(19) TZZ___T (11) EP 1 981 898 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C07F 15/00 (2006.01) C09K 11/06 (2006.01) 11.04.2012 Bulletin 2012/15 H05B 33/14 (2006.01) H01L 51/00 (2006.01) (21) Application number: 07750408.2 (86) International application number: PCT/US2007/003569 (22) Date of filing: 09.02.2007 (87) International publication number: WO 2007/095118 (23.08.2007 Gazette 2007/34) (54) Metal complexes of imidazo[1,2-f]phenanthridine ligands for use in OLED devices Metallkomplexe aus Imidazo[1,2-f]phenanthridin-Liganden und deren Verwendung in OLED Vorrichtungen Complexes métalliques de imidazo[1,2-f]phénanthridine et leur utilisation dans les dispositifs OLED (84) Designated Contracting States: • BROWN, Cory S. AT BE BG CH CY CZ DE DK EE ES FI FR GB GR Pittsburgh, PA 15219 (US) HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI • YEAGER, Walter H. SK TR Yardlet, PA 19067 (US) (30) Priority: 10.02.2006 US 772154 P (74) Representative: Kiriczi, Sven Bernhard 03.11.2006 US 856824 P Schneiders & Behrendt 11.12.2006 US 874190 P Rechtsanwälte Patentanwälte Mühlthaler Strasse 91c (43) Date of publication of application: 81475 München (DE) 22.10.2008 Bulletin 2008/43 (56) References cited: (60) Divisional application: EP-A- 1 647 554 WO-A-2004/085450 10007603.3 / 2 243 785 WO-A-2005/049762 WO-A1-2008/156879 11004983.0 / 2 399 922 JP-A- 2005 042 106 JP-A- 2005 298 483 (73) Proprietor: Universal Display Corporation • TANG K-C ET AL: "Rapid intersystem crossing Ewing, NJ 08618 (US) in highly phosphorescent iridium complexes" CHEMICAL PHYSICS LETTERS, vol. 386, no. 4-6, (72) Inventors: 11 March 2004 (2004-03-11), pages 437-441, • KNOWLES, David B. XP009089568 ISSN: 0009-2614 Apollo, PA 15613 (US) • DUAN J-P ET AL: "New iridium complexes as • LIN, Chun highly efficient orange-red emitters in organic Langhorne, PA 19047 (US) light-emitting diodes", ADVANCED MATERIALS, • MACKENZIE, Peter Borden vol. 15, no. 3, 5 February 2003 (2003-02-05), pages Newton, PA 18940 (US) 224-228, XP009089567, ISSN: 0935-9648, DOI: • TSAI, Jui-yi 10.1002/adma.200390051 Newtown, PA 18 940 (US) • WALTERS, Robert W. Remarks: Export, PA 15632 (US) Thefilecontainstechnicalinformationsubmittedafter • BEERS, Scott A. the application was filed and not included in this Flemington, NJ 08822 (US) specification Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 981 898 B1 Printed by Jouve, 75001 PARIS (FR) EP 1 981 898 B1 Description Technical Field 5 [0001] The present invention generally relates to organic light emitting devices (OLEDs), and organic compounds used in these devices. Background 10 [0002] Opto-electronic devices that make use of organic materials are becoming increasingly desirable for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting devices (OLEDs), organic pho- 15 totransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have per- formance advantages over conventional materials. For example, the wavelength at which an organic emissive layer emits light may generally be readily tuned with appropriate dopants. [0003] As used herein, the term "organic" includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. "Small molecule" refers to any organic material that is 20 not a polymer, and "small molecules" may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the "small molecule" class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone. Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or 25 phosphorescent small molecule emitter. A dendrimer may be a "small molecule," and it is believed that all dendrimers currently used in the field of OLEDs are small molecules. In general, a small molecule has a well-defined chemical formula with a single molecular weight, whereas a polymer has a chemical formula and a molecular weight that may vary from molecule to molecule. As used herein, "organic" includes metal complexes of hydrocarbyl and heteroatom- substituted hydrocarbyl ligands. 30 [0004] OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting. Several OLED materials and configurations are described in U.S. Patent Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety. [0005] OLED devices are generally (but not always) intended to emit light through at least one of the electrodes, and 35 one or more transparent electrodes may be useful in an organic opto-electronic devices. For example, a transparent electrode material, such as indium tin oxide (ITO), may be used as the bottom electrode. A transparent top electrode, such as disclosed in U.S. Patent Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, may also be used. For a device intended to emit light only through the bottom electrode, the top electrode does not need to be transparent, and may be comprised of a thick and reflective metal layer having a high electrical conductivity. 40 Similarly, for a device intended to emit light only through the top electrode, the bottom electrode may be opaque and/or reflective. Where an electrode does not need to be transparent, using a thicker layer may provide better conductivity, and using a reflective electrode may increase the amount of light emitted through the other electrode, by reflecting light back towards the transparent electrode. Fully transparent devices may also be fabricated, where both electrodes are transparent. Side emitting OLEDs may also be fabricated, and one or both electrodes may be opaque or reflective in 45 such devices. [0006] As used herein, "top" means furthest away from the substrate, while "bottom" means closest to the substrate. For example, for a device having two electrodes, the bottom electrode is the electrode closest to the substrate, and is generally the first electrode fabricated. The bottom electrode has two surfaces, a bottom surface closest to the substrate, and a top surface further away from the substrate. Where a first layer is described as "disposed over" a second layer, 50 the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is "in physical contact with" the second layer. For example, a cathode may be described as "disposed over" an anode, even though there are various organic layers in between. [0007] As used herein, "solution processible" means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form. 55 [0008] As used herein, and as would be generally understood by one skilled in the art, a first "Highest Occupied Molecular Orbital" (HOMO) or "Lowest Unoccupied Molecular Orbital" (LUMO) energy level is "greater than" or "higher than" a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds 2 EP 1 981 898 B1 to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LIMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A "higher" HOMO or LUMO energy level appears closer to the top of such a diagram than a "lower" 5 HOMO or LUMO energy level. [0009] The development of long-lived blue emissive phosphorescent dopants is recognized as a key unfulfilled objective of current OLED research and development. While phosphorescent OLED devices with emission peaks in the deep blue or near-UV have been demonstrated, the lifetimes of blue-emissive devices exhibiting 100 nits initial luminance have been on the order of several hundred hours (where "lifetime" refers to the time for the luminance to decline to 50% 10 of the initial level, at constant current). For example, iridium(III) complexes ofbidentate ligands derived from N-methyl- 2-phenylimidazoles can be used to prepare blue OLED devices, but very short lifetimes are observed with these dopants (about 250 hours at 100 nits initial luminescence).