Source: https://patents.justia.com/patent/20200006674
Timestamp: 2020-02-19 23:03:42
Document Index: 263658587

Matched Legal Cases: ['§119', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60']

US Patent Application for STABILITY OLED MATERIALS AND DEVICES Patent Application (Application #20200006674 issued January 2, 2020) - Justia Patents Search
Justia Patents US Patent Application for STABILITY OLED MATERIALS AND DEVICES Patent Application (Application #20200006674)
Jul 1, 2019 - Universal Display Corporation
Organic light emitting materials and devices comprising phosphorescent metal complexes comprising ligands comprising aryl or heteroaryl groups substituted at both ortho positions are described. An organic light emitting device, comprising: an anode, a hole transport layer; an organic emissive layer comprising an emissive layer host and an emissive dopant; an electron impeding layer; and electron transport layer; and a cathode disposed, in that order, over a substrate.
This application is a continuation of U.S. patent application Ser. No. 14/713,615, filed May 15, 2015, which is a divisional of U.S. patent application Ser. No. 11/241,981, filed Oct. 4, 2005, now U.S. Pat. No. 9,051,344, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 60/678,170, filed May 6, 2005; U.S. Provisional Application No. 60/701,929, filed Jul. 25, 2005; and U.S. Provisional Application No. 60/718,336, filed Sep. 20, 2005, the disclosures of which are incorporate herein by reference in their entirety.
The claimed invention was made by, on behalf of, and/or in connection with one or more of the following parties to a joint university corporation research agreement: Princeton University, University of Southern California, and Universal Display Corporation. The agreement was in effect on and before the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within the scope of the agreement.
The present invention generally relates to organic light emitting devices (OLEDs), and organic compounds used in these devices, as well as phoshorescent OLEDs having an electron impeding layer.
This application is also related to U.S. Pat. No. 8,148,891, which issued Apr. 3, 2012. The contents of this patent is herein incorporated by reference in their entirety. In one embodiment, the present invention provides an organic light emitting device, comprising: an anode; a hole transport layer; an organic emissive layer comprising an emissive layer host and an emissive dopant; an electron impeding layer; an electron transport layer; and a cathode disposed, in that order, over a substrate.
FIG. 63a and FIG. 63b show a device having an electron impeding layer and an energy level diagram for the device.
Generally, the excitons in an OLED are believed to be created in a ratio of about 3:1, i.e., approximately 75% triplets and 25% singlets. See, Adachi et al., “Nearly 100% Internal Phosphorescent Efficiency In An Organic Light Emitting Device,” J. Appl. Phys., 90, 5048 (2001), which is incorporated by reference in its entirety. In many cases, singlet excitons may readily transfer their energy to triplet excited states via “intersystem crossing,” whereas triplet excitons may not readily transfer their energy to singlet excited states. As a result, 100% internal quantum efficiency is theoretically possible with phosphorescent OLEDs. In a fluorescent device, the energy of triplet excitons is generally lost to radiationless decay processes that heat-up the device, resulting in much lower internal quantum efficiencies. OLEDs utilizing phosphorescent materials that emit from triplet excited states are disclosed, for example, in U.S. Patent No. 6,303,238, which is incorporated by reference in its entirety.
Hole transport layer 125 may include a material capable of transporting holes. Hole transport layer 130 may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. a-NPD and TPD are examples of intrinsic hole transport layers. An example of a p-doped hole transport layer is m-MTDATA doped with F4-TCNQ at a molar ratio of 50:1, as disclosed in United States Patent Application Publication No. 2003-0230980 to Forrest et al., which is incorporated by reference in its entirety. Other hole transport layers may be used.
Generally, injection layers are comprised of a material that may improve the injection of charge carriers from one layer, such as an electrode or an organic layer, into an adjacent organic layer. Injection layers may also perform a charge transport function. In device 100, hole injection layer 120 may be any layer that improves the injection of holes from anode 115 into hole transport layer 125. CuPc is an example of a material that may be used as a hole injection layer from an ITO anode 115, and other anodes. In device 100, electron injection layer 150 may be any layer that improves the injection of electrons into electron transport layer 145. LiF/Al is an example of a material that may be used as an electron injection layer into an electron transport layer from an adjacent layer. Other materials or combinations of materials may be used for injection layers. Depending upon the configuration of a particular device, injection layers may be disposed at locations different than those shown in device 100. More examples of injection layers are provided in U.S. Pat. No. 7,071,615, which issued Jul. 4, 2006, andis incorporated by reference in its entirety. A hole injection layer may comprise a solution deposited material, such as a spin-coated polymer, e.g., PEDOT:PSS, or it may be a vapor deposited small molecule material, e.g., CuPc or MTDATA.
A protective layer may be used to protect underlying layers during subsequent fabrication processes. For example, the processes used to fabricate metal or metal oxide top electrodes may damage organic layers, and a protective layer may be used to reduce or eliminate such damage. In device 100, protective layer 155 may reduce damage to underlying organic layers during the fabrication of cathode 160. Preferably, a protective layer has a high carrier mobility for the type of carrier that it transports (electrons in device 100), such that it does not significantly increase the operating voltage of device 100. CuPc, BCP, and various metal phthalocyanines are examples of materials that may be used in protective layers. Other materials or combinations of materials may be used. The thickness of protective layer 155 is preferably thick enough that there is little or no damage to underlying layers due to fabrication processes that occur after organic protective layer 160 is deposited, yet not so thick as to significantly increase the operating voltage of device 100. Protective layer 155 may be doped to increase its conductivity. For example, a CuPc or BCP protective layer 160 may be doped with Li. A more detailed description of protective layers may be found in U.S. Pat. No. 7,071,615, which issued Jul. 4, 2006, and is incorporated by reference in its entirety.
Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), such as described in U.S. Pat. No. 7,431,968, which issued Oct. 7, 2008, and is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink jet and OVJD. Other methods may also be used. The materials to be deposited may be modified to make them compatible with a 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 3-20 carbons is a preferred range. Materials with asymmetric structures may have better solution processibility than those having symmetric structures, 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.
It is also believed that the compounds having the ortho-disubstituted second ring will also increase the dihedral angle between the first and second rings, thereby substantially de-conjugating the second ring from the first ring. Electronic effects associated with such de-conjugation are believed to include: (i) a blue-shift of the phosphorescent emission, relative to an otherwise equivalent compound without ortho substitution, and (ii) a de-coupling of the singlet and triplet energies, such that it is possible to lower the energy of the singlet excited state and reduce the electrochemical gap of the dopant without red-shifting the phosphorescent emission. Lowering the singlet energy is expected to reduce the likelihood of singlet excited state decomposition, thereby resulting in improved device lifetimes. Reduction of the dopant electrochemical gap is expected to allow for the fabrication of lower operating voltage OLED devices. Density Functional Theory (DFT) calculations using Gaussian 98 with the G98B3lyp/cep-31 g basis set indicate that certain compounds of the current invention wherein the second ring is substituted with an aryl or heteroaryl ring or with an electron-withdrawing group are characterized by a LUMO which is substantially localized on the second ring and a HOMO which is substantially localized on the metal. These calculations further indicate that the lowest energy singlet transition has substantial metal-centered HOMO to second ring-centered LUMO character, while the lowest energy triplet transition is primarily from a metal-centered-HOMO to a higher-lying unoccupied orbital localized on the those rings directly bonded to the metal. As such, these calculations indicate that it is possible to reduce the LUMO energy of the dopant, and thence the both the singlet excited state energy and electrochemical gap, without reducing the triplet energy and red-shifting the emission. It is a novel feature of this invention to provide a means of minimizing the energy of the singlet excited state of the dopant without reducing the triplet energy. Depending on the substitution pattern, it is expected to be possible to either localize the LUMO of the molecule on the second ring, or to localize the HOMO on the second ring, and in both cases associate the singlet transition with the second ring while localizing the triplet transition on the metal and those groups directly bonded to it. It is understood that whether the LUMO or HOMO is localized on the second ring will depend on the substitution pattern of the entire molecule. In general, however, substitution of the second ring with aryl, heteroaryl or electron-withdrawing groups will tend to lower the energies of the orbitals associated with the second ring and can be used to localize the LUMO on that ring, while substitution of the second ring with electron donating groups can be used to localize the HOMO on that ring.
In the context of this invention, by “Set 1”, we mean structures d1 through d19 shown below:
Rla-e are each independently selected from the group consisting of hydrogen, hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, and F; in addition, any two of Rla-e may be linked to form a ring.
By “Set 2b” we mean the group consisting of 2,6-di-isopropylphenyl, 2,4,6-tri-isopropylphenyl, 2,6-di-isopropyl-4-phenylphenyl, 2,6-di-isopropyl-4-(3,5-dimethylphenyl)phenyl, 2,6-di-isopropyl-4-(2,6-dimethylphenyl)phenyl, 2,6-di-isopropyl-4-(4-pyridyl)phenyl, 2,6-di-isopropyl-4-(2,6-dimethyl-4-pyridyl)phenyl, 2,4-di-isopropyl-3-naphthyl, 2,6-di-isopropyl-4-cyanophenyl, 2,6-di-isopropyl-4-(9-carbazolyl)phenyl, 2,6-di-isopropyl-4-(9-phenyl-3-carbazolyl)phenyl, 2,6-di-isopropyl-4-(2,6-dimethyl-4-cyanophenyl)phenyl, 2,6-di-tert-butylphenyl, 2,6-di-tert-butyl-4-(3,5-dimethylphenyl)phenyl, 2,6-bit(trimethylsilyl)phenyl, 2,6-bis(dimethylphenylsilyl)phenyl, and 2,6-bis(trime thylsilyl)-4-(3,5-dimethylphenyl)-phenyl.
By “Set 2d” we mean structures c1 through c9 shown below:
Rla,e are each in dependently selected from the group consisting of hydrocarbyl comprising two or more carbons, heteroatom substituted hydrocarbyl, aryl, and heteroaryl;
Rb-d are each independently selected from the group consisting of H, F, cyano, alkoxy, aryloxy, hydrocarbyl, heteroatom substituted hydrocarbyl, aryl, and heteroaryl; in addition, any two of Rlb-d may be linked to form a ring; and
By “Set 3a,” we mean the structures f1 through f4:
Rla,b are each independently selected from the group consisting of hydrogen, hydrocarbyl, and heteroatom substituted hydrocarbyl, cyano, and F; in addition, Rla,b may be linked to form a ring; and
Rla-c are each independently selected from the group consisting of hydrogen, hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, and F; in addition, any two of Rla-c may be linked to form a ring; and
By “Set 4,” we mean structures t1 through t10:
Arl is aryl or heteroaryl; and
Rla-d are each independently selected from the group consisting of hydrogen, hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, and F; in addition, any two of Rla-d may be linked to form a ring.
By “Set 5a,” we mean structures l1 through l7:
Arl is aryl or heteroaryl.
By “Set 5b”, we mean structures l20 through l22:
Rla-i are each independently selected from the group consisting of hydrogen, hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, and F; in addition, any two of Rlc-i may be linked to form a ring; and
By “Set 5c”, we mean structures l40 through l46:
Rla-i are each independently selected from the group consisting of hydrogen, hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, and F; in addition, any two of Rlc-i may be linked to form a ring;
Arl is aryl or heteroaryl;
By “Set 6a,” we structures mc3, mc50, mc48, mc25, mc46, mc5, mc4, mc54, mc51, mc26a, mc26, mc39, mc49, mc6, mcg, mc8, mc4b, mc38b, mc15, mc26b, mc28b, mc32b, mc33b, mc34b, mc35b, mc29b, mc30b, mc31b, mc42b, mc43b, mc44b, and mc45b:
R2a-c and Rla-q are each independently selected from the group consisting of hydrogen, hydrocarbyl, and heteroatom substituted hydrocarbyl, cyano, and F; in addition, any two of R2a-c and Rla-q may be linked to form a ring, provided that if Rla and R2a are linked the ring is a saturated ring;
Arst is the second ring;
Rla-i are each independently selected from the group consisting of hydrogen, hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, and F; in addition, any two of Rla-i may be linked to form a ring; and
Arla,b are aryl or heteroaryl.
By “Set 6e,” we mean structures m1-m72 in Table 2 below, wherein gs1, gs2, and gs3 are the general structures set forth in Set 7 and 3,5-Me2Ph means 3,5-dimethylphenyl.
TABLE 2 Specific General Structure Structure R1a R1b R1c R1d R1e R1f
m1 gs1 CH3 H CH3 H H H m2 gs1 CH3 H CH3 H H F m3 gs1 CH3 H CH3 F H F m4 gs1 CH3 H CH3 F Ph F m5 gs1 iPr H iPr H H H m6 gs1 iPr H iPr H H F m7 gs1 iPr H iPr F H F m8 gs1 iPr H iPr F Ph F m9 gs1 Ph iPr Ph H H H m10 gs1 Ph iPr Ph H H F m11 gs1 Ph iPr Ph F H F m12 gs1 Ph iPr Ph F Ph F m13 gs1 Ph iPr Ph H H H m14 gs1 Ph iPr Ph H H F m15 gs1 Ph iPr Ph F H F m16 gs1 Ph iPr Ph F Ph F m17 gs1 3,5-Me2Ph H 3,5-Me2Ph H H H m18 gs1 3,5-Me2Ph H 3,5-Me2Ph H H F m19 gs1 3,5-Me2Ph H 3,5-Me2Ph F H F m20 gs1 3,5-Me2Ph H 3,5-Me2Ph F Ph F m21 gs1 3,5-Me2Ph H 3,5-Me2Ph H H H m22 gs1 3,5-Me2Ph H 3,5-Me2Ph H H F m23 gs1 3,5-Me2Ph H 3,5-Me2Ph F H F m24 gs1 3,5-Me2Ph H 3,5-Me2Ph F Ph F m25 gs2 CH3 H CH3 H H H m26 gs2 CH3 H CH3 H H F m27 gs2 CH3 H CH3 F H F m28 gs2 CH3 H CH3 F Ph F m29 gs2 iPr H iPr H H H m30 gs2 iPr H iPr H H F m31 gs2 iPr H iPr F H F m32 gs2 iPr H iPr F Ph F m33 gs2 Ph iPr Ph H H H m34 gs2 Ph iPr Ph H H F m35 gs2 Ph iPr Ph F H F m36 gs2 Ph iPr Ph F Ph F m37 gs2 Ph iPr Ph H H H m38 gs2 Ph iPr Ph H H F m39 gs2 Ph iPr Ph F H F m40 gs2 Ph iPr Ph F Ph F m41 gs2 3,5-Me2Ph H 3,5-Me2Ph H H H m42 gs2 3,5-Me2Ph H 3,5-Me2Ph H H F m43 gs2 3,5-Me2Ph H 3,5-Me2Ph F H F m44 gs2 3,5-Me2Ph H 3,5-Me2Ph F Ph F m45 gs2 3,5-Me2Ph H 3,5-Me2Ph H H H m46 gs2 3,5-Me2Ph H 3,5-Me2Ph H H F m47 gs2 3,5-Me2Ph H 3,5-Me2Ph F H F m48 gs2 3,5-Me2Ph H 3,5-Me2Ph F Ph F m49 gs3 CH3 H CH3 H H H m50 gs3 CH3 H CH3 H H F m51 gs3 CH3 H CH3 F H F m52 gs3 CH3 H CH3 F Ph F m53 gs3 iPr H iPr H H H m54 gs3 iPr H iPr H H F m55 gs3 iPr H iPr F H F m56 gs3 iPr H iPr F Ph F m57 gs3 Ph iPr Ph H H H m58 gs3 Ph iPr Ph H H F m59 gs3 Ph iPr Ph F H F m60 gs3 Ph iPr Ph F Ph F m61 gs3 Ph iPr Ph H H H m62 gs3 Ph iPr Ph H H F m63 gs3 Ph iPr Ph F H F m64 gs3 Ph iPr Ph F Ph F m65 gs3 3,5-Me2Ph H 3,5-Me2Ph H H H m66 gs3 3,5-Me2Ph H 3,5-Me2Ph H H F m67 gs3 3,5-Me2Ph H 3,5-Me2Ph F H F m68 gs3 3,5-Me2Ph H 3,5-Me2Ph F Ph F m69 gs3 3,5-Me2Ph H 3,5-Me2Ph H H H m70 gs3 3,5-Me2Ph H 3,5-Me2Ph H H F m71 gs3 3,5-Me2Ph H 3,5-Me2Ph F H F m72 gs3 3,5-Me2Ph H 3,5-Me2Ph F Ph F
By “Set 7,” we mean structures gs1 through gs3:
wherein Rla-f are as defined in Table 2 above.
In a fifth preferred embodiment, the second ring is substituted by a triphenylene group.
In an sixth preferred embodiment, the second ring is substituted by a group that comprises a carbazole.
In an twenty-ninth preferred embodiment, the metal complex is selected from the group consisting of compound mc2 from Set 6c, compound mc13 from Set 6c, compound mc17 from Set 6c, compound mc18 from Set 6c, compound mc19 from Set 6c, compound mc20 from Set 6c, compound mc21 from Set 6c, compound mc22 from Set 6c, compound mc23 from Set 6c, compound mc24 from Set 6c, compound mc36 from Set 6c, compound oa11 from Set 6c, compound mc51b from Set 6c, compound mc52b from Set 6c, compound oa12 from Set 6c, compound oa1 from Set 6c, compound oa2 from Set 6c, compound oa3 from Set 6c, compound oa8b from Set 6c, compound mc46b from Set 6c, compound mc49b from Set 6c, compound mc52b from Set 6c, compound mc53b from Set 6c, compound mc5 lb from Set 6c, compound mc40b from Set 6d and compound mc41b from Set 6d.
In a thirty-first preferred embodiment, the metal complex comprises a carbene donor. [0153] In a thirty-second preferred embodiment, the carbene donor is part of a bidentate, monoanionic ligand.
In a thirty-fourth embodiment, the triplet energy of the arene or heteroarene corresponding to the second ring is greater than about 2.5 eV. By “arene or heteroarene corresponding to the second ring”, we mean the molecule obtained by attaching a hydrogen atom to the second ring in place of the first ring. For example, when the second ring is 2,6-dimethylphenyl, the corresponding arene would be 1,3-dimethylbenzene. Similarly, when the second ring is 2,6-dimethyl-4-phenylphenyl, the corresponding arene would be 1,5-dimethyl-3-phenylbenzene. Triplet energies for common arenes and heteroarenes may be found in a variety of reference texts, including “Handbook of Photochemistry” 2nd edition (S. L. Murov, I. Carmichael, G. L. Hug, eds; Dekker, 1993, New York), or may be calculated by methods known to those skilled in the art, for example, by Density Functional Theory (DFT) calculations using Gaussian 98 with the G98/B3lyp/cep-31 g basis set. Triplet energies greater than about 2.5 eV correspond to triplet transition wavelengths shorter than about 500 nm. Without wishing to be bound by theory, the inventors suppose that in some cases, an excessively low triplet energy on the second ring will either red-shift the phosphorescent emission, or reduce the radiative quantum yield, or both.
In a thirty-ninth preferred embodiment, the calculated singlet-triplet gap is less than about 0.4 eV. By “calculated singlet-triplet gap” we mean the difference in energy between the lowest lying singlet excited state and the lowest lying triplet excited state of the metal complex as calculated by Density Functional Theory (DFT) methods using Gaussian 98 with the G98/B3lyp/cep-31 g basis set. In a fortieth preferred embodiment, the calculated singlet-triplet gap is less than about 0.3 eV. In a forty-first preferred embodiment, the calculated singlet-triplet gap is less than about 0.2 eV. In a forty-second preferred embodiment, the calculated singlet-triplet gap is less than about 0.1 eV.
In a twenty-eighth preferred embodiment, the metal complex is selected from Sets 6a-6c and 6e as defined above.
In a forty-fourth preferred embodiment, the metal complex comprises a carbene donor. [0205] In a forty-fifth preferred embodiment, the carbene donor is part of a bidentate, monoanionic ligand.
In a forty-eighth preferred embodiment, the molecular weight of the arene or heteroarene corresponding to the second ring is greater than about 230 g/mol. In a forty-ninth preferred embodiment, the molecular weight of the arene or heteroarene corresponding to the second ring is greater than about 430 g/mol. In a fiftieth preferred embodiment, the molecular weight of the arene or heteroarene corresponding to the second ring is greater than about 530 g/mol. In a fifty-first tpreferred embodiment, the molecular weight of the arene or heteroarene corresponding to the second ring is greater than about 750 g/mol.
In a sixtty-first preferred embodiment, delta E is less than about 0.6 eV; wherein delta E=(triplet energy in eV)−(modified electrochemical gap in eV); wherein the modified electrochemical gap in eV is equal to is the energy difference associated with one electron crossing the difference in voltage between the oxidation potential of the metal complex and the reduction potential of the neutral compound corresponding to the ligand. In a sixty-second preferred embodiment, delta E is less than about 0.5 eV. In a sixty-third preferred embodiment, delta E is less than about 0.4 eV. In a sixty-fourth preferred embodiment, delta E is less than about 0.3 eV. In a sixty- fourth preferred embodiment, delta E is less than about 0.2 eV.
In a third aspect, the invention provides a phosphorescent compound. The phosphorescent compound is a neutral metal complex of a monodentate, bidentate, tridentate, tetradentate, pentadentate, or hexadentate ligand. The ligand comprises at least one first aryl or heteroaryl ring directly bonded to the metal. This first ring is an imidazole, coordinated via a first nitrogen atom to the metal. In yet another preferred embodiment, the second ring is attached to a second nitrogen atom of the first ring. The first ring is substituted by a second aryl or heteroaryl ring which is not directly bonded to the metal and which is substituted at both ortho positions by groups other than H or halide. The metal is selected from the group consisting of the non-radioactive metals with atomic numbers greater than 40.
In a twenty-fourth preferred embodiment, the metal complex is selected from Sets 6a-6c and 6e.
In one embodiment, the present invention provides a device that addresses issues that arise when an OLED has an electron majority emissive layer. An electron majority emissive layer occurs when electrons migrate faster toward the anode side of the emissive layer than holes migrate toward the cathode side of the emissive layer. One type of electron majority emissive layer that is of particular concern is a hole trap, which occurs in some blue phosphorescent devices. A hole trap in the emissive layer can be achieved when the HOMO of the emissive layer host is at least about 0.5 eV lower, preferably about 0.5 eV to about 0.8 eV lower, than the HOMO of the emissive dopant. When holes enter such an emissive layer, the holes accumulate on dopant molecules near the hole transport layer/emissive layer interface. This, in turn, localizes recombination near the hole transport layer/emissive layer interface where excitons may be quenched by the hole transport layer. Localization of recombination can be measured by techniques known in the art, such as by using a probe doped layer as described in U.S. Pat. No. 7,807,275, which issued October 5, 2010, and is incorporated herein by reference in its entirety. To avoid localization near the hole transport layer, it is desirable to shift the holes, and thus recombination, further into the emissive layer. Hole shifting can be accomplished by a variety of architectural features including, but not limited to, inserting an electron impeding layer, creating a LUMO barrier, using an electron transport layer that is actually a poor electron transporter, inserting a thick organic layer between the emissive layer and the cathode, selecting an emissive layer host material that is a poor electron transporter, selecting a dopant to alter electron mobility of the emissive or transport layers, or otherwise reducing the electron density of the emissive layer.
IMP layers generally have relative electron conductivities less than typical hole blocking layers (HBLs), e.g., BAlq2, HPT, or BAlq. Preferably, the IMP layer has a relative electron conductivity that is not more than 0.001 of the electron mobility of Bphen, preferably not more than 0.0005 of the electron mobility of Bphen, and more preferably not more than 0.0001 of the electron mobility of Bphen. Suitable materials for the IMP include hole transporting materials and ambipolar materials. Materials can be characterized as hole transporting or ambipolar by fabricating a test OLED with the material in question sandwiched by an emissive HTL on its anode side and by an emissive ETL on its cathode side. Under applied voltage, such a device that contains a hole transporting material will have an EL spectrum dominated by the characteristic ETL EL. Under applied voltage, such a device that contains an ambipolar material will have an EL spectrum that contains substantial emission from both the HTL and ETL layers. Suitable test devices for characterizing a material as hole transporting or ambipolar could be fabricated, for example, as follows: CuPc(100 Å)/NPD(300 Å)/material-in-question (300 Å)/BAlq2(400 Å)/LiF (10 Å)/Al (1000 Å) or CuPc(100 Å)/NPD(300 Å)/material-in-question (300 Å)/Alq3(400 Å)/LiF (10 Å)/Al (1000 Å).
Suitable materials for the electron impeding layer include mCBP, which can be used in combination with many emissive layer materials, such as an emissive layer host that is mCP or mCBP and an emissive dopant that is one of compounds 1-5. See Table 3 and FIG. 52. This application is related to U.S. Provisional Application No. 60/678,170, filed on May 6, 2005, U.S. Provisional Application No. 60/701,929, filed on Jul. 25, 2005, U.S. Provisional Application No. 60/718,336, filed on Sep. 20, 2005 and U.S. Pat. No. 9,051,344, which issued Jun. 9, 2015. The contents of these applications is herein incorporated by reference in their entirety.
c) The electron impeding material can be a hole transporting material, i.e., a material having a hole mobility greater than its electron mobility. Thus, in one embodiment, the device includes an organic layer consisting essentially of a material having a hole mobility greater than its electron mobility, such as TCTA, Irppz, NPD, TPD, mCP, and derivatives thereof
In a preferred embodiment, the emissive dopant has a HOMO that is about −5 eV or higher. In another preferred embodiment, the HOMO of the electron impeding layer material is at least about 0.5 lower than the HOMO of the emissive dopant. See FIG. 62. In yet another preferred embodiment, the band gap of the electron impeding layer material is larger than the band gap of the emissive dopant. FIGS. 63a and 63b depict an energy level diagram for a device having an exemplary electron impeding layer.
In one embodiment, the present invention provides a device that emits blue light. In a preferred embodiment, the emissive dopant has a peak in the emission spectra that is less than about 500 nm, preferably less than 450 nm. The light emitted preferably has CIE coordinates of (X≤0.2, Y≤0.3). In a specific preferred embodiment, the emissive dopant is tris N-2,6 dimethylphenyl-2-phenylimidazole, referred to herein as compound 1.
HPT: 2,3,6,7, 10, 11-hexaphenyltriphenylene
Example 1 Synthesis Offac-mc3
A 50 mL Schlenk tube flask was charged with N-(2,6-dimethyl phenyl)-2-phenylimidazole (5.30 g, 21 mmol) and tris(acetylacetonate)iridium(III) (1.96 g, 4.0 mmol). The reaction mixture was stirred under a nitrogen atmosphere and heated at 240° C. for 48 hours. After cooling, the solidified mixture was washed first with absolute ethanol followed by hexane. The residue was further purified by a silica gel column to give fac-mc3 (3.10 g). The product was further purified by vacuum sublimation. 1H and MS results confirmed the desired compound. λmax of emission=476, 504 nm (CH2Cl2 solution at room temperature), CIE=(0.21, 0.43), Eox=0.05 V, irreversible reduction at Epc=−2.85 V (vs. Fc+/Fc, in 0.10M nBu4NPF6 solution (DMF) with Pt working and auxiliary electrodes and a non-aqueous Ag/Ag+ reference electrode, and scan rates of 100 mVs1).
Example 2 Synthesis Offac-mc25
Example 4 Synthesis Offac-mc4
A 2-neck 50 mL round bottom flask was charged with N-(2,6-dimethyl-4-phenylbenzene)-2-phenylimidazole (4.95 g, 15.3 mmol) and tris(acetylacetonate)iridium(III) (1.25 g, 2.54 mmol). The reaction mixture was stirred under a light nitrogen purge and heated at 230° C. for 20 hours. After cooling, the solidified mixture was dissolved with methylene chloride, transferred to a 100 mL flask, and evaporated without exposure to light. The residue was further purified by silica gel (treated with triethylamine) chromatography using 20% EtOAc/Hexanes as eluent to give fac-mc4 (˜1.0 g). This product was then recrystallized from diethyl ether. Attempts at sublimation of the dopant were unsuccessful to the thermal properties of the compound. 1H and MS results confirmed the structure of the compound. λmax of emission=475, 505 nm (methylene chloride solution at room temperature), CIE=(0.20, 0.41), Eox=0.05 V, quasi-reversible reduction at Epc=−2.9 V (vs. Fc+/Fc, in 0.10M Bun4NPF6 solution (DMF) with Pt working and auxiliary electrodes and a non-aqueous Ag/Ag+ reference electrode, and scan rates of 100 mVs−1).
Example 7 Synthesis of Fac-m c46
A round bottom flask was charged with a solution of Pd(OAc)2 (134 mg, 0.6 mmole), mc46i-1 (7.86 g, 24 mmole), phenylboronic acid(3.7 g, 28.8 mmole), 2 M solution of K2CO3 (32.4 ml), triphenylphosphine (630 mg, 2.4 mmole) and 50 ml of dimethoxyethane. The reaction mixture was heated to reflux for 17hrs. Then the mixture was diluted with water and the aqueous layer was extracted with EtOAc. The organic layers were washed with brine and dried (MgSO4). After removal of the solvent, the residue was purified by column chromatography on silca gel (10% EtOAc in hexanes) to give mc46i-2 (7 g, 90%).
A 2-neck 50 mL round bottom flask was charged mc46i-2 (1 g, 3 mmol) and tris(acetylacetonate)iridium(III) (377 mg, 0.77 mmol). The reaction mixture was stirred under a light nitrogen purge and heated at 200° C. for 20 hours. After cooling, the solidified mixture was dissolved with methylene chloride, transferred to a 100 mL flask, and evaporated without exposure to light. The residue was further purified by silica gel (treated with triethylamine) chromatography using 20% EtOAc/Hexanes as eluent to give fac-mc46 (338 mg). 1H and MS results confirmed the structure of the compound. λmax of emission=481 nm, 511 nm (methylene chloride solution at room temperature), CIE=(0.21, 0.46), Eox=0.09 V, irreversible reduction at Epc=−3.1 V (vs. Fc+/Fc, in 0.10M Bun4NPF6 solution (DMF) with Pt working and auxiliary electrodes and a non-aqueous Ag/Ag+ reference electrode, and scan rates of 100 mVs−1).
A 50 mL round bottom flask was charged mc3-Cl (162 mg, 1.12 mmol), silver trifluoromethansulfonate (576 mg,2.24 mmol), 10 ml of methanol and 10 ml of dichloromethane. The reaction mixture was stirred at room temperature for 2 hours. The reaction mixture was filtered and the filtrate was concentrated to dryness. The residue was transfer to a 50 mL round bottom flask which was charged with 2-pyrazopyridine(325 mg, 2.24 mmole), Sodium hydride(94.2 mg for 60% in mineral oil, 2.35 mmole) and 20 ml of anhydrous acetontrile. The reaction mixture was stirred under a light nitrogen purge and heated at 81° C. for 20 hours. After cooling, the reaction mixture was concentrated to dryness. The residue was further purified by silica gel (treated with triethylamine) chromatography using 40% EtOAc/ methylene chloride as eluent to give mc47 (700 mg). 1H and MS results confirmed the structure of the compound. λmax of emission=467, 494 nm (methylene chloride solution at room temperature), CIE=(0.20, 0.40), Eox=0.38 V(i), irreversible reduction at Epc=−3.06 V (vs. Fc+/Fc, in 0.10M Bun4NPF6 solution (DMF) with Pt working and auxiliary electrodes and a non-aqueous Ag/Ag+ reference electrode, and scan rates of 100 mVs−1).
A 1-neck 50 mL round bottom flask was charged with N-(2,6-dimethyl-4-(3,5-dimethylphenyl)benzene)-2-phenylimidazole (4.5 g, 12.8 mmol) and tris(acetylacetonate)iridium(III) (1.57 g, 3.2 mmol). The reaction mixture was stirred under a nitrogen atmosphere and heated at 200° C. for 60 hours. After cooling, the solidified mixture was dissolved with methylene chloride and purified by silica gel (treated with triethylamine) chromatography using 20% dichloromethane/hexanes as eluent. The solvent was removed and the product was then recrystallized from dichloromethane/methanol and filtered yielding 1.4 grams. The material was slurried in hot ethyl acetate and filtered to yield 1.2 grams of bright yellow solid. The material was further purified by sublimation. 1I-1 and MS results confirmed the structure of the compound. λmax of emission=476 nm (methylene chloride solution at room temperature), CIE=(0.23, 0.43).
A one neck 1000 ml round bottom flask wsa charged pentamethylaniline (36 g, 0.221 mol), 40% aqueous glyoxal (40 g, 0.221, mol), and 300 ml methanol. The mixture was stirred at room temperature for 20 hours and then benzaldehyde (47 g, 0.442 mol) and ammonium chloride (23.6 g, 0.442 mmol) were added. The mixture was heated to reflux for 1 hour and then 30 ml of phosphoric acid was added. The reaction was heated at reflux for 24 hours and then allowed to cool to room temperature. The methanol was removed by rotary evaporation. Ethyl acetate (500 ml) was added and the mixture is made basic with sodium hydroxide and water. The layers were separated and the organic layer was washed with brine, dried with magnesium sulfate, and the solvent removed. The mixture was purified by silica gel column with an 80% hexane/ethyl acetate to 50% hexane/ethyl acetate gradient as the eluent. The good fractions were combined and the solvent removed by rotary evaporation. The solid was further purified by vacuum distillation to yield N-(2,3,4,5,6-pentamethyl-benzene)-2-phenylimidazole.
A 50 mL round bottom flask was charged with N-(2,6-dimethylphenyl)-2-(p-tolylimidazole (4.50 g, 19 mmol) and tris(acetylacetonate)iridium(III) (1.87 g, 3.81 mmol). The reaction mixture was stirred under a light nitrogen purge and heated in a sand bath at 200° C. for 96 hours. After cooling, the solidified mixture was dissolved with methylene chloride, transferred to a 100 mL flask, and evaporated without exposure to light. The residue was further purified by silica gel (treated with triethylamine) chromatography using 10% methyelene chloride/hexanes as eluent to give fac-tris[N-(2,6-dimethyl phenyl)-2-p-tolylimidazole]iridium(III) (1.2 g). This product was then recrystallized from methylene chloride/hexanes to give 0.80 g as yellow crystals. Sublimation of the product yielded 0.42 g as yellow crystals. NMR and MS results confirmed the structure of the compound. λmax of emission=472, 502 nm (methylene chloride solution at room temperature), CIE=(0.21, 0.40), Tg =363.8° C. Eox=0.04 V, Ered=Not Detected (vs. Fc+/Fc, in 0.10M Bun4NPF6 solution (DMF) with Pt working and auxiliary electrodes and a non-aqueous Ag/Ag+ reference electrode, and scan rates of 100 mVs−1).
55.0 g (275 mmol) 4-bromo-2,6-dimethylaniline and 39.0 g glyoxal (40% solution, 275 mmol) were stirred in 500 mL methanol in a 1L round bottom flask for 16 hours. 68.3 g 4-fluorobenzaldehyde (550 mmol) and 29.4 g (550 mmol) ammonium chloride were then added and the mixture was allowed to achieve reflux for 2 hours. 38.5 mL phosphoric acid (85%) was added dropwise over 10 minutes and the mixture continued at reflux for 18 hours. The mixture was then evaporated of methanol and the residue poured into 700 mL water. 50% NaOH was added until the pH=9 and the mixture then extracted three times with ethyl acetate in a separatory funnel. The combined organic layers were dried over anhydrous MgSO4, filtered and evaporated of solvent to give a dark residue. The ligand was purified on a large column of silica using a gradient of 20% ethyl acetate/hexanes-30% ethyl acetate/hexanes. The product fractions were evaporated of solvent and the residue distilled via kugelrohr distillation. The resultant product was recrystallized from hexanes to give 12.5 g N-(4-bromo-2,6-dimethylphenyl)-2-(4-fluorophenyl)imidazole as a clean white solid. MS confirmed.
A 50 mL round bottom flask was charged with N-(2,6-dimethyl-4-{3,5-dimethylphenyl}phenyl)-2-(4-fluorophenyl)imidazole (6.30 g, 17 mmol) and tris(acetylacetonate)iridium(III) (1.67 g, 3.48 mmol). The reaction mixture was stirred under a light nitrogen purge and heated in a sand bath at 180° C. for 48 hours. After cooling, the solidified mixture was dissolved with methylene chloride, transferred to a 100 mL flask, and evaporated without exposure to light. The residue was further purified by silica gel (treated with triethylamine) chromatography using 20% Methyelene Chloride/Hexanes as eluent to give fac-tris[N-(2,6-dimethyl-4-{2,5-dimethylphenyl}phenyl)-2-(4-fluorophenypimidazole]iridium(III) as 1.7 g. A repeat of the chromatography gave 1.13 g product. The product was then recrystallized three times from methylene chloride/hexanes, methylene chloride/methanol and finally methylene chloride/hexanes to give 0.75 g mc51 as a yellow solid. Sublimation of the product yielded a negligible amount of purified material as the solids went into a melt and decomposed during the process. NMR and MS results confirmed the structure of the compound. λmax of emission=454, 786 nm (methylene chloride solution at room temperature), CIE=(0.19, 0.33).
To a 100 mL round bottom flask was added 5.0 g (14.2 mmol) N-(2,6-dimethyl-4-(3,5-dimethylphenyl)benzene)-2-phenylimidazole and 2.55 g (7.1 mmol) iridium chloride hexahydrate in 50 mL 2-methoxyethanol and 10 mL water. The mixture was refluxed under N2 atmosphere for 17 hours. The mixture was then cooled and the solids collected on a filter and rinsed with methanol and hexanes. The amount of chloro-bridged dimer achieved was 6.32 g and was used in the next step without further purification.
To a 500 mL round flask was added above phenyl imidazole (8.0 g, 18 mmol),phenylboronic acid (5.4 g, 44 mmol), palladium(II) acetate (0.25 g, 1.1 mmol), triphenylphosphine (1.2 g, 4.4 mmol), sodium carbonate (12.6 g, 119 mmol), and 200 mL of DME and 100 mL of water. The reaction was heated to reflux and stirred under a nitrogen atmosphere for 12 hours. The mixture was extracted with ethyl acetate and further purified by a silica gel column. Yield is 5.2 g. The ligand was confirmed by GC-MS.
N-(2,6-diphenyl-4-isopropyl phenyl)-2-(4-fluro phenyl)imidazole (0.43 g, 1.0 mmol) and tris(acetylacetonate)iridium(III) (0.12 g, 0.25 mmol) were added to a flask containing 5 mL of ethyleneglycol. The reaction mixture was heated to reflux and stirred under a nitrogen atmosphere for 24 hours. After cooling, the precipitate formed was filtered and washed with ethanol. The residue was extracted with CH2Cl2 and further purified by a silica gel column to give fac-tris[N-(2,6-diphenyl-4-isopropyl phenyl)-2-(4-fluorophenyl)imidazole]iridium(III) (0.15 g). 1H NMR result confirmed the desired compound. λmax of emission=460, 490 nm, CIE=(0.20, 0.34), Eox=0.18 V (r), Ered =−3.00 V (q) (vs. Fc+/Fc).
Ar3a=4-isopropylphenyi
N-(2,4,6-tri(4-isopropylphenyl)phenyl)-2-(4-fluorophenyl)imidazole (3.3 g, 5.6 mmol) and tris(acetylacetonate)iridium(III) (0.68 g, 1.4 mmol) were added to a flask containing 40 mL of ethylene glycol. The reaction mixture was heated to reflux and stirred under a nitrogen atmosphere for 24 hours. After cooling, the precipitate formed was filtered and washed with ethanol. The residue was extracted with CH2Cl2 and further purified by a silica gel column to give oa8 (1.0 g). 1H NMR result confirmed the desired compound. λmax emission=460, 490 nm, CIE=(0.20, 0.35). Eox=0.24 V, Ered =−2.80 V (q) (vs. Fc+/Fc, in 0.10M Bun4NPF6 solution (DMF) with Pt working and auxiliary electrodes and a non-aqueous Ag/Ag+ reference electrode, and scan rates of 100 mVs−1).
One 250 ml flask was charged with 4-phenyl imidazole (7.08 g, 49.12 mmole), 2-iodo-m-xylene(9.5 g, 40.93 mmole), copper (5.721 g, 90.046 mmole); 18-crown-6 (1.081 g, 4.09 mmole), K2CO3 (21.49 g, 155.53 mmole) and tetrahydronaphthalene (90 ml). Reaction was heated to 180 C for 68 hrs. Reaction mixture was then filtered through Celite and the filtrate was concentrated to dryness. The residue was subjected to kugelrohr distillation and 4 g of ligand was obtained. (39%).
One 25 ml of flask was charged with ligand (0.82 g, 3.339 mmole), IrCl3 (0.61 g, 1.67 mmole), water (2 ml) and 2-ethoxyethanol (8 ml). Reaction mixture was heated to 100 C for 20 h. Reaction was then filtered and the precipitation was collected to the chloro- bridge dimer (0.78 g, 65%).
A 50 mL round bottom flask was charged with dimer (400 mg, 0.277 mmol), Silver trifluoromethansulfonate (142 mg, 0.55 mmol), 10 ml of methanol and 10 ml of dichloromethane. The reaction mixture was stirred at room temperature for 2 hours. The reaction mixture was filtered and the filtrate was concentrated to dryness. The residue was transfer to a 50 mL round bottom flask which was charged with potassium tetrapyrazoborate (176 mg, 0.554 mmole) and 20 ml of anhydrous acetontrile. The reaction mixture was stirred under a light nitrogen purge and heated at 81° C. for 20 hours. After cooling, the reaction mixture was concentrated to dryness. The residue was further purified by chromatography (Al2O3, basic) using 40% heptane/methylene chloride as eluent to give target compound (200 mg, 37%) 1H and MS results confirmed the structure of the compound. λmax of emission=427,457,483nm (methylene chloride solution at room temperature).
Ar3b=3,5-dimethylphenyl
A round bottom flask was charged with a solution of Pd(OAc)2 (188 mg, 0.84 mmole), dibromo compound (5.12 g, 12.9 mmole), 3,5-dimethylphenylboronic acid(5.1 g, 34 mmole),2 M solution of K2CO3 (45.9 ml), triphenylphosphine (881 mg, 3.36 mmole) and 90 ml of dimethoxyethane. The reaction mixture was heated to reflux for 17hrs. Then the mixture was diluted with water and the aqueous layer was extracted with EtOAc. The organic layers were washed with brine and dried (MgSO4). After removal of the solvent, the residue was purified by column chromatography on silca gel (10% EtOAc in hexanes) to give ligand (4 g, 70%).
A 2-neck 50 mL round bottom flask was charged with ligand (4 g, 9.15 mmol) and tris(acetylacetonate)iridium(III) (1.12 g, 2.28 mmol). The reaction mixture was stirred under a light nitrogen purge and heated at 200° C. for 20 hours. After cooling, the solidified mixture was dissolved with methylene chloride, transferred to a 100 mL flask, and evaporated without exposure to light. The residue was further purified by silica gel (treated with triethylamine) chromatography using 20% EtOAc/Hexanes as eluent to give fac-tris complex (1 g). 1H and MS results confirmed the structure of the compound. λmax of emission=466, 492 nm (methylene chloride solution at room temperature), CIE=(0.21, 0.38), Eox=0.17 V (vs. Fc+/Fc, in 0.10M Bun4NPF6 solution (DMF) with Pt working and auxiliary electrodes and a non-aqueous Ag/Ag+ reference electrode, and scan rates of 100 mVs−1).
The chloro bridged dimer (2.0 g, 0.86 mmol) was dissolved in100 ml 1,2-dichloroethane and heated to reflux. Silver oxide (0.8 g, 3.4 mmol) was added followed by 1-phenyl-3-methyl-imidazolium iodide (0.50 g, 1.7 mmol). The mixture was heated at reflux for about 20 minutes. The filtrate was then evaporated down and the residue purified on a silica gel column (treated with triethylamine) using dichloromethane as the eluent. The pure fractions were evaporated of solvent and the solids recrystallized from methylene chloride/hexanes.
In a 1L round bottom flask, 50.4 g sodium hydroxide (1.26 mol) was dissolved in 500 mL water (˜10% solution). 66.6 g (.574 mol) 2-chloroethylamine hydrochloride was then added and the solution stirred in an ice bath at 0° C. until the salt was completely dissolved. 100 g (.631 mol) 4-fluorobenzoyl chloride was then added dropwise via an addition funnel into the vigorously stirred solution. After addition, the solution stirred at 0° C. for 1 hour followed by stirring at room temperature for 1 hour. The cloudy mixture was then filtered to remove the water and the solids washed with ether and then filtered to give ˜118 g crude (slightly wet) benzamide (Alternatively, the solids could be dissolved in methylene chloride, dried with magnesium sulfate, filtered and evaporated to completely remove water from the solids). These solids were recrystallized from 120 ml EtOAc/200 mL hexanes to give 88.2 g crystalline N-(2-chloroethyl)-4-fluorobenzamide after hexanes wash and drying (an additional 6.22 g benzamide recrystallized from the original water mother liquor). NMR confirmed the structure of this compound (81.4% total yield).
Step 2: Synthesis of N-(2,4,6-tribromophenyl)-2-(4-fluorophenyflimidazoline
To a dried 3L round bottom flask equipped with stirbar was added 55.6 g (.276 mol) N-(2-chloroethyl)-4-fluorobenzamide. This solid was then dissolved in 600 mL anhydrous m-xylene under N2 atmosphere and light heat. 86.1 g (.413 mol) phosphorus pentachloride was then added and the mixture was allowed to reflux under N2 for 2 hours (completely dissolving the PCI5). The solution was then cooled whereupon 100 g (.303 mol) tribromoaniline was added (Additionally, a base trap was attached to the condenser to neutralize generating HCl gas). This mixture was allowed to reflux for 20 hours. The solution was then allowed to cool and the imidazoline collected on a filter and washed with toluene followed by hexanes. The solids were then dissolved in methylene chloride and extracted with diluted NH4OH twice. The organic layer was dried over MgSO4, filtered and evaporated of solvent to give ˜65 g imidazoline. Recrystallization was achieved from methylene chloride/hexanes. NMR confirmed the structure of this compound.
Step 3: Aromatization of N-(2,4,6-tribromophenyl)-2-(4-fluorophenyflimidazoline
59.2 g (.124 mol) N-(2,4,6-tribromophenyl)-2-(4-fluorophenyl)imidazoline was added to a 2L flask equipped with stirbar. ˜1L MeCN was added and the mixture stirred at room temperature until the solids were dissolved. 33% KMnO4/Montmorillonite was added in portions (.248 mol) to the stirred mixture over a period of a few hours. After stirring overnight, the mixture was quenched with 200 mL EtOH and then poured over a celite mat to remove the oxidant. The filtrate was evaporated of solvent and the residue purified on a silica gel column using 20% EtOAc/MeCl2 as eluent. The product fractions were evaporated of solvent to give 18.8 g crude imidazole recrystallized from MeCl2/Hexanes (17.4 g, 29.4% yield). The product was confirmed by NMR.
13.36 g (28.1 mmol) N-(2,4,6-tribromophenyl)-2-(4-fluorophenyl)imidazole , 14.1 g (104mmoL) phenylboronic acid, 2.21 g (8.40 mmol) triphenylphosphine, 0.63 g (2.81 mmol) Pd(II) acetate, and 31.4 g (228 mmol) potassium carbonate were added to a 2L round bottom flask equipped with stir bar and refluxed in 800 mL DME/400 mL water overnight under N2 atmosphere. The mixture was then cooled, added to a separatory funnel and the water removed. The organic mixture was then enriched with 800 mL EtOAc and extracted with 2×400 mL portions of water. The organic layer was then dried over MgSO4, filtered and evaporated of solvent. Next, the residue was solubilized with 200 mL MeCl2 and dried on silica. This silica was then layered on top of a silica gel column that was eluted with a gradient of 30% EtOAc/hexanes-50% EtOAc/hexanes. The pure fractions, after evaporation of solvent, gave 9.3 g N-(2,4,6-triphenylphenyl)-2-(4-fluorophenyl)imidazole upon recrystallization from CH2Cl2/hexanes (71.0% yield). The product was confirmed by NMR.
Step 5: Ligation to form oa8c
The ligand from the preceding step was used to prepare oa8c following the procedure of Example 20.
Organic layers of the OLEDs were sequentially deposited by thermal evaporation from resistively heated alumina crucibles onto the substrates, at room temperature, at a base pressure of <10e-6 Ton. The rate of a single-component layer was controlled with one Inficon thickness monitor located close to the substrate. The specific rates for each material are given in Table 1 below. For the two-component emissive layer the rate of the dopant was controlled with an additional crystal monitor located close to the dopant evaporation source. The additional monitor was not exposed to the major flow of the host.
TABLE 1 Material Deposition Rate (Å)
CuPc 0.3 NPD 1.5 CBP 3.0 mCBP 3.0 Mcp 3.0 HPT 1.0 BAlq2 2.0 Alq3 2.5 LiF 0.5 Al 2.0
Device B: CuPc(100)/NPD(300)/CBP:cmpd A(6%,300)/HPT(100)/BAlq2(300) The definitions for materials CuPc, NPD, CBP, HPT, and BAlq2 have been given above; the structure of Compound A (abbreviated as “cmpd A”) is given in FIG. 3. The numbers in parentheses refer to the thickness of the layer in Angstroms, and the percentage after cmpd A refers to the weight percent of compound A in that layer.
The devices in Examples 24 and 25 are fabricated in high vacuum (<10−7 Ton) by thermal evaporation. The anode electrode is about 800 Å of indium tin oxide (ITO). Organic layers were deposited at rates between 0.3 to 3.0 Å/s. The cathode consists of 10 Å of LiF, deposited at 0.1 Å/s, followed by 1,000 Å of Al, deposited at 2 Å/s. All devices are encapsulated with a glass lid sealed with an epoxy resin in a nitrogen glove box (<1 ppm of H2O and O2) immediately after fabrication, and a moisture getter was incorporated inside the package. The exemplary emissive dopants are shown in FIG. 52.
Example 24: Specific exemplary devices of the invention (numbered in bold) as well as comparative devices are listed in Table 3. It is understood that the specific methods, materials, conditions, process parameters, apparatus and the like do not necessarily limit the scope of the invention.
Ex. Structure (All thicknesses are in angstroms, and doping concentration are wt %.)
1 CuPc (100)/NPD (300)/mCBP:compound 1 (9%, 300)/mCP (50)/Balq (400)/LiF/Al 2 CuPc (100)/NPD (300)/mCBP:compound 1 (9%, 300)/Balq (400)/LiF/Al 3 CuPc (100)/NPD (300)/mCBP:compound 1 (18%, 300)/mCP (50)/Balq (400)/LiF/Al 4 CuPc (100)/NPD (300)/mCBP:compound 1 (18%, 300)/Balq (400)/LiF/Al 5 CuPc (100)/NPD (300)/mCBP:compound 1 (9%, 300)/mCBP (50)/Balq (400)/LiF/Al 6 CuPc (100)/NPD (300)/mCP:compound 1 (9%, 300)/mCP (50)/Balq (400)/LiF/Al 7 CuPc (100)/NPD (300)/mCP:compound 1 (9%, 300)/Balq (400)/LiF/Al 8 CuPc (100)/NPD (300)/mCP:compound 1 (9%, 300)/mCBP (50)/Balq (400)/LiF/Al 9 CuPc (100)/NPD (300)/mCBP:compound 2 (9%, 300)/mCP (50)/Balq (400)/LiF/Al 10 CuPc (100)/NPD (300)/mCBP:compound 2 (9%, 300)/Balq (400)/LiF/Al 11 CuPc (100)/NPD (300)/mCP:compound 3 (9%, 300)/mCP (50)/Balq (400)/LiF/Al 12 CuPc (100)/NPD (300)/mCP:compound 3 (9%, 300)/mCBP (50)/Balq (400)/LiF/Al 13 CuPc (100)/NPD (300)/mCP:compound 3 (9%, 300)/Balq (400)/LiF/Al 14 CuPc (100)/NPD (300)/mCBP:compound 4 (9%, 300)/mCBP (50)/Balq (400)/LiF/Al 15 CuPc (100)/NPD (300)/mCBP:compound 4 (9%, 300)/Balq (400)/LiF/Al 16 CuPc (100)/NPD (300)/mCBP:compound 4 (9%, 300)/mCP (50)/Balq (400)/LiF/Al 17 CuPc (100)/NPD (300)/mCP:compound 5 (9%, 300)/mCP (50)/Balq (100)/Alq (400)/LiF/Al 18 CuPc (100)/NPD (300)/mCP:compound 5 (9%, 300)/Balq (100)/Alq (400)/LiF/Al
Example 25: Exemplary devices A-D include an electron impeding layer of variable thickness. Comparative devices E and F include a hole blocking layer of variable thickness.
Ex. Structure (All thicknesses are in angstroms, and doping concentration are wt %.) A CuPc (100)/NPD (300)/mCBP:compound 6 (9%, 300)/Alq3 (400)/LiF/Al B CuPc (100)/NPD (300)/mCBP:compound 6 (9%, 300)/mCBP (20)/Alq3 (400)/LiF/Al C CuPc (100)/NPD (300)/mCBP:compound 6 (9%, 300)/mCBP (50)/Alq3 (400)/LiF/Al D CuPc (100)/NPD (300)/mCBP:compound 6 (9%, 300)/mCBP (100)/Alq3 (400)/LiF/Al E Ir(ppy)3 (100)/NPD (300)/CBP:compound7 (8%, 300)/HPT (50)/Alq3 (450)/LiF/Al F Ir(ppy)3 (100)/NPD (300)/CBP:compound7 (8%, 300)/HPT (150)/Alq3 (350)/LiF/Al
1. A phosphorescent compound, wherein the phosphorescent compound is a neutral metal complex of a monodentate, bidentate, tridentate, tetradentate, pentadentate, or hexadentate ligand;
wherein the ligand comprises at least one first aryl or heteroaryl ring directly bonded to the metal;
wherein the first ring is substituted by a second aryl or heteroaryl ring which is not directly bonded to the metal and which is substituted at both ortho positions by groups other than H or halide;
wherein the first ring is an imidazole, benzene, naphthalene, quinolene, isoquinolene, pyridine, pyrimidine, pyridazine, pyrrole, oxazole, thiazole, oxadiazole, thiadiazole, furan, or thiophene ring;
wherein the metal is selected from the group consisting of the non-radioactive metals with atomic numbers greather than 40.
2. The compound according to claim 1, wherein the compound has a calculated singlet-triplet gap that is less than about 0.4 eV.
3. The compound according to claim 1, wherein the compound has a calculated singlet-triplet gap that is less than about 0.3 eV.
4. The compound according to claim 1, wherein the compound has a calculated singlet-triplet gap that is less than about 0.2 eV.
5. The compound according to claim 1, wherein the compound has a calculated singlet-triplet gap that is less than about 0.1 eV.
6. The compound according to claim 1, wherein the ligand has a reduction potential that is less negative than that of the corresponding ligand with a methyl group in place of the second ring by at least about 0.1 V.
7. The compound according to claim 1, wherein the ligand has a reduction potential that is less negative than that of the corresponding ligand with a methyl group in place of the second ring by at least about 0.2 V.
8. The compound according to claim 1, wherein the ligand has a reduction potential that is less negative than that of the corresponding ligand with a methyl group in place of the second ring by at least about 0.3 V.
9. The compound according to claim 1, wherein the ligand has a reduction potential that is less negative than that of the corresponding ligand with a methyl group in place of the second ring by at least about 0.4 V.
10. The compound according to claim 1, wherein the ligand has a reduction potential that is less negative than that of the corresponding ligand with a methyl group in place of the second ring by at least about 0.5 V.
11. The compound according to claim 1, wherein delta E of the compound is less than about 0.6 eV; wherein:
delta E=(triplet energy)−(modified electrochemical gap), wherein the triplet energy is the energy of the highest energy peak in the phosphorescence emission spectrum of said metal complex, in eV; and
the modified electrochemical gap is the difference between the oxidation potential of the metal complex and the reduction potential of the neutral compound corresponding to the ligand.
12. The compound according to claim 11, wherein delta E is less than about 0.5 eV.
13. The compound according to claim 11, wherein delta E is less than about 0.4 eV.
14. The compound according to claim 11, wherein delta E is less than about 0.3 eV.
15. The compound according to claim 11, wherein delta E is less than about 0.2 eV.
16. The compound according to claim 1, wherein the second ring is attached to a second nitrogen atom of the first ring.
17. The compound according to claim 1, wherein the metal is selected from the group consisting of Re, Ru, Os, Rh, Ir, Pd, Pt, Cu and Au.
18. The compound according to claim 1, wherein the metal is selected from the group consisting of Os, Ir, and Pt.
19. The compound according to claim 1, wherein the metal is Ir.
a cathode: and
an emissive layer, wherein the emissive layer is located between the anode and the cathode, and the emissive layer comprises a phosphorescent compound, and optionally a host, wherein the phosphorescent compound is a neutral metal complex of a monodentate, bidentate, tridentate, tetradentate, pentadentate, or hexadentate ligand; wherein the ligand comprises at least one first aryl or heteroaryl ring directly bonded to the metal; wherein the first ring is substituted by a second aryl or heteroaryl ring which is not directly bonded to the metal and which is substituted at both ortho positions by groups other than H or halide; wherein the first ring is an imidazole, benzene, naphthalene, quinolene, isoquinolene, pyridine, pyrimidine, pyridazine, pyrrole, oxazole, thiazole, oxadiazole, thiadiazole, furan, or thiophene ring; wherein the metal complex is an organometallic complex; and wherein the metal is selected from the group consisting of the non-radioactive metals with atomic numbers greather than 40.
Publication number: 20200006674
Inventors: Chun LIN (Yardley, PA), Peter B. MACKENZIE (Murrysville, PA), Robert W. WALTERS (Export, PA), Jui-Yi TSAI (Newtown, PA), Cory S. BROWN (Pittsburgh, PA), Jun DENG (Murrysville, PA)
Application Number: 16/458,735
International Classification: H01L 51/00 (20060101); C09K 11/06 (20060101); C07F 15/00 (20060101);