WO2007127069A1 - Dispositif électroluminescent comprenant un dérivé d'anthracène - Google Patents

Dispositif électroluminescent comprenant un dérivé d'anthracène Download PDF

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WO2007127069A1
WO2007127069A1 PCT/US2007/009165 US2007009165W WO2007127069A1 WO 2007127069 A1 WO2007127069 A1 WO 2007127069A1 US 2007009165 W US2007009165 W US 2007009165W WO 2007127069 A1 WO2007127069 A1 WO 2007127069A1
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layer
group
eil
lel
electron
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Denis Yurievich Kondakov
Scott Robert Conley
Kevin Paul Klubek
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Eastman Kodak Company
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Publication of WO2007127069A1 publication Critical patent/WO2007127069A1/fr

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/17—Carrier injection layers
    • H10K50/171—Electron injection layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/615—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/14—Carrier transporting layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/615—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
    • H10K85/626—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene containing more than one polycyclic condensed aromatic rings, e.g. bis-anthracene
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/649—Aromatic compounds comprising a hetero atom
    • H10K85/657—Polycyclic condensed heteroaromatic hydrocarbons
    • H10K85/6572—Polycyclic condensed heteroaromatic hydrocarbons comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H10K2102/10—Transparent electrodes, e.g. using graphene
    • H10K2102/101—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO]
    • H10K2102/103—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO] comprising indium oxides, e.g. ITO
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H10K2102/301—Details of OLEDs
    • H10K2102/351—Thickness
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/30—Coordination compounds
    • H10K85/321—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3]
    • H10K85/322—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3] comprising boron
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/30—Coordination compounds
    • H10K85/321—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3]
    • H10K85/324—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3] comprising aluminium, e.g. Alq3
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine

Definitions

  • This invention relates to an electroluminescent (EL) device comprising a light-emitting layer and including at least one electron transport layer containing an anthracene derivative and at least one electron injection layer contiguous to the electron transport layer and containing a phenanthroline derivative.
  • the device can provide desirable electroluminescent properties.
  • an organic EL device is comprised of an anode for hole injection, a cathode for electron injection, and an organic medium sandwiched between these electrodes to support charge recombination that yields emission of light. These devices are also commonly referred to as organic light-emitting diodes, or OLEDs. Representative of earlier organic EL devices are Gurnee et al. U.S. Pat. No. 3,172,862, issued Mar. 9, 1965; Gumee U.S. Pat. No. 3,173,050, issued Mar.
  • organic EL devices include an organic EL element consisting of extremely thin layers (e.g. ⁇ 1.0 ⁇ m) between the anode and the cathode.
  • organic EL element encompasses the layers between the anode and cathode. Reducing the thickness lowered the resistance of the organic layers and enabled devices to operate at much lower voltage.
  • one organic layer of the EL element adjacent to the anode is specifically chosen to transport holes, and therefore is referred to as the hole-transporting layer, and the other organic layer is specifically chosen to transport electrons and is referred to as the electron- transporting layer.
  • the light-emitting layer commonly consists of a host material doped with a guest material, otherwise known as a dopant.
  • EL devices that emit white light have proven to be very useful. They can be used with color filters to produce full-color display devices. They can also be used with color filters in other multicolor or functional-color display devices. White EL devices for use in such display devices are easy to manufacture, and they produce reliable white light in each pixel of the displays.
  • the OLEDs are referred to as white, they can appear white or off-white, for this application, the CIE coordinates of the light emitted by the OLED are less important than the requirement that the spectral components passed by each of the color filters be present with sufficient intensity in that light.
  • the CIE coordinates of the light emitted by the OLED are less important than the requirement that the spectral components passed by each of the color filters be present with sufficient intensity in that light.
  • One of the most common materials used in many OLED devices is tris(8-quinolinolato)aluminum (III) (AIq). This metal complex is an excellent electron-transporting material and has been used for many years in the industry. However, other materials such as anthracene derivatives have also been reported as useful electron-transporting materials, for example see JP 2005/174675.
  • Ara Kensuke and coworkers report an EL device in which the electron transport layer contains a naphthacene derivative and/or an anthracene derivative but preferably a naphthacene derivative.
  • the device also preferably includes an electron injection layer having a thickness of, preferably, 0.6 to 20 nm, and in particular, preferably, 1 to 10 nm.
  • an electron injection layer having a thickness of, preferably, 0.6 to 20 nm, and in particular, preferably, 1 to 10 nm.
  • such a device may not yield the most desirable electroluminescent properties.
  • the invention provides an electroluminescent device comprising a . cathode, an anode, and having therebetween a light emitting layer (LEL), the device further containing an electron transport layer (ETL) comprising an anthracene compound on the cathode side of the LEL and an organic electron injection layer (EIL) between the ETL and the cathode comprising a phenanthroline compou ⁇ id, wherein the thickness of the EIL and LEL are such that the ratio of the thickness of the EIL to LEL is greater than 0.125.
  • ETL electron transport layer
  • EIL organic electron injection layer
  • the Figure shows a schematic cross-sectional view of an OLED device that represents one embodiment of the present invention.
  • the invention is generally summarized above.
  • the invention provides for a multilayer electroluminescent device comprising a cathode, an anode, and at least one light-emitting layer (LEL).
  • the device further contains an electron transport layer (ETL) on the cathode side of the LEL that includes an anthracene compound.
  • ETL electron transport layer
  • the anthracene compound only contains one anthracene nucleus in order to keep the sublimation temperature in a desirable temperature range.
  • the anthracene compound includes only 6 to 12 rings, or even only 6 to 10 rings. Desirably the rings are carbocyclic.
  • the anthracene compound is substituted with aromatic groups in the 2-, 9 ⁇ , and 10-positions. This type of substitution affords desirable electrochemical properties.
  • the monoanthracene compound is substituted with a naphthyl or a biphenyl group in the 9-position and an independently selected naphthyl or a biphenyl group in thelO-position.
  • suitable groups include 2-naphthyl groups, 1- naphthyl groups, 4-biphenyl groups, and 3-bi ⁇ heny groups.
  • Useful groups also include phenyl groups and terphenyl groups.
  • the monoanthracene compound is substituted with an aryl group in the 2-position that includes no more than 2 fused rings, for example a 4-methylphenyl group, a 2- naphthyl group, or an unsubstituted phenyl.
  • the monoanthracene compound is substituted with hydrogen or an alkyl group in the 6-position.
  • alkyl groups include a methyl group and a f-butyl group.
  • the monoanthracene compound is substituted with an aromatic group in the 6-position.
  • the aromatic group is a carbocyclic group with no more than two fused rings, such as a phenyl group or a naphthyl group.
  • anthracene compound is represented by Formula (1).
  • w 1 , w 3 , w 4 , w 5 , w 6 , w 7 and w 8 represent hydrogen or an independently selected substituent group, such as an alkyl group, for example a methyl group or a f-butyl group, or an aromatic group such as a phenyl group or a naphthyl group.
  • the substituents w 2 , w 9 , and w 10 represent independently selected aromatic groups. Illustrative examples include, phenyl groups, terphenyl groups, naphthyl groups, biphenyl groups, benzimidazole groups, and thiophene groups. In one desirable embodiment, w 2 , w 9 , and w 10 represent independently selected carbocyclic aromatic groups. In a further embodiment, w 2 , w 9 , and w 10 represent independently selected aromatic groups, wherein each aromatic group includes no more than 2 fused rings. In another embodiment, substituents w 1 through w 10 each comprise no more than two fused rings. In one suitable embodiment, w 2 , w 6 , w 9 , and w 10 maybe the same or different and each represents an independently selected aromatic group, such as a phenyl group or a naphthyl group.
  • the substituents on the anthracene compound are chosen so that the anthracene compound has a LUMO (lowest occupied molecular orbital) energy value in the range of —2.4 eV to —2.6 eV. Desirably the range is -2.45 eV to -2.55 eV.
  • LUMO lowest occupied molecular orbital
  • Suitable anthracene compounds can be prepared by various synthetic routes described in the literature or by variations of such routes, for example as reported in US 2005/211958. Examples of useful anthracene compounds are shown below.
  • the electron transport layer may include more than one type of anthracene compound.
  • the ETL includes only anthracene compounds.
  • a desirable thickness of the electron transport layer is often 1 to 100 nm, frequently 5 to 50 am, and commonly 10 to 40 nm.
  • An electron injection layer is present on the cathode side of the ETL and contiguous to the ETL.
  • the EIL includes a phenanthroline compound.
  • the phenanthroline compound includes a 1 ,10-phenanthroline group.
  • the phenanthroline compound is represented by Formula (2).
  • each r is the same or different, and each represents a substituent, such as a methyl group or a phenyl group.
  • rn and p are independently 0-4, and n is 0-2.
  • At least one of r in Formula (2) represents an aromatic group including at least three fused rings, for example an anthracenyl group or a pyrenyl group.
  • at least one of m, n, and p is 1 or greater.
  • Useful phenanthroline materials include those described in commonly assigned Serial Nos. 11/289,856 and 11/290,214, both filed November 30, 2005.
  • the phenanthroline compound includes more than one 1 ,10-phenanthroline nucleus.
  • the phenanthroline compound includes two 1,10-phenanthroline nuclei that are directly bonded to one another.
  • the phenanthroline compound includes two 1,10-phenanthroline nuclei that are connected by a linking group.
  • the phenanthroline compound is represented by Formula (3).
  • each r is the same or different, and each represents a substituent.
  • m and x are independently 0-4; n, v, q, and u are independently 0-2.
  • L represents a divalent linking group, that is, a divalent species that bonds two independently selected phenanthroline groups together.
  • the linking group could be a divalent aromatic group, a divalent alkyl group, or a divalent heteroatom. Non-limiting examples of linking groups are shown below.
  • the LUMO energy level of the phenanthroline compound is equal to or nearly the same as the LUMO energy level of the anthracene material contained in the ETL. In one embodiment, the LUMO energy level of the phenanthroline compound is equal to or more positive than the LUMO energy level of the anthracene material.
  • the difference in LUMO energy levels of the EIL phenanthroline compound and the ETL anthracene material is 0.50 or less, 0.40 or less, 0.30 or less, 0.20 or less or even 0.10 eV or less.
  • the phenanthroline compound in the EIL has a LUMO energy value equal to or more positive than the LUMO energy value of the anthracene compound in the ETL.
  • a desirable thickness of the electron injection layer is often 1 to 30 nra, frequently 5 to 20 nm, and commonly in the range of 10 to 20 ran. In order to obtain the optimum device performance, it is important to optimize the thickness of each layer of an EL device. We have found that the relative thickness of the EIL to that of the LEL is also important.
  • the ratio of the thickness of the EIL to LEL should be greater than 0.125. Desirably this ratio is 0.25 or greater, or even 0.50 or greater. In one embodiment, the ratio of the thickness of the EIL to LEL is in the range of 0.125 to 1.50 or desirably in the range of 0.125 to 1.25. In another desirable embodiment, a further layer is present between the cathode and the EIL and contiguous to the EIL.
  • This layer represents an additional electron injection layer.
  • the further layer includes an inorganic material such as a low work-function alkaline metal or alkaline earth metal, such as Li, Cs, Ca, Mg.
  • an organic material doped with these low work-function metals can also be used effectively as the electron-injecting layer. Examples are Li- or Cs-doped AIq.
  • the further layer includes an alkali metal compound, such as LiF.
  • the further layer is often a thin layer deposited to a suitable thickness in a range of 0.1-3.0 nm.
  • a light-emitting layer is on the anode side of the electron transport layer.
  • the light-emitting layer can be comprised of a single material, but more commonly consists of a host material doped with a guest emitting material or materials where light emission comes primarily from the emitting materials and can be of any color.
  • the light-emitting layer includes a host material and a light-emitting material.
  • the LUMO energy level of the anthracene compound in the ETL is close to or slightly below the LUMO level of the host in the light-emitting layer.
  • the LEL includes a host material having a LUMO energy value that differs from the LUMO energy value of the anthracene compound in the ETL by no more than 0.2 eV or even no more than 0.1 eV.
  • the LUMO energy level of the ETL anthracene compound is equal to the LUMO energy level of the host in the light- emitting layer.
  • the light-emitting layer includes an anthracene host material.
  • Particularly useful anthracene host materials include anthracene substituted in the 9- and 10-positions with aromatic groups.
  • the anthracene host material bears aromatic groups in the 2-, 9-, and 10-positions. Examples of such groups include phenyl groups, naphthyl groups, and biphenyl groups.
  • anthracene materials for use in a light- emitting layer include: 2-(4-methyl ⁇ henyl)-9,10-di-(2-naphthyl)-anthracene; 9-(2- naphthyl)- 10-( 1 , 1 '-biphenyl)-anthracene; 9, 10-bis[4-(2,2-diphenylethenyl)phenyl]- anthracene, as well as the following listed compounds.
  • a co-host is present in the light-emitting layer.
  • e co-host may be a hole-transporting material such as a tertiary amine or a mixture of such compounds.
  • useful hole-transporting co- host materials are 4,4'-bis[-V-(l-naphthyl)--V-phenylamino]biphenyl (NPB), and 4,4'-bis[JV-(l -naphthyl)-N-(2-na ⁇ hthyl)amino]biphenyl (TNB) .
  • a co-host that is an electron-transporting material is present.
  • a useful example of electron-transporting co-host material is tris(8-quinolinolato)aluminum(III) (AIq).
  • the co-host When present, the co-host is often at a level of 1-50 % of the layer, frequently at 1-20 % of the layer, and commonly at a level of 5-15 % of the layer by volume.
  • the LEL includes a light-emitting material(s) which is desirably present in an amount of up to 15 % of the light-emitting layer by volume, commonly 0.1 — 10 % and more typically from 0.5-8.0 % of the layer by volume.
  • the light- emitting layer includes a light-emitting fluorescent material.
  • An important relationship for choosing a light-emitting fluorescent material for use with a host is a comparison of the excited singlet-state energies of the host and the fluorescent material. It is highly desirable that the excited singlet-state energy of the light-emitting material be lower than that of the host material.
  • the excited singlet-state energy is defined as the difference in energy between the emitting singlet state and the ground state. For non-emissive hosts, the lowest excited state of the same electronic spin as the ground state is considered the emitting state.
  • the layer may emit light ranging from blue to red depending on the nature of the light-emitting material.
  • Blue light is generally defined as having a wavelength range in the visible region of the electromagnetic spectrum of 450-480 nm, blue-green 480-510 nm, green 510-550, green-yellow 550-570 nm, yellow 570-590 nm, orange 590-630 nm and red 630-700 nm, as defined by R. W. Hunt, The Reproduction of Colour in Photography, Printing & Television, 4 th Edition 1987, Fountain Press. Suitable combinations of these components produce white light.
  • a useful device includes one or more materials that emit blue or blue-green light.
  • materials that emit blue or blue-green light are known in the art and are contemplated for use in the practice of the • present invention.
  • Particularly useful classes of blue emitters include perylene and its derivatives such as a perylene nucleus bearing one or more substituents such as an alkyl group or an aryl group.
  • a desirable perylene derivative for use as an emitting material is 2,5,8,11-tetra-r-butylperylene.
  • Another useful class of fluorescent materials includes blue or blue- green light emitting derivatives styrylarenes, such as distyrylbenzene and distyrylbiphenyl, including compounds described in US 5,121,029.
  • styrylarenes that provide blue or blue-green luminescence
  • examples include those represented by Formula (4a), listed below, wherein Ari, each Ar 2 , and A ⁇ 3 through Ar 8 are independently selected aryl or heteroaryl groups, which may contain additional fused rings and provided that two aryl or heteroaryl rings may be joined by ring fusion, m is 0 or 1.
  • Ari , each A ⁇ 2 , and A1 3 through Ar 8 represent phenylene or phenyl groups.
  • Ar 1 , each Ar 2 , and Ar 7 may be the same or different and each represents a divalent aromatic group.
  • Illustrative examples of such groups include a phenyl ene group, a naphthylene group, a quinolindiyl group and a thiendiyl group.
  • Ar 3 , Ar 4 , Ar 5 , and Ax 6 may be the same or different and each represents an aromatic group such as phenyl group, a fused aromatic ring group such as naphthyl, anthranyl or phenanthryl group, a heterocyclic aromatic ring group or monovalently linked aromatic ring groups such as a biphenyl group.
  • Ar and Ar 4 may be joined directly or through additional atoms to form a carbocyclic or heterocyclic ring.
  • p is 1 , 2, or 3. Illustrative examples of useful materials are shown below.
  • Another useful class of emitters comprise a boron atom.
  • Desirable light-emitting materials that contain boron include those described in US 2003/0198829, US 2003/0201415 and US 2005/0170204.
  • Suitable light-emitting materials, including those that emit blue or blue-green light, are represented by the structure Formula (5).
  • Ar a and Ar b independently represent the atoms necessary to form a five or six-membered aromatic ring group, such as a pyridine group.
  • Z a and Z b represent independently selected substituents, such as fluoro substituents.
  • W represents N or C-Y, wherein Y represents hydrogen or a substituent, such as an aromatic group, such as a phenyl group or a tolyl group, an alkyl group, such as a methyl group, a cyano substituent, or a trifluoromethyl substituent.
  • the light-emitting layer emits green light.
  • a particularly useful class of green light-emitting material includes quinacridone compounds such as those represented by Formula (6). Suitable quinacridones are described US 2004/0001969, US 6,664,396, US 5,593,788, and JP 09-13026.
  • si -sio independently represent hydrogen or an independently selected substituent, such as a phenyl group, a tolyl group, a halogen such as F, or an alkyl group, such as a methyl group. Adjacent substituents may combine to form rings, such as fused benzene ring groups.
  • Sn and S 12 independently represent an alkyl group or an aromatic group.
  • Sn and Si 2 independently represent a phenyl ring group, such as a phenyl ring or a tolyl ring.
  • Another useful class of green light-emitting materials includes coumarin compounds such as those represented by Formula (7). Suitable coumarins are described by Tang et al., US 4,769,292 and US 6,020,078.
  • wi i and Wi 2 represent an independently selected substituent, such as an alkyl group or aryl group, provided wi j and W 12 may combine with each other or with W1 3 and W 14 to form rings.
  • wn and W12 represent independently selected alkyl groups, provided wi 1 and W12 may combine with each other or with wu and Wj 4 to form saturated rings.
  • W13 — Wj 6 independently represent hydrogen or an independently selected substituent, such as phenyl ring group or a methyl group. Adjacent substituents may combine to form rings, such as fused benzene rings.
  • Wi 7 represents the atoms necessary to complete a heteroaromatic ring, such as a benzothiazole ring group. Illustrative examples of useful coumarin compounds are shown below.
  • a useful device includes one layer including a light-emitting material that emits blue or blue-green light and an additional layer emits yellow or red light and contains a of rubrene derivative.
  • a filter capable of controlling the spectral components of the white light such as red, green and blue can be placed overlying the device to give a device useful for color display.
  • the thickness of the LEL is often in the range of 5 to 50 nm, frequently in the range of 10 to 40 nm, and commonly in the range of 20 to 30 nm Unless otherwise specifically stated, use of the term “substituted” or “substituent” means any group or atom other than hydrogen. Additionally, unless otherwise specifically stated, when a compound with a substitutable hydrogen is identified or the term “group” is used, it is intended to encompass not only the substituent's unsubstituted form, but also its form further substituted with any substituent group or groups as herein mentioned, so long as the substituent does not destroy properties necessary for device utility.
  • a substituent group may be halogen or may be bonded to the remainder of the molecule by an atom of carbon, silicon, oxygen, nitrogen, phosphorous, sulfur, selenium, or boron.
  • the substituent may be, for example, halogen, such as chloro, bromo or fluoro; nitro; hydroxyl; cyano; carboxyl; or groups which may be further substituted, such as alkyl, including straight or branched chain or cyclic alkyl, such as methyl, trifluoromethyl, ethyl, /-butyl, 3-(2,4-di-f-pentylphenoxy) propyl, and tetradecyl; alkenyl, such as ethylene, 2-butene; alkoxy, such as methoxy, ethoxy, propoxy, butoxy, 2-methoxyethoxy, sec-butoxy, hexyloxy, 2-ethylhexyloxy, tetradecyloxy,
  • the substituents may themselves be further substituted one or more times with the described substituent groups.
  • the particular substituents used may be selected by those skilled in the art to attain desirable properties for a specific application and can include, for example, electron- withdrawing groups, electron-donating groups, and steric groups.
  • the substituents may be joined together to form a ring such as a fused ring unless otherwise provided.
  • groups and substituents thereof may include those having up to 48 carbon atoms, typically 1 to 36 carbon atoms and usually less than 24 carbon atoms, but greater numbers are possible depending on the particular substituents selected.
  • a coordinate bond is formed when electron rich atoms such as O or N, donate a pair of electrons to electron deficient atoms such as Al or B. It is well within the skill of the art to determine whether a particular group is electron donating or electron accepting. The most common measure of electron donating and accepting properties is in terms of Hammett ⁇ values. Hydrogen has a Hammett ⁇ value of zero, while electron donating groups have negative Hammett ⁇ values and electron accepting groups have positive Hammett ⁇ values.
  • Hammett ⁇ values for a large number of commonly encountered groups. Hammett ⁇ values are assigned based on phenyl ring substitution, but they provide a practical guide for qualitatively selecting electron donating and accepting groups. Suitable electron donating groups may be selected from -R', -OR', and -NR'(R") where R' is a hydrocarbon containing up to 6 carbon atoms and R" is hydrogen or R'.
  • electron donating groups include methyl, ethyl, phenyl, methoxy, ethoxy, phenoxy, -N(CH 3 ) 2 , -N(CH 2 CH 3 ) 2 , -NHCH 3 , - N(C 6 Hs) 2 , -N(CH 3 )(C 6 H 5 ), and -NHC 6 H 5 .
  • Suitable electron accepting groups maybe selected from the group consisting of cyano, ⁇ -haloalkyl, ⁇ -haloalkoxy, amido, sulfonyl, carbonyl, carbonyloxy and oxycarbonyl substituents containing up to 10 carbon atoms.
  • the present invention can be employed in many OLED device configurations using small molecule materials, oligomeric materials, polymeric materials, or combinations thereof. These include very simple structures comprising a single anode and cathode to more complex devices, such as passive matrix displays comprised of orthogonal arrays of anodes and cathodes to form pixels, and active-matrix displays where each pixel is controlled independently, for example, with thin film transistors (TFTs).
  • TFTs thin film transistors
  • the essential requirements of an OLED are an anode, a cathode, and an organic light-emitting layer located between the anode and cathode. Additional layers may be employed as more fully described hereafter.
  • a typical structure, especially useful for of a small molecule device is shown in the Figure and is comprised of a substrate 101, an anode 103, a hole-injecting layer 105, a hole-transporting layer 107, a light-emitting layer 109, an electron-transporting layer 110, an electron-injecting layer 111, an optional second electron-injecting layer 112 and a cathode 113.
  • a substrate 101 an anode 103, a hole-injecting layer 105, a hole-transporting layer 107, a light-emitting layer 109, an electron-transporting layer 110, an electron-injecting layer 111, an optional second electron-injecting layer 112 and a cathode 113.
  • the substrate may alternatively be located adjacent to the cathode, or the substrate may actually constitute the anode or cathode.
  • the organic layers between the anode and cathode are conveniently referred to as the organic EL element.
  • the total combined thickness of the organic layers is desirably less than 500 nm.
  • the anode and cathode of the OLED are connected to a voltage/current source 150 through electrical conductors 160.
  • the OLED is operated by applying a potential between the anode and cathode such that the anode is at a more positive potential than the cathode. Holes are injected into the organic EL element from the anode and electrons are injected into the organic EL element at the cathode.
  • Enhanced device stability can sometimes be achieved when the OLED is operated in an AC mode where, for some time period in the cycle, the potential bias is reversed and no current flows.
  • An example of an AC driven OLED is described in US 5,552,678.
  • the OLED device of this invention is typically provided over a supporting substrate 101 where either the cathode or anode can be in contact with the substrate.
  • the substrate can be a complex structure comprising multiple layers of materials. This is typically the case for active matrix substrates wherein TFTs are provided below the OLED layers. It is still necessary that the substrate, at least in the emissive pixilated areas, be comprised of largely transparent materials.
  • the electrode in contact with the substrate is conveniently referred to as the bottom electrode. Conventionally, the bottom electrode is the anode, but this invention is not limited to that configuration.
  • the substrate can either be light transmissive or opaque, depending on the intended direction of light emission. The light transmissive property is desirable for viewing the EL emission through the substrate.
  • Transparent glass or plastic is commonly employed in such cases.
  • the transmissive characteristic of the bottom support can be light transmissive, light absorbing or light reflective.
  • Substrates for use in this case include, but are not limited to, glass, plastic, semiconductor materials, silicon, ceramics, and circuit board materials. It is necessary to provide in these device configurations a light- transparent top electrode.
  • anode When the desired electroluminescent light emission (EL) is viewed through anode, the anode should be transparent or substantially transparent to the emission of interest.
  • Common transparent anode materials used in this invention are indium-tin oxide (ITO), indium-zinc oxide (IZO) and tin oxide, but other metal oxides can work including, but not limited to, aluminum- or indium-doped zinc oxide, magnesium-indium oxide, and nickel-tungsten oxide, hi addition to these oxides, metal nitrides, such as gallium nitride, and metal selenides, such as zinc selenide, and metal sulfides, such as zinc sulfide, can be used as the anode.
  • ITO indium-tin oxide
  • IZO indium-zinc oxide
  • tin oxide other metal oxides can work including, but not limited to, aluminum- or indium-doped zinc oxide, magnesium-indium oxide, and nickel-tungsten oxide, hi addition to these oxides
  • the transmissive characteristics of the anode are immaterial and any conductive material can be used, transparent, opaque or reflective.
  • Example conductors for this application include, but are not limited to, gold, indium, molybdenum, palladium, and platinum.
  • Typical anode materials, transmissive or otherwise, have a work function of 4.1 eV or greater. Desired anode materials are commonly deposited by any suitable means such as evaporation, sputtering, chemical vapor deposition, or electrochemical means.
  • Anodes can be patterned using well-known photolithographic processes. Optionally, anodes may be polished prior to application of other layers to reduce surface roughness so as to minimize shorts or enhance reflectivity.
  • HIL Hole-Injecting Layer
  • a hole-injecting layer 105 be provided between anode 103 and hole-transporting layer 107.
  • the hole-injecting material can serve to improve the film formation property of subsequent organic layers and to facilitate injection of holes into the hole-transporting layer.
  • Suitable materials for use in the hole-injecting layer include, but are not limited to, porphyrinic compounds as described in US 4,720,432, plasma-deposited fluorocarbon polymers as described in US 6,208,075, and some aromatic amines, for example, m-MTDATA (4,4',4"-tris[(3- methylphenyl)phenylamino]triphenylamine).
  • Alternative hole-injecting materials reportedly useful in organic EL devices are described in EP 0891121 and EP 1029909. Additional useful hole-injecting materials are described in US
  • HTL Hole-Transporting Layer
  • the hole-transporting layer 107 of the organic EL device contains at least one hole-transporting compound, such as an aromatic tertiary amine, where the latter is understood to be a compound containing at least one trivalent nitrogen atom that is bonded only to carbon atoms, at least one of which is a member of an aromatic ring.
  • the aromatic tertiary amine can be an arylamine, such as a monoaryl amine, diarylamine, triarylamine, or a polymeric arylamine. Exemplary monomelic triarylamines are illustrated by Klupfel et al. US 3,180,730. Other suitable triarylamines substituted with one or more vinyl radicals and/or comprising at least one active hydrogen containing group are disclosed by Brantley et al US 3,567,450 and US 3,658,520.
  • a more preferred class of aromatic tertiary amines are those which include at least two aromatic tertiary amine moieties as described in US 4,720,432 and US 5,061,569. Such compounds include those represented by structural Formula (A).
  • Q 1 and Q 2 are independently selected aromatic tertiary amine moieties and G is a linking group such as an arylene, cycloalkylene, or alkylene group of a carbon to carbon bond.
  • G is a linking group such as an arylene, cycloalkylene, or alkylene group of a carbon to carbon bond.
  • at least one of Qi or Q2 contains a polycyclic fused ring structure, e.g., a naphthalene.
  • G is an aryl group, it is conveniently a phenylene, biphenylene, or naphthalenediyl moiety.
  • a useftil class of triaiylamines satisfying structural Formula (A) and containing two triarylamine moieties is represented by structural Formula (B).
  • Rj and R 2 each independently represents a hydrogen atom, an aryl group, or an alkyl group or R] and R 2 together represent the atoms completing a cycloalkyl group;
  • R3 and R4 each independently represents an aryl group, which is in turn substituted with a diaryl substituted amino group, as indicated by structural Formula (C).
  • R 5 and R 6 are independently selected aryl groups. In one embodiment, at least one of R 5 or R 6 contains a polycyclic fused ring structure, e.g., a naphthalene.
  • tetraaryldiamines Another class of aromatic tertiary amines are the tetraaryldiamines. Desirable tetraaryldiamines include two diarylamino groups, such as indicated by Formula (C), linked through an arylene group. Useful tetraaryldiamines include those represented by Formula (D).
  • each Are is an independently selected arylene group, such as a phenylene, naphthylenediyl or anthracenediyl moiety and n is an integer of from 1 to 4.
  • Ar, R 7 , R 8 , and R 9 are independently selected aryl groups.
  • at least one of Ar, R 7 , Rg, and R 9 is a polycyclic fused ring structure, e.g., a naphthalene.
  • the various alkyl, alkylene, aryl, and arylene moieties of the foregoing structural Formulae (A), (B), (C), (D), can each in turn be substituted.
  • Typical substituents include alkyl groups, alkoxy groups, aryl groups, aryloxy groups, benzo and halogen such as fluoride.
  • the various alkyl and alkylene moieties typically contain from 1 to 6 carbon atoms.
  • the cycloalkyl moieties can contain from 3 to 10 carbon atoms, but typically contain five, six, or seven ring carbon atoms--e.g., cyclopentyl, cyclohexyl, and cycloheptyl ring structures.
  • the aryl and arylene moieties are usually phenyl and phenylene moieties.
  • the hole-transporting layer can be formed of a single or a mixture of aromatic tertiary amine compounds.
  • a triarylamine such as a triarylamine satisfying the Formula (B)
  • a tetraaryldiamine such as indicated by Formula (D).
  • a triarylamine is employed in combination with a tetraaryldiamine, the latter is positioned as a layer interposed between the triarylamine and the electron injecting and transporting layer.
  • useful aromatic tertiary amines are the following:
  • Another class of useful hole-transporting materials includes polycyclic aromatic compounds as described in EP 1,009,041. Tertiary aromatic amines with more than two amine groups may be used including oligomeric materials.
  • polymeric hole-transporting materials can be used such as poly(N-vinylcarbazole) (PVK), polythiophenes, polypyrrole, polyaniline, and copolymers such as poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) also called PEDOT/PSS.
  • LEL Light-Emitting Layer
  • the additional light-emitting layers (LEL) of the organic EL element may include a luminescent fluorescent or phosphorescent material where electroluminescence is produced as a result of electron-hole pair recombination in this region.
  • the host materials in the light-emitting layer can be an electron-transporting material, as defined below, a hole-transporting material, as defined above, or another material or combination of materials that support hole-electron recombination.
  • the emitting material is usually chosen from highly fluorescent dyes and phosphorescent compounds, e.g., transition metal complexes as described in WO 98/55561, WO 00/18851, WO 00/57676, and WO 00/70655.
  • Emitting materials are typically incorporated at 0.01 to 10 % by weight of the host material.
  • the host and emitting materials can be small non-polymeric molecules or polymeric materials such as polyfluorenes and polyvinylarylenes (e.g., ⁇ oly(p-phenylenevinylene), PPV).
  • polymers small molecule emitting materials can be molecularly dispersed into a polymeric host, or the emitting materials can be added by copolymerizing a minor constituent into a host polymer.
  • An important relationship for choosing an emitting material is a comparison of the bandgap potential which is defined as the energy difference between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the molecule.
  • the band gap of the dopant is smaller than that of the host material.
  • the host triplet energy level of the host be high enough to enable energy transfer from host to emitting material.
  • Host and emitting materials known to be of use include, but are not limited to, those disclosed in US 4,768,292, US 5,141,671, US 5,150,006, US 5,151,629, US 5,405,709, US 5,484,922, US 5,593,788, US 5,645,948, US 5,683,823, US 5,755,999, US 5,928,802, US 5,935,720, US 5,935,721, and US 6,020,078.
  • Form E Metal complexes of 8-hydroxyquinoline and similar derivatives constitute one class of useful host compounds capable of supporting electroluminescence, and are particularly suitable for light emission of wavelengths longer than 500 nm, e.g., green, yellow, orange, and red.
  • M represents a metal
  • n is an integer of from 1 to 4
  • Z independently in each occurrence represents the atoms completing a nucleus having at least two fused aromatic rings.
  • the metal can be monovalent, divalent, trivalent, or tetravalent metal.
  • the metal can, for example, be an alkali metal, such as lithium, sodium, or potassium; an alkaline earth metal, such as magnesium or calcium; an earth metal, such aluminum or gallium, or a transition metal such as zinc or zirconium.
  • alkali metal such as lithium, sodium, or potassium
  • alkaline earth metal such as magnesium or calcium
  • earth metal such aluminum or gallium, or a transition metal such as zinc or zirconium.
  • any monovalent, divalent, trivalent, or tetravalent metal known to be a useful chelating metal can be employed.
  • Z completes a heterocyclic nucleus containing at least two fused aromatic rings, at least one of which is an azole or azine ring. Additional rings, including both aliphatic and aromatic rings, can be fused with the two required rings, if required. To avoid adding molecular bulk without improving on function the number of ring atoms is usually maintained at 18 or less.
  • Illustrative of useful chelated oxinoid compounds are the following:
  • CO-I Aluminum trisoxine [alias, tris(8-quinolinolato)aluminum(III); AIq] CO-2: Magnesium bisoxine [alias, bis(8-quinolinolato)magnesium(II)]
  • CO-4 Bis(2-methyl-8-quinolinplato)alurainum(III)- ⁇ -oxo-bis(2-methyl-8- quinolinolato) aluminum(III)
  • CO-5 Indium trisoxine [alias, tris(8-quinolinolato)indium]
  • CO-6 Aluminum tris(5-methyloxine) [alias, tris(5-methyl-8-quinolinolato) aluminum(III)]
  • CO-7 Lithium oxine [alias, (8-quinolinolato)lithium(I)]
  • CO-8 Gallium oxine [alias, tris(8-quinolinolato)gallium(III)]
  • CO-9 Zirconium oxine [alias, tetra(8-quinolinolato)zirconium(IV)].
  • derivatives of anthracene constitute one class of useful host materials capable of supporting electroluminescence, and are particularly suitable for light emission of wavelengths longer than 400 nm, e.g., blue, green, yellow, orange or red.
  • Asymmetric anthracene derivatives as disclosed in US 6,465,115 and WO 2004/018587 are also useful hosts.
  • R 1 and R 2 represent independently selected aryl groups, such as naphthyl, phenyl, biphenyl, triphenyl, anthracene.
  • R 3 and R 4 represent one or more substituents on each ring where each s ⁇ bstituent is individually selected from the following groups:
  • Group 1 hydrogen, or alkyl of from 1 to 24 carbon atoms
  • Group 2 aryl or substituted aryl of from 5 to 20 carbon atoms
  • Group 3 carbon atoms from 4 to 24 necessary to complete a fused aromatic ring of anthracenyl; pyrenyl, or perylenyl;
  • Group 4 heteroaryl or substituted heteroaryl of from 5 to 24 carbon atoms as necessary to complete a fused heteroaromatic ring of furyl, thienyl, pyridyl, quinolinyl or other heterocyclic systems;
  • Group 5 alkoxylamino, alkylamino, or arylamino of from 1 to 24 carbon atoms;
  • Group 6 fluorine or cyano.
  • a useful class of anthracenes are derivatives of 9,10-di-(2- naphthyl) anthracene (Formula G).
  • R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 represent one or more substituents on each ring where each substituent is individually selected from the following groups: Group 1: hydrogen, or alkyl of from 1 to 24 carbon atoms;
  • Group 2 aryl or substituted aryl of from 5 to 20 carbon atoms;
  • Group 3 carbon atoms from 4 to 24 necessary to complete a fused aromatic ring of anthracenyl; pyrenyl, or perylenyl;
  • Group 4 heteroaryl or substituted heteroaryl of from 5 to 24 carbon atoms as necessary to complete a fused heteroaromatic ring of furyl, thienyl, pyridyl, quinolinyl or other heterocyclic systems;
  • Group 5 alkoxylamino, alkylamino, or arylamino of from 1 to 24 carbon atoms;
  • Group 6 fluorine or cyano.
  • Illustrative examples of useful anthracene materials have been previously described.
  • Benzazole derivatives constitute another class of useful host materials capable of supporting electroluminescence, and are particularly suitable for light emission of wavelengths longer than 400 nm, e.g., blue, green, yellow, orange or red.
  • n is an integer of 3 to 8;
  • Z is O, NR or S; and
  • R and R' are individually hydrogen; alkyl of from 1 to 24 carbon atoms, for example, propyl, t-butyl, heptyl, and the like; aryl or hetero-atom substituted aryl of from 5 to 20 carbon atoms for example phenyl and naphthyl, furyl, thienyl, pyridyl, quinolinyl and other heterocyclic systems; or halo such as chloro, fluoro; or atoms necessary to complete a fused aromatic ring.
  • L is a linkage unit consisting of alkyl, aryl, substituted alkyl, or substituted aryl, which conjugately or unconjugated connects the multiple benzazoles together.
  • An example of a useful benzazole is 2, 2', 2"-(l,3,5-phenylene)tris[l-phenyl-lH-benzimidazole].
  • Distyrylarylene derivatives are also useful hosts, as described in US 5,121,029.
  • Carbazole derivatives are particularly useful hosts for phosphorescent emitters.
  • Useful fluorescent emitting materials include, but are not limited to, derivatives of anthracene, tetracene, xanthene, perylene, rubrene, coumarin, rhodamine, and quinacridone, dicyanomethylenepyran compounds, thiopyran compounds, polymethine compounds, pyrilium and thiapyrilium compounds, fluorene derivatives, periflanthene derivatives, indenoperylene derivatives, bis(azinyl)amine boron compounds, bis(azinyl)methane compounds, and carbostyryl compounds.
  • Illustrative examples of useful fluorescent and phosphorescent emitting materials include, but are not limited to, the following compounds.
  • Preferred thin film-forming materials for use in forming additional electron- transporting layers of the organic EL devices of this invention include metal chelated oxinoid compounds, including chelates of oxine itself (also commonly referred to as 8-quinolinol or 8- hydroxyquinoline). Such compounds help to inject and transport electrons and exhibit both high levels of performance and are readily fabricated in the form of thin films.
  • Exemplary of contemplated oxinoid compounds are those satisfying structural Formula (E), previously described.
  • Triazines are also known to be useful as electron transporting materials. Further useful materials are silacyclopentadiene derivatives described in EP 1,480,280; EP 1,478,032; and EP 1,469,533. Substituted 1,10-phenanthroline compounds such as are disclosed in JP2003-115387; JP2004-311184; JP2001-267080; and WO2002-043449. Triazines are also known to be useful as electron transporting materials.
  • EIU Electron-Injecting Layer
  • Useful electron-injecting layers have also been described previously. More than one electron- injecting layer may be present. Additional electron-injecting layers, when present, include those described in US 5,608,287; 5,776,622; 5,776,623; 6,137,223; and 6,140,763, US 6,914,269.
  • a useful additional electron-injecting layer generally consists of a material having a work function less than 4.0 eV.
  • a thin-film containing low work-function alkaline metals or alkaline earth metals, such as Li, Cs, Ca, Mg can be employed.
  • an organic material doped with these low work-function metals can also be used effectively as the electron-injecting layer. Examples are Li- or Cs-doped AIq.
  • an additional electron-injecting layer includes LiF.
  • the additional electron-injecting layer is often a thin layer deposited to a suitable thickness in a range of 0.1-3.0 nm.
  • the cathode used in this invention can be comprised of nearly any conductive material. Desirable materials have good film-forming properties to ensure good contact with the underlying organic layer, promote electron injection at low voltage, and have good stability. Useful cathode materials often contain a low work function metal ( ⁇ 4.0 eV) or metal alloy.
  • One useful cathode material is comprised of a Mg: Ag alloy wherein the percentage of silver is in the range of 1 to 20 %, as described in U.S. Patent No. 4,885,221.
  • cathode materials includes bilayers comprising the cathode and a thin electron-injection layer (EIL) in contact with an organic layer (e.g., an electron transporting layer (ETL)) which is capped with a thicker layer of a conductive metal.
  • EIL electron transporting layer
  • the EIL preferably includes a low work function metal or metal salt, and if so, the thicker capping layer does not need to have a low work function.
  • One such cathode is comprised of a thin layer of LiF followed by a thicker layer of Al as described in U.S. Patent No. 5,677,572.
  • Other useful cathode material sets include, but are not limited to, those disclosed in U.S. Patent Nos. 5,059,861; 5,059,862, and 6,140,763.
  • the cathode When light emission is viewed through the cathode, the cathode must be transparent or nearly transparent. For such applications, metals must be thin or one must use transparent conductive oxides, or a combination of these materials.
  • Optically transparent cathodes have been described in more detail in US 4,885,211, US 5,247,190, JP 3,234,963, US 5,703,436, US 5,608,287, US 5,837,391, US 5,677,572, US 5,776,622, US 5,776,623, US 5,714,838, US 5,969,474, US 5,739,545, US 5,981,306, US 6,137,223, US 6,140,763, US 6,172,459, EP 1 076 368, US 6,278,236, and US 6,284,3936.
  • Cathode materials are typically deposited by any suitable method such as evaporation, sputtering, or chemical vapor deposition. When needed, patterning can be achieved through many well known methods including, but not limited to, through-mask deposition, integral shadow masking as described in US 5,276,380 and EP 0 732 868, laser ablation, and selective chemical vapor deposition.
  • layers 109 and 111 can optionally be collapsed into a single layer that serves the function of supporting both light emission and electron transportation. It also known in the art that emitting materials maybe included in the hole-transporting layer, which may serve as a host. Multiple materials may be added to one or more layers in order to create a white-emitting OLED, for example, by combining blue- and yellow-emitting materials, cyan- and red-emitting materials, or red-, green-, and blue-emitting materials.
  • White- emitting devices are described, for example, in EP 1 187 235, US 20020025419, EP 1 182 244, US 5,683,823, US 5,503,910, US 5,405,709, and US 5,283,182 and may be equipped with a suitable filter arrangement to produce a color emission. Additional layers such as electron or hole-blocking layers as taught in the art may be employed in devices of this invention. Hole-blocking layers may be used between the light emitting layer and the electron transporting layer. Electron-blocking layers may be used between the hole-transporting layer and the light emitting layer. These layers are commonly used to improve the efficiency of emission, for example, as in US 20020015859.
  • This invention may be used in so-called stacked device architecture, for example, as taught in US 5,703,436 and US 6,337,492.
  • the organic materials mentioned above are suitably deposited by any means suitable for the form of the organic materials. In the case of small molecules, they are conveniently deposited through sublimation, but can be deposited by other means such as from a solvent with an optional binder to improve film formation. If the material is a polymer, solvent deposition is usually preferred.
  • the material to be deposited by sublimation can be vaporized from a sublimator "boat" often comprised of a tantalum material, e.g., as described in US 6,237,529, or can be first coated onto a donor sheet and then sublimed in closer proximity to the substrate. Layers with a mixture of materials can utilize separate sublimator boats or the materials can be pre-mixed and coated from a single boat or donor sheet.
  • Patterned deposition can be achieved using shadow masks, integral shadow masks (US 5,294,870), spatially-defined thermal dye transfer from a donor sheet (US 5,688,551, US 5,851,709 and US 6,066,357) and inkjet method (US 6,066,357).
  • One preferred method for depositing the materials of the present invention is described in US 2004/0255857 and USSN 10/945,941 where different source evaporators are used to evaporate each of the materials of the present invention.
  • a second preferred method involves the use of flash evaporation where materials are metered along a material feed path in which the material feed path is temperature controlled.
  • each material may be evaporated using different source evaporators or the solid materials may be mixed prior to evaporation using the same source evaporator.
  • OLED devices are sensitive to moisture or oxygen, or both, so they are commonly sealed in an inert atmosphere such as nitrogen or argon, along with a desiccant such as alumina, bauxite, calcium sulfate, clays, silica gel, zeolites, alkaline metal oxides, alkaline earth metal oxides, sulfates, or metal halides and perchlorates.
  • a desiccant such as alumina, bauxite, calcium sulfate, clays, silica gel, zeolites, alkaline metal oxides, alkaline earth metal oxides, sulfates, or metal halides and perchlorates.
  • Methods for encapsulation and desiccation include, but are not limited to, those described in U.S. Patent No. 6,226,890.
  • barrier layers such as SiOx, Teflon, and alternating inorganic/polymeric layers are known in the art for encapsulation.
  • OLED devices of this invention can employ various well-known optical effects in order to enhance its properties if desired. This includes optimizing layer thicknesses to yield maximum light transmission, providing dielectric mirror structures, replacing reflective electrodes with light-absorbing electrodes, providing anti glare or anti-reflection coatings over the display, providing a polarizing medium over the display, or providing colored, neutral density, or color conversion filters over the display. Filters, polarizers, and antiglare or anti-reflection coatings maybe specifically provided over the cover or as part of the cover.
  • Embodiments of the invention may provide advantageous features such as higher luminous yield, lower drive voltage, and higher power efficiency, longer operating lifetimes or ease of manufacture.
  • Embodiments of devices useful in the invention can provide a wide range of hues including those useful in the emission of white light (directly or through filters to provide multicolor displays).
  • Embodiments of the invention can also provide an area lighting device.
  • the invention and its advantages are further illustrated by the specific examples that follow.
  • the term “percentage” or “percent” and the symbol “%” indicate the volume percent (or a thickness ratio as measured on a thin film thickness monitor) of a particular first or second compound of the total material in the layer of the invention and other components of the devices. If more than one second compound is present, the total volume of the second compounds can also be expressed as a percentage of the total material in the layer of the invention.
  • Example 1 Electrochemical Redox Potentials and Estimated Energy Levels. LUMO and HOMO values are typically estimated experimentally by electrochemical methods. The following method illustrates a useful means to measure redox properties.
  • a Model CHI660 electrochemical analyzer (CH Instruments, Inc., Austin, TX) was employed to carry out the electrochemical measurements. Cyclic voltammetry (CV) and Osteryoung square-wave voltammetry (SWV) were used to characterize the redox properties of the compounds of interest.
  • a glassy carbon (GC) disk electrode (A 0.071cm 2 ) was used as working electrode.
  • the GC electrode was polished with 0.05 ⁇ m alumina slurry, followed by sonication cleaning in Milli-Q deionized water twice and rinsed with acetone in between water cleaning. The electrode was finally cleaned and activated by electrochemical treatment prior to use.
  • a platinum wire served as counter electrode and a saturated calomel electrode (SCE) was used as a quasi- reference electrode to complete a standard 3-electrode electrochemical cell.
  • Ferrocene (Fc) was used as an internal standard (E FC ⁇ 0.50 V vs. SCE in 1 :1 acetonitrile/toluene, 0.1 M TBAF).
  • a mixture of acetonitrile and toluene (50%/50% v/v, or 1 : 1) was used as the organic solvent system.
  • the testing solution was purged with high purity nitrogen gas for approximately 5 minutes to remove oxygen and a nitrogen blanket was kept on the top of the solution during the course of the experiments. All measurements were performed at ambient temperature of 25 ⁇ 1°C.
  • oxidation and reduction potentials were determined either by averaging the anodic peak potential (Ep,a) and cathodic peak potential (E ⁇ ,c) for reversible or quasi- reversible electrode processes or on the basis of peak potentials (in SWV) for irreversible processes.
  • LUMO and HOMO values are calculated from the following:
  • E 0 Ox vs. Fc (E 0 O x vs. SCE) - EFC
  • E Fo is the oxidation potential E 0x , of ferrocene; Estimated lower limit for LUMO and HOMO vlaues;
  • the LUMO value of compounds of interest can also be estimated from molecular orbital calculations. Typical calculations are carried out by using the B3LYP method as implemented in the Gaussian 98 (Gaussian, Inc., Pittsburgh, PA) computer program.
  • the basis set for use with the B3LYP method is defined as follows: MIDI! for all atoms for which MIDI! is defined, 6-3 IG* for all atoms defined in 6-3 IG* but not in MIDI!, and either the LACV3P or the LANL2DZ basis set and pseudopotential for atoms not defined in MIDI! or 6-3 IG*, with LACV3P being the preferred method. For any remaining atoms, any published basis set and pseudopotential may be used.
  • MIDI!, 6-3 IG* and LANL2DZ are used as implemented in the Gaussian98 computer code and LACV3P is used as implemented in the Jaguar 4.1 (Schrodinger, Inc., Portland Oregon) computer code. Calculations provide the energy level of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in Hartree units where 1 Hartree unit is 27.21 eV.
  • HOMO highest occupied molecular orbital
  • LUMO lowest unoccupied molecular orbital
  • a series of EL devices (1-1 through 1-11) were constructed as described below.
  • ITO indium-tin oxide
  • HIL fluorocarbon
  • HIL hole-injecting layer
  • NPB hole-transporting material 4'-Bis[JV-(l-naphthyl)-JV- phenylamino]biphenyl
  • LEL light-emitting layer
  • D-I light-emitting material
  • EIL electron-injecting layer
  • the above sequence completed the deposition of the EL device.
  • the device was then hermetically packaged in a dry glove box for protection against ambient environment.
  • the devices were tested for luminous efficiency at an operating current of 20 mA/cm 2 and the results are reported in Table 2b in the form of luminous yield (cd/A) and efficiency (w/A), and power efficiency (lm/watt).
  • Device efficiency is the radiant flux (in watts) produced by the device per amp of input current, where radiant flux is the light energy produced by the device per unit time. Light intensity is measured perpendicular to the device surface, and it is assumed that the angular profile is Lambertian. Drive voltage is reported in volts and is corrected for the ITO voltage drop. Table 2b. Testing results for device 1-1 through 1-11.
  • the ratio of the thickness of the EIL layer to the thickness of the LEL is also critical. Comparative device 1-7, having a low EIL/LEL ratio, provides much higher voltage and lower efficiency than devices 1-8 through 1-11 having a more optimum EIL/LEL ratio.
  • a series of EL devices (2-1 through 2-12) were constructed in the same manner as device 1-1, as described below.
  • ITO indium-tin oxide
  • a light-emitting layer (LEL) corresponding to a host material 1-1, TBADN or AIq and including light-emitting material D-I or D-2 was deposited to a thickness of either 20 nm or 40 nm over the HTL. See Table 3 a for a description of the LEL host, dopant, and thickness of each device.
  • ETL electron-transporting layer
  • TBADN TBADN
  • EIL electron-injecting layer
  • the above sequence completed the deposition of the EL device.
  • the device was then hermetically packaged in a dry glove box for protection against ambient environment.
  • This example illustrates the relative device performance when an anthracene compound bearing aromatic groups in the 2-, 9-, and 10-positions, such as 1-1, is included in the electron transport layer versus the case when the anthracene bears aromatic groups in the 9- and 10-position and an alkyl group in the 2-position (TBADN). Although all the devices provide good luminance and relatively low voltage, devices with an ETL including a anthracene compound bearing aromatic groups in the 2-, 9-, and 10-positions are especially desirable.
  • Example 4 Fabrication of Device 3-1 through 3-6.
  • a series of EL devices (3-1 through 3-6) were constructed in a manner similar to device 1-1 as described below.
  • ITO indium-tin oxide
  • LEL light-emitting layer
  • ETL electron-transport layer
  • EIL electron-injecting layer
  • the above sequence completed the deposition of the EL device.
  • the device was then hermetically packaged in a dry glove box for protection against ambient environment.
  • the devices were tested in the same manner as device 1-1 and the results are given in Table 4b.
  • Table 4a The LEL 3 ETL, and EIL of device 3-1 through 3-6.
  • the inventive devices 3-5 and 3-6 afford greater power efficiency than the comparatives 3-1 and 3-2, which do not include both an ETL and an EIL.
  • the inventive devices, which have the desired EIL/LEL thickness ratio, also provide lower voltage and greater power efficiency relative to comparative 3-3 and 3-4, which do not have an EIL/LEL thickness ratio in a desirable range.
  • a series of EL devices (4-1 through 4-12) were constructed in a manner similar to device 1 -1, as described below.
  • ITO indium-tin oxide
  • HIL hole-injecting layer
  • a layer of hole-transporting material 4,4'-Bis[N-(l-naphthyl)-_V- phenylaminojbiphenyl (NPB) was deposited to a thickness of 75 nm.
  • An electron-transporting layer (ETL) composed of the material I- 1 was vacuum-deposited over the LEL. The thickness of the ETL is also reported in Table 5a. 5.
  • An electron-injecting layer (EIL) composed Bphen was deposited over the
  • ETL to a thickness shown in Table 5a. 6.
  • 0.5 nm layer of lithium fluoride was vacuum deposited onto the EIL, followed by a 150 nm layer of aluminum, to form a cathode layer.
  • the above sequence completed the deposition of the EL device.
  • the device was then hermetically packaged in a dry glove box for protection against ambient environment.
  • the devices were tested in the same manner as device 1-1 and the results are given in Table 5b.
  • Table 5a The LEL, ETL, and EIL of device 4-1 through 4-12.
  • a series of EL devices (5-1 through 5-3) were constructed in a manner similar to device 1-1, as described below.
  • ITO indium-tin oxide
  • LEL light-emitting layer
  • An electron-transporting layer (ETL) composed of the material 1-1 was vacuum-deposited over the LEL to a thickness of 25.0 nm.
  • An electron-injecting layer composed of Bphen, TPBI, or Liq (see Table 6a) was deposited over the ETL to a thickness of 10 nm. 10. 0.5 nm layer of lithium fluoride was vacuum deposited onto the EIL, followed by a 150 nm layer of aluminum, to form a cathode layer.
  • the above sequence completed the deposition of the EL device.
  • the device was then hermetically packaged in a dry glove box for protection against ambient environment.
  • the devices were tested in the same manner as device 1-1 and the results are given in Table 6b.
  • Table 6a The LEL, ETL, and EIL of device 5-1 through 5-3.
  • inventive device 5-1 which includes a phenanthroline material in the EIL, affords significantly lower voltage and higher efficiency than the comparative devices, 5-2 and 5-3, which contain alternative electron injection materials.
  • a series of EL devices (6-1 through 6-3) were constructed in a manner similar to device 1- 1 , as described below.
  • ITO indium-tin oxide
  • CFx fluorocarbon
  • HIL hole-injecting layer
  • LEL light-emitting layer
  • An electron-transporting layer composed of the material 1-1 or AIq (see Table 7a) was vacuum-deposited over the LEL to a thickness of 25.0 nm.
  • An electron-injecting layer composed of Bphen, DPBiP, or AIq (see Table 7a) was deposited over the ETL to a thickness of 10 nm.
  • the device was then hermetically packaged in a dry glove box for protection against ambient environment.
  • the devices were tested in the same manner as device 1-1 and the results are given in Table 7b.
  • Table 7a The LEL, ETL, and EIL of device 6-1 through 6-3.
  • the inventive device 6-1 affords both lower voltage and higher luminance relative to comparative device 6-2, having an EIL that does not include a phenanthroline derivative.
  • Device 6-1 is especially advantaged over comparative device 6-3, which uses AIq in both the ETL and EIL.
  • a series of EL devices (7-1 through 7-5) were constructed in a manner similar to device 1-1, as described below.
  • ITO indium-tin oxide
  • HIL hole-injecting layer
  • LEL light-emitting layer
  • ETL electron-transporting layer
  • EIL electron-injecting layer
  • the above sequence completed the deposition of the EL device.
  • the device was then hermetically packaged in a dry glove box for protection against ambient environment.
  • the devices were tested in the same manner as device 1-1 and the results are given in Table 8b.
  • Table 8a The LEL 5 ETL 5 and EIL of device 7-1 through 7-5.
  • inventive devices 7-4 and 7-5 using an anthracene electron transport material 1-1 in combination with a phenanthroline electron injection material II-2, produce high power efficiency with low voltage relative to the comparative device 7-1 having only an anthracene material.
  • inventive devices also have an EIL to LEL thickness ratio in a desirable range and perform much better relative to comparison devices 7-2 and 7-3, which have a ratio outside this range.
  • HIL Hole-Injecting layer
  • ETL Electron-Transporting layer
  • EIL Electron-Injecting layer

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Optics & Photonics (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

Un dispositif électroluminescent comprend une cathode, une anode et a entre celles-ci une couche électroluminescente (LEL), le dispositif contient en outre une couche de transport d'électrons (ETL) comprenant un composé d'anthracène du côté de la cathode de la couche électroluminescente LEL et une couche d'injection d'électrons organique (EIL) entre la couche de transport d'électrons ETL et la cathode comprenant un composé de phénanthroline, dans lequel les épaisseurs de la couche d'injection d'électrons organique EIL et de la couche électroluminescente LEL sont telles que le rapport de l'épaisseur de la couche d'injection d'électrons organique EIL sur la couche électroluminescente LEL est supérieur à 0,125.
PCT/US2007/009165 2006-04-27 2007-04-13 Dispositif électroluminescent comprenant un dérivé d'anthracène WO2007127069A1 (fr)

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US11/412,676 US9666826B2 (en) 2005-11-30 2006-04-27 Electroluminescent device including an anthracene derivative

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WO2009066779A1 (fr) * 2007-11-22 2009-05-28 Idemitsu Kosan Co., Ltd. Élément el organique
US8877354B2 (en) 2009-08-25 2014-11-04 Canon Kabushiki Kaisha Heterocyclic compound and organic light-emitting device using the same
US9153790B2 (en) 2009-05-22 2015-10-06 Idemitsu Kosan Co., Ltd. Organic electroluminescent device
CN105552243A (zh) * 2016-01-29 2016-05-04 桂林电子科技大学 一种紫外有机发光器件及其制备方法
US10439156B2 (en) 2013-05-17 2019-10-08 Semiconductor Energy Laboratory Co., Ltd. Light-emitting element, light-emitting device, display device, lighting device, and electronic device
US10505120B2 (en) 2011-02-28 2019-12-10 Semiconductor Energy Laboratory Co., Ltd. Light-emitting device

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WO2006004138A1 (fr) * 2004-07-07 2006-01-12 Semiconductor Energy Laboratory Co., Ltd. Dérivé de phénanthroline et élément luminescent et dispositif luminescent utilisant ledit dérivé
US20060040132A1 (en) * 2004-08-20 2006-02-23 Eastman Kodak Company White OLED having multiple white electroluminescence units

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WO2003060956A2 (fr) * 2002-01-18 2003-07-24 Lg Chem, Ltd. Nouveau materiau permettant de transporter des electrons et affichage organique electroluminescent utilisant ledit materiau
WO2004053018A1 (fr) * 2002-12-06 2004-06-24 Shuang Xie Dispositifs electroluminescents
WO2006004138A1 (fr) * 2004-07-07 2006-01-12 Semiconductor Energy Laboratory Co., Ltd. Dérivé de phénanthroline et élément luminescent et dispositif luminescent utilisant ledit dérivé
US20060040132A1 (en) * 2004-08-20 2006-02-23 Eastman Kodak Company White OLED having multiple white electroluminescence units

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009066779A1 (fr) * 2007-11-22 2009-05-28 Idemitsu Kosan Co., Ltd. Élément el organique
JP5270571B2 (ja) * 2007-11-22 2013-08-21 出光興産株式会社 有機ｅｌ素子
US8759819B2 (en) 2007-11-22 2014-06-24 Idemitsu Kosan Co., Ltd. Organic electroluminescence device
US9054319B2 (en) 2007-11-22 2015-06-09 Idemitsu Kosan Co., Ltd. Organic electroluminescence device
US9153790B2 (en) 2009-05-22 2015-10-06 Idemitsu Kosan Co., Ltd. Organic electroluminescent device
US8877354B2 (en) 2009-08-25 2014-11-04 Canon Kabushiki Kaisha Heterocyclic compound and organic light-emitting device using the same
US10505120B2 (en) 2011-02-28 2019-12-10 Semiconductor Energy Laboratory Co., Ltd. Light-emitting device
US10930852B2 (en) 2011-02-28 2021-02-23 Semiconductor Energy Laboratory Co., Ltd. Light-emitting device
US11508912B2 (en) 2011-02-28 2022-11-22 Semiconductor Energy Laboratory Co., Ltd. Light-emitting device
US10439156B2 (en) 2013-05-17 2019-10-08 Semiconductor Energy Laboratory Co., Ltd. Light-emitting element, light-emitting device, display device, lighting device, and electronic device
CN105552243A (zh) * 2016-01-29 2016-05-04 桂林电子科技大学 一种紫外有机发光器件及其制备方法

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TW200803006A (en) 2008-01-01

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