(223 INTERNATIONAL APPLICATION PURLISRED UNDER THE PATENT CODPERATION TREATY (PCT}
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`(43) International Publication Date
`T
`WO 03/040287 Al
`iS May 2003 (15.05.2003)
`PC
`
`
`(74) Agent: WANG, Chen: E. 1. Du Pont De Nemours And
`Compery, Legal Parent Records Center, 4417 Lancaster
`Pike, Wilmington, DE 10805 (US).
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`Si, SK, SL. 1, TM, TN, TR, TT, TS, UA, UG, US, UZ,
`Ve, YN, YU, ZA, 2M, 2,
`
`(84) Designated States (regionaftt ARIPO patent (OH, GM,
`RE, LS, MW, M%, SD, SL, SZ, TH, UG, ZAM, ZW
`Eurasian patent (AM, A¥, BY, RG, R24, MB, RU, TS, TM),
`Buropean patent (AT, BE, 8G, CH, CY, C2, DR, DK, BR,
`BS, Hi, PR, OB, GR, TB, PS, LU, MC, NL, PT, SH, SR,
`TR}, OAPT patent (BE, BI, CE CG, CL CM, GA, GN, GQ,
`GW, ML, MR, NE, SN, TD, TQ).
`
`Published:
`a with international search report
`~-
` befbre the expiration af the time limit for amending the
`claims and to be republished in the event ofrecep? of
`aeerinarns
`
`For nvo-letter codes and other abbreviations, refer to the “Catid-
`anos Notes on Codes andAbbreviations” appearing at the begin-
`ning ofeach regudar issue ofthe PCT Gazette.
`
`HOSB 34/14, HOLL 3120
`
`(21) International Application Number;
`
` PCT/U80235430
`
`(22} International Filing Bate:
`4 November 2002 (04.11.2002)
`
`(25) Fillug Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`G8} Priority Data:
`60/347,016
`
`7 November 2001 (07.11.2061)
`
`US
`
`(7) Applicant gor all designated Statex except USh B.D
`PONT DE NEMOURS AND COMPANY [USAUST: 1007
`Market Street, Wilington, DS 19898 (08).
`
`72} Loventars; and
`LECLODX,
`78) Javentars/Applicants Gor US only:
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`DE [9809 GS). PETROV, Viacheslay, A, [RUAISh 2
`Cappa Court, Hockessin, DE 19707 (US). SIMETH, Erie,
`Maurice (US/US), 103 West Sutton Pisce, Wilmington,
`DE 19816 CUS. WANG, Ving [USAIS) 4010 Gran.
`mount Read, Wilmington, DE 19870 (55).
`
`t {
`
`($4) Tile: ELECTROLUMINESCENT PLATINUM COMPOUNDS AND DEVICES MADE WITH SUCH COMPOUNDS
`
`(87) Abstract: The present invention js severally directed to electroluminesecent P(E) complexes whieh have emission maxima
`acres the visible spectrum, and devices that are made with the PD complexes.
`
`I Le
`WO03/040257Al
`
`

`

`WO 03040287
`
`POTUS8082/353430
`
`TITLE
`
`ELECTROLUMINESCENT PLATINUM COMPOUNDS
`
`It
`
`AND DEVICES MADE WITH SUCH COMPOUNDS
`BACKGROUND OF THE INVENTION
`Figid of the Invention
`This invention relates to slectrolurninescent complexes of
`platinum(il) which have emission spectra across the visible spectrum.
`aiso relates to electronic devices in which the active layer includes an
`electroluminescent Ptctl) complex.
`
`Descriptionof the Related Art
`Organic electronic devices that emit light, such as light-emitting
`diodes that make up displays, are present in many different kinds of
`electronic equipment.
`In all such devices, an organic light-emitting layeris
`sandwiched between two electrical contact layers. Atleast one of the
`electrical contact layers is light-transmitting so that light can pass through
`the electrical contactlayer. The organic layer emits light through the light-
`transmitting electrical contact layer upon application of electricity across
`the electrical contact layers.
`It is well known te useorganic electroluminescent compounds as
`the active componentin light-emitting diodes. Simple organic molecules
`such as anthracene, thiadiazole derivatives, and coumarin derivatives are
`known to show electroluminescence. Semiconductive conjugated
`polymers have also been used as electroluminescent components, as has
`been disclosed in, for example, Friend et al., US. Patent 5,247,190,
`Heegeret al., U.S. Patent 5,408,109, and Nakano et al., Published
`European Patent Application 443 861. Gomplexes of 8~-hydroxyquinolate
`with trivalent metal ions, particularly aluminum, have been extensively
`used as electroluminescent components, as has been disclosedin, for
`example, Tang et al, U.S. Patent 5,552,678.
`Electroluminescent devices withan light-emitting layer of polymer
`doped with organometallic complexes of platinum have been disclosed by
`Burrows and Thompson in published PCT applications WO 00/57675.
`However, there is a continuing need for efficient electroluminescent
`compounds which emit light across the visible spectrum.
`SUMMARY OF THE INVENTION
`The present invention is directed to a metal compiex having
`Formula f or Formuta H:
`
`id
`
`15
`
`2u
`
`28
`
`30
`
`

`

`WO 8340287
`
`PCTIUSO2/95430
`
`PHL?
`
`PtLiss4
`
`{)
`
`(fl)
`Where:
`
`10
`
`15
`
`20
`
`in Formula i:
`i? is a monoanionic bidentate ligand;
`in Formuta tf:
`L> is a monodentate ligand; and
`L* is a monodentate phosphineligand:
`inFormulae|andtk:
`L' is selected fram Formula fH, shown in Figure 1, and
`Formula Vil, shown in Figure 2, where:
`in Formulae {ll and Vil:
`&' through &* are the sameordifferent at each occurrence and
`are CR’or N;
`R? is the same ordifferent at each occurrence and is selected
`from H, D, Ca(H+Flanet, F, OCn(H+Fens, OCF2Y, SR, and
`N(R*}a, or adjacent R’? groupscan join to form a 5- or 6-
`membered ring:
`Ri is H, Gatland;
`Yis H, Ci, or Br
`nis an integer from 1 through 12;
`in Formula Nk:
`Ais Nor SR®,
`R' is the same ordifferent at each occurrence and is selected
`from D, Cn(H+Fane, F, OCnfH+F}ones, OCF, SR? and
`N(R), or adjacent R groups can join to form a 5- or 6-
`membered ring:
`ois 0, 1 or 2; and
`inFormuiaVit:
`R* through R’are the sameor differant at each occurrence and
`are selected from H, 0, Ca(H+Fhanss, F, OCn(H+Font,
`OCF2Y, SR*, and N{R°)2,0r adjacent R groups can join to
`forma 5- or 8-membered ring.
`
`25
`
`30
`
`SadeLea
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`

`WO 03/040257
`
`PCTOS0233436
`
`In another embodiment, the present invention is directed to an
`organic electronic device having at least one active layer cornprising the
`above metal complex, or combinations of the above metal cornplexes.
`As used herein, the term “compound”ts intended to mean an
`electrically uncharged substance made up of molecules that further
`consist of atoms, wherein the atoms cannot be separated by physical
`means. The term “ligand” is intended to mean a molecule, ion, or atom
`that is attached to the coordination sphere of a metallic ion. The letter “L”
`is used fo designate a ligand having a nominal (-1) charge formed from the
`neutral parent compound, “HL”, by the loss of a hydrogen ion. The term
`“somplex”, when used as a noun, is intended to mean a compound having
`at least one metallic ion and at least one ligand. The term “6-dicarbonyl’is
`intended to meana neutral compound in which two ketone groups are
`present, separated by a CHR group. The term “B-enolate"is intended to
`mean the anionic form of the 8-dicarbanyl in which the H fram the CHR
`group betweenthe two carbonyl groups has been abstracted. The term
`“group” is intended fo mean a part of a compound, such as a substituentin
`an organic compound or a ligand in a complex. The phrase “adjacent to,”
`when used to refer to layers in a device, does not necessarily mean that
`one layer is immediately next to another layer. On the other hand, the
`phrase “adjacent R groups,” is used to refer to R groups that are next to
`each other in a chemical formula (.¢., R groups that are on atoms joined
`by a bond). The term “photoactive” refers to any material that exhibits
`electroluminescence and/or photosensitivity.
`In addition, the IUPAC
`numbering system is used throughout, where the groups from the Periodic
`Table are numbered from left to right as 1 through18 (CRC Handbookof
`Chemistry and Physics, 81°Edition, 2000).
`In the Formulae and
`Equations, the letters A, £, L,.R, Q, Y and Z are used to designate atoms
`cr groups which are defined within. All other letters are used to designate
`conventional atomic symbols. The term “(H+F)" is intended to meanall
`combinations of hydrogen and fluorine, including completely
`hydrogenated, partially fluorinated or perfluorinated substituents. By
`*ernission maximum”is meant the wavelength, in nanometers, at which
`the maximurn intensity of electroluminescence is obtained.
`Electroluminescence is generally measured in a diode structure, In which
`the material fo be tested is sandwiched between twoelectrical contact
`layers and a voltage is applied. Thelight intensity and wavelength can be
`measured, for example, by a photodiode and a spectrograph, respectively.
`3
`
`10
`
`1S
`
`20
`
`2
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`30
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`35
`
`

`

`WO 039/040257
`
`POT/US02/35430
`
`DESCRIPTION OF THE DRAWINGS
`Figure 1 shows Formulae [if through Vil for the ligand 1’in the
`metal complex of the invention.
`Figure 2 shows Formulae Vil through X for the ligand L’in the
`metal complex of the invention.
`Figure 3 showsFormula X]for the §-enolate ligand and Formula Xit
`for the phosphinoalkoxide ligand useful in the Invention.
`Figure 4 shows Equation (1) for synthesis of the parent ligand
`compounds, HL’, useful in the invention.
`Figure 5 shows the formulae of L° ligands useful in the invention.
`Figures 6A and 6B show the formulaeof L‘ ligands useful in the
`invention.
`Figure 7 shows Equations (2) and (3} for forming complexes of
`Formula |, useful in the invention.
`Figure 8 shows Equation (4) for forming complexes of Formula {l,
`useful in the invention.
`
`Figure 9 is a schematic diagram of a light-emitting device (LED).
`Figure 10 is a schematic diagram of an LED testing apparatus.
`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
`The metal complexes of the invention have Formula f or Formula i,
`given above, and are referred to as cyclometallated complexes. The
`platinurn is in the +2 oxidation state and is fetracoordinate. The complex
`in Formula | is a cyclometailated complex with an additional monoanionic
`bidentate ligand, L7. The complex in Formula I! is a cyclometallated
`complex with two additional monodentate ligands, L? and L*. The
`preferred cyclometallated complexes are neutral and non-ionic, and can
`be sublimed intact. Thin films of these materials obtained via vacuum
`deposition exhibit good to excellent electroluminescent properties.
`The complexesof the invention have emission spectra with maxima
`ranging from the blue region through the red region. The color of emission
`oan be tuned by selection of the appropriate ligands, as discussed below.
`Ligand L' having Formula Ill, shown In Figure 1, is derived from a
`parent compound in which a thienyl group @when A is S} or pyrrolyl group
`(when A is NR®) is bonded to a 6-membered ring having at feast one
`nitrogen.it is preferred that a is 0. When A is NR’°,it is preferred that R*is
`CHs.
`
`10
`
`15
`
`20
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`30
`
`35
`
`

`

`WO O3/040287
`
`PCTSS54}
`
`19
`
`i5
`
`20
`
`When all E are CR’, and the R® groups are individual substituents
`that are not joined to form a ring, the ligands are derived from thieny!- and
`pyrrolyl-pyridine parent compounds.
`[t is preferred that there is at least
`one deuterium or fluorine-containing substituent on the pyridine ring, more
`preferably at the E' and E° positions. Preferred fluorine-containing
`substituents are F and CF.
`Other types of ligands having the general structure of Formuia ll,
`have quinoline or isoquinoline groupsin place of pyridine, as shown in
`Formulae (V through Vi of Figure t. Ligand L’ having Formula IV, shown
`in Figure 1, is derived from a thienyl- or a pyrrolyl-quinoline parent
`compound. Ligand L* having Formula V or Formula VI, shown in Figure 4,
`is derived from a thienyl- or a pyrroly-isoquinoline parent compound.
`In
`these figures § is 0 or an integer from 1 through 4, R'a, and A are as
`defined above in Formulalil. It is preferred that at least one substituent on
`the quinoline or isoquinoline ring is selected from D, Cn{Fpan. F,
`OCa(Phenez, and OCF2Y.
`Ligand L' having Formula Vil, shown in Figure 2, is derived fram a
`parent compoundin which a phenyl group is bonded to a 6-membered
`ring having at least one nitrogen.
`Whenall £ are CR’, and the R? groupsare individual substituents
`that are not joined to form a ring, the ligands are derived from phenyl-
`pyridine parent compounds. {tis preferred that there is at least one
`deuterium or fluorine-containing substituent on the ligand, more preferably
`at the E' and E* positions. Preferred fluorine-containing substituents are F
`and GF.
`Other types of ligands having the general structure of Formula Vil,
`have quinoline or isoquinoline groups in place of pyridine, as shown in
`Formulae Vill through X, of Figure 2. Ligand L' having Formula Vill,
`shown in Figure 2, is derived from a phenyl-quinoline parent compound.
`Ligand L' having Formula 1X or Formula X, shown in Figure 2, is derived
`from a phenyl-isoquinoline parent compound.
`In these figures 4 is 0 or an
`integer from 1 through 4, and R' and o are as defined above in Formula
`iH, and R*through R’ are as defined above in Formula Vii. [tis preferred
`that at feast one substituent on the ligand is selected from D, Ca(Fjanes, F,
`OCA(Fener, and OCFRY.
`
`The parent ligand compounds, HL', can generally be prepared by
`standard palladium-catalyzed Suzuki or Kumada cross-coupling of the
`5
`
`

`

`WO 03/080237
`
`PCEAISOZ/33430
`
`corresponding heterocyclic aryi chloride with an organoboronic acid or
`arganomagnesium reagent, as describedin, for example, O. Lohse,
`P.Thevenin, E. Waldvogel Synlett, 1999, 45-48. This reaction is illustrated
`for a phenyl-isoquinoline, where R and R’ represent substituents, in
`Equation (1)in Figure 4. The partially or fully deuterated ligand parent
`compoundscan generally be prepared bythe same coupling methads
`using deuterated components. The deuterated components are often
`commercially available, or can be made by known synthetic methods.
`The L? ligand is a monoanionic bidentate ligand.
`In general these
`ligands have N, ©, P, or S as coordinating atoms and form 5- or 6-
`membered rings when coordinated to the platinum. Suitable coordinating
`groups include amina, imino, amido, alkoxide, carboxylate, phosphino,
`thiolate, and the like. Examples of suitable parent compounds for these
`ligands include 6-dicarbonyls (8-enolate ligands), and their N and S
`analogs; amino carboxylic acids (aminocarboxyilate ligands); pyridine
`carboxylic acids (iminocarboxylate ligands); salicylic acid derivatives
`(salicylate ligands}; hydroxyquinolines (hydroxyquinolinate ligands) and
`their S analogs; and diaryiphosphinoalkanois (diaryiphosphinoalkoxide
`ligands).
`The 8-enolate ligands generally have Formula Xi shownin Figure 3,
`where R° is the sameor different at each occurrence. The R® groups can
`be hydrogen, halogen, substituted or unsubstituted alkyf, aryl, alkylary! or
`heterocyclic groups. Adjacent R® groups can be joined to form five- and
`six-memberedrings, which can be substituted. Preferred R° groups are
`selected from H, F, Cp(H+Flone4, -CgHs, -C4H3S, and -C4H30, where n
`is an integer from 1 through 12, preferably from 1 {fo 6,
`Examples of suitable 8-enolate ligands include the compounds
`listed below. The abbreviation for the B-enolate form is given below in
`brackets.
`
`10
`
`30
`
`35
`
`{(FOD]
`
`2,4-pentanedionate facac]
`4,3-diphenyl-1,3-propanedionate [Di]
`2,2,6,6-tetramethyl-3,5-heptanedionate [TMH]
`4,4,4-tnfluoro-1-(2-thienyl)-1 ,3-butanedionate [TTFA
`7, 7-dimethyl-1,1,1,2,2,3,3-heptafiuoro-4,6-cctanedionate
`
`4,1,1,3,5,5,5-heptafluoro-2,4-pentanedionate [F7acac]
`1,1,7,5,5,5-hexaflouro-2,4-pentanedionate [F6acac}
`{-phenyl-3-methyl-4-/-butyryl-pyrazolinonate [FMBP]
`6
`
`

`

`WO 63/040287
`
`POTAUSO2/35430
`
`The 8-dicarbony! parent compounds, are generally available
`commercially. The parent compound 1,1,1,3,5,5,5-heptafiuoro-2,4-
`pentanediane, CF3aC(O}CFHC(O)CF3 , can be prepared using a two-step
`synthesis, based on the reaction of perflueropentene-2 with ammonia,
`follawed by a hydrolysis step. This compound should be stored and
`reacted under anyhydrous conditions as it is susceptible to hydrolysis.
`The hydroxyquinolinate ligands can be substituted with groups such
`as alkyl or alkoxy groups which may be partially or fully fluorinated.
`Examples of suitable hydroxyquinalinate ligands include (with abbreviation
`provided in brackets):
`8-hydroxyquinolinate [8hq}
`2-methyi-8-hydroxyquinalinate [Me-Shaq]
`10-hydroxybenzoaquinolinate [10-hbaq]
`The parent hydroxyquinoline compounds are generally available
`commercially.
`Phosphino alkoxide ligands generally have Formula All, shown in
`Figure 3, where
`R® canbe the sameordifferent at each occurrenceand is selected
`from Ca(H+Foq, and Ce(H+F)s,
`R' can be the sameordifferent at each occurrence andisselected
`from H and C.(H+F)an.4, and
`$ is 2 or 3,
`Examples of sultable phosphino alkoxide ligands include (with
`abbreviation provided in brackets):
`3-{diphenylphosphino)}-1-oxypropane [dppO]
`1,1-bis(trifluoromethy!)-2-(diphenyiphosphino)-ethoxide [timdpeO]
`Some of the parent phasphino alkanol compounds are available
`commercially, or can be prepared using known procedures, such as, for
`example, the procedure reported for timdpeO in inorg. Chem. 1988, v.24,
`p.36eo.
`The L? ligand is a monodentate ligand. Preferably this ligand is
`monoanionic. Such ligands can have O or § as coordinating atoms, with
`coordinating groups such as alkoxide, carboxylate, thiocarboxylate,
`dithiocarboxyiate, sulfonate, thiolate, carbamate, dithiocarbamate,
`thiocarbazone anions, sulfonamide anions, and the like.
`In some cases,
`ligands such as 8-enolates can act as monodentate ligands. The ° ligand
`can aiso be a coordinating anion such as halide, nitrate, sulfate,
`
`10
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`td A
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`35
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`

`

`WO U3/40287
`
`PCEUSOR356H)
`
`hexahaloantimonate, and the like. Examples of suitable L* ligands are
`shown in Figure 5.
`The L? figands are generally available commercially.
`The L? ligand is a monodentatephosphine ligand. Preferably,this
`ligand in non-ionic.The phosphine ligands can have Formula Xiil
`
`PArg
`
`(XH)
`
`10
`
`15
`
`20
`
`25
`
`30
`
`tas tab
`
`where Ar represents an aryl or heteroaryl group. The Ar group can be
`unsubstituted or substituted with alkyl, heteroalkyl, aryl, heteroaryl, halide,
`carboxyl, suifoxy!, or amino groups. Examples of suitable L? ligands are
`shown in Figures 6A and 6B, where the "Me" is used to designate a methyl!
`group in Formulae 6-3, 6-8, 6-8 of Figure 6A and Formulae 6-13, 6-16, 6-
`17, 8-18, 6-19, and 6-21 of Figure 6B. The L* phosphine ligands are
`generally available commercially.
`The calor of luminescence of the complexes of Formulae | and Hi, is
`largely determined by the choice of ligands, L', L?, L° and L*.
`In general,
`the color is shifted to longer wavelengths (“red-shifted”) when L' has
`Formula tH. The color is shifted to shorter wavelengths (‘blue-shifted’)
`when L' has Formula VIL The complex is also blue-shifted when the
`nitrogen-containing ring of the ligand has at least one substituent bonded
`through a heteroatom having non-bonding pi electrons, most preferably
`oxygen, or at least one substitufent capable of sigma electron donation,
`such as alkyl groups, and preferably methyl. However, exceptions to
`these general guidelines do occur.
`The luminescence efficiency of the complexes may be improved by
`using L' ligands in which some orall of the hydrogens have been replaced
`with deuterium.
`Complexes of Forrnula | are generally prepared from metal chioride
`salts by first forming the bridged chloride dimer. This reaction is illustrated
`for a thienyl-pyridine ligand in Equation (2), shown in Figure 7. Complexes
`of Formula | are then formed by adding a salt of the parent ligand
`compound, such as Nal”, to the bridged chloride dimer. This reaction is
`ilustrated using the sodium salt of a B-enolate ligand in Equation (3) in
`Figure 7. The salts of the parent ligand compounds can be made by any
`conventional methods, such as by the addition of sodium hydride to HL? in
`an inert solvent.
`
`

`

`WO 03/0402357
`
`POT/USOL35830
`
`Examples of metal complexes of the invention having Formula | are
`given in Table 1 below. At each occurrence, a and delta are zero.
`
`Table 1.
`
`A
`
`|
`
`Substituents
`
`rs .
`
`:
`|
`i
`¢
`N-CH, [E's P= Et=CH |
`
`lp i
`
`t
`|
`~saommnssnemnnnrrernrrntnnsd
`acac-
`
`
`
`acaCc
`
`xX |. [R®=CFs
`
`|
`
`acac
`
`acac
`
`|
`
`eo
`
`
`
`iy OCH;
`
`
`
`
`th oo.«ojkl=68=£*=CH |Vii | timdped
`
`
`
`
`
`= CF,
`
`E*= COCH,
`R° = CF,
`{pte ge =ft=CH
`E*= COCH;
`
`i
`4-1
`
`|
`
`Vi
`
`-
`
`TMH
`
`
`
`Ris F
`
`i ot
`an
`
`VHO
`
`of
`
`-
`
`= F=Et=CH
`
`Ria F
`lina
`
`

`

`PCEUS02/35430
`
`Substituents
`
`Ete Et = CH
`E? = COC{CH3) 3
`
`WO 03/0402357
`
`Complex
`
`|
`
`i
`
`Formula
`
`Rak
`
`Complexes of Formula ll are also generally prepared byfirst
`forming the bridged chloride dimer. To the dimeris then added the other
`two ligands, Preferably, L° is monoanionic and is added as the silversait,
` Agl*. 14 is addedas the neutralligand or, in the case of anionic ligands,
`as a salt such as Nal‘. The preferred reaction is illustrated for a bridged
`chioride dimer having a phenyl-pyridine ligand in Equation (4), shown in
`Figure 8.
`A combinatorial library of cornplexes having Formula fl was
`prepared where L' was selected from oneof the ligandsin Table 2 below,
`L° was selectedfrom the ligands shown in Figure 5, and L* was selected
`from the ligands shown in Figures GA and 6B,
`
`5
`
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`

`WO 03/640257
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`POT/US62/35430
`
`Table 2.
`
`
`
`gE’ =? = E*=CH
`ES=CCF,
`
`El=—*=E*=CH |
`
`
`| BE? = CCF;
`|
`
`E' = £°= E* = CH
`
`E* = COCHs
`
`LR=CF,
`
`
`
`
`Most of the complexes having ligand 2-a or 2-b have red to red-
`orange luminescence. Most of the complexes having ligands 2-c, 2-d, 2-e,
`or 2-f have blue or blue-green luminescence.
`Electronic Device
`The present invention alsa relates to an electronic device
`comprising at least one photoactive layer positioned between two
`electrical contact layers, wherein the at least one photoactive layer of the
`device includes the complex of the invention. As shown in Figure 9, a
`typical device 100 has an anode layer 110 and a cathode layer 150 and
`electroactive layers 120, 130 and optionally 140 between the anode 110
`and cathode 150. Adjacent to the ancede is a hole injection/transport layer
`120. Adjacent to the cathode is an optional layer 140 comprising an
`electron transport materiai, Between the hole injection/transport layer 120
`and the cathode (or optional electron transport layer) is the photoactive
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`layer 130. Layers 120, 130, and 140 are individually and collectively
`referred to as the active layers.
`Depending upon the application of the device 100, the photoactive
`layer 130 can be a light-emitting layer that is activated by an applied
`voltage (such as ina light-emitting diade or light-emitting electrochemical
`cell}, a layer of material that responds to radiant energy and generates a
`signal with or without an applied bias voltage (such as in a photodetector).
`Examples of photodetectors include photoconductive cells, photoresistors,
`photoswitches, phototransistors, and phototubes, and photovoltaic cells,
`as these terms are describe in Markus, John, Electronics and Nucleonics
`Dictionary, 470 and 476 (McGraw-Hill, Inc. 1966).
`The complexes of the invention are particularly useful as the active
`material in the emitting layer of an OLED, or as electron transport material
`in layer 140, Preferablythe platinum complexes of the invention are used
`as the light-emitting material in diodes. When used in layer 130, if has
`been found that the complexes of the invention do not need to be in a solid
`matrix diluent in order fo be effective. A layer that is greater than 20% by
`weight metal complex, based on the total weight of the layer, up to
`substantially100% by weight metal complex, can be used as the emitting
`layer. By “substantially 100%" # is meant that the metal complexis the
`only material in the layer, with the possible exception of impurities or
`adventitious byproducts from the process to form the layer. Additional
`materiais can be present in the emitting layer with the metal complex. For
`example, a fluorescent dye may be present to alter the color of emission.
`A diluent may also be added. Preferably, the diluent facilitates charge
`transport in the layer. The diluent can be a polymeric material, such as
`poly(N-viny! carbazole) and polysilane.
`It can also be a small molecule,
`such as 4,4’-N,N’-dicarbazole biphenylor tertiary aromatic amines. When
`a diluent is used, the metal complex is generally present in a small
`amount, usually less than 20% by weight, preferably less than 10% by
`weight, based on the total weight of the layer.
`One type of diluent which is useful with the platinum metal
`complexes of the invention, is a conjugated polymer in which the triplet
`excited state of the polymer is at a higher energy level than the triplet
`excited state of the platinum complex. Examples of suitable conjugated
`polymers include polyarylenevinylenes, polyfluorenes, polyoxadiazoles,
`polyanilines, polythiophenes, polypyridines, polyphenylenes, copolymers
`thereof, and combinations thereof. The conjugated polymer can be a
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`copolymer having non-conjugated portions of, for example, acrylic,
`methacrylic, or vinyl, monomeric units. Particularly useful are
`homopolymers and copolymers of fluorene and substituted fluorenes.
`in some cases the metal complexes of the invention may be
`present in more than one isomeric form, or mixtures of different complexes
`may be present. {t will be understood that in the above discussion of
`OLEDs, the term “the metal complex” Is intended to encompass mixtures
`of complexes and/or isomers.
`The device generally also includes a support (not shown) which can
`be adjacent to the anode or the cathode. Most frequently, the support is
`adjacent the anode. The supportcan be flexible or rigid, organic or
`inorganic. Generally, glass or flexible organic films are used as a support.
`The anode 110is an electrode that is particularly efficient for injecting or
`collecting positive charge carriers. The anodeis preferably made of
`materiais containing a metal, mixed metal, alloy, metal oxide or mixed-
`metal oxide. Suitable metals include the Group 11 metals, the metals in
`Groups 4, 5, and 6, and the Group 8-10 transition metals.
`if the anode is
`to be light-transmitting, mixed-metal oxides of Groups 12, 13 and 14
`metals, such as indium-tin-oxide, are generally used. The anode 110 may
`also comprise anorganic material such as polyaniline as described in
`“Flexible light-emitting diodes made from soluble conducting polymers,”
`Nature vol. 357, pp 477-478 (11 June 1992).
`The anode layer 110 is usually applied by a physical vapor
`deposition processor spin-cast process. The term “physical vapor
`deposition” refers to various deposition approaches carried out in vacuo.
`Thus, for example, physical vapor deposition includes all forms of
`sputtering, including jon beam sputtering, as well as all forms of vapor
`deposition such as e-beam evaporation and resistance evaporation. A
`specific form of physical vapor deposition which is useful is rf magnetron
`sputtering.
`There is generally a hole transport layer 120 adjacent the anode.
`Examples of hole transport materials for layer 120 have been summarized
`for example, in Kirk~-Othmer Encyclopedia of Chemical Technology, Fourth
`Edition, Vol. 18, p. 837-860, 1996, by Y. Wang. Both hole transporting
`molecules and polymers can be used. Commonly used hole transporting
`molecules, in addition to TPD and MPMP mentioned above,are:
`1, 1-bis[(di-4-tolylamino) phenyljcyclohexane (TAPC); N,N‘-bis{4-
`maethyiphenyl)-N,N'-bis(4-ethyipheny)-[1, 1-3, 3'-dimethyhbiphenyl]-4,4-
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`diamine (ETPD); tetrakis-(3-methyipheny!}-N,N,N’.N’-2,5-
`phenylenediamine (PDA); a-phenyl-4-N,N-diphenylaminostyrene (TPS):
`p-(diethylamino)benzaldehyde diphenylhydrazone (DEH); triphenylarnine
`(TPA), 1-phenyl-3-[p-(diethylamino)styryl}-$-[p-(diethyviamino)pheny!]
`pyrazoline (PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-y))cyclobutane
`(DCZB), N.N.N'N’-tetrakis(4-methylpheny!)-(1, 1'-bipheny))-4,4"-diamine
`(TTB); and porphyrinic compounds, such as copper phthalocyanine.
`‘Commonly used hole transporfing polymers are polyvinylcarbazole,
`(phenyimethy)polysilane, poly(3,4-ethylendioxythiaphene) (PEDOT), and
`polyaniline.
`it is also possible to obtain hole transporting polymers by
`doping hole transporting molecules such as those mentioned above into
`polymers such as polystyrene and polycarbonate,
`Optional layer 140 can function both to facilitate electron transport,
`and also serve as a buffer layer or anti-quenching layer to prevent
`quenchingreactions at layer interfaces. Preferably, this layer promotes
`electron mobility and reduces quenching reactions. Examples of electron
`transport materials for optional layer 140 include metal chelated oxinoid
`compounds, such astris(8-hydroxyquinolatojaluminum (Alq.);
`phenanthroline-based campounds, such as 2,9-dimethyl-4,7-diphenyi-
`+,10-phenanthroline (DDPA) or 4,7-diphenyl-1,10-phenanthroline (DPA),
`and azole compounds such as 2-(4-biphenylyl)-5-(4--butyiphenyl}-17,3,4-
`oxadiazole (PBD) and 3-(4-biphenyly))-4-phenyl-5-(4---butyiphenyl}- 1 ,2,4-
`triazole (TAZ).
`The cathode 150 is an electrode that is particularly efficient for
`injecting or collecting electrons or negative charge carriers. The cathode
`can be any metal or nonmetal having a lower work function than the first
`electrical contact layer (in this case, an anode). Materials for the second
`electrical contact layer can be selected frorn alkali metals of Group 1 (e.g.,
`Li, Cs), the Group 2 (alkaline earth) metals, the Group 12 metals, the
`lanthanides, and the actinides. Materials such as aluminum, indiurn,
`calcium, barium, samarium and magnesium, as well as.combinations, can
`be used.
`
`it is knownto have other layers in organic electronic devices. For
`example, there can be a layer (not shown) between the conductive
`polymer layer 120 and the active layer 130 to facilitate positive charge
`transport and/or band-gap matching of the layers, or to function as a
`protective layer. Similarly, there can be additional layers (not shown)
`between the active layer 130 and the cathode layer 150 fo facilitate
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`negative charge transport and/or band-gap matching betweenthelayers,
`or to function as a protective layer. Layers that are knownin the art can
`be used.
`in addition, any of the above-described layers can be made of
`two or morelayers. Alternatively, some orail of inorganic anode layer
`110, the conductive polymerlayer 120, the active layer 130, and cathode
`layer 150, may be surface treated to increase charge carrier transport
`efficiency. The choice of materials for each of the componentlayers is
`preferably determined by balancing the goais of providing a device with
`high device efficiency.
`it is understood that each functional layer may be made up of more
`than one layer.
`The device can be prepared by sequentially vapor depositing the
`individual layers on a suitable substrate. Substrates such as glass and
`polymeric films can be used. Conventional vapor deposition techniques
`can be used, such as thermal evaporation, chemical vapor deposition, and
`the like. Alternatively, the organic layers can be coated from solutions or
`dispersions in suitable solvents, using any conventional coating technique.
`In general, the different layers will have the following range of thicknesses:
`anode 110, 500-5000A, preferably 1000-20004;hole transport layer 120,
`50-2500A, preferably 200-2000A;light-emitting layer 130, 10-1000 A,
`preferably 100-800A;:optional electron transport layer 140, 50-1000A,
`preferably 100-800A; cathode 150, 200-10,000A, preferably 300-5000A.
`The location of the electron-hole recombination zone in the device, and
`thus the emission spectrum of the device, is affected by the relative
`thickness of each layer. For examples, when an emitter, such as Algs is
`used as the electron transport layer, the electron-hole recombination zone
`can be in the Alqs layer. The emission would then be that of Aigs, and not
`the desired sharp lanthanide emission. Thus the thickness of the electron-
`transport layer must be chosen so that the electron-hole recombination
`zone is in the light-emitting layer. The desired ratio of layer thicknesses
`will depend on the exact nature of the materials used.
`It is understood thatthe efficiency of the devices of the invention
`made with metal complexes, can be further improved by optimizing the
`other layers in the device. For example, more efficient cathodes such as
`Ca, Ba, Mg/Ag, or LIF/Al can be used. Shaped substrates and novel hole
`transport materials that result in a reduction in operating voltage or
`increase quantum efficiency are also applicable. Additional layers can
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`also be added to tailor the eneray levels of the various layers and facilitate
`electroluminescence.