Copper(I)-carbene complexes and organic electroluminescent devices

Abstract

Devices comprising an organic light emitting device are provided. The devices can include an anode; a cathode; and an organic layer, disposed between the anode and the cathode. The organic layer comprising at least one host material comprising a phosphorescent complex comprising novel phosphorescent trigonal copper carbene complexes. The complex comprise a carbene ligand coordinated to a three coordinate copper atom. The complex may be used in organic light emitting devices. In particular, the complexes may be especially useful in OLEDs used for lighting applications.

Claims

1. A first device comprising an organic light emitting device, further comprising: an anode; a cathode; and an organic layer, disposed between the anode and the cathode, the organic layer comprising an emissive dopant and a first host material comprising a carbene ligand coordinated to a three coordinate copper atom, wherein the first host material has the formula: ##STR00241## wherein Cu is a monovalent copper atom; wherein the carbene represented by X.sub.1—C*—X.sub.2 is a monodentate ligand selected from the group consisting of ##STR00242## ##STR00243## wherein z is 1, 2, 3, or 4; wherein each of Y.sub.1 and Y.sub.2 form a bond with Cu; wherein at least one of (i) to (x) is true: (i) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00244## ##STR00245## (ii) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00246## ##STR00247## ##STR00248## (iii) Y.sub.1 is ##STR00249## and Y.sub.2 is a monodentate ligand selected from the group consisting of ##STR00250## (iv) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00251## ##STR00252## ##STR00253## (v) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00254## ##STR00255## ##STR00256## (vi) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00257## (vii) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00258## (viii) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00259## (ix) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00260## and (x) Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00261## wherein, when present, X is selected from the group consisting of NR, O, S, Se, CR.sub.2, and CO; each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl, and heteroaryl; Y.sub.3 and Y.sub.4 are independently selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, and heteroaryl; Y.sub.3 and Y.sub.4 are optionally joined to form a cycle, which may be extended by fusion n is 0, 1, or 2, and m is 0, 1, or 2.

2. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00262## ##STR00263## ##STR00264##

3. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00265## ##STR00266## ##STR00267##

4. The device of claim 1, wherein Y.sub.1 is ##STR00268## and Y.sub.2 is a monodentate ligand selected from the group consisting of ##STR00269##

5. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00270## ##STR00271## ##STR00272##

6. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00273## ##STR00274## ##STR00275##

7. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00276##

8. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00277##

9. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00278##

10. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00279##

11. The device of claim 1, wherein Y.sub.1-Y.sub.2 is selected from the group consisting of: ##STR00280##

12. The device of claim 1, wherein the first host meets one of option (iv) and option (v), and Y.sub.3 and Y.sub.4 are selected from the group consisting of the following (a) to (e): ##STR00281## wherein, in each of (a) to (e), the dashed lines represent bonds to the boron (B).

13. A first device comprising an organic light emitting device, further comprising: an anode; a cathode; and an organic layer, disposed between the anode and the cathode, the organic layer comprising an emissive dopant and a first host material selected from the group consisting of: ##STR00282## ##STR00283##

14. The device of claim 13, wherein the first host material is selected from the group consisting of: ##STR00284##

15. The device of claim 13, wherein the first host material is selected from the group consisting of: ##STR00285##

16. The device of claim 13, wherein the first host material is selected from the group consisting of: ##STR00286##

17. The device of claim 13, wherein the first host material is selected from the group consisting of: ##STR00287##

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an organic light emitting device.

(2) FIG. 2 shows an inverted organic light emitting device that does not have a separate electron transport layer.

(3) FIG. 3 shows complexes comprising a carbene ligand coordinated to a three coordinate copper atom.

(4) FIG. 4 shows .sup.1H-NMR spectrum of Complex 1.

(5) FIG. 5 shows .sup.1H-NMR spectrum of Complex 2.

(6) FIG. 6 shows .sup.1H-NMR spectrum of Complex 3.

(7) FIG. 7 shows .sup.1H-NMR spectrum of Complex 4.

(8) FIG. 8 shows MALDI spectrum of Complex 1.

(9) FIG. 9 shows MALDI spectrum of Complex 2.

(10) FIG. 10 shows MALDI spectrum of Complex 3.

(11) FIG. 11 shows MALDI spectrum of Complex 4.

(12) FIG. 12 shows the absorption spectrum of Complex 1.

(13) FIG. 13 shows the absorption spectrum of Complex 2.

(14) FIG. 14 shows the absorption spectrum of Complex 3.

(15) FIG. 15 shows the absorption spectrum of Complex 4.

(16) FIG. 16A shows absorption spectrum of Complex 4;

(17) FIG. 16B shows the emission spectra of Complex 4.

(18) FIG. 17A shows excitation and emission spectra of Complex 1;

(19) FIG. 17B shows excitation and emission spectra of Complex 2.

(20) FIG. 18A shows excitation and emission spectra of Complex 3;

(21) FIG. 18B shows excitation and emission spectra of Complex 4.

(22) FIG. 19A shows the x-ray structure of Complex 2;

(23) FIG. 19B shows the x-ray structure of Complex 4.

(24) FIG. 20 shows the .sup.31P-NMR spectrum of Complex 1.

(25) FIG. 21. shows the .sup.1H-NMR spectrum of Complex 5.

(26) FIG. 22 shows the X-ray structure of Complex 5.

(27) FIG. 23 shows LCMS spectrum of Complex 6.

(28) FIG. 24A shows corrected emission and excitation spectra of Complex 5 in 2MeTHF at 77K;

(29) FIG. 24B shows corrected emission and excitation spectra of Complex 6 in 2MeTHF at 77K.

(30) FIG. 25 shows a corrected emission spectrum of Complex 4 in PMMA film at room temperature.

(31) FIG. 26A shows a corrected emission spectrum of Complex 4 in CH.sub.2Cl.sub.2 at room temperature;

(32) FIG. 26B shows a corrected emission spectrum of Complex 2 in CH.sub.2Cl.sub.2 at room temperature.

(33) FIG. 27 shows .sup.1H-NMR spectrum of Complex 7.

(34) FIG. 28A shows .sup.1H-NMR spectrum of Complex 7;

(35) FIG. 28B shows the .sup.11B-NMR spectrum of Complex 7.

(36) FIG. 29A shows excitation and emission spectra of Complex 7 in 2MeTHF at 77K;

(37) FIG. 29B shows excitation and emission spectra of Complex 8 in 2MeTHF at 77K.

(38) FIG. 30A shows absorption spectrum of Complex 7;

(39) FIG. 30B shows the X-ray structure of Complex 7.

DETAILED DESCRIPTION

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

(41) The initial OLEDs used emissive molecules that emitted light from their singlet states (“fluorescence”) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.

(42) More recently, OLEDs having emissive materials that emit light from triplet states (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, vol. 395, 151-154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.

(43) FIG. 1 shows an organic light emitting device 100. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, and a cathode 160. Cathode 160 is a complex cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 may be fabricated by depositing the layers described, in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporated by reference.

(44) More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including complex cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.

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

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

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

(48) 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. patent application Ser. No. 10/233,470, now U.S. Pat. No. 7,431,968, which 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.

(49) Devices fabricated in accordance with embodiments of the invention may be incorporated into a wide variety of consumer products, including flat panel displays, computer monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads up displays, fully transparent displays, flexible displays, laser printers, telephones, cell phones, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, micro-displays, vehicles, a large area wall, theater or stadium screen, or a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present invention, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees C., and more preferably at room temperature (20-25 degrees C.).

(50) The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.

(51) The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl, heterocyclic group, aryl, aromatic group, and heteroaryl are known to the art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32, which are incorporated herein by reference.

(52) Novel trigonal planar copper complexes with a carbene ligand are provided (illustrated in FIG. 3). In particular, the complexes include a monodentate or a bidentate carbene ligand coordinated to a three coordinate copper atom. The complex can be either charged or neutral. These complexes may be advantageously used in organic light emitting devices.

(53) Phosphorescent copper complexes and their incorporation into organic light emitting diodes (OLEDs) is known. See, e.g., Armaroli, N.; Accorsi, G.; Holler, M.; Moudam, O.; Nierengarten, J. F.; Zhou, Z.; Wegh, R. T.; Welter, R., Highly luminescent Cu—I complexes for light-emitting electrochemical cells. Advanced Materials 2006, 18, (10), 1313-1316; Zhang, Q. S.; Zhou, Q. G.; Cheng, Y. X.; Wang, L. X.; Ma, O. G.; Jing, X. B.; Wang, F. S., Highly efficient green phosphorescent organic light-emitting diodes based on Cu—I complexes. Advanced Materials 2004, 16, (5), 432436; Yersin, H.; Monkowius, D.; Czerwieniec, R.; Yu, 1., Copper(I) N-heterocyclic chelate phosphine complexes as blue-emitting materials for organic electroluminescence devices. PCT Int. Appl. (2010), WO 2010031485 A1 20100325; and Ikeda, S.; Nagashima, H.; Ogiwara, T., Copper complexes and their use for luminescent materials, organic electroluminescence elements, and devices containing the elements. Jpn. Kokai Tokkyo Koho (2008), JP 2008303152 A 20081218. However, the reported complexes have limitations. A new class of highly phosphorescent copper complexes, with both carbene and chelating anionic ligands, are provided. It is believed that the carbene ligand will give the complex stability and enhance phosphorescence. The chelating anionic ligand is a high triplet energy ligand, capable of supporting metal-to-ligand charge transfer interactions. The complexes in this class may provide high energy phosphorescence, which can be useful in the fabrication of doped OLEDs, in which the copper complex is an emissive dopant. These materials may also be used as host materials to support an emissive dopant in an OLED structure. For example, a dipyridyl borate complex in this class of compounds has an emission maximum of 475 nm and a photoluminescence efficiency of 0.95 in the solid state. Suitable substitution of the pyridyl groups can red or blue shift this emission substantially. The ability to tune emission energies may make these copper complexes excellent emitters and host materials for OLEDs. It is thought that the emission energy may be shifted high enough to make these compounds suitable host materials for deep blue to violet emissive dopants.

(54) Phosphorescent OLEDs have relied largely on heavy metal complexes as emitters. In particular, devices often utilize emitters containing Ir or Pt to induce spin orbit coupling. Tetrahedral copper complexes have been reported, and are known to phosphoresce at room temperature. However, tetrahedral copper complexes may have certain limitations. In particular, flattening distortions may increase the non-radiative rate, which leads to a decrease in luminescence efficiency. Trigonal planar copper carbene complexes have now been found to give efficient phosphorescence at room temperature. We believe that this is the first observation of phosphorescence from trigonal planar copper complexes.

(55) Trigonal planar copper complexes may also have several advantages for use in OLEDs. In particular, the trigonal planar copper complexes have comparatively short lifetimes, in the tens of microsecond range (see Table 1). Table 1 shows the lifetimes of several different trigonal planar copper carbene complexes. Generally, the lifetime of the trigonal copper complex is longer than an Ir complex (i.e., 1-10 μs) but shorter than that of a platinum porphyrin complex.

(56) TABLE-US-00001 TABLE 1 λmax 77K Solid state QY Lifetime 77K 2MeTHF 2MeTHF Complex 1 31.8% τ.sub.1 = 1143 μs (30.1%) 440 nm τ.sub.2 = 458.5 μs (69.6%) Complex 2  2.6% τ = 10.6 μs 605 nm Complex 3  0.5% τ = 0.7 μs 615 nm Complex 4 43.3% τ = 55.9 μs 545 nm   33% (PMMA film)

(57) In particular, several of the copper complexes provide efficient phosphorescence at room temperature and have comparatively short lifetimes, i.e., in the 10's of microsecond range. Table 2 shows the lifetimes of several different trigonal planar copper carbene complexes.

(58) TABLE-US-00002 TABLE 2 Solid Lifetime 77K state QY 2MeTHF λmax 77K 2MeTHF Complex 1 31.8% τ = 656 μs 443 nm Complex 2  2.6% τ.sub.1 = 1.8 μs (24%) 630 nm τ.sub.2 = 4.6 μs (76%) Complex 3  0.5% τ = 0.7 μs 645 nm Complex 4   58% τ = 55.9 μs 555 nm   35% (PMMA film) Complex 5 13.5% τ = 2312 μs 562; 574; 610; 660 nm Complex 6   21% τ = 55 μs 560 nm

(59) Trigonal planar copper complexes may also be particularly useful in OLEDs used for certain applications. In particular, copper complexes provide a broader line spectrum which is especially useful for lighting applications. Further, a device comprising a trigonal planar copper complex in combination with only one other complex may cover red, green, and blue colors. For example, a device comprising a trigonal planar copper complex and a blue emitter may cover all colors required for lighting.

(60) Novel phosphorescent complexes are provided, the complexes comprising a carbene ligand coordinated to a three coordinate copper atom.

(61) In one aspect, the carbene ligand has the formula:

(62) ##STR00044##
*C is a divalent carbon atom coordinated to a monovalent copper atom Cu. X.sub.1 and X.sub.2 are substituents independently selected from alkyl, amine, phosphine, heteroalkyl, aryl and heteroaryl. X.sub.1 and X.sub.2 may be further substituted, and X.sub.1 and X.sub.2 are optionally linked to form a cycle. In one aspect, the carbene ligand is monodentate. Preferably, each of X.sub.1 and X.sub.2 independently forms a bond with *C. A first bond is formed between *C and an atom X′.sub.1 in substituent X.sub.1, and a second bond is formed between *C and an atom X′.sub.2 in substituent X.sub.2. X′.sub.1 and X′.sub.2 are independently selected from the group consisting of C, N, O, S and P.

(63) In another aspect, the carbene ligand is monodentate.

(64) In one aspect, X.sub.1 and X.sub.2 are not joined to form a cycle. In another aspect, X.sub.1 and X.sub.2 are joined to form a cycle.

(65) In one aspect, the copper complex is neutral. Neutral complexes may be particularly beneficial for use in OLEDs. For example, a neutral complex can be deposited via vapor deposition. In another aspect, the copper complex is charged.

(66) In one aspect, the complex has the formula:

(67) ##STR00045##
Yi is independently selected from the group consisting of alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. Yi is a monodentate ligand or a bidentate ligand. n is 1 or 2. Preferably, n is 2.

(68) In another aspect, the complex has the formula:

(69) ##STR00046##
Y.sub.1 and Y.sub.2 are substituents that are independently selected from the group consisting of alkyl, heteroalkyl, aryl and heteroaryl. Y.sub.1 and Y.sub.2 may be further substituted. Y.sub.1 and Y.sub.2 are joined. Each of Y.sub.1 and Y.sub.2 form a bond with Cu. A first bond is formed between Cu and an atom Y′.sub.1 in substituent Y.sub.1 and a second bond is formed between Cu and an atom Y′.sub.2 in substituent Y.sub.2. Y′.sub.1 is selected from the group consisting of N, P, *C, O, and S. Y′.sub.2 is selected from the group consisting of N, P, *C, tetravalent carbon, O, and S. Preferably, Y′.sub.1 is N.

(70) The Cu atom, the Y′.sub.1 atom and the Y′.sub.2 atom in the complex are included in a ring that can be, for example, a 4-membered, 5-membered, 6-membered, 7-membered, or 8-membered ring. Preferably, the ring comprising Cu, Y′.sub.1 and Y′.sub.2 is a 5-membered or 6-membered ring.

(71) In one aspect, Y.sub.1 is selected from the group consisting of pyridyl, pyrazole, alkyl amine, imidazole, benzimidazole, triazole, tetrazole, pyridazine, pyrimidine, pyrazine, triazine, tetrazine, oxazole, thiazole, benzoxazole and benzothiazole.

(72) In another aspect, Y.sub.1-Y.sub.2 is selected from the group consisting of:

(73) ##STR00047## ##STR00048##
X is selected from the group consisting of NR, O, S, Se, CR.sub.2, and CO. Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. Each ring is further substituted by a substituent selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(74) In one aspect, each R includes a substituent independently selected from the group consisting of carbazole, dibenzofuran, dibenzothiophene, azacarbazole, azadibenzofuran, and azadibenzothiophene.

(75) In yet another aspect, Y.sub.1-Y.sub.2 is selected from the group consisting of:

(76) ##STR00049## ##STR00050## ##STR00051##

(77) X is selected from the group consisting of NR, O, S, Se, CR.sub.2, and CO. Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. Each ring is further substituted by a substituent selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(78) In one aspect, each R includes a substituent independently selected from the group consisting of carbazole, dibenzofuran, dibenzothiophene, azacarbazole, azadibenzofuran, and azadibenzothiophene.

(79) In another aspect, Y.sub.i is an unconjugated, monoanionic ligand containing BY.sub.4.sup.−, SO.sub.3Y.sup.−, CY.sub.4.sup.−, SiO.sub.4.sup.−, OY.sub.2.sup.−, or SY.sub.2.sup.−. Each Y is independently selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteralkyl and heteroaryl.

(80) In one aspect, Y.sub.i is BY.sub.4.sup.−. In another aspect, the ligand Yi comprises two monodentate ligands, at least one of which is BY.sub.4.sup.−. Preferably, the ligand Y.sub.i has the formula:

(81) ##STR00052##

(82) More preferably, the ligand Y.sub.i that comprises two monodentate ligands, at least one of which is BY.sub.4.sup.−, is selected from the group consisting of:

(83) ##STR00053##

(84) Y.sub.1 and Y.sub.2 are independently selected from the group consisting of pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, pyrazolyl, imidazolyl, benzimidazolyl, oxazolyl, thiszolyl, benzoxazolyl, benzothiazolyl and phosphine. Y.sub.1 and Y.sub.2 may be extended by fusion, e.g., benzanulation. Additionally, Y.sub.1 and Y.sub.2 may be further substituted with alkyl, aryl, donor or acceptor groups. Y.sub.3 and Y.sub.4 are independently selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteralkyl and heteroaryl. In one aspect, Y.sub.3 and Y.sub.4 are joined to form a cycle, may be extended by fusion, e.g., benzanulation.

(85) In another aspect, Y.sub.i is a bidentate ligand having the formula BY.sub.4.sup.−. Preferably, the ligand Y.sub.i is selected from the group consisting of:

(86) ##STR00054##
In this aspect, Y.sub.1 is a bidentate chelating ligand having the formula:

(87) ##STR00055##
Y′.sub.1-Y″.sub.1 represents a neutral, i.e., uncharged, chelating ligand. Y′.sub.1-Y″.sub.1 are capable of coordinating to a metal center.

(88) Specific examples of the Y′.sub.1-Y″.sub.1 ligand include, but are not limited to, ligands having the structure:

(89) ##STR00056##

(90) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(91) Y.sub.1 and Y.sub.2 are independently selected from the group consisting of pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, pyrazolyl, imidazolyl, benzimidazolyl, oxazolyl, thiszolyl, benzoxazolyl, benzothiazolyl and phosphine. Y.sub.1 and Y.sub.2 may be extended by fusion, e.g., benzanulation. Additionally, Y.sub.1 and Y.sub.2 may be further substituted with alkyl, aryl, donor or acceptor groups.

(92) Y.sub.3 and Y.sub.4 are independently selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteralkyl and heteroaryl. In one aspect, Y.sub.3 and Y.sub.4 are joined to form a cycle, which may be extended by fusion, e.g., benzanulation.

(93) In one aspect, Y.sub.1 and Y.sub.2 are the same. Specific examples of ligands where Y.sub.1 and Y.sub.2 are the same include, but are not limited to, ligands selected from the group consisting of:

(94) ##STR00057## ##STR00058## ##STR00059##

(95) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. C* is a divalent carbon atom. n is 0, 1, or 2. m is 0, 1, or 2.

(96) In one aspect, Y.sub.1 and Y.sub.2 are different. Specific examples of ligands where Y.sub.1 and Y.sub.2 are different include, but are not limited to, ligands selected from the group consisting of:

(97) ##STR00060## ##STR00061##

(98) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(99) In one aspect, Y.sub.3 and Y.sub.4 are selected from the group consisting of:

(100) ##STR00062##

(101) In one aspect, Y.sub.i is SO.sub.3Y.sup.−. Specific examples of ligands Y.sub.i having the formula SO.sub.3Y.sup.− include, but are not limited to, ligands having the structure:

(102) ##STR00063##

(103) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(104) In one aspect, Y.sub.i is CY.sub.4.sup.−. Preferably, CY.sub.4.sup.− has the formula:

(105) ##STR00064##

(106) Specific examples of ligands Y.sub.i having the formula CY.sub.4.sup.− include, but are not limited to, ligands having the structure:

(107) ##STR00065##

(108) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(109) In one aspect, Y.sub.3 and Y.sub.4 are selected from the group consisting of:

(110) ##STR00066##

(111) In another aspect, Y.sub.i is SiY.sub.4.sup.−. Specific examples of ligands Y.sub.i having the formula SiY.sub.4.sup.− include, but are not limited to, ligands having the structure:

(112) ##STR00067##

(113) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(114) In one aspect, Y.sub.3 and Y.sub.4 are selected from the group consisting of:

(115) ##STR00068##

(116) In another aspect, Y.sub.i is OY.sub.2.sup.−. Preferably, OY.sub.2.sup.− has the formula:

(117) ##STR00069##

(118) Specific examples of ligands Y.sub.i having the formula OY.sub.2.sup.− include, but are not limited to, ligands having the structure:

(119) ##STR00070##

(120) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(121) In one aspect, Y.sub.3 and Y.sub.4 are selected from the group consisting of:

(122) ##STR00071##

(123) In yet another aspect, Y.sub.i is SY.sub.2.sup.−. Preferably, SY.sub.2.sup.− has the formula:

(124) ##STR00072##

(125) Specific examples of ligands Y.sub.i having the formula SY.sub.2.sup.− include, but are not limited to, ligands having the structure:

(126) ##STR00073##

(127) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(128) In one aspect, the complex comprises two copper (I) centers. Non-limiting examples of complexes comprising two copper (I) centers include complexes selected from the group consisting of:

(129) ##STR00074##

(130) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(131) In a further aspect, the carbene ligand is selected from the group consisting of:

(132) ##STR00075## ##STR00076##
Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. z is 1, 2, 3, or 4.

(133) Preferably, the carbene is

(134) ##STR00077##
More preferably, the carbene is

(135) ##STR00078##
R′.sub.1 and R′.sub.2 may represent mono, di, tri, or tetra substitutions. R′.sub.1 and R′.sub.2 are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. In one aspect, at least one of R′.sub.1 and R′.sub.2 is an alkyl having three or more carbon atoms.

(136) Preferably, the complex is selected from the group consisting of:

(137) ##STR00079## ##STR00080##

(138) Preferably, the complex is selected from the group consisting of:

(139) ##STR00081## ##STR00082##

(140) More preferably, the complex is:

(141) ##STR00083##

(142) In another aspect, the complex has the formula:

(143) ##STR00084##
Y.sub.1 and Y.sub.2 are substituents that are independently selected from the group consisting of alkyl, heteroalkyl, aryl and heteroaryl. Y.sub.1 and Y.sub.2 may be further substituted. Y.sub.1 and Y.sub.2 are not joined. Each of Y.sub.1 and Y.sub.2 form a bond with Cu.

(144) In one aspect, the complex is selected from the group consisting of:

(145) ##STR00085##

(146) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

(147) In another aspect, the carbene ligand is bidentate. Preferably, the complex is selected from the group consisting of:

(148) ##STR00086##

(149) Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. Z is a monodentate ligand.

(150) In one aspect, the complex is included in a polymer. In another aspect, the complex is included in the repeat unit of the polymer. In yet another aspect, the complex is pendant on the polymer. Preferably, the polymer is selected from the group consisting of:

(151) ##STR00087##
Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. m is greater than 2. n is 0-20.

(152) In another aspect, the complex is included in a dendritic complex. Preferably, the dendritic complex is

(153) ##STR00088##
The core is a molecule or a polyvalent element selected from the group consisting of C, Si, Ge, Sn, Pb, N, P, and As. Each R is independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. m is greater than 1. n is 0-20.

(154) In yet another aspect, the complex is included in a small molecule.

(155) Devices comprising the phosphorescent complexes are also provided. A first device comprising an organic light emitting device further comprising an anode, a cathode; and an organic layer, disposed between the anode and the cathode. The organic layer further comprising a phosphorescent complex itself comprising a three coordinate copper atom and a carbene ligand. Preferably, the first device is a consumer product. The device may comprise a complex having Formula I, Formula II, Formula III, or Formula IV, as described above. Selections for the substituents, ligands, and complexes described as preferred for the complexes having Formula I, Formula II, Formula III, or Formula IV are also preferred for use in a device that comprises a complex including a complex having Formula I, Formula II, Formula III, or Formula IV. These selections include those described for X.sub.1, X.sub.2, X′.sub.1, X′.sub.2, Y.sub.1, Y.sub.2, Y′.sub.1, Y′.sub.2, Yi, R, X, and Z.

(156) Selections for the substituents, ligands, and complexes described as preferred for the complexes having Formula I, Formula II, Formula III, or Formula IV are also preferred for use in a device that comprises a complex including a complex having Formula I, Formula II, Formula III, or Formula IV. These selections include those described for X.sub.1, X.sub.2, X′.sub.1, X′.sub.2, Y.sub.1, Y.sub.2, Y.sub.3, Y.sub.4, Y.sub.5, Y″.sub.1, Y′.sub.2, Y.sub.i, R, X, and Z.

(157) Such devices may contain the trigonal copper complex as a neat thin film. In particular, an OLED comprising a pure film of the complex may have a higher luminescent efficiency than an OLED that comprises the complex doped with another material. Previously, it was thought that complexes cannot be used in pure films because of self-quenching. However, the trigonal copper complexes provided herein may not demonstrate the self-quenching problems seen in other complexes.

(158) The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the complexes disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

(159) In addition to and/or in combination with the materials disclosed herein, many hole injection materials, hole transporting materials, host materials, dopant materials, exiton/hole blocking layer materials, electron transporting and electron injecting materials may be used in an OLED. Non-limiting examples of the materials that may be used in an OLED in combination with materials disclosed herein are listed in Table 3 below. Table 3 lists non-limiting classes of materials, non-limiting examples of complexes for each class, and references that disclose the materials.

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EXPERIMENTAL

Complex Examples

(161) Several of the complexes were synthesized as follows:

Example 1. Synthesis of Complex 1

(162) Chloro[1,3-bis(2,6-di-1-propylphenyl)imidazol-2-ylidene]copper(I) (487.59 mg, 0.25 mmol) and silver triflate (64.2 mg, 0.25 mmol) were mixed under nitrogen in 25 mL flask and 10 mL of dry THF were added. Reaction mixture was stirred at RT for 30 minutes. Solution of 1,2-bis(diphenylphosphino)benzene (111.6 mg, 0.25 mmol) in dry THF (5 mL) was added. Reaction mixture was stirred at RT overnight. Resulting mixture was filtered through Celite® and solvent was evaporated on rotovap. Recrystallization from CH.sub.2Cl.sub.2 by vapor diffusion of Et.sub.2O gave 130 mg (49.6%) of white needle crystals. Structure confirmed by .sup.1H-NMR spectrum of [(IPR)Cu(dppbz)]OTf (CDCl.sub.3, 400 MHz).

Example 2. Synthesis of Complex 2

(163) Chloro[1,3-bis(2,6-di-1-propylphenyl)imidazol-2-ylidene]copper(I) (121.9 mg, 0.25 mmol) and silver triflate (64.2 mg, 0.25 mmol) were mixed under nitrogen in 25 mL flask and 10 mL of dry THF were added. Reaction mixture was stirred at RT for 30 minutes. Solution of 1,10-phenanthroline (45.05 mg, 0.25 mmol) in dry THF (5 mL) was added. Reaction mixture turned yellow and was stirred at RT overnight. Resulting mixture was filtered through Celite® and solvent was evaporated on rotovap. Recrystallization from CH.sub.2Cl.sub.2 by vapor diffusion of Et.sub.2O gave 120 mg (61.4%) of yellow crystals. Anal. calcd. for C.sub.40H.sub.44CuF.sub.3N.sub.4O.sub.3S: C, 61.48; H, 5.68; N, 7.17. Found: C, 61.06; H, 5.61; N, 7.14. Structure was confirmed by .sup.1H-NMR spectrum of [(IPR)Cu(phen)]OTf (CDCl.sub.3, 400 MHz).

Example 3. Synthesis of Complex 3

(164) Chloro[1,3-bis(2,6-di-1-propylphenyl)imidazol-2-ylidene]copper(I) (195.1 mg, 0.4 mmol) and silver triflate (102.7 mg, 0.4 mmol) were mixed under nitrogen in 25 mL flask and 10 mL of dry THF were added. Reaction mixture was stirred at RT for 30 minutes. Solution of 2,2′-bipyridine (62.4 mg, 0.4 mmol) in dry THF (5 mL) was added. Reaction mixture turned orange and was stirred at RT overnight. Resulting mixture was filtered through Celite® and solvent was evaporated on rotovap. Recrystallization from CH.sub.2Cl.sub.2 by vapor diffusion of Et.sub.2O gave 215 mg (70.9%) of orange crystals. Anal. calcd. for C.sub.38H.sub.44CuF.sub.3N.sub.4O.sub.3S: C, 60.26; H, 5.86; N, 7.40; Found: C, 60.18; H, 5.82; N, 7.38. Structure was confirmed by .sup.1H-NMR spectrum of [(IPR)Cu(bipy)]OTf (CDCl.sub.3, 400 MHz).

Example 4. Synthesis of Complex 4

(165) 2-(2-Pyridyl)benzimidazole (78.1 mg, 0.4 mmol) was dissolved in 10 mL of dry THF under N.sub.2 and this solution was transferred via cannula to suspension of sodium hydride (17.6 mg, 0.44 mmol, 60% in mineral oil) in dry THF. Reaction mixture was stirred at RT for 1 h and then chloro[1,3-bis(2,6-di-1-propylphenyl)imidazol-2-ylidene]copper(I) (195.1 mg, 0.4 mmol) was added. Reaction mixture was stirred at RT for 3 h. The resulting mixture was filtered through Celite® and solvent was removed by rotary evaporation. Recrystallization by vapor diffusion of Et.sub.2O into a CH.sub.2Cl.sub.2 solution of product gave 154 mg (59.5%) of dark yellow crystals. Anal. calcd. for C.sub.39H.sub.44CuN.sub.5: C, 72.47; H, 6.86; N, 10.48. Found: C, 72.55; H, 6.94; N, 10.84.

Example 5. Synthesis of Complex 5

(166) 1-(1H-benzimidazol-2-yl)-isoquinoline (46 mg, 0.19 mmol) was dissolved in 10 mL of dry THF under N.sub.2 and this solution was transferred via cannula to suspension of sodium hydride (8.36 mg, 0.209 mmol, 60% in mineral oil) in dry THF. The reaction mixture was stirred at RT for 1 h and then chloro[1,3-bis(2,6-di-1-propylphenyl)imidazol-2-ylidene]copper(I) (92.6 mg, 0.19 mmol) was added. The reaction mixture was stirred at RT for 3 h. The resulting mixture was filtered through Celite® and solvent was removed by rotary evaporation. Recrystallization by vapor diffusion of Et.sub.2O into a CH.sub.2Cl.sub.2 solution of product gave 50 mg (38%) of orange crystals.

Example 6. Synthesis of Complex 6

(167) 2-(2-Pyridyl)benzimidazole (78.1 mg, 0.4 mmol) was dissolved in 10 mL of dry THF under N.sub.2 and this solution was transferred via cannula to suspension of sodium hydride (17.6 mg, 0.44 mmol, 60% in mineral oil) in dry THF. The reaction mixture was stirred at RT for 1 h and then chloro[1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene]copper(I) (161.4 mg, 0.4 mmol) was added. The reaction mixture was stirred at RT for 3 h. The resulting mixture was filtered through Celite®. Solvent was removed by rotary evaporation and 178 mg (79%) of light-yellow solid was obtained.

Example 7. Synthesis of Complex 7

(168) Sodium dimethylbis(2-pyridyl)borate Na[(CH.sub.3).sub.2B(py).sub.2] (66 mg, 0.3 mmol) and chloro[1,3-bis(2,6-di-1-propylphenyl)-4,5-dihydroimidazol-2-ylidene]copper(I) (SIPr)CuCl (146.9 mg, 0.3 mmol) were mixed under N.sub.2 atmosphere in 25 mL flask. Freshly distilled THF (10 ml) was added and reaction mixture was stirred at RT for 1 h. Resulting mixture was filtered through Celite® and solvent was evaporated on rotovap. Recrystallization from acetone/hexane gave 85 mg (43.5%) of white solid. .sup.1H-NMR (acetone-d.sub.6, 400 MHz, ppm): δ −0.28 (s, 6H), 1.14 (d, 12H), 1.32 (d, 12H), 3.56 (sept, 4H), 4.21 (s, 4H), 6.56-6.60 (m, 2H), 7.20 (td, 2H), 7.27-7.30 (m, 6H), 7.38 (t, 2H), 7.50 (d, 2H).

Example 8. Synthesis of Complex 8

(169) Sodium dimethylbis(2-pyridyl)borate Na[(CH.sub.3).sub.2B(py).sub.2] (68.7 mg, 0.312 mmol) and chloro[1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene]copper(I) (106 mg, 0.26 mmol) were mixed under N.sub.2 atmosphere in 25 mL flask. Freshly distilled THF (10 ml) was added and reaction mixture was stirred at RT for 1 h. Solvent was evaporated on rotovap. The crude solid was washed with hexane, redissolved in CH.sub.2Cl.sub.2 and filtered. Removal of solvent gave 90 mg (61.3%) of white solid. .sup.1H-NMR (acetone-d.sub.6, 400 MHz, ppm): δ −0.13 (broad d, 6H), 2.21 (s, 12H), 2.30 (s, 6H), 6.57-6.60 (m, 2H), 7.02 (s, 4H), 7.23 (td, 2H), 7.34 (d, 2H), 7.44 (s, 2H), 7.52 (d, 2H).

(170) It is understood that the various embodiments described herein are by way of example only, and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted with other materials and structures without deviating from the spirit of the invention. The present invention as claimed may therefore includes variations from the particular examples and preferred embodiments described herein, as will be apparent to one of skill in the art. It is understood that various theories as to why the invention works are not intended to be limiting.