des brevets
`
`Europaisches
`Patentamt
`European
`Patent Office
`Office européen
`
`(11)
`
`EP 2 551 932 A2
`
`(12)
`
`EUROPEAN PATENT APPLICATION
`
`(43) Date of publication:
`30.01.2013 Bulletin 2013/05
`
`(51)
`
`Int Cl.:
`HO1L 51/00 (2996.91)
`
`(21) Application number: 12178243.7
`
`(22) Dateoffiling: 27.07.2012
`
`
`(84) Designated Contracting States:
`AL AT BE BG CH CY CZ DE DK EE ES FI FRGB
`GR HR HU IE IS IT LILT LU LV MC MK MT NL NO
`PL PT RO RS SE SISK SMTR
`
`Designated Extension States:
`BA ME
`
`(30) Priority: 28.07.2011 US 201113193173
`
`(71) Applicant: Universal Display Corporation
`Ewing, NJ 08618 (US)
`
`(74)
`
`Dyatkin, Alexey B.
`Ewing, NJ New Jersey 08618 (US)
`Kottas, Gregg
`Ewing, NJ New Jersey 08618 (US)
`Xia, Chuanjun
`Ewing, NJ New Jersey 08618 (US)
`Li, David Z.
`Ewing, NJ New Jersey 08618 (US)
`
`Representative: Kopf, Korbinian Paul
`Maiwald Patentanwalts GmbH
`Elisenhof
`Elisenstrasse 3
`
`(72) Inventors:
`¢ Zeng, Lichang
`Ewing, NJ New Jersey 08618 (US)
`
`
`80335 Munchen (DE)
`
`(54)
`
`Host materials for phosphorescent oleds
`
`Novel aryl silicon and aryl germanium host ma-
`(57)
`terials are described. These compounds improve OLED
`device performance when used as hosts in the emissive
`layer of the OLED.
`
` Soo
`
`Compound 1
`
`Formula |
`
`EP2551932A2
`
`
`
`Printed by Jouve, 75001 PARIS (FR)
`
`_ FIGURE 3
`
`

`

`Description
`
`EP 2 551 932 A2
`
`[0001] The claimed invention was made by, on behalf of, and/or in connection with one or moreof the following parties
`to a joint university corporation research agreement: Regents of the University of Michigan, Princeton University, The
`University of Southern California, and the Universal Display Corporation. The agreement wasin effect on and before
`the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within
`the scope of the agreement.
`
`FIELD OF THE INVENTION
`
`[0002] The presentinvention relates to compoundssuitable for use as hast materials in OLEDs, specifically compounds
`comprising arylgermane and arylsilane groups.
`
`BACKGROUND
`
`[0003] 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 astheir 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-
`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.
`[0004] OLEDs make useof 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 asflat panel displays,
`illumination, and
`backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and
`5,707,745, which are incorporated herein by reference in their entirety.
`[0005] One application for phosphorescent emissive moleculesis a full color display. Industry standards for such a
`display call for pixels adapted to emit particular colors, referred to as “saturated” colors. In particular, these standards
`call for saturated red, green, and blue pixels. Color may be measured using CIE coordinates, which are well known to
`the art.
`
`[0006] One example of a green emissive molecule is tris(2-pheny|pyridine)iridium, denoted Ir(ppy)3, which has the
`following structure:
`
`”
`
`In this, and later figures herein, we depict the dative bond from nitrogen to metal (here, Ir) as a straight line.
`[0007]
`[0008] As used herein, the term "organic" includes polymeric materials as well as small molecule organic materials
`that may be usedto fabricate organic opto-electronic devices. "Small molecule” refers to any organic material that is not
`a polymer, and "small molecules" may actually be quite large. Small molecules may include repeat units in some cir-
`cumstances. For example, using a long chain alky| group as a substituent does not remove a molecule from the "small
`molecule" class. Small molecules mayalso 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
`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.
`[0009] As used herein, "top" means furthest away from the substrate, while "bottom" means closest to the substrate.
`Wherea first layer is described as "disposed over" a secondlayer, the first layer is disposed further away from substrate.
`There may be other layers between the first and second layer, unlessit is specified that the first layer is "in contact with"
`the second layer. For example, a cathode may be described as "disposed over” an anode, even though thereare various
`organic layers in between.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`5S
`
`

`

`EP 2 551 932 A2
`
`[0010] 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.
`[0011] A ligand may be referred to as "photoactive" when it
`is believed that the ligand directly contributes to the
`photoactive properties of an emissive material. A ligand may be referred to as "ancillary" when it is believed that the
`ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand mayalter
`the properties of a photoactive ligand.
`[0012] 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) energylevel is "greater than” or "higher
`than" asecond HOMO or LUMO energylevel if the first energy level is closer to the vacuum energylevel. Since ionization
`potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds
`to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LUMO energy level corresponds
`to an electron affinity (EA) having a smaller absolute value (an EAthat 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 energylevel appears closerto the top of such a diagram than a "lower"
`HOMO or LUMO energy level.
`[0013] As used herein, and as would be generally understood by one skilled in the art, a first work function is "greater
`than"or “higher than" a second workfunction if the first work function has a higher absolute value. Because work functions
`are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function is more
`negative. On a conventional energy level diagram, with the vacuum level at the top, a "higher" work function is illustrated
`as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy
`levels follow a different convention than work functions.
`
`[0014] More details on OLEDs, andthe definitions described above, can be found in US Pat. No. 7,279,704, whichis
`incorporated herein by referencein its entirety.
`
`SUMMARYOF THE INVENTION
`
`[0015] A compoundof Formula | is provided.
`
`Ar
`
`;
`
`Formula I
`
`Ar and Ar’ are independently selected from the group consisting of phenyl, biphenyl, naphthyl, dibenzothiophene, and
`dibenzofuran, which are optionally further substituted. Z is selected from Si and Ge. Lis a single bond or comprisesaryl,
`amino, or combinations thereof, and L is optionally further substituted.
`[0016] Ais agroup directly bonded to Z and is selected from the group consisting of dibenzofuran, dibenzothiophene,
`azadibenzofuran, azadibenzothiophene, dibenzoselenophene, azadibenzoselenophene, and combinations thereof,
`which are optionally further substituted with at least one group selected from the group consisting of hydrogen, deuterium,
`halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, arylthio, arylseleno, pyridine, triazine, imidazole, benzimida-
`zole, nitrile, isonitrile, and combinations thereof, and wherein the substitution is optionally fused to the group directly
`bondedto Z.
`
`B contains a group selected from the group consisting of carbazole, azacarbazole, and combinations thereof,
`[0017]
`which are optionally further substituted with at least one group selected from the group consisting of hydrogen, deuterium,
`halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,
`aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and com-
`binations thereof, and wherein the substitution is optionally fused to the carbazole or azacarbazole group.
`[0018]
`In one aspect, A is selected from the group consisting of:
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`5S
`
`—X
`2 4
`Xa
`|
`X4
`
`Xg~
`=.oo
`\ oe
`Xs
`
`Y;
`
`weeXo
`
`Y4
`
`/
`
`x
`
`Sx
`
`

`

`EP 2 551 932 A2
`
`ys
`—
`
`\
`X10
`
`Y4
`
`/
`
`Xe
`x
`-Be
`=x 7
`xy
`
`,
`
`
`
`/
`
`Xp
`Xa,
`/
`Se
`
`Zs
`=
`
`\
`“
`
`Yo
`
`Y¥
`
`‘
`
`/
`
`pie
`Xa
`NS
`ara) XS
`X=Xa
`ff
`™ ekg
`'
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`5S
`
`sok,
`
`Y, and Y» are independently selected from the group consisting of O, S, and Se, X, to X49 are independently selected
`from the group consisting of CR’ and N, and wherein each benzo ring contains at most one N. R’ is selected from the
`group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, arylthio, arylseleno,
`pyridine, triazine, imidazole, benzimidazole, nitrile, isonitrile, and combinations thereof. R is selected from the group
`consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryl, heteroaryl, aryloxy, amino,
`and combinations thereof.
`
`

`

`[0019]
`
`In one aspect, L is selected from the group consisting of:
`
`EP 2 551 932 A2
`
`
`
`10
`
`15
`
`20
`
`25
`
`In one aspect, L is a single bond. In another aspect, L contains at least one phenyl bonded directly to Z.
`[0020]
`In one aspect, Ar and Ar’are phenyl. In another aspect, Ar, Ar are independently substituted with at least one
`[0021]
`group selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,
`aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,
`nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
`[0022]
`In one aspect, the compound is selected from the group consisting of Compound 1 - Compound 11.
`
`[0023]Afirst device is provided. In one aspect, the first device comprises an organic light-emitting device, further
`30
`comprising an anode, a cathode, and an organic layer, disposed between the anode and the cathode, comprising a
`compound having the formula:
`
`35
`
`40
`
`45
`
`50
`
`5S
`
`Ar
`
`;
`
`Formula I.
`
`Ar and Ar’ are independently selected from the group consisting of phenyl, biphenyl, napthyl, dibenzothiophene, and
`dibenzofuran, which are optionally further substituted. Z is selected from Si and Ge. Lis a single bond or comprises aryl,
`amino, or combinations thereof, and L is optionally further substituted.
`[0024] Ais agroup directly bonded to Z and is selected from the group consisting of dibenzofuran, dibenzothiophene,
`azadibenzofuran, azadibenzothiophene, dibenzoselenophene, azadibenzoselenophene, and combinations thereof,
`which are optionally further substituted with at least one group selected from the group consisting of hydrogen, deuterium,
`halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, arylthio, arylseleno, pyridine, triazine, imidazole, benzimida-
`zole, nitrile, isonitrile, and combinations thereof, and wherein the substitution is optionally fused to the group directly
`bonded to Z.
`
`B contains a group selected from the group consisting of carbazole, azacarbazole, and combinations thereof,
`[0025]
`which are optionally further substituted with at least one group selected from the group consisting of hydrogen, deuterium,
`halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,
`aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and com-
`binations thereof, and wherein the substitution is optionally fused to the carbazole or azacarbazole group.
`[0026]
`Inone aspect, the organic layer is an emissive layer and the compound of Formula | is a host. In another aspect,
`the organic layer further comprises an emissive dopant. In one aspect, the emissive dopant is a transition metal complex
`having at least one ligand selected from the group consisting of:
`
`

`

`EP 2 551 932 A2
`
`—
`
`“\
`
`Ra
`
`/
`
`.
`
`~
`
`N
`
`Se -
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`5S
`
`

`

`EP 2 551 932 A2
`
`mE) “ PY " Rc WN
`WA. WA
`NOM
`NT
`SN
`>>
`Nn
`Nv
`
`ae
`
`Ry"
`
`Ry”
`
`Re,
`
`Re
`
`Re
`
`wherein R,, R,, and R, can represent mono, di, tri or tetra substitutions.
`[0027] R,, R,, and R, are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl,
`cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,
`acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof,
`and wherein two adjacent substituents of R,, R,, and R, are optionally joined to form a fused ring.
`[0028]
`In one aspect the emissive dopant has the formula
`
`HP)
`
`10
`
`15
`
`20
`
`25
`
`30
`
`D is a 5- or 6-membered carbocyclic or heterocyclic ring and R,, Rj, and R3 independently represent mono, di, tri or
`tetra substitution. Each of R;, Ro, and R3 are independently selected from the group consisting of hydrogen, deuterium,
`halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,
`aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and com-
`binations thereof. X-Y represents anotherligand, andnis 1, 2, or 3. Ry can be optionally linked to ring D.
`35
`[0029]
`In another aspect, the device further comprises a second organic layer that is a non-emissive layer and the
`compound having Formula | is a material in the second organic layer.
`[0030]
`In one aspect, the second organic layer is a blocking layer and the compound having Formula | is a blocking
`material in the second organic layer.
`[0031]
`In one aspect, the second organic layer is an electron transporting layer and the compound having the Formula
`| is an electron transporting material in the second organic layer.
`[0032]
`In one aspect, the first device is a consumer product. In another aspect, the first device is an organic light-
`emitting device.
`
`40
`
`45
`
`50
`
`5S
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0033]
`[0034]
`[0035]
`[0036]
`
`FIG. 1 shows an organic light-emitting device.
`FIG. 2 showsan inverted organic light-emitting device that does not have a separate electron transport layer.
`FIG. 3 shows a compound of Formula I.
`FIG. 4 shows a sample OLED device structure incorporating compounds of Formula I.
`
`DETAILED DESCRIPTION
`
`[0037] Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an
`anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the
`organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an
`electron and hole localize on the same molecule, an "exciton," which is a localized electron-hole pair having an excited
`energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the
`exciton may be localized on an excimeror an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also
`
`

`

`EP 2 551 932 A2
`
`occur, but are generally considered undesirable.
`[0038]
`The initial OLEDs used emissive molecules that emitted light from their singlet states (“fluorescence”) as dis-
`closed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by referencein its entirety. Fluorescent emission
`generally occurs in a time frame of less than 10 nanoseconds.
`[0039] More recently, OLEDs having emissive materials that emit light from triplet states ("phosphorescence") have
`been demonstrated. Baldo etal., "Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,"
`Nature, vol. 395, 151-154, 1998; ("Baldo-I") and Baldo et al., "Very high-efficiency green organic light-emitting devices
`based on electrophosphorescence," Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) ("Baldo-II"), which are incorporated by
`referencein their entireties. Phosphorescenceis described in more detail in US Pat. No. 7,279,704 at cols. 5-6, which
`are incorporated by reference.
`[0040]
`FIG. 1 shows an organic light emitting device 100. The figures are not necessarily drawn to scale. Device 100
`mayinclude a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking
`layer 130, an emissive layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer
`150, a protective layer 155, and a cathode 160. Cathode 160 is a compound cathode having a first conductive layer 162
`and a second conductive layer 164. Device 100 may be fabricated by depositing the layers described, in order. The
`properties and functions of these various layers, as well as example materials, are described in more detail in US
`7,279,704 at cols. 6-10, which are incorporated by reference.
`[0041] More examplesfor each of these layers are available. For example, a flexible and transparent substrate-anode
`combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by referencein its entirety. An example of a
`p-doped hole transport layer is m-MTDATA doped with F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S.
`Patent Application Publication No. 2003/0230980, which is incorporated by referencein its entirety. Examples of emissive
`and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in
`its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed
`in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by referencein its entirety. U.S. Pat.
`Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes
`including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-
`conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat.
`No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their
`entireties. Examplesof injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is
`incorporated by referencein its entirety. A description of protective layers may be found in U.S. Patent Application
`Publication No. 2004/0174116, which is incorporated by referencein its entirety.
`[0042]
`FIG. 2 showsan inverted OLED 200. The device includes a substrate 210, a cathode 215, an emissive layer
`220, a hole transport layer 225, and an anode 230. Device 200 maybe fabricated by depositing the layers described,
`in order. Because the most common OLED configuration has a cathode disposed over the anode, and device 200 has
`cathode 215 disposed under anode 230, device 200 may bereferred to as an "inverted" OLED. Materials similar to those
`described with respect to device 100 may be used in the corresponding layers of device 200. FIG. 2 provides one
`example of how some layers may be omitted from the structure of device 100.
`[0043] The simple layered structure illustrated in FIGS. 1 and 2 is provided by way of non-limiting example, and it is
`understood that embodiments of the invention may be used in connection with a wide variety of other structures. The
`specific materials and structures described are exemplary in nature, and other materials and structures may be used.
`Functional OLEDs may be achieved by combining the various layers described in different ways, or layers may be
`omitted entirely, based on design, performance, and cost factors. Other layers not specifically described may also be
`included. Materials other than those specifically described may be used. Although many of the examples provided herein
`describe various layers as comprising a single material, it is understood that combinations of materials, such as a mixture
`of host and dopant, or more generally a mixture, may be used. Also, the layers may have various sublayers. The names
`given to the various layers herein are not intended to bestrictly limiting. For example, in device 200, hole transport layer
`225 transports holes and injects holes into emissive layer 220, and may be described as a hole transport layer or a hole
`injection layer. Inone embodiment, an OLED maybe described as having an “organic layer" disposed between a cathode
`and an anode. This organic layer may comprise a single layer, or may further comprise multiple layers of different organic
`materials as described, for example, with respect to FIGS. 1 and 2.
`[0044]
`Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric
`materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in
`its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may bestacked, for
`example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by referencein its entirety. The
`OLED structure may deviate from the simple layered structureillustrated in FIGS. 1 and 2. For example, the substrate
`may include an angled reflective surface to improve out-coupling, such as a mesa structure as described in U.S. Pat.
`No. 6,091,195 to Forrest et al., and/or a pit structure as described in U.S. Pat. No. 5,834,893 to Bulovic et al., which are
`incorporated by reference in their entireties.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`5S
`
`

`

`EP 2 551 932 A2
`
`[0045] Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable
`method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat.
`Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition
`(OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrestet al., which is incorporated by referencein its entirety,
`and deposition by organic vapor jet printing (OVJP), such as described in U.S. patent application Ser. No. 10/233,470,
`which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other
`solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For
`the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through
`a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference
`in their entireties, and patterning associated with some of the deposition methods such as ink-jet and OVJD. Other
`methods mayalso be used. The materials to be deposited may be modified to make them compatible with a particular
`deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably
`containing at least 3 carbons, may be used in small molecules to enhancetheir ability to undergo solution processing.
`Substituents having 20 carbons or more may be used, and 3-20 carbons is a preferred range. Materials with asymmetric
`structures may havebetter solution processibility than those having symmetric structures, because asymmetric materials
`may have a lowertendencyto recrystallize. Dendrimer substituents may be used to enhancethe ability of small molecules
`to undergo solution processing.
`[0046] Devices fabricated in accordance with embodiments of the invention may be incorporated into a wide variety
`of consumerproducts, including flat panel displays, computer monitors, televisions, billboards, lights for interior or exterior
`illumination and/or signaling, heads up displays, fully transparent displays, flexible displays, laser printers, telephones,
`cell phones, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, micro-
`displays, vehicles, a large area wall, theater or stadium screen, or a sign. Various control mechanisms may be used to
`control devices fabricated in accordancewith the present invention, including passive matrix and active matrix. Many of
`the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees
`C., and more preferably at room temperature (20-25 degreesC.).
`[0047] The materials and structures described herein may have applications in devices other than OLEDs. For example,
`other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and
`structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.
`[0048] The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl, heterocyclic group, aryl, aromatic group,
`and heteroaryl are known to the art, and are defined in US 7,279,704 at cols. 31-32, which are incorporated herein by
`reference.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`[0049] A compoundof Formula|is provided.
`
`35
`
`Ar
`
`2
`
`Formula I
`
`40
`
`Ar and Ar’ are independently selected from the group consisting of phenyl, biphenyl, naphthyl, dibenzothiophene, and
`dibenzofuran, which are optionally further substituted. Z is selected from Si and Ge. Lis a single bond or comprisesaryl,
`amino, or combinations thereof, andLis optionally further substituted.
`[0050] Ais agroup directly bonded to Z and is selected from the group consisting of dibenzofuran, dibenzothiophene,
`azadibenzofuran, azadibenzothiophene, dibenzoselenophene, azadibenzoselenophene, and combinations thereof,
`which are optionally further substituted with at least one group selected from the group consisting of hydrogen, deuterium,
`halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, arylthio, arylseleno, pyridine, triazine, imidazole, benzimida-
`zole, nitrile, isonitrile, and combinations thereof, and wherein the substitution is optionally fused to the group directly
`bonded to Z.
`
`45
`
`50
`
`5S
`
`B contains a group selected from the group consisting of carbazole, azacarbazole, and combinations thereof,
`[0051]
`which are optionally further substituted with at least one group selected from the group consisting of hydrogen, deuterium,
`halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,
`aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and com-
`binations thereof, and wherein the substitution is optionally fused to the carbazole or azacarbazole group.
`[0052] An "aryl" group is an aromatic all carbon group, which can contain one or more fusedrings within it. Merely by
`way of example, and without any limitation, exemplary aryl groups can be phenyl, naphthalene, phenanthrene, coran-
`nulene, etc. A"heteroaryl" group is an "aryl" group containing at least one heteroatom. Merely by way of example, and
`without any limitation, exemplary heteroaryl groups can be pyridine, quinoline, phenanthroline, azacorannulene, etc.
`Both "aryl" and "heteroaryl" groups can have multiple attachment points connecting them to other fragments.
`[0053]
`In one embodiment, A is selected from the group consisting of:
`
`

`

`EP 2 551 932 A2
`
`S
`
`7
`xe
`
`MOEKe
`
`45
`
`rs,
`Xa
`ae Yo
`i
`|
`¥,
`x
`Y4
`2
`SPT TO ONS:
`
`Xx,
`
`XH Kp
`
`pe
`Keys.
`wok
`ee,
`XS
`
`"
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`R~N
`
`
`
`Y, and Y5 are independently selected from the group consisting of O, S, and Se, X, to X49 are independently selected
`from the group consisting of CR’ and N, and wherein each heteroaromatic ring contains at most one N. R’ is selected
`
`10
`
`

`

`EP 2 551 932 A2
`
`from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, arylthio,
`arylseleno, pyridine, triazine, imidazole, benzimidazole, nitrile, isonitrile, and combinations thereof. R is selected from
`the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryl, heteroaryl
`aryloxy, amino, and combinations thereof. The dashed lines in the chemical structures disclosed herein represent a
`bond through any position on that group capable of forming a single bond with another atom.
`[0054]
`In some embodiments, the A group serves as an electron transporter and the linker unit (L) and the B group
`serve as the hole transporter.
`[0055]
`It is to be understood that when a molecular fragment is described as being a substituent or otherwise attached
`to another moiety, its name may be written as if it were a fragment (e.g. naphthyl, dibenzofuryl) or as if it were the whole
`molecule (e.g. naphthalene, dibenzofuran). As used herein, these different waysof designating a substituent or attached
`fragment are considered to be equivalent.
`[0056] As used herein, fragments containing the following structure:
`
`Ag
`&
`fT
`BA
`Ag
`
`x
`
`\
`
`Asp,
`3
`“YsAg
`Ag
`
`are called DBX groups, i.e. dibenzo X, where X is any of the atoms or groups described herein. In the DBX group, A,-Ag
`can comprise carbon or nitrogen.
`[0057]
`In one embodiment, L is selected from the group consisting of:
`
`
`
`[0058]
`to Z.
`
`In one embodiment, L is a single bond. In another embodiment, L contains at least one phenyl! bonded directly
`
`In one embodiment, Ar and Arare phenyl. In another embodiment, Ar, Ar are independently substituted with
`[0059]
`at least one group selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl,
`arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, car-
`boxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
`[0060] The novel compounds of Formula! disclosed herein contain of two different moieties, groups A and B, connected
`with an arylsilane or aryl germane spacer, resulting in an asymmetric structure. By “asymmetric”it is meant that groups
`A and B, as described above, have different structures. The compounds of Formula | have a number of advantageous
`properties when used in OLED devices. Firstly, inclusion of two distinct moieties allows fine-tuning the energy levels of
`the resultant compound, which may facilitate charge injection from adjacent layers and modulate charge trapping by the
`emitter dopants. Secondly, the two different moieties can be independently selected to have as electron and/or hole
`transport properties, yielding compounds with bipolar charge transport characteristics. These characteristics may not
`only suppressesoperation voltage but also balance electron and hole fluxes to achieve an extended charge recombination
`
`11
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`5S
`
`

`

`EP 2 551 932 A2
`
`zone. Thirdly, the arylsilane and arylgermane spacers break the conjugation between groups A and B, retaining high
`triplet energy for the entire molecule, and thus effectively reducing quenching.
`[0061] The compounds of Formula | have additional advantages over known symmetric analogs because compounds
`of Formula | are less prone to crystallization. As a result, compounds of Formula | possess improvedfilm uniformity,
`which, without being bound by theory, is believed to be a result of reduction in phase separation between the emitters
`and host mat