4″-tris[3-methylphenyl)phenylamino]-triphenylamine) (JP-A-4-308688), TBDB ( =N,N,N',N'-tetra(4-biphenyl)-diaminobiphenylene), TAPC (=1,1-bis(4-di-p-tolylaminophenyl)cyclo-hexane), TAPPP (=1 , 1-bis(4-di-p-tolylaminophenyl)-3-phenylpropane), BDTAPVB (= 1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl ]vinyl]benzene), TTB (=N,N,N′,N′-tetra-p-tolyl-4,4′-diaminobiphenyl), TPD (=4,4′-bis[N-3-methylphenyl ]-N-phenylamino)-biphenyl), N,N,N′,N′-tetraphenyl-4,4′″-diamino-1,1′,4′,1″,4″,1 '''-Quaterphenyl and the like are preferred, as well as tertiary amines containing carbazole units such as TCTA(=4-(9H-carbazol-9-yl)-N,N-bis[4-(9H -carbazol-9-yl)phenyl]benzenamine) and the like are preferred. Similarly, hexaazatriphenylene compounds according to US 2007/0092755 A1 and phthalocyanine derivatives (e.g. H ₂ Pc, CuPc (=copper phthalocyanine), CoPc, NiPc, ZnPc, PdPc, FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl ₂ SiPc, (HO)AlPc, (HO)GaPc, VOPc, TiOPc, MoOPc, GaPc--O--GaPc) are preferred.

Triarylamine compounds of the following formulas (TA-1) to (TA-12) are particularly preferred, and EP1162193B1, EP650955B1, Synth. Ｍｅｔａｌｓ １９９７、９１（１－３）、２０９、ＤＥ１９６４６１１９Ａ１、ＷＯ２００６／１２２６３０Ａ１、ＥＰ１８６００９７Ａ１、ＥＰ１８３４９４５Ａ１、ＪＰ０８０５３３９７Ａ、ＵＳ６２５１５３１Ｂ１、ＵＳ２００５／０２２１１２４、ＪＰ０８２９２５８６Ａ、ＵＳ７３９９５３７Ｂ２、ＵＳ２００６／００６１２６５Ａ１、ＥＰ１６６１８８８、およびＷＯ２００９／０４１６３５に開示されている。 Said compounds of formulas (TA-1) to (TA-12) may be optionally substituted.

Further compounds that can be used as hole injection materials are described in EP0891121A1 and EP1029909A1, injection layers are generally described in US2004/0174116A1.

These arylamines and heterocyclic compounds commonly utilized as hole-injecting and/or hole-transporting materials preferably have >-5.8 eV (vs. vacuum level) in the polymer, particularly Resulting in a HOMO greater than -5.5 eV.

Compounds with electron-injecting and/or electron-transporting properties are, for example, pyridine, pyrimidine, pyridazine, pyrazine, oxadiazole, quinoline, quinoxaline, anthracene, benzanthracene, pyrene, perylene, benzimidazole, triazine, ketone, phosphine oxide and Phenazine derivatives, in addition to triarylboranes, and further O-, S- or N-containing heterocyclic compounds with low LUMO (LUMO=lowest unoccupied molecular orbital).

Particularly suitable compounds for the electron-transporting and electron-injecting layers are metal chelates of 8-hydroxyquinoline (eg LiQ, AlQ ₃ , GaQ ₃ , MgQ ₂ , ZnQ ₂ , InQ ₃ , ZrQ ₄ ), BAlQ, Ga oxinoid complexes, 4- Azaphenanthrene-5-ol-Be complexes (US5529853A, see formula ET-1), butadiene derivatives (US4356429), heterocyclic optical brighteners (US4539507), benzimidazole derivatives (US2007/0273272A1) such as TPBI (US5766779, 1,3,5-triazines, for example spirobifluorenyltriazine derivatives (for example according to DE 102008064200), pyrenes, anthracenes, tetracenes, fluorenes, spirofluorenes, dendrimers, tetracenes (for example rubrene derivatives), 1,10-phenanthroline derivatives (JP2003-115387, JP2004-311184, JP2001-267080, WO02/043449), silacyclopentadiene derivatives (EP1480280, EP1478032, EP1469533), borane derivatives such as Si-containing triarylborane derivatives (US2007 /0087219A1, see Formula ET-3), pyridine derivatives (JP2004-200162), phenanthrolines, especially 1,10-phenanthroline derivatives such as BCP and Bphen, and also some bound via biphenyl or other aromatic groups. phenanthroline (US2007-0252517A1) or phenanthroline bound to anthracene (US2007-0122656A1, see formulas ET-4 and ET-5).

Also suitable are heterocyclic organic compounds such as thiopyran dioxide, oxazole, triazole, imidazole or oxadiazole. Five-membered rings containing N, such as oxazole, preferably 1,3,4-oxadiazoles, such as formulas ET-6, ET-7, ET-8 and ET-9 disclosed inter alia in US 2007/0273272 A1 compounds of; A. Levin, M. S. See Skorobogatova, Khimiya Geterotsiklicheskikh Soedinenii 1967(2), 339-341, preferably compounds of formula ET-10, silacyclopentadiene derivatives. Preferred compounds are the following formulas (ET-6) to (ET-10):

It is likewise possible to utilize derivatives of organic compounds such as fluorenone, fluorenylidenemethane, perylenetetracarbonate, anthraquinonedimethane, diphenoquinone, anthrone and anthraquinonediethylenediamine.

Preferred are 2,9,10-substituted anthracenes (with 1- or 2-naphthyl and 4- or 3-biphenyl) or molecules containing two anthracene units (see US2008/0193796A1, formula ET-11). Also very advantageous is the attachment of 9,10-substituted anthracene units to benzimidazole derivatives (see US2006/147747A and EP 1551206A1, formulas ET-12 and ET-13).

Compounds capable of producing electron-injecting and/or electron-transporting properties preferably yield a LUMO of less than -2.5 eV (vs. vacuum level), particularly preferably less than -2.7 eV.

The formulations of the invention may also contain phosphors. The term emitter means a material that allows radiative transitions to the ground state with luminescence after excitation, which can occur by any type of energy transfer. Generally, two classes of emitters are known: fluorescent and phosphorescent emitters. The term fluorescent emitter means a material or compound that undergoes a radiative transition from an excited singlet state to the ground state. The term phosphorescent emitter means a luminescent material or compound that preferably contains a transition metal.

Emitters are often referred to as dopants when the dopant induces the above properties in the system. Dopant in a system comprising matrix material and dopant is taken to mean the minor component of the mixture. Correspondingly, matrix material in a system comprising matrix material and dopant is taken to mean the higher proportion component of the mixture. The term phosphorescent emitter can thus also be taken to mean, for example, a phosphorescent dopant.

Compounds capable of emitting light include, among others, fluorescent emitters and phosphorescent emitters. These contain inter alia stilbenes, stilbeneamines, styrylamines, coumarins, rubrenes, rhodamines, thiazoles, thiadiazoles, cyanines, thiophenes, paraphenylenes, perylenes, phthalocyanines, porphyrins, ketones, quinolines, imines, anthracenes and/or pyrene structures. Contains compounds that Particularly preferred are compounds that can emit from the triplet state with high efficiency even at room temperature, ie exhibit electrophosphorescence rather than electrofluorescence, which often leads to increased energy efficiency. Suitable for this purpose are primarily compounds containing heavy atoms with an atomic number greater than 36. Compounds containing d- or f-transition metals satisfying the above conditions are preferred. Corresponding compounds containing elements of groups 8-10 (Ru, Os, Rh, Ir, Pd, Pt) are particularly preferred here. Suitable functional compounds here are the various complexes described, for example, in WO 02/068435 A1, WO 02/081488 A1, EP 1239526 A2 and WO 2004/026886 A2.

Preferred compounds that can function as fluorescent emitters are described by the following examples. Preferred fluorescent emitters are selected from the class of monostyrylamines, distyrylamines, tristyrylamines, tetrastyrylamines, styrylphosphines, styryl ethers, and arylamines.

A monostyrylamine is taken to mean a compound which contains one substituted or unsubstituted styryl group and at least one, preferably aromatic amine. A distyrylamine is taken to mean a compound which contains two substituted or unsubstituted styryl groups and at least one, preferably aromatic, amine. A tristyrylamine is taken to mean a compound containing three substituted or unsubstituted styryl groups and at least one, preferably aromatic amine. A tetrastyrylamine is taken to mean a compound which contains four substituted or unsubstituted styryl groups and at least one, preferably aromatic, amine. The styryl group is particularly preferably stilbene and may be further substituted. Corresponding phosphines and ethers are defined analogously to the amines. Arylamines or aromatic amines in the sense of the invention are taken to mean compounds containing three substituted or unsubstituted aromatic or heteroaromatic ring systems directly attached to the nitrogen. Preferably, at least one of these aromatic or heteroaromatic ring systems is a fused ring system, preferably having at least 14 aromatic ring atoms. Preferred examples of these are aromatic anthracenamines, aromatic anthracenediamines, aromatic pyrenamines, aromatic pyrenediamines, aromatic chrysenamines or aromatic chrysenediamines. An aromatic anthracenamine is taken to mean a compound in which one diarylamino group is bonded directly to an anthracene group, preferably in the 9-position. Aromatic anthracenediamines are taken to mean compounds in which two diarylamino groups are bonded directly to an anthracene group, preferably in the 2,6 or 9,10 positions. Aromatic pyrenamines, pyrenediamines, chrysenamines and chrysenediamines are defined analogously, wherein the diarylamino groups are preferably attached to the pyrene in the 1- or 1,6-position.

Further preferred fluorescent emitters are indenofluorenamines or indenofluorenediamines, especially as described in WO2006/122630; benzoindenofluorenamines or benzoindenofluorenediamines, especially as described in WO2008/006449; dibenzoindenofluoreneamine or dibenzoindenofluorenediamine.

Examples of compounds from the class of styrylamines that can be used as fluorescent emitters are substituted or unsubstituted tristilbenamines or dopants as described in WO2006/000388, WO2006/058737, WO2006/000389, WO2007/065549 and WO2007/115610. be. Distyrylbenzene and distyrylbiphenyl derivatives are described in US5121029. Additional styrylamines can be found in US2007/0122656A1.

Particularly preferred styrylamine compounds are the compound of formula EM-1 described in US7250532B2 and the compound of formula EM-2 described in DE102005058557A1:

Particularly preferred triarylamine compounds are compounds of formula EM-3 to EM-15 and derivatives thereof disclosed in CN1583691A, JP08/053397A and US6251531B1, EP1957606A1, US2008/0113101A1, US2006/210830A, WO2008/006449 and DE102008035413. is:

Further preferred compounds that can be used as fluorescent emitters are naphthalene, anthracene, tetracene, benzanthracene, benzophenanthrene (DE102009005746), fluorene, fluoranthene, periflanthene, indenoperylene, phenanthrene, perylene (US 2007/0252517 A1), pyrene, chrysene, decacyclene. , coronene, tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, fluorene, spirofluorene, rubrene, coumarin (US4769292, US6020078, US2007/0252517A1), pyran, oxazole, benzoxazole, benzothiazole, benzimidazole, pyrazine, cinnamate , diketopyrrolopyrroles, acridones, and derivatives of quinacridones (US2007/0252517A1).

Among anthracene compounds, 9,10-substituted anthracenes, such as 9,10-diphenylanthracene and 9,10-bis(phenylethynyl)anthracene, are particularly preferred. 1,4-bis(9'-ethynylanthracenyl)-benzene is also a preferred dopant.

Similarly, derivatives of rubrene, coumarin, rhodamine, quinacridones such as DMQA (=N,N'-dimethylquinacridone), dicyanomethylenepyrans such as DCM (=4-(dicyanoethylene)-6-(4-dimethylaminostyryl) -2-methyl)-4H-pyran), thiopyrans, polymethines, pyrylium and thiapyrylium salts, periflanthenes, and indenoperylenes are preferred.

Blue fluorescent emitters are preferably polyaromatic compounds such as 9,10-di(2-naphthylanthracene) and other anthracene derivatives, derivatives of tetracene, xanthene, perylene such as 2,5,8,11-tetra -t-butylperylene and the like, phenylenes such as 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl, fluorene, fluoranthene, arylpyrene (US2006/0222886A1), arylenevinylene (US5121029, US5130603), bis(azinyl)imine-boron compounds (US2007/0092753A1), bis(azinyl)methene compounds, and carbostyryl compounds.

Further preferred blue fluorescent emitters are C.I. H. Chen et al.: "Recent developments in organic electroluminescent materials" Macro-mol. Symp. 125, (1997) 1-48 and "Recent progress of molecular organic electroluminescent materials and devices" Mat. Sci. and Eng. R, 39 (2002), 143-222.

Further preferred blue fluorescent emitters are the hydrocarbons disclosed in DE102008035413.

Preferred compounds that can function as phosphorescent emitters are described by the following examples.

Examples of phosphorescent emitters are disclosed by WO00/70655, WO01/41512, WO02/02714, WO02/15645, EP1191613, EP1191612, EP1191614 and WO2005/033244. In general, all phosphorescent complexes such as those used in phosphorescent OLEDs according to the prior art and known to the person skilled in the art in the field of organic electroluminescence are suitable, and the person skilled in the art will be able to formulate further phosphorescent complexes without inventive step. can be used.

The phosphorescent metal complex preferably contains Ir, Ru, Pd, Pt, Os or Re, more preferably Ir.

Preferred ligands are 2-phenylpyridine derivatives, 7,8-benzoquinoline derivatives, 2-(2-thienyl)pyridine derivatives, 2-(1-naphthyl)pyridine derivatives, 1-phenylisoquinoline derivatives, 3-phenylisoquinoline derivatives, or 2-phenylquinoline derivatives. All these compounds may be substituted for the blue color, eg by fluoro, cyano and/or trifluoromethyl substituents. The ancillary ligand is preferably acetylacetonate or picolinic acid.

Particularly suitable are complexes of Pt or Pd with tetradentate ligands of formula EM-16.

The compound of formula EM-16 is described in more detail in US 2007/0087219 A1, to which reference is made here for purposes of disclosure for the explanation of the substituents and subscripts in the above formula. Additionally, Pt-porphyrin complexes with extended ring systems (US2009/0061681A1) and Ir complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin-Pt(II), Tetraphenyl-Pt(II) tetrabenzoporphyrin (US2009/0061681A1), cis-bis(2-phenylpyridinato-N,C ² ')Pt(II), cis-bis(2-(2'-thienyl) pyridinato-N,C ³ ′)Pt(II), cis-bis(2-(2′-thienyl)-quinolinato-N,C ⁵ ′)Pt(II), (2-(4,6-difluorophenyl) pyridinato-N,C ² ′)Pt(II) (acetylacetonate) or tris(2-phenylpyridinato-N,C ² ′)Ir(III) (=Ir(ppy) ₃ , green), bis (2-phenylpyridinato-N,C ² )Ir(III) (acetylacetonate) (=Ir(ppy) ₂ acetylacetonate, green, US2001/0053462A1, Baldo, Thompson et al., Nature 403, (2000) , 750-753), bis(1-phenylisoquinolinato-N,C ² ′)(2-phenylpyridinato-N,C ² ′)iridium(III), bis(2-phenylpyridinato-N ,C ² ′)(1-phenylisoquinolinato-N,C ² ′)iridium(III), bis(2-(2′-benzothienyl)pyridinato-N,C ³ ′)iridium(III) (acetylaceto nate), bis(2-(4′,6′-difluorophenyl)pyridinato-N,C ² ′)iridium(III) (picolinate) (FIrpic, blue), bis(2-(4′,6′-difluoro Phenyl)pyridinato-N,C ² ′)Ir(III) (tetrakis(1-pyrazolyl)borate), tris(2-(biphenyl-3-yl)-4-tert-butylpyridine)iridium(III), (ppz ) ₂ Ir(5phdpym) (US2009/0061681A1), (45ooppz) 2Ir(5phdpym) (US2009/0061681A1), derivatives of ₂ -phenylpyridine-Ir complexes such as PQIr (=iridium(III) bis(2-phenylquino lyl-N,C ² ')acetylacetonate), tris(2-phenylisocyanate) Norinato-N,C)Ir(III) (red), bis(2-(2′-benzo[4,5-a]thienyl)pyridinato-N,C ³ )Ir (acetylacetonate) ([Btp ₂ Ir (acac)], red, Adachi et al., Appl. Phys. Lett. 78 (2001), 1622-1624).

Also suitable are complexes of trivalent lanthanides, such as Tb ³⁺ and Eu ³⁺ (J. Kido et al., Appl. Phys. Lett. 65 (1994), 2124; Kido et al., Chem. Lett. 657, 1990; US 2007/0252517 A1), or phosphorescent complexes of Pt(II), Ir(I), Rh(I) with maleonitrile dithiolate (Johnson et al., JACS 105, 1983, 1795), Re(I) tricarbonyl-diimine complexes (Inter alia Wrighton, JACS 96, 1974, 998), Os(II) complexes with cyano ligands and bipyridyl or phenanthroline ligands (Ma et al., Synth. Metals 94, 1998, 245).

Further phosphorescent emitters with tridentate ligands are described in US6824895 and US10/729238. Red-emitting phosphorescent complexes are found in US6835469 and US6830828.

Particularly preferred compounds for use as phosphorescent dopants are described inter alia in US 2001/0053462 A1 and Inorg. Chem. 2001, 40(7), 1704-1711, JACS 2001, 123(18), 4304-4312 and compounds of formula EM-17 and derivatives thereof.

Derivatives are described in US7378162B2, US6835469B2 and JP2003/253145A.

Additionally, compounds of formulas EM-18 to EM-21 and their derivatives as described in US7238437B2, US2009/008607A1 and EP1348711 can be utilized as emitters.

Quantum dots can likewise be used as emitters and these materials are disclosed in detail in WO2011/076314A1.

In particular, compounds utilized as host materials in conjunction with emissive compounds include materials from various classes of substances.

The host material generally has a larger bandgap between HOMO and LUMO than the emitter material utilized. In addition, preferred host materials exhibit the properties of either hole or electron transport materials. Additionally, the host material can have both electron and hole transport properties.

A host material is sometimes also called a matrix material, especially when the host material is used in combination with a phosphorescent emitter in an OLED.

Preferred host or co-host materials, especially for use with fluorescent dopants, are oligoarylenes (e.g. 2,2',7,7'-tetraphenylspirobifluorene or dinaphthylanthracene according to EP 676461), especially fused aromatic groups. Containing oligoarylenes such as anthracene, benzoanthracene, benzophenanthrene (DE102009005746, WO2009/069566), phenanthrene, tetracene, coronene, chrysene, fluorene, spirofluorene, perylene, phthaloperylene, naphthaloperylene, decacyclene, rubrene, etc., oligoarylenevinylenes (for example DPVBi according to EP 676461 = 4,4′-bis(2,2-diphenylethenyl)-1,1′-biphenyl or spiro-DPVBi), polypodal metal complexes (for example according to WO 04/081017), especially metals of 8-hydroxyquinoline complexes, for example metal complexes of AlQ ₃ (=aluminium(III) tris(8-hydroxyquinoline)) or bis(2-methyl-8-quinolinolato)-4-(phenylphenolato)aluminum, additionally imidazole chelates (US 2007/0092753 A1), and quinoline metal complexes, aminoquinoline-metal complexes, benzoquinoline-metal complexes, hole-conducting compounds (for example according to WO2004/058911), electron-conducting compounds, especially ketones, phosphine oxides, sulfoxides, etc. (eg according to WO2005/084081 and WO2005/084082), atropisomers (eg according to WO2006/048268), boronic acid derivatives (eg according to WO2006/117052) or benzanthracenes (eg according to WO2008/145239).

Particularly preferred compounds capable of functioning as host or co-host materials are selected from the class of oligoarylenes, including anthracene, benzanthracene and/or pyrene, or atropisomers of these compounds. An oligoarylene in the sense of the invention is intended to be understood as meaning a compound in which at least three aryl or arylene groups are attached to one another.

Preferred host materials are selected especially from compounds of formula (H-1)

(wherein Ar ⁴ , Ar ⁵ and Ar ⁶ are the same or different at each occurrence and are optionally substituted aryl or heteroaryl groups having 5 to 30 aromatic ring atoms; and p represents an integer ranging from 1 to 5; the sum of π electrons in Ar ⁴ , Ar ⁵ and Ar ⁶ is at least 30 if p=1, at least 36 if p=2, p= 3 is at least 42).

In compounds of formula (H-1), the Ar ⁵ group particularly preferably represents anthracene, the Ar ⁴ and Ar ⁶ groups are bonded at the 9 and 10 positions, wherein these groups optionally may be substituted. Very particularly preferably at least one of the Ar ⁴ and/or Ar ⁶ groups is 1- or 2-naphthyl, 2-, 3- or 9-phenanthrenyl or 2-, 3-, 4-, 5-, 6- is a condensed aryl group selected from - or 7-benzoanthracenyl. Anthracene-based compounds are described in US2007/0092753A1 and US2007/0252517A1, for example 2-(4-methylphenyl)-9,10-di-(2-naphthyl)anthracene, 9-(2-naphthyl)-10 -(1,1′-biphenyl)anthracene and 9,10-bis[4-(2,2-diphenylethenyl)phenyl]anthracene, 9,10-diphenylanthracene, 9,10-bis(phenylethynyl)anthracene, and 1,4-bis(9′-ethynylanthracenyl)benzene. Compounds containing two anthracene units (US2008/0193796A1) such as 10,10'-bis[1,1',4',1'']terphenyl-2-yl-9,9'-bisanthracenyl is also preferred.

Further preferred compounds are arylamines, styrylamines, fluoresceins, diphenylbutadiene, tetraphenylbutadiene, cyclopentadiene, tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, coumarins, oxadiazoles, bisbenzoxazolines, oxazoles, pyridines, pyrazines, imines , benzothiazole, benzoxazole, derivatives of benzimidazole (US2007/0092753A1) such as 2,2′,2″-(1,3,5-phenylene)tris[1-phenyl-1H-benzimidazole], aldazine, Stilbene, styrylarylene derivatives such as 9,10-bis[4-(2,2-diphenylethenyl)-phenyl]anthracene and distyrylarylene derivatives (US5121029), diphenylethylene, vinylanthracene, diaminocarbazole, pyran, thiopyran , diketopyrrolopyrroles, polymethines, cinnamates, and fluorescent dyes.

Derivatives of arylamines and styrylamines such as TNB (=4,4′-bis[N-(1-naphthyl)-N-(2-naphthyl)amino]biphenyl) are particularly preferred. Metal oxinoid complexes such as LiQ or _AlQ3 can be used as cohosts.

オリゴアリーレンをマトリックスとして含む好ましい化合物が、ＵＳ２００３／００２７０１６Ａ１、ＵＳ７３２６３７１Ｂ２、ＵＳ２００６／０４３８５８Ａ、ＷＯ２００７／１１４３５８、ＷＯ２００８／１４５２３９、ＪＰ３１４８１７６Ｂ２、ＥＰ１００９０４４、ＵＳ２００４／０１８３８３、ＷＯ２００５／０６１６５６Ａ１、ＥＰ０６８１０１９Ｂ１、ＷＯ２００４／０１３０７３Ａ１、ＵＳ５０７７１４２、ＷＯ２００７／ 065678, and DE 102009005746, where particularly preferred compounds are described by formulas H-2 to H-8.

Additionally, compounds that can be used as hosts or matrices include materials that are used with phosphorescent emitters.

These compounds can also be utilized as structural elements in polymers, CBP (N,N-biscarbazolylbiphenyl), carbazole derivatives (for example WO2005/039246, US2005/0069729, JP2004/288381, EP1205527 or 086851), azacarbazoles (for example according to EP 1617710, EP 1617711, EP 1731584 or JP 2005/347160), ketones (for example according to WO 2004/093207 or DE 102008033943), phosphine oxides, sulfoxides and sulfones (for example according to WO 2005/003253, aromatics), oligophenylenes Amines (for example according to US 2005/0069729), bipolar matrix materials (for example according to WO 2007/137725), silanes (for example according to WO 2005/111172), 9,9-diarylfluorene derivatives (for example according to DE 102008017591), azaboroles or boronic esters (for example WO 2006/117052), triazine derivatives (e.g. according to DE 102008036982), indolocarbazole derivatives (e.g. according to WO 2007/063754 or WO 2008/056746), indenocarbazole derivatives (e.g. according to DE 102009023155 and DE 102009031021), diazaphosphole derivatives (e.g. 050D8021) triazole derivatives, oxazoles and oxazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, distyrylpyrazine derivatives, thiopyran dioxide derivatives, phenylenediamine derivatives, tertiary aromatic amines, styrylamines, amino-substituted chalcone derivatives, indoles, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic dimethylidene compounds, carbodiimide derivatives, metal complexes of 8-hydroxyquinoline derivatives which may further contain triarylaminophenol ligands, such as AlQ ₃ (US2007/ 0134514 A1), metal complexes/polysilane compounds, and thiophene, benzothiophene and dibenzothiophene derivatives.

An example of a preferred carbazole derivative is mCP (=1,3-N,N-di-carbazolylbenzene (=9,9′-(1,3-phenylene)bis-9H-carbazole)) (formula H-9 ), CDBP (=9,9′-(2,2′-dimethyl[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole), 1,3-bis(N,N′ -dicarbazolyl)benzene (=1,3-bis(carbazol-9-yl)benzene), PVK (polyvinylcarbazole), 3,5-di(9H-carbazol-9-yl)biphenyl, and CMTTP (formula H-10) ). Compounds of particular mention are disclosed in US2007/0128467A1 and US2005/0249976A1 (formulas H-11 and H-13).

Preferred tetraaryl-Si compounds are described, for example, in US2004/0209115, US2004/0209116, US2007/0087219A1, and H.I. Gilman, E. A. Zuech, Chemistry & Industry (London, United Kingdom), 1960, 120.

Particularly preferred tetraaryl-Si compounds are described by formulas H-14 through H-21.

Particularly preferred compounds from group 4 for the preparation of matrices for phosphorescent dopants are disclosed inter alia in DE102009022858, DE102009023155, EP652273B1, WO2007/063754 and WO2008/056746, wherein particularly preferred compounds are of the formulas H-22 to Described by H-25.

With respect to the semiconductor compounds that can be utilized according to the invention and that can serve as host materials, materials containing at least one nitrogen atom are particularly preferred. These preferably include aromatic amines, triazine derivatives and carbazole derivatives. Therefore, carbazole derivatives in particular show surprisingly high efficiency. Triazine derivatives provide unexpectedly long lifetimes for electronic devices.

It may also be preferred to utilize a plurality of different matrix materials, in particular at least one electron-conducting matrix material and at least one hole-conducting matrix material, as a mixture. Equally preferred is the use of mixtures of charge transporting matrix materials and electrically inactive matrix materials which, if not to a significant extent, participate in charge transport, as described, for example, in WO 2010/108579. .

It is further possible to employ compounds that improve the transition from the singlet state to the triplet state, are used to support functional compounds with emissive properties, and improve the phosphorescent properties of these compounds. Suitable for this purpose are in particular carbazole and bridged carbazole dimer units, as described for example in WO2004/070772A2 and WO2004/113468A1. Also suitable for this purpose are ketones, phosphine oxides, sulfoxides, sulfones, silane derivatives and similar compounds, as described, for example, in WO2005/040302A1.

An n-dopant here is taken to mean a reducing agent, ie an electron donor. Preferred examples of n-dopants are W(hpp) ₄ and other electron-rich metal complexes according to WO2005/086251A2, P=N compounds (e.g. WO2012/175535A1, WO2012/175219A1), naphthylene carbodiimides (e.g. (e.g. WO2012/031735A1), free radicals and diradicals (e.g. EP1837926A1, WO2007/107306A1), pyridines (e.g. EP2452946A1, EP2463927A1), N-heterocyclic compounds (e.g. WO2009/000237A1), and acridine and phenazine (e.g. US2007/1433) ).

Additionally, the formulation may include a wide bandgap material as a functional material. A wide bandgap material is taken to mean a material within the meaning of the disclosure of US 7,294,849. These systems exhibit particularly advantageous performance data in electroluminescent devices.

A compound used as a wide bandgap material can preferably have a bandgap of 2.5 eV or more, preferably 3.0 eV or more, particularly preferably 3.5 eV or more. The bandgap can be calculated by, among other things, the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO).

Additionally, the formulation may include a hole blocking material (HBM) as a functional material. By hole-blocking material is meant a material that prevents or minimizes the transport of holes (positive charges) in multilayer systems, especially when this material is arranged in the form of a layer adjacent to the light-emitting layer or the hole-conducting layer. . Generally, hole-blocking materials have a lower HOMO level than hole-transporting materials in adjacent layers. A hole-blocking layer is often placed between the light-emitting layer and the electron-transporting layer in an OLED.

In principle, any known hole blocking material can be used. In addition to other hole-blocking materials described elsewhere in this application, advantageous hole-blocking materials include metal complexes (US2003/0068528) such as bis(2-methyl-8-quinolinolato)(4-phenylpheno Rath)aluminum (III) (BAlQ) and the like. Fac-tris(1-phenylpyrazolato-N,C2)-iridium(III) (Ir(ppz) ₃ ) has also been utilized for this purpose (US2003/0175553A1). Phenanthroline derivatives, such as BCP, or phthalimides, such as TMPP, are likewise available.

Further advantageous hole blocking materials are described in WO00/70655A2, WO01/41512 and WO01/93642A1.

Additionally, the formulation may include an electron blocking material (EBM) as a functional material. Electron-blocking material means a material that prevents or minimizes the transport of electrons in a multilayer system, especially if this material is arranged in the form of a layer adjacent to the light-emitting layer or the electron-conducting layer. Generally, electron blocking materials have a higher LUMO level than electron transporting materials in adjacent layers.

In principle, any known electron blocking material can be used. Advantageous electron blocking materials, in addition to other electron blocking materials described elsewhere in this application, are transition metal complexes such as Ir(ppz) ₃ (US 2003/0175553).

Electron blocking materials can preferably be selected from amines, triarylamines and derivatives thereof.

Further, the organic semiconductor material in the formulation, if it is a low molecular weight compound (i.e. "small molecule"), is preferably 3,000 g/mol or less, more preferably 2,000 g/mol or less, most preferably 1,000 g/mol. /mol or less.

Also of particular interest are semiconductor compounds characterized by a high glass transition temperature. In this context, particularly preferred functional compounds that can be utilized as organic semiconductor materials in formulations have a glass transition temperature of 70° C. or higher, preferably 100° C. or higher, more preferably 125° C. or higher, most preferably 150° C. or higher.

The formulation may further comprise a polymer as organic semiconducting material. The compounds described above as organic semiconductor materials often have relatively low molecular weights and can also be mixed with polymers. It is likewise possible to incorporate these compounds covalently into polymers. This is possible in particular with compounds substituted by reactive leaving groups such as bromine, iodine, chlorine, boronic acid or boronate esters, or by reactive polymerizable groups such as olefins or oxetanes. They can be used as monomers for the preparation of corresponding oligomers, dendrimers or polymers. Oligomerization or polymerization here preferably occurs via halogen or boronic acid functionalities or via polymerizable groups. Furthermore, it is possible to crosslink the polymer via groups of this type. The compounds and polymers according to the invention can be utilized as crosslinked or non-crosslinked layers.

Polymers that can be used as organic semiconducting materials often contain the units or structural elements described in the context of the above compounds, inter alia those disclosed and extensively described in WO02/077060A1, WO2005/014689A2 and WO2011/076314A1. These are incorporated herein by reference. Functional materials can originate, for example, from the following classes:
Group 1: structural elements capable of producing hole-injection and/or hole-transport properties; group 2: structural elements capable of producing electron-injection and/or electron-transport properties; group 3: groups 1 and 2 a structural element that combines the properties described in relation to
Group 4: Structural elements with luminescent properties, in particular phosphorescent groups;
Group 5: Structural elements that improve the transition from the so-called singlet state to the triplet state;
Group 6: Structural elements that influence the morphology or emission color of the resulting polymer; Group 7: Structural elements typically used as scaffolds.

Structural elements here may also have different functions, and no clear assignment need be advantageous. For example, Group 1 structural elements may function as scaffolds as well.

Polymers with hole-transporting or hole-injecting properties that are used as organic semiconductor materials containing structural elements from group 1 may preferably also contain units corresponding to the hole-transporting or hole-injecting materials described above. good.

Further preferred structural elements of group 1 are, for example, triarylamines, benzidines, tetraaryl-para-phenylenediamines, carbazoles, azulenes, thiophenes, pyrrole and furan derivatives, and further O-, S- or N-containing heterocycles with high HOMO is a compound of the formula These arylamines and heterocyclic compounds preferably have a HOMO above -5.8 eV (vs. vacuum level), particularly preferably above -5.5 eV.

Especially preferred are polymers with hole-transporting or hole-injecting properties containing at least one repeat unit of the formula HTP-1 below:

(Wherein the symbols have the following meanings:
Ar ¹ is in each case the same or different for different repeating units and is a single bond or an optionally substituted monocyclic or polycyclic aryl group;
Ar ² is in each case the same or different for different repeat units and is an optionally substituted monocyclic or polycyclic aryl group;
Ar ³ is in each case the same or different for different repeat units and is an optionally substituted monocyclic or polycyclic aryl group;
m is 1, 2 or 3).

Particularly preferred are repeating units of HTP-1 selected from the group consisting of units of the formulas HTP-1A to HTP-1C:

(Wherein the symbols have the following meanings:
R ^a is the same or different at each occurrence and is H, substituted or unsubstituted aromatic or heteroaromatic group, alkyl, cycloalkyl, alkoxy, aralkyl, aryloxy, arylthio, alkoxycarbonyl, silyl or carboxyl group , a halogen atom, a cyano group, a nitro group, or a hydroxy group;
r is 0, 1, 2, 3 or 4;
s is 0, 1, 2, 3, 4 or 5).

Especially preferred are polymers with hole-transporting or hole-injecting properties containing at least one repeat unit of formula HTP-2:

(Wherein the symbols have the following meanings:
T ¹ and T ² are independently selected from thiophene, selenophene, thieno[2,3-b]thiophene, thieno[3,2-b]thiophene, dithienothiophene, pyrrole and aniline, wherein these the group may be substituted by one or more radicals R ^b ;
R ^b is halogen, -CN, -NC, -NCO, -NCS, -OCN, -SCN, -C(=O)NR ⁰ R ⁰⁰ , -C(=O)X, -C( ═O) R ⁰ , —NH ₂ , —NR ⁰ R ⁰⁰ , —SH, —SR ⁰ , —SO ₃ H, —SO ₂ R ⁰ , —OH, —NO ₂ , —CF ₃ , —SF ₅ , optional independently from an optionally substituted silyl, carbyl or hydrocarbyl group having from 1 to 40 carbon atoms, optionally substituted with and optionally containing one or more heteroatoms selected;
R ⁰ and R ⁰⁰ are each independently H or optionally substituted and optionally substituted having 1 to 40 carbon atoms, optionally containing one or more heteroatoms a carbyl or hydrocarbyl group which may be
Ar ⁷ and Ar ⁸ are, independently of each other, optionally substituted and optionally bonded at the 2,3-position of one or both of the adjacent thiophene or selenophene groups, monocyclic or polycyclic represents a cyclic aryl or heteroaryl group;
c and e are independently of each other 0, 1, 2, 3 or 4, where 1<c+e≦6;
d and f are independently of each other 0, 1, 2, 3 or 4).

Preferred examples of polymers with hole-transporting or hole-injecting properties are described inter alia in WO2007/131582A1 and WO2008/009343A1.

Polymers with electron-injecting and/or electron-transporting properties that are used as organic semiconductor materials containing structural elements from group 2 may preferably also contain units corresponding to the electron-injecting and/or electron-transporting materials described above. good.

Further preferred structural elements of group 2 with electron-injecting and/or electron-transporting properties are, for example, from pyridine, pyrimidine, pyridazine, pyrazine, oxadiazole, quinoline, quinoxaline and phenazine groups, additionally triarylborane groups, or derived from additional O-, S- or N-containing heterocyclic compounds with low LUMO levels. These group 2 structural elements preferably have a LUMO of less than -2.7 eV (vs. vacuum level), particularly preferably less than -2.8 eV.

The organic semiconducting material can preferably be a polymer containing structural elements from group 3, wherein structural elements improving hole and electron mobility (i.e. structural elements from groups 1 and 2) are , are directly coupled to each other. Some of these structural elements can act as emitters, where the emission color can be shifted to green, red or yellow, for example. Their use is therefore advantageous, for example, for the production of other emission colors or broadband emission by naturally blue-emitting polymers.

Polymers with luminescent properties which are used as organic semiconductor materials containing structural elements from group 4 may preferably contain units corresponding to the emitter materials described above. Preference is given here to polymers containing the aforementioned luminescent metal complexes containing corresponding units containing phosphorescent groups, in particular elements of groups 8-10 (Ru, Os, Rh, Ir, Pd, Pt).

Polymers used as organic semiconducting materials containing units of group 5 that improve the transition from the so-called singlet state to the triplet state can preferably be used to support phosphorescent compounds, preferably the above groups It is a polymer containing 4 structural elements. A polymeric triplet matrix can be used here.

Suitable for this purpose are, in particular, carbazole and linked carbazole dimer units as described, for example, in DE 103 04 819 A1 and DE 103 28 627 A1. Also suitable for this purpose are ketones, phosphine oxides, sulfoxides, sulfones and silane derivatives, as described, for example, in DE 103 49 033 A1, and similar compounds. Additionally, preferred structural units can be derived from the compounds described above in connection with the matrix material utilized with the phosphorescent compound.

Further organic semiconducting materials are preferably polymers containing units of group 6 which influence the morphology or emission color of the polymer. Besides the polymers mentioned above, these are those which have at least one further aromatic or another conjugated structure not counted in the above groups. Thus, these groups have little or no effect on charge carrier mobility, non-organometallic complexes, or singlet-triplet transitions.

Structural units of this type can influence the morphology or emission color of the resulting polymer. Depending on the structural units, these polymers can therefore also be used as emitters.

For fluorescent OLEDs, therefore, aromatic structural elements with 6 to 40 C atoms or trans-, stilbene- or bisstyrylarylene derivative units are preferred, each of which may be substituted by one or more radicals. . Here, 1,4-phenylene, 1,4-naphthylene, 1,4- or 9,10-anthrylene, 1,6-, 2,7- or 4,9-pyrenylene, 3,9- or 3,10 -perylenylene, 4,4'-biphenylene, 4,4''-terphenylylene, 4,4'-bi-1,1'-naphthylene, 4,4'-tranylene, 4,4'-stilbenylene, or 4,4 Particular preference is given to using groups derived from ''-bisstyrylarylene derivatives.

The polymers used as organic semiconductor materials preferably contain units of group 7 and preferably aromatic structures with 6 to 40 C atoms which are often used as backbones.

These are inter alia 4,5-dihydropyrene derivatives, 4,5,9,10-tetra-hydropyrene derivatives, fluorene derivatives, for example disclosed in WO2003/020790A1, for example in US5962631, WO2006/052457A2 and WO2006/118345A1. 9,9-spirobifluorene derivatives such as those disclosed in WO2005/104264A1, such as 9,10-phenanthrene derivatives disclosed in WO2005/014689A2, such as 9,10-dihydrophenanthrene derivatives disclosed in WO2004/041901A1 and 5,7-dihydrodibenzoxepine derivatives and cis- and trans-indenofluorene derivatives disclosed in WO2004/113412A2 and binaphthylene derivatives disclosed for example in WO2006/063852A1 and for example WO2005/056633A1, EP1344788A1, Including further units disclosed in WO2007/043495A1, WO2005/033174A1, WO2003/099901A1 and DE102006003710.

Fluorene derivatives disclosed for example in US 5,962,631, WO2006/052457A2 and WO2006/118345A1, e.g. spirobifluorene derivatives disclosed in WO2003/020790A1, e.g. Structural units of group 7 selected from benzofluorene, dibenzofluorene, benzothiophene and dibenzofluorene groups and their derivatives are particularly preferred.

A particularly preferred group 7 structural element is represented by the general formula PB-1:

(wherein the signs and subscripts have the following meanings:
A, B and B' are each also the same or different for different repeating units, preferably -CR ^c R ^d -, -NR ^c -, -PR ^c -, -O-, - S-, -SO-, -SO _2- , -CO-, -CS-, -CSe-, -P(=O)R ^c -, -P(=S)R ^c - and -SiR ^c R ^d - is a divalent group selected from;
R ^c and R ^d at each occurrence are H, halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(=O)NR ⁰ R ⁰⁰ , —C(=O) X, —C(=O)R ⁰ , —NH ₂ , —NR ⁰ R ⁰⁰ , —SH, —SR ⁰ , —SO ₃ H, —SO ₂ R ⁰ , —OH, —NO ₂ , —CF ₃ , —SF ₅ , an optionally substituted silyl, carbyl or hydrocarbyl group having from 1 to 40 carbon atoms, optionally substituted and optionally containing one or more heteroatoms wherein R ^c and R ^d may optionally form a spiro group with the fluorene radical to which they are attached;
X is halogen;
R ⁰ and R ⁰⁰ are each independently H or optionally substituted and optionally substituted and optionally containing one or more heteroatoms having 1 to 40 carbon atoms a carbyl or hydrocarbyl group which may be
g is independently 0 or 1 at each occurrence and h is independently 0 or 1 at each occurrence, wherein the sum of g and h in the subunit is preferably 1 ;
m is an integer of 1 or more;
Ar ¹ and Ar ² independently of each other are optionally substituted monocyclic or polycyclic aryl optionally bonded to the 7,8- or 8,9-position of the indenofluorene or representing a heteroaryl group;
a and b are 0 or 1 independently of each other).

When the R ^c and R ^d groups form a spiro group with the fluorene group to which they are attached, this group preferably represents spirobifluorene.

Particularly preferred are repeat units of formula PB-1 selected from the group consisting of units of formulas PB-1A to PB-1E:

(wherein R ^c has the meaning given above for formula PB-1, r is 0, 1, 2, 3 or 4 and R ^e has the same meaning as the radical R ^c ) .

R ^e is preferably -F, -Cl, -Br, -I, -CN, -NO ₂ , -NCO, -NCS, -OCN, -SCN, -C(=O)NR ⁰ R ⁰⁰ , -C (=O)X, -C(=O)R ⁰ , -NR ⁰ R ⁰⁰ , optionally substituted silyl, aryl or hetero with 4 to 40, preferably 6 to 20 C atoms an aryl group or a linear, branched or cyclic alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 20, preferably 1 to 12 C atoms, wherein , one or more hydrogen atoms may optionally be replaced by F or Cl, and the R ⁰ , R ⁰⁰ groups and X have the meanings given above for formula PB-1.

Particularly preferred are repeat units of formula PB-1 selected from the group consisting of units of formulas PB-1F to PB-1I:

(Wherein the symbols have the following meanings:
L is H, halogen or an optionally fluorinated linear or branched alkyl or alkoxy group with 1 to 12 C atoms, preferably methyl, i-propyl, t-butyl , representing n-pentoxy or trifluoromethyl;
L′ is an optionally fluorinated linear or branched alkyl or alkoxy group with 1 to 12 C atoms, preferably representing n-octyl or n-octyloxy).

Polymers containing two or more of the structural elements of groups 1-7 above are preferred for the practice of this invention. Furthermore, it may be provided that the polymer preferably contains two or more of the structural elements from one group above, ie comprises a mixture of structural elements selected from one group.

In particular, besides at least one structural element (group 4) having luminescent properties, preferably at least one phosphorescent group, at least one further structural element of groups 1 to 3, 5 or 6 above can be added. Particular preference is given to polymers containing, wherein these are preferably selected from groups 1-3.

The proportions of the various classes of groups, when present in the polymer, can be within wide ranges, where these are known to those skilled in the art. If in each case the proportion of one class present in the polymer selected from structural elements of groups 1 to 7 above is preferably in each case 5 mol % or more, particularly preferably in each case 10 mol % or more , amazing benefits can be achieved.

The preparation of white-emitting copolymers is described in detail inter alia in DE 103 43 606 A1.

To improve solubility, the polymer may contain corresponding groups. Preferably, the polymer contains substituents so that an average of at least 2 non-aromatic carbon atoms, particularly preferably at least 4 and especially preferably at least 8 non-aromatic carbon atoms per repeat unit It may be specified that there is, where the average relates to the number average. Here individual carbon atoms can be replaced by O or S, for example. However, it is possible that a certain proportion, optionally all repeat units, do not contain substituents containing non-aromatic carbon atoms. Short-chain substituents are preferred here, since long-chain substituents can adversely affect the layers obtainable with organic functional materials. The substituents preferably contain up to 12 carbon atoms, preferably up to 8 carbon atoms, particularly preferably up to 6 carbon atoms in the straight chain.

The polymers utilized as organic semiconductor materials according to the invention can be random, alternating or regioregular copolymers, block copolymers, or combinations of these copolymer morphologies.

In a further aspect, the polymer utilized as organic semiconducting material can be a non-conjugated polymer with side chains, where this aspect is particularly important for polymer-based phosphorescent OLEDs. In general, phosphorescent polymers can be obtained by free-radical copolymerization of vinyl compounds, wherein these vinyl compounds have at least one unit with a phosphorescent emitter and /or contain at least one charge transport unit. Further phosphorescent polymers are described inter alia in JP2007/211243A2, JP2007/197574A2, US7250226B2 and JP2007/059939A.

In a further preferred embodiment, the non-conjugated polymer contains backbone units linked together by spacer units. Examples of such triplet emitters based on non-conjugated polymers based on backbone units are disclosed in DE 10 2009 023 154, for example.

In a further preferred embodiment, non-conjugated polymers can be designed as fluorescent emitters. Preferred fluorescent emitters based on non-conjugated polymers with side chains contain anthracene or benzoanthracene groups, or derivatives of these groups, in side chains, where these polymers are for example JP 2005/108556, JP 2005/285661 and JP2003/338375.

These polymers can often be utilized as electron or hole transport materials, where they are preferably designed as non-conjugated polymers.

Furthermore, the organic semiconductor material in the formulation preferably has a molecular weight _Mw of 10,000 g/mol or more, particularly preferably of 20,000 g/mol or more, particularly preferably of 50,000 g/mol or more, in the case of polymeric organic semiconductor materials. have

Here, the molecular weight M _w of the polymer is preferably in the range from 10,000 to 2,000,000 g/mol, particularly preferably in the range from 20,000 to 1,000,000 g/mol, very particularly preferably 50,000 g/mol. 000 to 300,000 g/mol. The molecular weight _Mw is determined by GPC (=gel permeation chromatography) against internal polystyrene standards.

The publications cited above for descriptions of semiconductor compounds are hereby incorporated by reference for the purpose of disclosure.

The formulations according to the invention may contain all the organic semiconducting materials required for the production of the respective functional layer of the electronic device. For example, if the hole-transporting, hole-injecting, electron-transporting or electron-injecting layer is constructed precisely from one functional compound, the formulation contains precisely this compound as the organic semiconductor material. For example, if the emissive layer comprises an emitter in combination with a matrix or host material, the formulation may include a mixture of emitter and matrix or host material as the organic semiconductor material, as described in more detail elsewhere in this application. contain exactly.

Besides the aforementioned ingredients, the formulations according to the invention may contain further additives and processing aids. These are, inter alia, surface-active substances (surfactants), lubricants and greases, viscosity-regulating additives, conductivity-increasing additives, dispersants, hydrophobizing agents, adhesion promoters, flow improvers , defoamers, deaerators, diluents which may be reactive or non-reactive, fillers, adjuvants, processing aids, dyes, pigments, stabilizers, sensitizers, nanoparticles, and inhibitors including.

More preferably, the solution contains at least two or more solvents to control the drying and fluid properties of the solution. The second and subsequent solvents used are expected to be those that provide good solubility for the material of the printed layer, or blends of solvents with similar boiling points. If the solubility is not good, the film does not form a homogeneous film and tends to crystallize.

Small amounts of polymers can also be included to facilitate film formation without affecting device performance. Surfactants or volatile surfactants can be added to the ink at levels that do not impair device performance. Additionally, a film forming agent can be added to the solution.

The solution may be of the hot-melt type, ie liquid at the printing temperature and having a viscosity of less than 5 cP at 10° C. above the melting point of the solvent, but solid at room temperature. Solvents must be capable of being evaporated or sublimed at atmospheric or reduced pressure (down to 10 ⁻⁷ torr), optionally with heat up to 200° C., to leave essentially no solvent residue. must.

Listed below are some exemplary solvents that can be used in the solutions of the present invention. However, WO2011/076325A1 and other prior art documents also list possible solvents that can be used for the solution as long as the solution has a resulting viscosity of 5 cP or less.

The invention will now be described in more detail by reference to the following examples, which are illustrative only and do not limit the scope of the invention.

[Example]
Example 1
A printing ink was prepared by the following procedure.

0.10 g of hole transport polymer HTM-001 was weighed into a glass vial. To this was added 20 ml of mesitylene. A small magnetic stirrer bar was added to seal the glass vial. This was warmed to 35-40° C. and stirred for 2 hours to ensure complete dissolution of the solid material. After dissolution, the lid was removed and helium was bubbled through for 20 minutes to degas, after which the container was placed in a vacuum desiccator and left overnight to remove the helium.

5 ml of ink was filtered using a 0.45μ filter (25 mm diameter, from Millipore) into the ink reservoir mounted on the Pixdro LP50 and then purged through the Fujifilm SQ printhead.

An additional 10 ml of ink was filtered into the ink container. To evaluate the printing performance of the inks, a full inkjet test was performed and the inkjet behavior was observed and described. The inkjet waveform was optimized and the effect of varying voltage/frequency and pulse width on droplet velocity was also evaluated. Using a standard waveform, one or two droplets could easily be obtained, and with further manipulation it was possible to obtain multiple droplets.
Print head: Fujifilm Dimatix SQ
Drop volume: 10 pl Drop volume Drop diameter: about 27 microns
Temperature: 25°C
Formulation: 0.5% HTM-001 in mesitylene
Viscosity: 0.975 cp at 20°C
Pixel width: 23μ
Bank width: 5μ
Viscosity is determined by measuring with an AR-G2 rheometer manufactured by TA Instruments at a temperature of 25°C. This measurement can be performed over a shear range of 10-1000 s ⁻¹ using a 40 mm parallel plate configuration.
Single Drop Printing FIG. 2 shows the optimized waveform and the resulting drop for single drop printing. The delay on this image was 200 μs, so the droplet velocity is around 2 ms ⁻¹ .

After performing the initial alignment, printing with a single drop is shown in FIG. In this case the alignment is good and the droplet is centered in the channel. Extravasation is evident in both cases.

It was concluded that using a single drop of 10 pl it was not possible to print a single channel and spillover was always present.

Example 2
Printing Two Drops Inks were prepared in a manner similar to that described in Example 1. The printing parameters used were quite standard, with the same initial rise and fall times. As shown, two droplets of generally uniform size are formed.

FIG. 4 shows the optimized waveform and resulting drop formation when printing two drops. The strobe delay was 200 μs, so the velocity of the fast droplet was around 3 ms ⁻¹ .

FIG. 5 shows the result of printing using two drops. Again, it is found impossible to achieve single-channel printing.

These have a drop volume of 4-6 pl, resulting in a diameter of approximately 20-23 microns, which is very close to the size of the printed channels. Therefore, it is not surprising that these drops did not land within a width of one pixel; Slight deviations from printing can result in ink locations in adjacent channels.

Example 3
Printing Multiple Drops The final test is to print multiple drops. When examining the effect of printing parameters on droplet formation, it was observed that under certain conditions, a series of relatively stable droplets of similar size was formed. The printing parameters have been optimized to give as many small droplets as possible with the best separation.

FIG. 6 shows the waveform for obtaining multiple drops and the resulting droplet formation.

FIG. 6 shows that a series of approximately equally sized droplets can be achieved. In this case there are 7 individual droplets. These droplets are expected to have a volume of around 1.45 pl and a volume of around 14 um in diameter. It is now much smaller than the channel.

Example 7 shows that it is possible to achieve printing using multiple drops, in this case seven drops.

This clearly shows that by changing the waveform it is possible to obtain multiple droplets and thus successful printing.
Below, the matters described in the claims as originally filed are added as they are.
[1] A method of manufacturing one or more layers of an OLED containing at least one organic semiconductor material, comprising:
- selecting a printhead for a piezoelectric printing device for printing said OLED; - printing a solution onto a substrate using said piezoelectric printing device, said solution comprising at least one organic a process containing a solvent and at least one organic semiconductor material; and
- drying the printed solution;
including
the solution has a viscosity of less than 5 cP;
characterized in that the electrical impulses for actuating the piezoelectric printing device are controlled corresponding to the printing head used such that at least two droplets of essentially equal size are formed. ,Method.
[2] The method of [1], wherein the solution comprises a small molecule organic semiconductor material at a concentration of at least 1.0%.
[3] The method of [1], wherein the solution contains a polymeric organic semiconductor material at a concentration of 2.5% or less.
[4] The method of any one of [1] to [3], wherein the solution comprises at least two organic solvents resulting in a viscosity of less than 5 cP.
[5] The method of [4], wherein the boiling points of the at least two solvents have a minimum difference of at least 10°C.
[6] The method of any one of [1] to [5], wherein the solution has two solvents with boiling points in the range of 150°C to 300°C.
[7] The method of any one of [1] to [6], wherein the step of drying the solution comprises a vacuum drying process after printing the OLED.
[8] The method of [7], wherein the curing step in the vacuum drying process is performed at a temperature of 20°C or higher.
[9] Any of [1] to [8], wherein controlling the electrical impulse for actuating the piezoelectric printing device comprises controlling a maximum voltage, rise, fall and/or length of the electrical impulse or the method according to item 1.
[10] The method according to any one of [1] to [9], wherein the printing is performed using a print head with a size of 30 pl or less.
[11] An OLED manufactured using the method according to any one of [1] to [10].
[12] A piezoelectric printing device having a printhead, wherein said piezoelectric printing device is supplied with a printing solution comprising at least one organic solvent and at least one organic semiconductor material, said printhead essentially comprising: A piezoelectric printing device, characterized in that it is actuated by electrical impulses which are controlled correspondingly to said printhead such that at least two droplets of size equal to are formed.
[13] The piezoelectric printing device of [12], wherein the print head has a size of 30 pl or less.
[14] The piezoelectric printing device of [12] or [13], wherein the printing solution comprises small molecule OLEDs at a concentration of at least 1.0%.
[15] The piezoelectric printing device of [12] or [13], wherein the printing solution comprises a polymer OLED (POLED) concentration of 2.5% or less.
[16] The piezoelectric printing device of any one of [12]-[15], wherein the printing solution comprises at least two organic solvents resulting in a viscosity of less than 5 cP.
[17] The piezoelectric printing device of any one of [12]-[16], wherein the boiling points of the at least two printing solvents have a minimum difference of at least 10°C.
[18] The piezoelectric printing device of any one of [12] to [17], wherein the printing solution has two solvents with boiling points in the range of 150°C to 300°C.

Claims (10)

A method of manufacturing one or more layers of an OLED containing at least one organic semiconductor material, comprising:
- selecting a printhead for a piezoelectric printing device for printing said OLED; - printing a solution onto a substrate using said piezoelectric printing device, said solution comprising at least one organic containing a solvent and at least one organic semiconductor material; and - drying the printed solution,
the solution has a viscosity of less than 5 cP;
The electrical impulse for actuating the piezoelectric printing device is sized such that at least two droplets are formed with a diameter difference of no more than 20% between the droplet having the largest diameter and the droplet having the smallest diameter. is controlled corresponding to said print head used, which produces droplets of 30 pl or less. 2. The method of claim 1, wherein the solution comprises a small molecule organic semiconductor material concentration of at least 1.0%. 2. The method of claim 1, wherein the solution contains a concentration of polymeric organic semiconductor material of 2.5% or less. 4. A method according to any preceding claim, wherein the solution comprises at least two organic solvents resulting in a viscosity of less than 5 cP. 5. The method of claim 4, wherein the boiling points of said at least two organic solvents have a minimum difference of at least 10<0>C. 6. A method according to any one of claims 1 to 5, wherein the solution comprises two organic solvents with boiling points in the range 150[deg.]C to 300[deg.]C. 7. The method of any one of claims 1-6, wherein the step of drying the solution comprises a vacuum drying process after printing the OLED. 8. The method of claim 7, wherein the curing step in the vacuum drying process is performed at a temperature of 20[deg.]C or higher. 9. Any one of the preceding claims, wherein controlling the electrical impulse for actuating the piezoelectric printing device comprises controlling the maximum voltage, rise, fall and/or length of the electrical impulse. the method of. 10. A method according to any one of the preceding claims, wherein said printing is performed with a printhead of size 30pl or less.

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