Complexes for OLEDs

I. (Technical field) In the present invention, the formula L₂OLED compounds of MX (in the formula, L and X are different bidentate ligands and M is a metal, especially iridium), their synthesis, and as a dopant in a host, of the OLED With respect to being used to form a light emitting layer.

II. (Background Technology) II.A. General Background Organic light emitting devices (OLEDs) are composed of several organic layers, one of which is electroluminescent by applying a voltage through the device. It is composed of organic materials that can be made to produce luminescence. CW Tang et al., Appl. Phys. Lett., 51, 913, (1987). Some OLEDs have been shown to have sufficient brightness, color range, and working life to be used as a practical alternative to LCD-based natural color flat panel displays [SR Forrest, PE Burrows. (Burrows), and ME Thompson, Laser Focus World, Feb. (1995)]. Since many of the organic thin films used in such devices are transparent in the visible spectral range, they are in the form of vertically stacked OLEDs that emit red (R), green (G), and blue (B). It is possible to realize a completely new type of display pixel that can be placed and given a simple manufacturing method, a small RGB pixel size, and a large filling rate. International Patent Application No. PCT / US95 / 15790.

A transparent OLED (TOLED) is reported in International Patent Application No. PCT / US97 / 02681, which indicates an important step for realizing stacked RGB pixels that have high resolution and can be addressed independently. The TOLED exhibits greater than 71% transparency when switched off and emits light from both the top and bottom device surfaces with great efficiency (quantum efficiency close to 1%) when the device is switched on. The TOLED uses transparent indium tin oxide (ITO) as the hole injection electrode and an Ng-Ag-ITO electrode layer for electron injection. A device is disclosed in which the ITO side of the Ng-Ag-ITO layer is used as a hole injection contact for a second different color emitting OLED laminated on top of the TOLED. Each layer of laminated OLED (SOLED) can be addressed independently and emits its own characteristic color. This colored emission is transmitted through an adjacently laminated transparent, independently addressable organic layer (s), transparent contacts, and a glass substrate, and the relative output of the red and blue emission layers. Allows the device to emit any color that can be produced by changing the.

The PCT / US95 / 15790 application discloses an integrated SOLED that is a color-adjustable display device that can independently change and adjust both intensity and color with externally supplied power. Thus, the PCT / US95 / 15790 application illustrates the principle of achieving integrated natural color pixels with high resolution made possible by the small pixel size. Moreover, relatively low cost manufacturing techniques can be used to manufacture such devices as compared to conventional methods.<patcit num="1"><text>International Patent Application PCT / US95 / 15790</text></patcit><patcit num="2"><text>International Patent Application PCT / US97 / 02681</text></patcit><nplcit num="1"><text>CWTang et al., Appl. Phys. Lett., 51, 913 (1987)</text></nplcit><nplcit num="2"><text>SR Forrest, PE Burrows, and ME Thompson, Laser Focus World, Feb. (1995)</text></nplcit>

<p> II.B. Luminous background II.B.1. Basics II.B.1.a. Singlet and triplet excitons Since light is generated by molecular excited states or exciton decay in organic materials, understanding their properties and interactions is currently significant due to their potential use in indicators, lasers, and other lighting applications. It is important for the design of effective light emitting devices of interest. For example, if the exciton symmetry is different from that of the ground state, the exciton's radioactive relaxation becomes impossible and the luminescence becomes slow and inefficient. Since the ground state is usually antisymmetric in the exchange of electron spins containing excitons, the decay of symmetric excitons breaks symmetry. Such excitons are known as triplets, and the term reflects the degeneracy of that state. Only one symmetric state (ie, singlet) exciton occurs in any of the three triplet excitons formed by electrical excitation in the OLED. [MA Baldo, DF O'Brien, ME Thompson, and SR Forest (Forrest), "Very high-efficiency green OLED based on electrophosphorescence" green organic light-LED devices based on electrophosphorescence), Applied Physics Letters, 75, 4-6, (1999)]. Luminescence from the non-symmetrical process is known as phosphorescence. Characteristically, phosphorescence has a low probability of transition and may persist for up to a few seconds after excitation. Fluorescence, on the other hand, begins with a rapid decay of singlet excitation. It is very efficient because this process occurs between states of the same symmetry.</p><p> Many organic materials exhibit fluorescence from singlet excitons. However, it has also been confirmed that only a few can produce effective room temperature phosphorescence due to the triplet. For example, in most optical brighteners, the energy contained in the triplet state is wasted. However, when the triplet excited state perturbs, for example, by spin-orbit coupling (typically due to the presence of heavy metal atoms), effective phosphorescence is more likely to occur. In this case, triplet excitation has some singlet property, which has a greater probability of radioactive decay to the ground state. In fact, phosphorescent dyes with these properties exhibit high efficiency electroluminescence.</p><p> Only a few organic materials have been shown to exhibit effective room temperature phosphorescence due to the triplet. In contrast, many optical brighteners are known [CH Chen, J. Shi, and CW Tang, "Recent Developments in Molecular Organic Electroluminescence Materials" ( Recent developments in molecular organic electroluminescent materials), Macromolecular Symposia., 125, 1-48, (1997); U. Blackmann, "Lambdachrome Laser Dyes", Lambda Physik, Göttingen, 1997], the fluorescence efficiency in solution can be close to 100%. Not unusual (CH Chen, 1997, see above). Fluorescence is unaffected by triplet-triplet annihilation, which reduces phosphorescence at high excitation densities [MA Baldo and others, "High efficiency phosphorescent emission from organic electroluminescent devices". , Nature, 395, 151-154, (1998); MA Baldo, ME Thompson, and SR Forest, "An analytic model of triplet-triplet annihilation in electrophosphorescent devices", 1999]. Therefore, fluorescent materials are suitable for many electroluminescence applications, especially passive matrix indicators.</p>

<p> II.B.1.b. Overview of the basics of the present invention In the present invention, the formula LL L M [where L, L , and L are different bidentate ligands, and M is a metal with an atomic number greater than 40 forming an octahedral complex. It is preferably the metal of the third series transition metal of the periodic table transition series]. Alternatively, M can be a metal of a second series transition metal, or a main group metal, such as Zr and Sb. Some of such organic metal complexes exhibit electroluminescence and luminescence coming from the lowest energy ligand or MLCT state. Such electroluminescent compounds can be used as dopants in the host layer of the emitter layer of the light emitting diode. The present invention further describes the formula LL L M (where L, L and L are the same or different, where L, L , and L are monoanionic bidentate ligands. , M is a metal forming an octahedral complex, preferably a third series metal of the transition metal, more preferably Ir or Pt, and the atom coordinating those ligands is sp.²It relates to a complex of hybridized carbons and heteroatoms. The present invention further comprises L₂MX [In the equation, L and X are different bidentate ligands, L is sp²It is coordinated to M by hybrid orbital carbon and L atoms with heteroatoms, where M is the metal forming the octahedral complex, preferably iridium (Ir)]. These compounds can act as dopants in the host layer, which acts as the emitter layer of the organic light emitting diode.</p><p> The compound of the present invention has the formula L.₂M (μ-Cl)₂ML₂(In the formula, L is a bidentate ligand and M is a metal such as Ir), and the direct of the chloride-crosslinked dimer and the substance XH that acts to introduce the bidentate ligand X. It can be produced by the reaction. XH can be, for example, acetylacetone, 2-picolinic acid, or N-methylsalitylanilide, where H represents hydrogen. The resulting product is of formula L₂It has MX, in which case an octahedral coordination of bidentate ligands L, L, and X can be obtained around M.</p><p> Equation L₂The compound obtained by MX can be used as a phosphorescent body of an organic light emitting device. For example, compounds where L = (2-phenylbenzothiazole), X = acetylacetonate, and M = Ir (compound omitted as BTIr) are 4,4'to form an emitter layer in the OLED. When used as a dopant in -N, N'-dicarbazole-biphenyl (CBP) (at a level of 12% by mass), it exhibits a quantum efficiency of 12%. For reference, the formula CBP is:</p><p><chemistry num="1"><img file="JP4358168B2_D0001.tif" /></chemistry></p><p> L₂In the synthetic method for producing MX, L itself is a fluorescent substance, but the obtained L₂It can be used advantageously when MX is a phosphor. One special example of this is the case of L = coumarin-6.</p><p> The synthetic method promotes the binding of L and X pairs with certain desired properties.</p><p> By choosing L and X properly, L₃Complex L for M₂You can adjust the color of MX. For example, Ir (ppy)₃And (ppy)₂Both Ir (acac) give a strong green luminescence with a λmax of 510 nm [ppy stands for phenylpyridine]. However, if the X ligand is formed from picolinic acid rather than from acetylacetone, there is a small blue transition of about 15 nm.</p><p> In addition, X is L so that carriers (holes or electrons) are trapped in X (or L) without causing degradation in emission quality.₃The M complex can be selected to have a certain HOMO level. In this way, carriers (holes or electrons) that could otherwise cause harmful oxidation or reduction of phosphors would be blocked. Carriers trapped in the distance will easily recombine with intermolecularly opposite carriers or with carriers from adjacent molecules.</p><p> The present invention and various aspects thereof will be discussed in more detail in the examples below. However, those embodiments can also be actuated by different mechanisms. The various mechanisms by which the various aspects of the invention operate are discussed, but they do not limit the scope of the invention.</p><p> II.B.1.c. Dexter and Foerster mechanism Discussing the theory of the underlying energy transfer mechanism will help to understand the different aspects of the invention. Two mechanisms have generally been discussed for the transfer of energy to receptor molecules. Dexter Movement [DL Dexter, "A theory of sensitized luminescence in solids", J. Chem. In the first mechanism of Phys., 21, 836-850, (1953)], the excitation can jump directly from one molecule to the next. This is a short-range process that relies on overlapping molecular orbitals of adjacent molecules. It also retains the symmetry of the donor-receptor pair [E. Wigner and EW Wittmer, "Structure of Diatomic Molecular Spectrum by Quantum Mechanics" (Uber die Struktur der zweiatomigen Molekelspektren nach der Quantenmechanik) , Zeitshrift fur Physik, 51, 859-886, (1928); M. Klessinger and J. Michl, "Excited states and photochemistry of organic molecules" (VCH Publishing, New York, 1995). Therefore, the energy transfer of Eq. (1) is not possible depending on the Dexter mechanism. In the second mechanism of Felster transfer [T. Felster, "Intermolecular Energy Transfer and Fluorescence" (Zwischenmolekulare Energiewanderung and Fluoreszenz), Annalen der Physik, 2, 55-75 (1948); T. Felster, "Fluoreszenz organischer Verbindugen" (Vandenhoek and Ruprecht, Gettingen, 1951)], energy transfer of equation (1) is possible. In Felster's movement, as with transmitters and antennas, the dipoles of donor and receptor molecules bind and energy can move. Dipoles are caused by allowed transitions in both donor and receptor molecules. This typically limits the Felster mechanism to movement between singlet states.</p><p> Nevertheless, as long as the phosphor can emit light by some perturbation of the state, such as by spin-orbit coupling introduced by heavy metal atoms, it can also serve as a donor in Felster movement. Can be done. The efficiency of this process is determined by the luminescence efficiency of the phosphor [F. Wilkinson, "Advances in Photochemistry", WA Noise (Noyes), G. Hammond, and JN Pitts. ) Edit, John Wiley &amp; Sons, New York, 1964, pp.241-268], that is, if radioactive transitions are more likely to occur than non-radioactive decay, energy transfer will be effective. Such triplet / singlet movements have been predicted by Felster [T. Felster, "Transfer mechanisms of electronic exitation", Discussions of the Faraday Society, 27, 7-17. ,, (1959)], confirmed by Ermolaev and Sveshnikova [VL Elmoraev and EB Sveshnikova, Inductive-resonance transfer of energy from aromatic. molecules in the triplet state), Doklady Akademii Nauk SSSR, 149, 1295-1298, (1963)], they transfer energy at 77K or 90K using a range of phosphorescent and fluorescent acceptors in solid media. Detected. Long-distance migration has been observed, for example with triphenylamine as the donor and chrysoidine as the receptor, with an interaction range of 52 Å.</p><p> The remaining condition for Felster migration is that the absorption spectrum overlaps the emission spectrum of the donor, assuming that the energy levels between the excited and ground state molecular pairs resonate. In Example 1 of the present application, we see the green phosphor (2-phenylpyridine) iridium [Ir (ppy) 3; MA Baldo, et al., Appl. Phys. Lett., 75, 4-6, (1999). )], And red fluorescent dye, [2-methyl-6- [2- (2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolidine-9-yl) ethenyl] -4H-pyrrole- Iridium] Propane-dinitrile] ["DCM2"; CW Tang, SA Van Slyke, and CH Chen, "Electroluminescence of doped organic films", J. Appl .. Phys., 65, 3610-3616, (1989)] was used. DCM2 absorbs in green and due to the local polarization field it emits at wavelengths between λ = 570 nm and λ = 650 nm [V. Bulovic et al. Devices (Bright, saturated, red-to-yellow organic light-emitting devices based on polarization-induced spectral shifts), Chem. Phys. Lett., 287, 455-460, (1998)].</p><p> Doping fluorescent guests into the phosphorescent host material allows Förster energy transfer from the triplet state. Unfortunately, such systems are affected by competing energy transfer mechanisms that degrade overall efficiency. In particular, the close proximity of the host and guest increases the likelihood of dexter movement from the host to the guest triplet. As excitons approach the guest triplet state, they are effectively lost. This is because these fluorescent dyes typically exhibit extremely inefficient phosphorescence.</p><p> In order to maximize the transfer of the host triplet to the fluorescent dye singlet, it is desirable to maximize the dexter transfer of the phosphor to the triplet state and at the same time minimize the transfer of the fluorescent dye to the triplet state. Since the Dexter mechanism transfers energy between adjacent molecules, reducing the concentration of the fluorescent dye reduces the probability of triplet-triplet transfer to the dye. On the other hand, long-distance Felster movement to the singlet state is unaffected. In contrast, the transfer of phosphors to the triplet state is necessary to utilize the host triplet and can be ameliorated by increasing the concentration of phosphors.</p><p> II.B.2. Correlation between device structure and light emission Devices with structures based on the use of layers of organic photoelectronic materials generally rely on the general mechanism of providing optical light emission. This mechanism is typically based on the luminescent recombination of the captured charge. In particular, OLEDs have at least two thin organic layers that separate the anode and cathode of the device. The material of one of these layers is the "hole transport layer" (HTL), which is specifically selected based on its ability to transport holes in the material, and the material of the other layer is specifically selected according to its ability to transport electrons. It is an "electron transport layer" (ETL). With such a structure, the device can be seen as a diode, which is a forward bias when the potential applied to the anode is higher than the potential applied to the cathode. Under these bias conditions, the anode injects holes (positive charge carriers) into the hole transport layer, while the cathode injects electrons into the electron transport layer. As a result, the portion of the luminescence medium adjacent to the anode forms the hole injection and transport region, while the portion of the luminescence medium adjacent to the cathode forms the electron injection and transport region. The injected holes and electrons move toward the oppositely charged electrodes, respectively. Localization of electrons and holes in the same molecule forms Frenkel excitons. This short-lived recombination is visualized when an electron falls from its conduction potential into the valence band, and under certain conditions is preferentially relaxed by the luminescence mechanism. According to this view of the working mechanism of a typical thin-layer organic device, the electroluminescence layer has a luminescence region that receives mobile charge carriers (electrons and holes) from each electrode.</p><p> As mentioned above, the emission from the OLED is typically due to fluorescence or phosphorescence. There is a problem with the use of phosphorescence. It has been found that the phosphorescence efficiency drops rapidly at high current densities. A long phosphorescence lifetime causes saturation of the light emitting part, and triplet / triplet annihilation also causes a decrease in efficiency. Another difference between fluorescence and phosphorescence is that the triplet energy transfer from the conductive host to the luminescence guest molecule is typically slower than that of the singlet. The long-distance dipole-dipole bond (Felster transfer) that governs the energy transfer of a singlet is (theoretically) prohibited for the triplet by the principle of spin symmetry conservation. Therefore, in the case of triplets, energy transfer is typically caused by the diffusion of excitons into adjacent molecules (Dexter transfer), and significant overlap of donor and receptor excitation wavefunctions results in energy transfer. Is mandatory. Another problem is that the triplet diffusion distance is typically longer (eg&gt; 1400 Å) compared to a typical singlet diffusion distance of about 200 Å. Therefore, in order for the phosphorescent device to realize these possibilities, the device structure needs to be optimal for triplet characteristics. The present invention utilizes the property of long-range triplet diffusion to improve external quantum efficiency.</p><p> Successful use of phosphorescence promises enormous prospects for organic electroluminescence devices. For example, the advantage of phosphorescence is that (in part) all excitons based on the triplet of the phosphorescence device (formed by the recombination of holes and electrons in the EL) are energized in some electroluminescence material. Being able to be involved in mobility and luminescence. On the other hand, a singlet-based fluorescence apparatus results in giving fluorescence luminescence only in a small proportion of excitons.</p><p> Another method is to utilize the phosphorescence process to improve the efficiency of the fluorescence process. Fluorescence is, in principle, 75% less efficient due to a number three times larger than the symmetric excited state.</p><p> II.C. Material background II.C.1. Basic heterostructure Typically, there is at least one electron transport layer and at least one hole transport layer, so there are layers of different materials that form a heterostructure. The material that produces electroluminescence emission is the same material that acts as the electron transport layer or hole transport layer. Such devices in which the electron transport layer or the hole transport layer also acts as a light emitting layer are referred to as having a single heterostructure. Alternatively, the electroluminescence material may be present in another light emitting layer between the hole transport layer and the electron transport layer, which is called a double heterostructure. The other light emitting layer may contain light emitting molecules doped into the host, or the light emitting layer may be essentially composed of light emitting molecules.</p><p> That is, it is relatively as a dopant in the charge carrier layer, in addition to the light emitting material which exists as a main component in the charge carrier layer, that is, the hole transport layer or the electron transport layer and functions as both the charge carrier material and the light emitting material. Luminescent material may be present at low concentrations. In the presence of dopants, the main material in the charge carrier layer can be referred to as the host compound or accepting compound. The material present as the host and dopant is selected to provide a high level of energy transition from the host to the dopant material. In addition, these materials need to be able to produce acceptable electrical properties for OLEDs. Further, it is preferred that such host and dopant materials can be introduced into the OLED using convenient manufacturing techniques, especially with materials that can be readily incorporated into the OLED using vacuum deposition methods. ..</p><p> II.C.2. Exciton blocking layer An exciton blocking layer can be placed within the OLCD device to substantially prevent exciton diffusion, thereby effectively retaining the excitons within the light emitting layer and increasing the efficiency of the device. .. The material of the blocking layer is characterized by an energy difference (forbidden bandwidth) between its lowest depletion molecular orbital (LUMO) and its highest occupied molecular orbital (HOMO). This forbidden bandwidth substantially prevents the diffusion of excitons through the blocking layer, but has minimal effect on the voltage when the finished electroluminescence device is switched on. Therefore, it is preferred that the forbidden bandwidth be greater than the energy level of excitons generated in the light emitting layer so that such excitons cannot be present in the blocking layer. In particular, the forbidden bandwidth of the blocking layer is at least as large as the energy difference between the triplet state and the ground state of the host.</p><p> In the presence of a blocking layer between the Hall conductive host and the electron transport layer, the following properties, listed in order of relative importance, are required.</p><p> 1. The energy difference between LUMO and HOMO in the blocking layer is greater than the energy difference between the triplet and ground state singlet of the host material. 2. Triplets in the host material are not quenched by the blocking layer. 3. The ionization potential (IP) of the blocking layer is greater than the ionization potential of the host (meaning that holes are retained in the host). 4. The energy level of the LUMO of the blocking layer and the energy level of the LUMO of the host are close enough so that the change in the total conductivity of the device is less than 50%. 5. The blocking layer should be as thin as possible, provided it has a layer thickness sufficient to effectively block the movement of excitons from the light emitting layer to the adjacent layer.</p><p> That is, in order to block excitons and holes, the ionization potential of the blocking layer should be greater than that of the HTL, while at the same time the electron affinity of the blocking layer is approximately equal to that of the ETL to facilitate electron transport. Should be. [When using radioactive (luminescent) molecules without a whole transport host, the above rules for selecting a blocking layer are modified by replacing the word "host" with "luminescent molecules". ]</p><p> Determining the properties of ancillary states with a blocking layer between the electron conductive host and the hole transport layer (listed in order of importance): </p><p> 1. The energy difference between LUMO and HOMO in the blocking layer is greater than the energy difference between the triplet and ground state singlet of the host material. 2. Triplets in the host material are not quenched by the blocking layer. 3. The LUMO energy of the blocking layer is greater than the LUMO energy of the (electron transport) host. (Meaning that the electron is held on the host). 4. The ionization potential of the blocking layer and the host is such that holes are easily injected from the barrier into the host and the change in total conductivity of the device is less than 50%. 5. The blocking layer should be as thin as possible, provided it has a layer thickness sufficient to effectively block the movement of excitons from the light emitting layer to the adjacent layer.</p><p> [When using radioactive (luminescent) molecules without an electron transport host, the above rules for selecting a blocking layer are modified by replacing the word "host" with "luminescent molecules". ]</p><p> II.D. color With respect to color, OLEDs are manufactured using materials that provide electroluminescence emission in a relatively narrow band with a center near the selected spectral region corresponding to one of the three major colors, red, green and blue. It is desirable to allow them to be used as a colored layer in OLEDs or SOLEDs. It is also desirable that such compounds can be easily vapor-deposited as thin layers using vacuum-deposited methods and that they can be easily incorporated into OLEDs produced entirely from vacuum-deposited organic materials.</p><p> U.S. Patent Application Serial No. 08 / 774,333 (approved), filed December 23, 1996, relates to a luminescent compound-containing OLED that produces saturated red light emission.</p><p> III. (Disclosure of Invention) As a general level, the present invention relates to a complex of metal M having an atomic number greater than 40, where M forms an octahedral complex with three bidentate ligands. The metals include main group metals such as Sb, "second series transition metals of the periodic table transition series", preferably "third series transition metals of the periodic table transition series", most preferably Ir and Pt. Is included. The organometallic complex can be used in the emitter layer of the organic light emitting diode. The complex can be drawn as LL L M (in the formula, L, L , and L represent bidentate ligands and M represents a metal). An example in which all ligands are different is shown in FIG.</p><p> The present invention further relates to an organic metal complex of a metallic substance M and a monoanionic bidentate ligand, in which case M is the sp of the ligand.²Hybrid orbital carbons and heteroatoms are coordinated. The complex is L₃M (in this case, each ligand L substance is the same), LL L M (in this case, each ligand substance L, L , L is different), or L₂It may be in the form of MX (in this case, X is a monoanionic bidentate ligand). Ligand L is generally expected to be more involved in the luminescence process than X. Preferably M is a transition metal of the third series, most preferably M is Ir or Pt. The present invention is L₃With respect to the meridianal isomer of M, in this case the heteroatom (eg, nitrogen) of the two ligands L is in the trans form. M to ligand sp²In an embodiment in which hybrid orbital carbons and heteroatoms are coordinated, metals M, sp.²Rings with hybrid orbital carbons and heteroatoms preferably have 5 or 6 atoms.</p><p> Further, in the present invention, a complex of a transition metal substance M having bidentate ligands L and M is placed in the emitter layer of the organic light emitting diode by the formula L.₂Regarding use as a compound of MX. A preferred embodiment is the formula L as a dopant in a host layer configured to function as an emitter layer in an organic light emitting diode.₂It is a compound of IrX (in the formula, L and X are different bidentate ligands).</p><p> The present invention also relates to an improved synthesis of organometallic molecules that function as light emitters in light emitting devices. The compounds of the present invention have the following reactions: L₂M (μ-Cl)₂ML₂+ XH L₂MX + HCl [in the formula, L₂M (μ-Cl)₂ML₂Is a chloride-crosslinked dimer with L as the bidentate ligand and M as a metal such as Ir; XH reacts with the crosslinked chloride to introduce the bidentate ligand X. Bronsted acid, in which case XH can be, for example, acetylacetone, 2-picolinic acid, or N-methylsalicylicylanilide. ] Can be manufactured according to. This method is L₂M (μ-Cl)₂ML₂It involves binding the chloride cross-linked dimer to the XH material. L₂MX has a nearly octahedral arrangement of bidentate ligands L, L, and X around M.</p><p> The present invention further describes the phosphorescent body in the organic light emitting device as the formula L.₂Concerning the use of MX compounds. For example, compounds where L = (2-phenylbenzothiazole), X = acetylacetonate, and M = Ir (abbreviated as BTIr) are used as dopants in CBP to form the emitter layer in the OLED. When used (at the level of 12% by mass), it exhibits a quantum efficiency of 12%. For reference, the formula for 4,4'-N, N'-dicarbazole-biphenyl (CBP) is:</p><p><chemistry num="2"><img file="JP4358168B2_D0002.tif" /></chemistry></p><p> The present invention further relates to an organometallic complex L.₂Regarding MX, in this case L itself is a fluorescent substance, but the obtained L₂MX is a phosphor. One special example of this is the case of L = coumarin-6.</p><p> The present invention further comprises L₃Complex L with respect to M₂It also concerns the proper selection of L and X to make MX color adjustments. For example, Ir (ppy)₃And (ppy)₃Both Ir (acac) give a strong green luminescence with a λmax of 510 nm [ppy stands for phenylpyridine]. However, if the X ligand is formed from picolinic acid rather than from acetylacetone, there is a small blue transition of about 15 nm.</p><p> In addition, L so that carriers (holes or electrons) are trapped in X (or L) without causing degradation in emission quality.₃It relates to selecting X to have a certain HOMO level for the M complex. In this way, carriers (holes or electrons) that could otherwise cause harmful oxidation (or reduction) of phosphors would be blocked. Carriers trapped in the distance will easily recombine with intermolecularly opposite carriers or with carriers from adjacent molecules.</p><p> V. (Detailed description of the present invention) VA chemistry The present invention can be doped into the host layer of the emitter layer of the organic light emitting diode.₂Concerning the synthesis and use of certain organometallic molecules of MX. In some cases, equation L₂MX molecules can be used in the emitter layer at increased concentrations or as is. In the present invention, the formula L₂MX (in the formula, L and X are different bidentate ligands, M is a metal that forms an octahedral complex, preferably a metal selected from the third column of transition elements in the periodic table, most preferably. The present invention relates to an organic light emitting device having an emitter layer containing a molecule of (Ir or Pt), and the emitter layer still emits light having a maximum value at a certain wavelength λmax.</p><p> VA1. Dopant The general chemical formula for molecules doped in the host phase is L₂MX (in the formula, M is a transition metal forming an octahedral complex, L is a bidentate ligand, and X is a different bidentate ligand).</p><p> Examples of L are 2- (1-naphthyl) benzoxazole, (2-phenylbenzoxazole), (2-phenylbenzothiazole), (2-phenylbenzothiazole), (7,8-benzoquinolin), coumarin, (Thienylpyridine), phenylpyridine, benzothienylpyridine, 3-methoxy-2-phenylpyridine, thienylpyridine, and tolylpyridine.</p><p> Examples of X are acetylacetone (acac), hexafluoroacetylacetonate, salicylidene, picolinate, and 8-hydroxyquinolinate.</p><p> Yet another example of L and X is given in Figure 39, and yet another example of L and X is Comprehensive Coordination Chemistry (Editorial Chief G. Wilkinson, Pergamon Press) Volume 2. In particular, it can be found in Chapter 20.1 (after page 715) by M. Calligaris and L. Randaccio and in Chapter 20.4 (after page 793) by RS Bug (Vagg).</p><p> VA2. Formula L₂MX Molecule Synthesis VA2.a. Reaction Method Formula L₂The MX compound can be prepared according to the following formula: L₂M (μ-Cl)₂ML₂+ XH L₂MX + HCl [in the formula, L₂M (μ-Cl)₂ML₂Is a chloride-bridged dimer with L as a bidentate ligand, M is a metal such as Ir; XH reacts with the cross-linked chloride to introduce the bidentate ligand X. Bronsted acid, in which case XH can be, for example, acetylacetone, hexafluoroacetylacetone, 2-picolinic acid, or N-methylsalitylanilide. ] L₂MX has a nearly octahedral arrangement of bidentate ligands L, L, and X around M.</p><p> VA2.b. Example L₂Ir (μ-Cl)₂IrL₂The complex is IrCl₃ NH₂Manufactured from O and suitable ligands by the methods of the literature [S. Sprouse, KA King, PJ Spellane, RJ Watts, J. Am. Chem. Soc., 106 , 6647-6653, (1984); General References: GA Carlson et al., Inorg. Chem., 32, 4483, (1993); B. Schmid et al., Inorg. Chem., 33, 9, (1993). ); F. Graces et al., Inorg. Chem., 27, 3464, (1988); MG Colombo et al., Inorg. Chem., 32, 3088, (1993); A. Mamo et al. , Inorg. Chem., 36, 5947, (1997); S. Serroni et al., J. Am. Chem. Soc., 116, 9086, (1994); AP Wilde et al., J. Phys. Chem., 95, 629, (1991); JH van Diemen et al., Inorg. Chem., 31, 3518, (1992); MG Colombo et al., Inorg. Chem., 33, 545, (1994) ].</p><p> Ir (3-MeOppy)₃.. Ir (acac)₃(0.57 g, 1.17 mM) and 3-methoxy-2-phenylpyridine (1.3 g, 7.02 mM) were mixed in 30 ml of glycerol and N₂It was heated to 200 ° C for 24 hours. The resulting mixture was added to 100 ml of 1M HCl. Precipitate is collected by filtration and CH as an eluent₂Cl₂Purified by column chromatography using the product to give the product as a bright yellow solid (0.35 g, 40%). MS (EI): m / z (relative strength) 745 (M^-, 100), 561 (30), 372 (35). The emission spectrum is shown in FIG.</p><p> tpyIrsd. Chloride cross-linked dimer (tpyIrCl)₂(0.07g, 0.06mM), salicylidene (0.022g, 0.16mM) and Na₂CO₃(0.02 g, 0.09 mM) was mixed in 10 ml 1,2-dichloroethane and 2 ml ethanol. Mix the mixture for 6 hours until the TLC no longer detects the dimer.₂Refluxed inside. The reaction was then cooled and the solvent was evaporated. Excess salicidene was removed by gentle heating in vacuum. CH residual solid₂Cl₂It was redissolved in and the insoluble inorganic material was removed by filtration. Concentrate the filtrate and CH as an eluent₂Cl₂The product was column chromatographed using a bright yellow solid (0.07 g, 85%). MS (EI): m / z (relative strength) 663 (M⁺, 75), 529 (100), 332 (35). The emission spectrum is shown in FIG. 8 and the proton NMR spectrum is shown in FIG.</p><p> thpyIrsd. Chloride cross-linked dimer (thpyIrCl)₂(0.21g, 0.19mM), (thpyIrCl)₂Processed in the same way as. Yield: 0.21g, 84%. MS (EI): m / z (relative strength) 647 (M⁺, 100), 513 (30), 486 (15), 434 (20), 324 (25). The emission spectrum is shown in FIG. 10 and the proton NMR spectrum is shown in FIG.</p><p> btIrsd. Chloride cross-linked dimer (btIrCl)₂(0.05g, 0.039mM), (tpyIrCl)₂Processed in the same way as. Yield: 0.05g, 86%. MS (EI): m / z (relative strength) 747 (M)⁺, 100), 613 (100), 476 (30), 374 (25), 286 (32). The emission spectrum is shown in FIG. 12, and the proton NMR spectrum is shown in FIG.</p><p> Ir (bq)₂(acac), BQIr. Chloride cross-linked dimer (Ir (bq)₂ Cl)₂(0.091 g, 0.078 mM), acetylacetone (0.021 g), and sodium carbonate (0.083 g) were mixed in 10 ml 2-ethoxyethanol. Mix the mixture for 10 hours until the TLC no longer detects the dimer.₂Refluxed inside. The reaction was then cooled and the yellow precipitate was filtered. The product was purified by flash chromatography with dichloromethane. Product: Bright yellow solid (91% yield).¹1 H NMR (360MHz, Acetone-d₆), ppm: 8.93 (d, 2H), 8.47 (d, 2H), 7.78 (m, 4H), 7.25 (d, 2H), 7.15 (d, 2H), 6.87 (d, 2H), 6.21 (d, 2H), 5.70 (s, 1H), 1.63 (s, 6H). MS, e / z: 648 (M⁺, 80%), 549 (100%). The emission spectrum is shown in FIG. 14, and the proton NMR spectrum is shown in FIG.</p><p> Ir (bq)₂(Facac), BQIrFA. Chloride cross-linked dimer (Ir (bq)₂Cl)₂(0.091 g, 0.078 mM), hexafluoroacetylacetone (0.025 g), and sodium carbonate (0.083 g) were mixed in 10 ml 2-ethoxyethanol. Mix the mixture for 10 hours until the TLC no longer detects the dimer.₂Refluxed inside. The reaction was then cooled and the yellow precipitate was filtered. The product was purified by flash chromatography with dichloromethane. Product: Yellow solid (69% yield).¹1 H NMR (360MHz, Acetone-d₆), ppm: 8.99 (d, 2H), 8.55 (d, 2H), 7.86 (m, 4H), 7.30 (d, 2H), 7.14 (d, 2H), 6.97 (d, 2H), 6.13 (d, 2H), 5.75 (s, 1H). MS, e / z: 684 (M⁺, 59%), 549 (100%). The emission spectrum is shown in FIG.</p><p> Ir (thpy)₂(acac), THP Ir. Chloride cross-linked dimer (Ir (thpy)₂Cl)₂(0.082 g, 0.078 mM), acetylacetone (0.025 g), and sodium carbonate (0.083 g) were mixed in 10 ml 2-ethoxyethanol. Mix the mixture for 10 hours until the TLC no longer detects the dimer.₂Refluxed inside. The reaction was then cooled and the yellow precipitate was filtered. The product was purified by flash chromatography with dichloromethane. Product: Yellow-orange solid (80% yield).¹1 H NMR (360MHz, Acetone-d₆), ppm: 8.34 (d, 2H), 7.79 (m, 2H), 7.58 (d, 2H), 7.21 (d, 2H), 7.15 (d, 2H), 6.07 (d, 2H), 5.28 (s, 1H), 1.70 (s, 6H). MS, e / z: 612 (M⁺, 89%), 513 (100%). The emission spectrum is shown in FIG. 17 (denoted as "THIr") and the proton NMR spectrum is shown in FIG.</p><p> Ir (ppy)₂(acac), PPIr. Chloride cross-linked dimer (Ir (ppy)₂Cl)₂(0.080 g, 0.078 mM), acetylacetone (0.025 g), and sodium carbonate (0.083 g) were mixed in 10 ml 2-ethoxyethanol. Mix the mixture for 10 hours until the TLC no longer detects the dimer.₂Refluxed inside. The reaction was then cooled and the yellow precipitate was filtered. The product was purified by flash chromatography with dichloromethane. Product: Yellow solid (87% yield).¹1 H NMR (360MHz, Acetone-d₆ ), ppm: 8.54 (d, 2H), 8.06 (d, 2H), 7.92 (m, 2H), 7.81 (d, 2H), 7.35 (d, 2H), 6.78 (m, 2H), 6.69 (m, 2H), 6.20 (d, 2H), 5.12 (s, 1H), 1.62 (s, 6H). MS, e / z: 600 (M⁺, 75%), 501 (100%). The emission spectrum is shown in FIG. 19 and the proton NMR spectrum is shown in FIG.</p><p> Ir (bthpy)₂(acac), BTP Ir. Chloride cross-linked dimer (Ir (bthpy)₂Cl)₂(0.103 g, 0.078 mM), acetylacetone (0.025 g), and sodium carbonate (0.083 g) were mixed in 10 ml 2-ethoxyethanol. Mix the mixture for 10 hours until the TLC no longer detects the dimer.₂Refluxed inside. The reaction was then cooled and the yellow precipitate was filtered. The product was purified by flash chromatography with dichloromethane. Product: Yellow solid (49% yield). MS, e / z: 712 (M⁺, 66%), 613 (100%). The emission spectrum is shown in FIG.</p><p> [Ir (ptpy)₂Cl]₂: IrCl₃ XH₂A solution of O (1.506 g, 5.030 mM) and 2- (p-tolyl) pyridine (3.509 g, 20.74 mM) in 2-ethoxyethanol (30 ml) was refluxed for 25 hours. The yellow-green mixture was cooled to room temperature and 20 ml of 1.0 M HCl was added to precipitate the product. The mixture was filtered and washed with 100 ml of 1.0 M HCl, then with 50 ml of methanol and then dried. The product was obtained as a yellow powder (1.850 g, 65%).</p><p> [Ir (ppz)₂Cl]₂: IrCl₃ XH₂A solution of O (0.904 g, 3.027 mM) and 1-phenylpyrazole (1.725 g, 11.96 mM) in 2-ethoxyethanol (30 ml) was refluxed for 21 hours. The gray-green mixture was cooled to room temperature and 20 ml of 1.0 M HCl was added to precipitate the product. The mixture was filtered and washed with 100 ml of 1.0 M HCl, then with 50 ml of methanol and then dried. The product was obtained as a light gray powder (1.133 g, 73%).</p><p> [Ir (C6)₂Cl]₂: IrCl₃ XH₂O (0.075 g, 0.251 mM) and coumarin C6 [3- (2-benzothiazolyl) -7- (diethyl) coumarin] [Aldrich] (0.350 g, 1.00 mM) in 2-ethoxyethanol (15 ml) The contained solution was refluxed for 22 hours. The dark red mixture was cooled to room temperature and 20 ml of 1.0 M HCl was added to precipitate the product. The mixture was filtered and washed with 100 ml of 1.0 M HCl and then with 50 ml of methanol. The product was dissolved in methanol and precipitated. The solid was filtered and washed with methanol until no green luminescence was observed in the filtrate. The product was obtained as an orange powder (0.0657 g, 28%).</p><p> Ir (ptpy)₂acac (tpyIr): [Ir (ptpy)₂Cl]₂A solution of (1.705 g, 1.511 mM), 2,4-pentanediol (3.013 g, 30.08 mM), and (1.802 g, 17.04 mM) in 1,2-dichloroethane (60 ml) was refluxed for 40 hours. .. The yellow-green mixture was cooled to room temperature and the solvent was removed under reduced pressure. 50 ml CH of product₂Cl₂It was taken inside and filtered through Celite. The solvent was removed under reduced pressure to give the product of orange crystals (1.696 g, 89%). The emission spectrum is shown in FIG. The results of the X-ray diffraction study of the structure are shown in Fig. 23. It was found that the nitrogen atom of the tpy (trilpyridyl) group is in the trans form. From the X-ray study, the number of reflections was 4663 and the R factor was 5.4%.</p><p> Ir (C6)₂acac (C6Ir): [Ir (C6)₂Cl]₂CDCl₃ 2 drops of 2,4-pentandione and excess Na in the solution₂CO₃Was added. The tube was heated at 50 ° C. for 48 hours and then filtered through a short Celite filling in a Pasteur pipette. The solvent and excess 2,4-pentandione were removed under reduced pressure to give the product as an orange solid. The emission of C6 is shown in FIG. 24, and the emission of C6Ir is shown in FIG.</p><p> Ir (ppz)₂Picolinate (PZIrp): [Ir (ppz)₂Cl]₂CH (0.0545g, 0.0530mM) and picolinic acid (0.0525g, 0.426mM)₂Cl₂The solution in (15 ml) was refluxed for 16 hours. The light green mixture was cooled to room temperature and the solvent was removed under reduced pressure. The resulting solid was placed in 10 ml of methanol and the light green solid was precipitated from the solution. The supernatant liquid is removed by tilting, and the solid is CH.₂Cl₂Dissolved in and filtered through a short silica filling. The solvent was removed under reduced pressure to give the product of light green crystals (0.0075 g, 12%). The light emission is shown in FIG.</p><p> 2- (1-naphthyl) benzoxazole, (BZO-Naph). 11.06 g, 101 mM 2-aminophenol was mixed with 15.867 g, 92.2 mM 1-naphthoic acid in the presence of polyphosphoric acid. Heat the mixture and N₂The mixture was stirred at 240 ° C. for 8 hours. The mixture was cooled to 100 ° C and water was added to it. Insoluble residues are collected by filtration, washed with water, then excess 10% Na₂CO₃It was made into a slurry again inside. The alkaline slurry was filtered and the product was thoroughly washed with water and dried in vacuo. The product was purified by vacuum distillation. BP 140 ° C / 0.3mmHg. Yield 4.8g (21%).</p><p> Tetrakis [2- (1-naphthyl) benzoxazole C², N] (μ-dichloro) diiridium, [(Ir₂(BZO-Naph)₄Cl)₂]. Iridium trichloride hydrate (0.388 g) was combined with 2- (1-naphthyl) benzoxazole (1.2 g, 4.88 mM). The mixture was dissolved in 2-ethoxyethanol (30 ml) and then refluxed for 24 hours. The solution was cooled to room temperature and the resulting orange solid product was collected in a centrifuge tube. The dimer was washed with methanol and then with chloroform for 4 centrifugation / redispersion cycles. Yield 0.66g.</p><p> Bis [2- (1-naphthyl) benzoxazole] Acetylacetoneate, Ir (BZO-Naph)₂(acac), (BONIr). Chloride cross-linked dimer [Ir₂(BZO-Naph)₄Cl]₂(0.66 g, 0.46 mM), acetylacetone (0.185 g), and sodium carbonate (0.2 g) were mixed in 20 ml of dichloroethane. Mixture, N₂Refluxed in for 60 hours. The reaction was then cooled and the orange / red precipitate was collected in a centrifuge tube. The product was washed with a water / methanol (1: 1) mixture, followed by four centrifugation / redispersion cycles with methanol. An orange / red solid product was produced by sublimation. SP 250 ° C / 2 × 10^-5Thor. Yield 0.57g (80%). The emission spectrum is shown in FIG. 27 and the proton NMR spectrum is shown in FIG.</p><p> Bis (2-phenylbenzothiazole) Iridium Acetylacetone (BTIr): 2.1 mM 2-phenylbenzothiazole iridium chloride dimer (2.7 g) in 120 ml 2-ethoxyethanol at room temperature. , 9.8 mM (0.98 g, 1.0 ml) of 2,4-pentandione was added. About 1 g of sodium carbonate was added and the mixture was heated in nitrogen for several hours in an oil bath and refluxed. The reaction mixture was cooled to room temperature and the orange precipitate was removed by vacuum filtration. The filtrate was concentrated and methanol was added to further precipitate the product. Continuous filtration and precipitation gave a yield of 75%. The emission spectrum is shown in FIG. 29 and the proton NMR spectrum is shown in FIG.</p><p> Bis (2-phenylbenzoxazole) iridium acac (BOIr): 2.4 mM 2-phenylbenzoxazole iridium chloride dimer (3.0 g) in 120 ml 2-ethoxyethanol at room temperature, 9.8 2,4-Pentandione of mM (0.98 g, 1.0 ml) was added. About 1 g of sodium carbonate was added and the mixture was heated in nitrogen overnight (~ 16 hours) in an oil bath and refluxed. The reaction mixture was cooled to room temperature and the yellow precipitate was removed by vacuum filtration. The filtrate was concentrated and methanol was added to further precipitate the product. Continuous filtration and precipitation gave a yield of 60%. The emission spectrum is shown in FIG. 31 and the proton NMR spectrum is shown in FIG.</p><p> Bis (2-phenylbenzothiazole) iridium (8-hydroxyquinolate) (BTIrQ): 0.14 mM 2-phenylbenzothiazole iridium chloride dimer (0.19 g) was placed in 20 ml 2-ethoxyethanol. 4.7 mM (0.68 g) of 8-hydroxyquinoline was added to the solution at room temperature. Approximately 700 mg of sodium carbonate was added and the mixture was heated in nitrogen overnight (23 hours) in an oil bath and refluxed. The reaction mixture was cooled to room temperature and the red precipitate was removed by vacuum filtration. The filtrate was concentrated and methanol was added to further precipitate the product. Continuous filtration and precipitation gave a yield of 57%. The emission spectrum shown in FIG. 33, the proton NMR scan showing the spectra in Figure 34.</p><p> Bis (2-phenylbenzothiazole) iridium picolinate (BTIrP): 0.80 mM 2-phenylbenzothiazole iridium chloride dimer (1.0 g) in a solution at room temperature in 60 ml dichloromethane at 2.14 mM ( 0.26 g) of picolinic acid was added. The mixture was heated in nitrogen for 8.5 hours in an oil bath and refluxed. The reaction mixture was cooled to room temperature and the yellow precipitate was removed by vacuum filtration. The filtrate was concentrated and methanol was added to further precipitate the product. Continuous filtration and precipitation produced about 900 mg of impure product. The emission spectrum is shown in FIG.</p><p> Bis (2-phenylbenzoxazole) iridium picolinate (BOIrP): 0.14 mM 2-phenylbenzoxazole iridium chloride dimer (0.18 g) in a solution at room temperature in 20 ml dichloromethane, 0.52 mM (2-phenylbenzoxazole). 0.064 g) of picolinic acid was added. The mixture was heated in nitrogen overnight (17.5 hours) in an oil bath and refluxed. The reaction mixture was cooled to room temperature and the yellow precipitate was removed by vacuum filtration. The precipitate was dissolved in dichloromethane and transferred to a glass bottle to remove the solvent. The emission spectrum is shown in FIG.</p><p> A comparative emission spectrum for different L'in the btIr complex is shown in FIG.</p><p> VA2.c. Advantages over conventional methods This synthetic method has certain advantages over conventional methods. Expression PtL₃Compounds cannot be sublimated without decomposition. Expression IrL₃There is a problem in obtaining the compound of. Some ligands are Ir (acac)₃And give a tris complex, but more than half of the ligands we studied do not react cleanly in the next reaction: 3L + Ir (acac)₃ L₃The yield of Ir + acacH (in the formula, L = 2-phenylpyridine, benzoquinoline, 2-thienylpyridine) is typically 30%. The preferred route to the Ir complex is the chloride-crosslinked dimer L by the following reaction:₂M (μ-Cl)₂ML₂Can be by: 4L + IrCl₃ NH₂O L₂M (μ-Cl)₂ML₂+ 4HCl Less than 10% of the ligands we studied could not give the Ir dimer cleanly in high yields, but the trimeric tris complex IrL₃Only a few ligands are affected by the conversion to: L₂M (μ-Cl)₂ML₂+ 2Ag^-+ 2L L₃Ir + 2AgCl</p><p> We have found that a much more effective method for producing phosphorescent complexes is to use chloride-crosslinked dimers to form luminescent materials. The dimer itself does not emit intense light, probably because it is strongly quenched by adjacent metal (eg, iridium) atoms. It has been found that chloride ligands can be replaced by chelate ligands by the following chemical changes to give stable octahedral metal complexes: L₂M (μ-Cl)₂ML₂+ XH L₂MX + HCl</p><p> We have extensively studied the system in the case of M = iridium. The obtained iridium complex emits strong light and has a life of 1 to 3 microseconds (μsec) in most cases. Such lifetimes have been shown to be phosphorescent [see Charles Kittel, Introduction to Solid State Physics]. The transition in these materials is metal ligand charge transfer (MLCT).</p><p> In the detailed description below, we have analyzed the emission spectrum and lifetime data for many different complexes, all of which are L.₂It can be characterized as MX (M = Ir) [where L is a cyclometallated (bidentate) ligand and X is a bidentate ligand]. In almost all cases, the luminescence of these complexes is based on the MLCT transition between Ir and L ligands, or a mixture of that transition and the interligand transition. A special example is given below. From theoretical and spectroscopic studies, the complex has an octahedral coordination around the metal (eg, in the case of the nitrogen heterocycle of the L ligand, there is a trans-octopal arrangement in the Ir octahedron).</p><p> In particular, FIG. 1 shows L in the case of L = 2-phenylpyridine, X = acac, picolinate (from picolinic acid), salicylanilide, or 8-hydroxyquinolinate.₂The structure for IrX is given.</p><p> VA2.d.facial isomer vs. meridian isomer L₂Due to slight changes in the synthetic pathway that produces IrX, equation L₃It can form the meridian isomer of Ir. L previously disclosed₃All Ir complexes have a facial arrangement of chelating ligands. Meridianal L as a phosphor in OLED₃The formation and use of Ir complexes are disclosed herein. The two structures are shown in Figure 2.</p><p> Facial L₃The Ir isomers are L and Ir (acac) in refluxed glycerol, as described in Formula 1 (below).₃Manufactured by reaction with. L₃The preferred route to the Ir complex is the chloride-crosslinked dimer according to formula 2 + 3 (below) [L₂Ir (μ-Cl)₂IrL₂]. The product of Equation 3 is Ir (acac)₃It is the same facial isomer formed from. The advantage of the latter manufacturing method is Facial-L₃The yield of Ir is even better. If the third ligand (without Ag +) is added to the dimer in the presence of base and acetylacetonate, good yields of meridianal isomers will be obtained. The meridian isomer is not converted to a facial isomer by recrystallization, reflux in a coordinating solvent, or sublimation. Two examples of these meridian complexes, mer-Irppy and mer-Irbq (Fig. 3), have been formed, but we have a stable facial-L.₃We believe that the Ir-giving ligand can be similarly in the meridian form.</p><p> (1) 3L + Ir (acac)₃ Facial L₃Ir + acacH (in formula, L = 2-phenylpyridine, benzoquinoline, 2-thienylpyridine) typically yields 30%. (2) 4L + IrCl₃ NH₂O L₂Ir (μ-Cl)₂IrL₂+ 4HCl Yield typically greater than 90%. See attached spectrum for example of L. This is also sufficient for all ligands that are effective in (1). (3) L₂Ir (μ-Cl)₂IrL₂+ 2Ag ++ 2L 2 facial L₃Ir + 2AgCl Typically 30% yield. Sufficiently holds only for the same ligand that is sufficiently effective for (1). (4) L₂Ir (μ-Cl)₂IrL₂+ XH + Na₂CO₃+ L Meridianal L₃Ir typically yields greater than 80%. XH = Acetylacetone.</p><p> Unexpectedly, the photophysics of the meridian isomers are different from those of the facial type. This can be seen in the details of the spectra discussed below, but those spectra show a marked red transition and are broader in the meridian isomers relative to their facial counterparts. The emission line is as if it were a facial L₃It looks as if a red band is added to the characteristics of Ir. The structure of the meridian isomer is, for example, with respect to the arrangement of the N atoms of the ligand around Ir.₂Similar to that of the IrX complex. Especially when L = ppy ligand, the nitrogen of L ligand is mer-Ir (ppy).₃And (ppy)₂Both Ir (acac) are transformer type. Furthermore, mer-L₃One of the L ligands of the Ir complex is L₂It has the same coordination as the X ligand of the IrX complex. To illustrate this point, (ppy) in Figure 4₂Next to Ir (acac), mer-Ir (ppy)₃The model of is shown. mer-Ir (ppy)₃One of the ppy ligands is (ppy)₂It is coordinated to the Ir center in the same geometrical state as the acac ligand of Ir (acac).</p><p> L₃The HOMO and LUMO energies of the Ir molecule are clearly affected by isomer selection. These energies control the current-voltage characteristics and lifetime of OLEDs produced with these phosphors and are of great importance.</p><p> The synthesis for the two isomers depicted in Figure 3 is as follows.</p><p> [Synthesis of meridian isomers]: mer-Irbq: 91 mg (0.078 mM) [Ir (bq)₂Cl]₂ Dimer, 35.8 mg (0.2 mM) 7,8-benzoquinoline, 0.02 mg acetylacetone (about 0.2 mM), and 83 mg (0.78 mM) sodium carbonate, 12 ml 2-ethoxyethanol (as available) Boiled in an inert atmosphere for 14 hours. Upon cooling, a yellow-orange precipitate is formed, filtered and flash chromatographed (silica gel, CH).₂Cl₂) (Yield 72%).¹H NMR (360MHz, dichloromethane-d₂), ppm: 8.31 (q, 1H), 8.18 (q, 1H), 8.12 (q, 1H), 8.03 (m, 2H), 7.82 (m, 3H), 7.59 (m, 2H), 7.47 (m, 2H), 7.40 (d, 1H), 7.17 (m, 9H), 6.81 (d, 1H), 6.57 (d, 1H). MS, e / z: 727 (100%, M⁺). The NMR spectrum is shown in Figure 38.</p><p> mer-Ir (tpy)₃: IrCl₃ XH₂O (0.301g, 1.01mM), 2- (p-tolyl) pyridine (1.027g, 6.069mM), 2,4-pentandione (0.208g, 2.08mM), and Na₂CO₃A solution of (0.350 g, 3.30 mM) in 2-ethoxyethanol (30 ml) was refluxed for 65 hours. The yellow-green mixture was cooled to room temperature and 20 ml of 1.0 M HCl was added to precipitate the product. The mixture is filtered, washed with 100 ml 1.0 M HCl, then washed with 50 ml methanol, then dried and the solid CH₂Cl₂It was dissolved in and filtered through a short filler of silica. The solvent was removed under reduced pressure to give the product as a yellow-orange powder (0.265 g, 38%).</p><p> VA3. Possible host molecules The present invention relates to the use of the dopant in the host phase. This host phase may consist of a molecule having a carbazole moiety. Molecules that fall within the scope of the invention are included in:</p><p><chemistry num="3"><img file="JP4358168B2_D0003.tif" /></chemistry></p><p> [Lines indicate possible substitutions with alkyl or aryl groups at the available carbon atoms (s) indicated by the ring. ]</p><p> Yet another preferred molecule with carbazole functionality is 4,4'-N, N'-dicarbazole-biphenyl (CBP), which has the formula:</p><p><chemistry num="4"><img file="JP4358168B2_D0004.tif" /></chemistry></p><p> VB1. Use in the device The equipment structure selected for use is very similar to that of standard vacuum-deposited. As an overview, the hole transport layer (HTL) is first deposited on an ITO (indium tin oxide) coated glass substrate. For a device that gives 12% quantum efficiency, the HTL consists of an NPD of 30 nm (300 Å). An emitter layer is formed by depositing a thin film of organic metal doped into the host matrix on the NPD. As an example, the emitter layer was CBP containing 12% by weight bis (2-phenylbenzothiazole) iridium acetylacetonate (called BTIr), the layer thickness being 30 nm (300 Å). A blocking layer is deposited on top of the emitter layer. The blocking layer consisted of butocproin (BCP) and was 20 nm (200 Å) thick. An electron transport layer is deposited on the blocking layer. The electron transport layer is Alq with a thickness of 20 nm.₃It consisted of. The device is completed by depositing Mg-Ag electrodes on the electron transport layer. It has a thickness of 100 nm. All vapor deposition is 5x10^-5The vacuum was lower than that of Thor. The device was tested in air without packaging.</p><p> When a voltage is applied between the cathode and anode, holes are injected from the ITO into the NPD and transported by the NPD layer, while electrons are injected from MgAg into Alq and transported through Alq and BCP. The holes and electrons are then injected into the EML, carrier recombination occurs at the CBP, an excited state is formed, energy transfer to the BTIr occurs, and finally the BTIr molecule is excited and radioactively decayed.</p><p> As illustrated in Figure 5, the quantum efficiency of this device is about 0.01mA / cm.²The current density of is 12%.</p><p> Related terms are: ITO is the transparent conductive phase of indium tin oxide that acts as an anode. ITO is a degenerate semiconductor formed by doping a broadband semiconductor. ITO carrier concentration is 10¹⁹/cm³Beyond. BCP is a layer that blocks excitons and transports electrons. Alq₃Is an electron injection layer. Other hole transport layer materials may be used. For example, a TPD hole transport layer can be used.</p><p> BCP acts as an electron transport layer and an exciton blocking layer, which has a thickness of about 10 nm (100 Å). BCP is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (also known as batocproin) and has the following formula:</p><p><chemistry num="5"><img file="JP4358168B2_D0005.tif" /></chemistry></p><p> Alq acting as an electron injection / electron transport layer₃Has the following equation:</p><p><chemistry num="6"><img file="JP4358168B2_D0006.tif" /></chemistry></p><p> In general, the amount of doping is varied to achieve the optimum amount of doping.</p><p> VB2. Formulation of fluorescent ligands in phosphorescent complexes As mentioned above, the fluorescent material has certain advantages as a light emitter in the device. L₂If the L-ligand used to make the MX (eg, M = Ir) complex has high fluorescence quantum efficiency, to allow efficient intersystem transitions in and out of the triplet state of the ligand. , Ir Metal strong spin orbital coupling can be used. The concept is that Ir makes the L ligand an effective phosphorescent center. Using this method, any fluorescent dye can be used to make effective phosphorescent molecules from it (ie, L fluoresces, but L₂MX (M = Ir) emits phosphorescence).</p><p> As an example, L when L = coumarin and X = acac₂Manufactured IrX. This is referred to as coumarin-6 (C6Ir). This complex gives a strong orange luminescence, while coumarin itself shines green. Both coumarin and C6Ir spectra are given in the figure.</p><p> Other optical brighteners would be expected to show similar spectral transitions. Due to the large number of fluorescent dyes developed for dye lasers and other applications, this method is expected to result in a very wide range of phosphorescent materials.</p><p> In order to form a 5- or 6-membered ring metallocycle, a fluorescent dye having a suitable functional group is required so that it can be metallized with a metal (eg, iridium). All L ligands we have studied to date are sp²It has a hybrid orbital carbon and a heterocyclic N atom and can therefore react with Ir to form a 5-membered ring.</p><p> Carrier trap with VB3.X or L ligand Potential degradation reactions, including holes or electrons, can occur in the emitter layer. The resulting oxidation or reduction alters the luminescent material and degrades its performance.</p><p> For maximum efficiency of phosphor-doped OLEDs, it is important to control holes or electrons that cause unwanted oxidation or reduction reactions. One way to do this is to trap carriers (holes or electrons) at the phosphorescent dopant. It is advantageous to trap carriers far from the atoms or ligands involved in phosphorescence. Carriers trapped in such a distance will easily recombine with intermolecularly opposite carriers or with carriers from adjacent molecules.</p><p> Figure 6 shows an example of a phosphor designed to trap holes. The diarylamine group of the salicylanilide group is expected to have a HOMO level (based on electrochemical measurements) 200-300 mV higher than that of the Ir complex so that holes are trapped exclusively at the amine group. Become. The holes are easily trapped at the amine, but the luminescence from this molecule will come from the MLCT and from the interligand transition from the Ir (phenylpyridine) system. The electrons trapped in this molecule are most likely to be in one of the pyridyl ligands. Intermolecular recombination will mostly result in the formation of excitons in the Ir (phenylpyridine) system. The presence of the trap site will not have a significant effect on the luminescence energy of the complex, as the trap site is on a typical X ligand that is not extensively included in the luminescence process. L₂It is possible to design related molecules in which electron carriers are trapped far away from the Ir system.</p><p> VB4. Color adjustment IrL₃As can be seen in the system, the emission color is greatly influenced by the L ligand. This is consistent with luminescence including MLCT or interligand transitions. We have a tris complex (ie IrL₃) And L₂The emission spectra were very similar in all cases where both IrX complexes could be produced. For example, Ir (ppy)₃And (ppy)₂Ir (acac) [acronym = PPIr] gives a strong green emission with a λmax of 510 nm. A similar trend is Ir (BQ)₃ And Ir (thpy)₃, Those L₂It is also seen when compared to Ir (acac) derivatives, i.e., in some cases there is no significant discrepancy in luminescence between the two complexes.</p><p> However, in other cases, the choice of X-ligand affects both the energy and efficiency of emission. acac and salicylanilide L₂IrX complexes give very similar spectra. So far, the picolinic acid derivatives we have produced show a slight blue transition (15 nm) in their emission spectra for the acac and salicylanilide complexes of the same ligand. This can be seen in the BTIr, BTIrsd, and BTIrpic spectra. In all three of these complexes, we expect luminescence to arise primarily from MLCT and mutual L transitions, with picolinic acid ligands altering the energy of the metal orbit, thereby affecting the MLCT band.</p><p> If the triplet level is "L"₂If you use an X-ligand that has a lower energy than the Ir "framework, you can observe the luminescence from that X-ligand. This is the case for the BTIrQ complex. In this complex, the emission intensity is very weak, centered at 650 nm. This is totally unexpected. This is because all the emission of the system based on the BT ligand is at about 550 nm. The luminescence in this case is almost entirely from the Q-system transition. Heavy metal quinolate (eg IrQ₃Or PtQ₂) Is centered at 650 nm. The complex itself emits light with a very low efficiency, &lt;0.01. L₂Both the energy and efficiency of the IrQ material are consistent with the emission based on the "X". If luminescence from the X ligand or "IrX" system was efficient, this would have been a good red illuminant. It is important to note that although all of the examples listed here are strong "L" illuminants, this does not exclude good phosphors formed from "X" based luminescence. ..</p><p> Even if the selection of X ligand is bad, L₂It may severely quench the luminescence from the IrX complex. Both hexafluoro-acac and diphenyl-acac complexes are L₂When used as the X ligand of an IrX complex, it gives very weak luminescence or does not show any luminescence. It is not entirely clear why these ligands quench luminescence so strongly, but one of these ligands attracts more electrons than acac and the other attracts more electrons. give away. The spectrum of BQIrFA is given in the figure. The emission spectrum of this complex is slightly translocated from BQIr, as predicted by the much stronger electron-withdrawing properties of the hexafluoroacac ligand. The emission intensity from BQIrFA is at least two orders of magnitude weaker than that of BQIr. Due to this terrible quenching problem, complexes of these ligands were not studied.</p><p> Description of VC and other molecules CBP was used in the equipment described here. The present invention is also effective with the use of other hole transport molecules known to those of skill in the art for acting as a hole transport layer of the OLED.</p><p> In particular, the present invention is also effective with the use of carbazole functional groups or other molecules having similar arylamine functional groups.</p><p> Use of VD equipment The OLEDs of the present invention can be used in virtually any type of device with OLEDs, such as large screen displays, vehicles, computers, televisions, printers, large area walls, theater or stadium screens. It can be used for bulletin boards or OLEDs embedded in signs.</p><p> The present invention described herein may be used in conjunction with the following pending applications: "High Reliability, High Efficiency, Accumulatory Organic Luminescent Devices and Methods for Manufacturing thereof" (High Reliability, High Efficiency, Integratable Organic Light Emitting Devices and Methods of Producing Same), US Patent Application Serial No. 08 / 774,119 (filed December 23, 1996); Movel Materials for Multicolor Light Emitting Devices), Serial No. 08 / 850,264 (filed May 2, 1997); "Electron Transporting and Light Emitting Layers Based on Organic Free Raicals", Serial No. 08 / 774,120 (filed December 23, 1996) (published September 22, 1998 as US Pat. No. 5,811,833); "Multicolor Display Devices", Serial No.08 / 772,333 (filed December 23, 1996); "Red-Emitting Organic Light Emitting Devices (OLED's)", Serial No.08 / 774,087 (December 23, 1996) (Approved); "Driving Circuit For Stacked Organic Light Emitting Devices", Serial No. 08 / 792,050 (filed February 3, 1997) (May 1998) Published as US Pat. No. 5,757,139 on 26 March); "High Efficiency Organic Light Emitting Device Structures", Serial No. 08 / 772,332 (filed December 23, 1996) ( Published as US Pat. No. 5,834,893 on November 10, 1998); "Vacuum Deposited Non-Polymer Flexible Organic Light Emitting Device" (Vacuum Deposited, Non-Polymeric Flexible Organic Light Emitting Devices), Serial No. 08 / 789,319 (filed January 23, 1997) (published December 1, 1998 as US Pat. No. 5,844,363); "Displays Having Mesa Pixel Configuration", Serial No. 08 / 794,595 (filed February 3, 1997); "Stacked Organic Light Emitting Devices", Serial No. 08 / 792,046 (1997 2) Filed on March 3, 1999) (published June 29, 1999 as US Pat. No. 5,917,280); "High Contrast Transparent Organic Light Emitting Devices", Serial No. 08 / 792,046 (1997) (Applicationed on February 3, 2014); "High Contrast Transparent Organic Light Emitting Device Display" Organic Light Emitting Device Display), Serial No. 08 / 821,380 (filed March 20, 1997); "Organic Light Emitting Devices Containing A Metal containing a metal complex of 5-hydroxy-quinoxalin as a host material" Complex of 5-Hydroxy-Quinoxaline as A Host Material), Serial No. 08 / 838,099 (filed April 15, 1997) (published January 19, 1999 as US Pat. No. 5,861,219); (Light Emitting Devices Having High Brightness), Serial No. 08 / 844,353 (filed April 18, 1997); "Organic Semiconductor Laser", Serial No. 08 / 859,468 (1997) Filed on May 19); "Saturated Full Color" Stacked Organic Light Emitting Devices), Serial No. 08 / 858,994 (filed May 20, 1997) (published August 3, 1999 as US Pat. No. 5,932,895); "Plasma Treatment of Conductive Layers" ( Plasma Treatment of Conductive Layers), PCT / US97 / 10252 (filed June 12, 1997); Novel Materials for Multicolor Light Emitting Diodes, Serial No. 08 / 814,976 (Filing March 11, 1997); "Novel Materials for Multicolor Light Emitting Diodes", Serial No. 08 / 771,815 (Filing December 23, 1996); "Organic Patterning of Thin Films for the Fabrication of Organic Multi-color Displays), PCT / US97 / 10289 (filed June 12, 1997); and "Double Heterostructure Infrared and Vertical Cavity Surface Emitting Organic Lasers", Filed May 8, 1998, PCT / US98 / 09480; Published March 23, 1998, US Patent No. 5,874,803; Published January 13, 1998, US Patent No. 5,707,745; Published December 30, 1997, US Patent No. 5,703,436; and published May 26, 1998, US Pat. No. 5,757,026. Each pending application is included here as a whole for reference.</p>

<figref num="1">L with expected structure for PPIr₂It is a diagram showing the expected structure of IrX complexes, and four examples of X ligands used for these complexes are also shown. The structure shown is for acac derivatives and replaces the OO ligand with the NO ligand for other X-type ligands.</figref><figref num="2">L₃It is a figure which shows the comparison of the facial and the meridian isomer of M.</figref><figref num="3">Molecular formula of the mer isomer disclosed here: mer-Ir (ppy)₃And mer-Ir (bq)₃It is a figure which shows. PPY (or ppy) stands for phenylpyridyl and BQ (or bq) stands for 7,8-benzoquinoline.</figref><figref num="4">mer-Ir (ppy)₃And (ppy)₂It is a figure which shows the model of Ir (acac).</figref><figref num="5A">In FIG. 5, FIG. 5A is a diagram showing data (quantum efficiency vs. current density) of an electroluminescence apparatus when BTIr having a mass of 12% is put in CBP. BTIr stands for bis (2-phenylbenzothiazole) iridium acetylacetonate. FIG. 5B is a diagram showing an emission spectrum from the device.</figref><figref num="5B">In FIG. 5, FIG. 5A is a diagram showing data (quantum efficiency vs. current density) of an electroluminescence apparatus when BTIr having a mass of 12% is put in CBP. BTIr stands for bis (2-phenylbenzothiazole) iridium acetylacetonate. FIG. 5B is a diagram showing an emission spectrum from the device.</figref><figref num="6">It is a figure of a typical molecule for trapping a hole.</figref><figref num="7">Ir (3-MeOppy)₃It is a figure which shows the emission spectrum of.</figref><figref num="8">It is a figure which shows the emission spectrum of tpyIrsd.</figref><figref num="9">It is a figure which shows the proton NMR spectrum of tpyIrsd (= typIrsd).</figref><figref num="10">It is a figure which shows the emission spectrum of thpyIrsd.</figref><figref num="11">It is a figure which shows the proton NMR spectrum of thpyrIrsd.</figref><figref num="12">It is a figure which shows the emission spectrum of btIrsd.</figref><figref num="13">It is a figure which shows the proton NMR spectrum of btIrsd.</figref><figref num="14">It is a figure which shows the emission spectrum of BQIr.</figref><figref num="15">It is a figure which shows the proton NMR spectrum of BQIr.</figref><figref num="16">It is a figure which shows the emission spectrum of BQIrFA.</figref><figref num="17">It is a figure which shows the emission spectrum of THIr (= thpy; THP Ir).</figref><figref num="18">It is a figure which shows the proton NMR spectrum of THPIr.</figref><figref num="19">It is a figure which shows the emission spectrum of PPIr.</figref><figref num="20">It is a figure which shows the proton NMR spectrum of PPIr.</figref><figref num="21">It is a figure which shows the emission spectrum of BTHPIr (= BTPIr).</figref><figref num="22">It is a figure which shows the emission spectrum of tpyIr.</figref><figref num="23">It is a figure which shows the crystal structure of tpyIr which shows the trans type arrangement of nitrogen.</figref><figref num="24">It is a figure which shows the emission spectrum of C6.</figref><figref num="25">It is a figure which shows the emission spectrum of C6Ir.</figref><figref num="26">It is a figure which shows the emission spectrum of PZIrP.</figref><figref num="27">It is a figure which shows the emission spectrum of BONIr.</figref><figref num="28">It is a figure which shows the proton NMR spectrum of BONIr.</figref><figref num="29">It is a figure which shows the emission spectrum of BTIr.</figref><figref num="30">It is a figure which shows the proton NMR spectrum of BTIr.</figref><figref num="31">It is a figure which shows the emission spectrum of BOIr.</figref><figref num="32">It is a figure which shows the proton NMR spectrum of BOIr.</figref><figref num="33">It is a figure which shows the emission spectrum of BTIrQ.</figref><figref num="34">It is a figure which shows the proton NMR spectrum of BTIrQ.</figref><figref num="35">It is a figure which shows the emission spectrum of BTIrP.</figref><figref num="36">It is a figure which shows the emission spectrum of BOIrP.</figref><figref num="37">It is a figure which shows the emission spectrum of the btIr type complex which has a different ligand.</figref><figref num="38">It is a figure which shows the proton NMR spectrum of mer-Irbq.</figref><figref num="39">L₂FIG. 5 shows other suitable L and X ligands for MX compounds.</figref><figref num="40">It is a figure which shows the example of the LL L M compound.</figref>