Europaisches Patentam?
`
`vl Office curopéen des brevets
`{19} ) | European PatentOffice
`
`ay
`
`ay 079 Al
`
`(12)
`
`EUROPEAN PATENT APPLICATION
`published in accordance with Art. 158(3) EPG
`
`{51} int Ch:
`HOSB 33/72 2006-04)
`COFF S/0Q 2008.08
`
`HOSE 33/14 28a1}
`COOK 119g eonsen
`
`international apptination number.
`PCTAIP2Z005/003920
`
`.{
`
`86)
`
`(43} Date of publication:
`22.11.2006 Bulletin 2006/47
`
`(21) Application nuraber: 05720192.3
`
`(22} Date of fing: 07.03.2005
`
`{87} International publication number:
`WO 2005/069024 (22.08.2005 Gazette 2005/38)
`
`
`{84} Dasignated Contracting States:
`DE
`
`* OGATA, Tamoyuki, Mitsubishi Chemical
`Gr Science &
`
`Yokohama-shi, Kanagawa 227-8502 (JP)
`+ TANAKA, Asato, Mitsubishi Chemical Gr.Science
`
`& Y
`
`okohama-shi, Kanagawa 227-8502 {JP}
`
`(74) Representative: Vossius & Partner
`Sishertatrasse 4
`81675 Minchen (DE)
`
`{30} Priority: 2143.2004 JP 2004066958
`28.01.2008 JP 2005021983
`
`i71} Applicant: Mitsubishi Chemical Corporation
`Tokyo
`108-0014 {UP}
`
`{72} inventors:
`« EDA, Koichiro, Mitsubishi Chemical Gr. Science &
`Yokohama-shi, Kanagawa 227-8502 {UP}
`
`{54}
`
`COMPOSITION FOR CHARGE-TRANSPORTING FILM AND fON COMPOUND, CHARGE-
`TRANSPORTING FILM AND ORGANIC ELEC TROLUMINESCENT DEVICE USING SAME, AND
`METHOD FOR MANUFACTURING ORGANIC ELEC TROLUMINESCENT DEVICE AND METHOD
`FOR PRODUCING CHARGE-TRANSPORTING FILM
`
`An excellamt composition for a charge-transpart
`{57}
`film, whieh cart be used to oroduce an organic efectrofu-
`minescence device having excellant heat-resistant prop-
`any, high hole injection/ransport capacity and capable
`of furictionwig af 6 iow voltage, is cropasec.
`t comprises at least an ionic compound expressed by
`the following general formule (1) or the like and a charge-
`transporting comoaund,
`
`+
`iRtit_eial_mete
`
`am
`2; 1
`
`{t)
`
`fT,
`
`wherein in general formula (1):
`RAMrepresents an ongenic group bound to Al Wa acarbon
`atorn ATS represents an arbitrary group; Al! and RIE
`may combine fogether to farm a ring:
`Al represents an chement belonging 1 the third and sub-
`sequert periods and group 17 of the fong form periodic
`table:
`2,°) represents @ counter anion, and
`n, represents an ionic valency of the counter anion.
`
`
`
`
` Printed oy ke "ADO PARIS (FRY
`
`EP1725079Al
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`

`

`EP 1 725 O75 Al
`
`Description
`
`fTechirdosd Piel}
`
`{8004} The present invention relates to a compasition for a charge-transport film and an ionic compound, a change-
`transcort him anc organic electraluminescence device using thern, and prochiction methods of the organic slectrolum-
`nescence device and the charge-transport film. Specifically, the present invention relates fo an excellent carnposition
`lay a charge-transpart fimand an ionic cormpound which can be used to proces an organic alectratuminescance device
`having excellent heat-resistant property and capable of funchoning at a low vallage, a charge-transport Him using either
`the composition Gr the compound, and their production methods, as well as an organic electroluminescence davice
`uaing either the oarngosition ay the compound and fis procuntion method.
`
`Background An}
`
`{8002} Recently, an alectraluminascence JEL} device using organic materials organic electraluminescence device},
`in place of inorganic materials, has been developed. Gne of the important issues with an organic electrolaninescence
`davice is how to achieve high liminous efficiency. In this respect, 2 great progress has been made by use of a hole-
`transport iayar containing aromatic amines and an emitiing layer containing 6-hydroxyquinoling aluminium coraniex,
`[4003] An irnportant problemthat has to be overcome fo expand the demand for an organic electroluminesscence
`device is how to lower its driving valtage. For example, it is required that displey devices of porpaible instruments can
`operate at a icw driving voltage from a battery. For its general use also, apart from portable instruments, the cost of
`driving iG depends on driving voltage, and the cost becomes lower as the driving vallage is lowered. Gradual increase
`in driving: voltage: an corfinuous use aso oresents a serigus problem in maintaining stability in performance of disnlay
`devices,
`
`In orderfo saive these problems, attempts are being made te mix an elactron-accenting campaind with a hale-
`f8004]
`transporting cormmpourtd.
`[8005]
`For exarnple, in Patent Document 1, § is indicated that, by mixing tis¢+-bromonhany! ariniumbexachionan-
`timanate) (TBPAH) as an siectran-accepting compound with a hole-transporting macromolecule compound, tis possible
`te obtain an organic electroluminescencea device capable of functioning at a low voltage.
`[0006]
`In Patert Docurent 2, a method is described, wherein an electron-accepting compound ferric chloride UH)
`iFeCh} is mixed with a hole-transporting compound by means of vacuum vapor deposition.
`[B007]
`In Patent Document 5, a method is described. wherein an electron-accenting compound tris(pentafiuorophenyl)
`borane (PPS) is mixed with @ hole-transporting mecrometecule carapounc by means of a wet opeting method to form
`@ hole-injection layer.
`[8008] When a hole-transporting compound is mixed with an clectron-accepting compound, electrons are transferred
`fram the bale-transporting campound to the electror-accepting compound, and an lome campound is formed which
`oongiste of a cation radical of the hole-transporting campound and a counter anion originating from the electron-accenting
`compound.
`80038]
`VWrhen TBPAH described in Patent Document 7 is Used as an electron-accepting compound, the courter anion
`is SHC. When FeCl, described in Patent Document 2 is used as an electron-accepting compound, the counter anion
`is Cl (or FeCt,}. When PPS described in Patent Document 3 is used as an electran-accepting compound, ihe counter
`arton is art anion radical shawn below.
`
`{O01O}
`
`oyot
`
`‘edwa
`
`

`

`EP 1725 O78 Ai
`
`[Chemical Formula 1]
`
`
`
`(An anion radical means a chernical species having unpaired slectrons and neqative charge. The negative chargeis
`thought to be spread over the entire molecule, However, in the above chemical formula, the resonance strunture thought
`to have the dreatest possible contribution is shawn.}
`[8071]
`In Patent Document 4, an ionic compound consisting of an aminium cation radical and SbF. or BF, is indicated
`as a component of a charge-tanspart film of a phatovaitanic instrument (organic solar battery).
`[A012] Patent Document 4 suggests the use of an ionic cornpound consisting of an aminiuen cation radical and a
`courier anion as a component of an electro-conductive ocating fir (charqe-teansport fils). As counter anions are
`exernpiified hadide ion such as [. polyhalide tion such as Bry, Gxoric acid fon such as iO. and PO, kat consisting of
`center ion and halogen suck as BF, FeCl, Sifyand RuCl, carboxylate ion such as CFCOO’, sulfonate jon such
`
`as OF,SO,0°, ate compiles originating fram sulfonate ion such ag (CF.804),Al. Gag’, Cag, and Byalt, o*.
`[80173]
`lonic compounds consisting of an aminium cation radical and a counter anion have an absorption band in the
`near infrared region and In Patert Docurnent 8, an indication is given to use these compounds as infrared cut fiter.
`Tetraphenylborate ion is axamplified as a counter anion.
`{o014]
`[Patent Document 1] Japanese Patent Laid-Open Application Na. HE! 11-289750
`iPatent Document 2] Japanese Patent Laid-Open Appiiogtion No. HEP 11-251067
`iPatent Document 3] Japanese Fatent Laid-Open Apoiication No. 2003-31385
`iPatent Ducurmant 4] Japanese Patent Laid-Open Apoticatios Na, 2009-197842
`iPatent Docurnent 4] United States Patent No. 5853908
`iPatent Document 6] Japanese Patent Laid-Open Application No, 2000-229931
`
`iDisciosure of the Invention]
`
`iPrablarn to Be Solved by the invention}
`
`[8015] However, TBPAH described in Patent Document t is poar in its heat stability andis decomposed hy heat during
`yapor deposition, making it unsuitable for use for the formation af a hnole-infeotion layer by means of co-deposition. This
`compound, therefore, is usually mixed with a hole-transporting compound by a wet coating method. However, because
`of ite poor solubility,is rot suitable for the wet coating methon, either. Furthermore, slectron-accepting property of
`TRPAH is weak and, even whenrnixed with a hole-fransporting Compound, there ig a imit below which the driving voltage
`of a device cannat be lowered, Anather prablem is that antimony atom contained in TBPAR shows strong toxicity arc
`is root desirable framthie point of view.
`(@O016] FeCl, deseribect in Patent Document 2 is corcusive in nature aad damages a vacuum vapor deousition imstru-
`ment, making 8 unsuitable to be used with this instrument. On the other hand, [FO dnciumi tin oxide}, which is routinely
`used as cathode of an organic electroluminescence device, has some extent of roughness on ifs surface (approx, 1Gnm)},
`is ich in locally lonated projections in many omses, andis liable to short circuit arising from this property. it is preferable,
`therefore, to form a hole-injection layer an a cathode by a wet coating method. in this context, the solubility of FeCl, in
`solvents is extremely poor and, benause of this, FeCl, ia not suitable for the wet coating method, aither,
`{fA017] When TBPAH or FeCl, mentioned above, is used as electron-accepting compcaund, a counter anion of an
`ionic compound formed is SbCl, or Chiar FeCi, }. Because negative charge is localized in these anions, theyinferact
`strongly with a radical cation of a hote-transporting cormpound, and tranofer of positive charge is difficult to occur, as the
`renult af which drivitg valtac: is mot sufficienfly low.
`{2018} When an ionic compound, which is described in Patent Documant 4 or & and which comprises an aminium
`
`oyot
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`‘edwa
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`

`

`EP 1725 O78 Ai
`
`cafion radical and a counter anion selected fram the group consisting of hatide ion such as b, polyhalide ton such as
`Bry’, oxonia acid jon such as Cid): PO, ions consisting of center elementtke By, FeCly, SIF_?, Aol,and halogen,
`carboxylate coumer anion such as OF,COO, sulfonate inn such as CF,SOQ.O0°, is osed as a Comparant alia hobe-
`irgection jayer of an organic slactrolurninescense device, the anion interacts strongly with the amihium cation radical
`beacause negative charge is localized in the anion, and transfer of positive charge is difficult to occur, as the result of
`which driving vollage is not sufficiently low.
`[6019]
`PPS described in Patent Document 3 is poor jn tts heat stability and, therefore, an organic electroluminescence
`device contairdng PPS is aise poor in heat stability, rnaking it unsuitable for practical use. Furthermore, PPS sublimes
`very easy and, when healingfdrying is conducted af ¢ temperatura of 12°C or higher at the ime of the formation of a
`hole-injection layer containing PPE by the method of wet coating, the cormpound is lost by sublimation and the driving
`vollage of an organic elsotraluminescence device is higher than when healing/drying is conducted at a temperature
`lower than 120°C. In the production of an organic electraluminescence device, it ia oreferable to use a hole-injection
`layer which can be heated/dried af a higher temperature, for sxarmmie 200"Cor higher, in order to simplify the production
`precess and io realize the stable device characteristics. PPS is sat preferable from thease poinis of view, either,
`in
`addition, the control of the concentration of PPS is. diffioult at the time of co-deposition because of ts very easy sublimation,
`and itis aiso unsultabie for use for the formation of a nole-injection layer by co-depasition with hole-transporting materials.
`[8020]
`Furthermore, when PPB describac in Patent Document 3 is used as electran-accapting compound, a counter
`aren farmed in mn ionic compound is an anion nadieal descripad previously, and does not setisfy the octet rule. it is
`therefore unstable thermodynamical and electrachemically, and this qresents a stability problem including thermosta-
`bility of a coating solution (composiion) and thermostability af devices.
`{8021} Vhen arn ionic compound disclosed in Patent Dacurment § which comprises an aminium cation nadioal anda
`counter anion, selected from the group consisting of carboxylate ion such as CF.COCY, sulfonate ion such as CFSO.,
`afe complex odginating fram sulfanate ion soch as (CF.50.4),Ab, Gag. Cge* and Bist, 2. is usec as a camporant of
`a hofe-injection Jayer of an orgarie eleotraluntinescence devicg, the ionic compound is vostable thermodynaminally and
`electrochemically clue to the structure of the counter anion, and the stability of the device, inciucing the heal statiiity of
`the coatiig solution compositions and heat stability of the device characteristics, is considered Inadequate.
`[@G22] The present invention has been mace in order fo solve these problems. The purpose of the present invention
`is: to provide excellent carnposition for a charge-transport film and ionic compound which can be used to obtain an
`organic slectwoluminescence cievice which has excellant haat stability. has nigh hole-iniectiontransport capability, is
`capable of functioning af a haw driving vollage and has excalient driving stability including heat stability; to provide, using
`the above, an organic elactroluminescence device which can be operated at a low voliage and has excelent driving
`stability including heat stability. and the method of producing the same: fo provide charge-transpart film using the above
`and the method of producing the same.
`
`oyot
`
`iMeans for Solving the Problem}
`
`(00233 The present inventors have carded out an intensive investigation and found that if is possible to obtain a
`composition for a charge-transpod fim having axcelient heal stability and high hole-iniectionJiransnod capability by
`nmuxing with a charge-transporing compound an ienis compound in which an element belonging fo groups 16-17 of the
`periodic table has al least one organic group honded tc itiacarbon. Ifwas also found that, by using he above composition,
`it is possible to obtain an organic electroluminescence device capable of functioning at a low voltage. These findings
`lec us fo the effective solution of the above-mentioned problems.
`[024]
`Further, an intensive investigation was carried out on an lonic campound consisting of a charge-transporting
`cation sadical and a counter anion, wherein the ionic compaund is farmed when an eleciroan-accepting compound is
`
`mixed wiht & charge-transporting compound. As a result, it was possiinie to obtain a composition for a charge-transport
`fiir Raving excetlent heat stability ancl high bole-injection/transport capability, by usirig an ionic compound comprising
`a charge-transpeoting catlon cadical are a coumter anion, which anton has an element belonging to group 13 of the
`
`
`penacio fake ard four aromatic substituenbs bonded to the elemmant. Furthermore, by sing
`compasitiod, was
`nossible to obtain an organic electraluminescence device caneble of functioning af a low voltage. Thus. we hase found
`the wayto solve effectively ihe problems presented above and the present Invention has baen completed.
`[8025] Aecording fc an aspect of the present invention, there is providect a compasition for a charge-lranspart flim,
`comprising atleash a charge-fransporting compound: and an ionic compound (hereinafter, a cation raclical of this wharge-
`transporting compound is called an“electron-accapting ionic compound" so .aa to be distinguished from an ionic compound
`comprising 4& counter anion, represented by helow-described general formula (7), as a matter of canwenience} selected
`frarn the group consisting of the campounds expressed by the following general formulae (1-13),
`
`‘edwa
`
`

`

`EP 1725 O78 Ai
`
`[Chemical Formula 2}
`
`M4
`
`oyot
`
`‘edwa
`
`wherain in general formulae (1) - (3): AUT, Re! and R=! represent, indapendenily of each other, an organic group bound
`to Al-83, respectively, via a carbon atom: RES, Re=, RES and FA*-Rrepresent, independently of each other, an arbitrary
`group: lwo or more neighboring groups of R!'-Ro4 may combine together fo form a ring: Al-A? each represent an element
`helonging to the third and subsequent periods in the periodic table: A! renresents an element belonging te qroup 17 of
`the long fonn sericdic table; A® represents an element belonging to group 16 of the long form periodic table; AS represents
`an slement bslonging fo group 15 of the long form periodic table; 2)" -Z5°° represent, independentlyof each other, a
`counter anion; and ni-ng renresent, independently of each other, an ionic valency of the counter anion.
`[8026] According fo ancihner aspect of fre resent invention, there is provided an organic elactrofuminescancedevies,
`comprising: @ substrate; an anode ard cathode formed on said substrate, an emitting layer disposed between said
`andde and said cathode, anc a imyer formed between said anode and said emitting layer using a composition for a
`charge-transport film as defined above.
`[8027] According to stil another aspect of the invention, there is orovided an organic slectroluminescence device,
`comprising: a substrate; an anode and a cathode formed on said substrate; an emitting layer disposed between said
`anode and said cathode, @ layer, disposed Selween said anode and sani cathode, that conigins at least one electron-
`accepting ionic compound selected from the group consisting of the compounds expressed by the above described
`general formuiae (1) - 3}
`{8028} According to stif another aspect of the invention, there is provided a method af groducing an organic ehactra-
`luminescence device as defined above, comprising the step of drying said camposition for a charge-transport iimby
`heating at a higher fermperature than the glass tuansition ternperaiive of sald charge-transporting compourd.
`{0029} According ki sil andiher asnect of the hiwendion, there is provided a method of producing a charge-franspart
`film by wet coating method using a composition for a charge-transpart film as defined abowe, comprising the step of
`drying said composition for a charge-transport film by heating ata higher temperature than the glass transition temperature
`of said charge-transposting cornpound.
`[8039] According to stil another aspect of the Invention, there is provided a ionic cornpound (hereinafter called an
`“jan fadical compound’,
`if necessary, so as to be distinguished from an ionic cornpound selected from a group of
`compounds reprasented by above-clascibed gqaneral formulae {1)-(3}, as & matter of convenience} composed of a nation
`radical of a charge-transporting compound and 4 counter anion, wherein saici counter anion is expressed bythe following
`general formula (7}
`
`

`

`EP 1725 O78 Ai
`
`{Chemical Pormula 3}
`
`Ar’ 4
`
`Ar’? —p4—ar’4
`a
`Ar’?
`
`(7)
`
`wharein in the general formula (7): £8 represents an olement belonging to grcup 13 of the long form periodic tabla; and
`Ar??.Ar?4 represent, Independently af each other, an aromatic hydrocarion group that ray heve substituents or an
`aromatic heterocyclic group that may have substituents.
`[8031] According to sill another aspect of the invention, thera is provided a compasition for a charge-transport film,
`comprising af least an jon radical compound as defined before.
`{Q032] According to stil another aspact of the invention, there ig provided a charge-transport fir, comprising at least
`@n ion radical compound as defined before.
`{8033} According to stil another aspect af the invention, there is provided an organic clectroluminescence device,
`carmprising a layer comprising at least an ion radical campound as defined before.
`
`{8034}
` Accercing to stil anather aspect of the invention, there is provinied an electron-accenting compound ta be
`oootamed ina charge-transpart filo together with @ charge-franspartiig compound, wherein a resistivity RR, fQern} of
`acharge-transpart film 1, which is composed of said electron-accepting compound and a change-transparting campound,
`and resistivity RA, [(Qero] of a charge-treansport film 2, which is composed of a charge-transporting compound, meet the
`follwing relation
`
`RR,/RERp < 8x1077
`
`oyot
`
`‘edwa
`
`on the conditions: thet a same compound is used as the charge-ransparting compounds contained in the change-
`transport fil1 andthe charge-transpart hie 2, anc that the rebtivdy is the value of {ied intensty [VWomourrent density
`[Afon?]} where the (held intensity [VéernVourrent density [A/orn®}} is obtained from a field intensity to be applied when a
`oharge-transport film having a film thickness of between 100-206 nm and a current-carrying area of C.04 omcarries
`an alectric currant corrasponding to 4 current density of batween 4-6 mA‘om® while being sandwichad batween an anode
`and a cathode,
`[8055] According to stil ariothar aspect of the Irivention, there are provided a composition for a charge-transport fim
`and charge-transport fim, comprising above described slectron-accepting compound and charge-transooriing com-
`pound, and is provided an organic electroluminescence device comprising said charge-transport fm.
`
`iAcivantageous Effects of the invention]
`
`[9036] The composition for a charge-transport film of the present invention comprises an above-mentioned siectron-
`accepting jodie compound in additan to a charge-transporting compound. As 4 result, @ charge-transport fim farmed
`has an excatignt heat-resistant property and shows bigh hole-injection/transpart capabiity.
`[8037] An organic elactroluminescence device of the present Invention comprises the above-mentioned siectron-
`accepihig ionic carnpoundit a layer preserd between a cathode and an anode or emitting layer, As a result, the device
`shows an excellent heat-resistant property and is capable of functioning at a low voltage leaoling to stability in driving.
`[8038]
`Furthermore, according in the production methads of an organic ebectrohiminescence device and a change-
`transport film of the present invention, if is possibie to include 4 healingvorying proces ai a high tamperature wher 4
`
`layer or a film is formed by a wet coating method using the above-mentioned composition for a charge-transport fim.
`The prochiction method is, therefore, axpacted to be made simple, and davine characteristics of film characteristics are
`expected fo be improved reqyardiog stability.
`[6039] The foric compounds (ion rachoal cornpounds) of the present invention consist of a cation radical of a charge-
`transporting compound and a counter anion expressed by the general formula (7). A counter anion expressed by the
`general fornula (7} is stable both thernodynamically and electrochemically. Therefore. the ionic compounds of the
`
`

`

`EP 1725 O78 Ai
`
`present invention (on racinal compounds) are superior in bath heat resistance and electrochemical durability. Further-
`ior,a counter anion axpressed bythe genaral formula (7}, magativa charge is diffused anc at nealized, and hacause
`of this, is intareotion with @ cadiun is woak, preserding litte obstacle la charge-transport.
`[8040] The composition for a charge transport film of the present invention comprises an above-mentioned ion radical
`compound. As a resul, ihe charge transport film formed has an excellant heat-resistant propery, excellent electrochem-
`ical durability and shows high hole-injectanftransport capability.
`[8041] The charge-tranaport film of the present invention coamprises the above-mentianed ion radica! compourtds. As
`arasull, it hasan excaliont haalt-rasistant property and excellent electrochemical durability, and shows high bala-inbection/s
`transport capability.
`[8042]
`Furthermore, an organic slectrolurninescance device of the present invention comprises a layer containing, at
`least, ion radical compounds described above. As a reauit, the device has an excellent heat-resistant oroperty, is capable
`a functioning at a low voltage, and is excellent in driving stability.
`
`iBriat Description of the Drawings}
`
`{8043}
`
`[Fig. 1} Figs. t{a) to 1{c) are schematic oroes-sectional views iNustrating exarnples of the structure of organic elec-
`trolurninescence devices of one embodiment of the praesent invention.
`[Fig. 2] Absorption spectra of campotnd 3, itustrated compound (4-1), and compound 4 in 1 siO4 M methylene
`obloride sofution.
`
`fExpianation for syrmbais}
`
`food}
`
`10a, 1606, 106c:
`Ot:
`192:
`
` orgarie electrolurninescence device
`substrate
`anode
`
`153:
`14:
`105;
`O68:
`tor:
`
`oyot
`
`hole-injectiaonlayer
`hole-fansport layer
`emitting layer
`electran transport layer
`cathode
`
`iBest Modefor Carrying Out the invention)
`
`[6045] The nresert Inventian wif be explainsd in detail below referring to one embodiment. However, R is to be
`understood that the following explanation about constituent features is presented as a representative example of an
`embodiment of the present invention, and the present inventian is not limited t theae constituent features.
`
`{L fonie Compound tian Radical Compound)
`
`[6046] The ionic compound of the present invention comprises a cation radical of a charge-transporting compound,
`and a couster amon represented by tha general formula (7} shawn below. In ine exolanatiog which fallows, this ionic
`harmpound is called “ion radical carnpounc? for the sake of convenience. incinientally, in the present invention, a charge-
`transporting compound is usoaly a hoale-transporting compound. Thesetore, in this descrmtcn, amnlanation wil be given
`
`CHT
`esuminion thet & charge-transeorting sormpourid is a hole-fransporling compound, upless otheewise megtonend.
`
`‘edwa
`
`vere 1-1. Counter Anion]
`
`A counter anion, which is an anion of an ion radical compound of the present invention, is a chemical snecies
`[8047]
`represented by the following general formula (7}.
`
`

`

`EP 1725 O78 Ai
`
`[Chemical Formula 4]
`
`Ar’!
`io
`Ar??—E*—Ars
`
`(7)
`
`Ar’3
`
`Gi the general forruda (7), E* represents an elament helonsing to the group 12 af the long form periodic table and
`Ar!-Ar?? represent, independantly of cach other, an aromatic hydrocarbon group that may have subshtuents or an
`aromatic heteronyclic group that may have substituents.)
`[6048]
`[In the general formula (7}, E* represents, independently of each other, an elermant which belongs to group 13
`of thelong form periodic table. Preferable is a boron atom, aluminum atom or gallium atom. Particularly preferabie is a
`boron atom, beacause the campound is then chemically stable, easy ta synthesize and easyto purify.
`[6049]
`[In the general formula (7), Ar?)-Ar?4 represant, indepandently of each otter, an aromatic hydrocarbon group
`oY an arainatic heterocyclic graup.
`[080] As aromatic hydrocarbon group js preferred @ univalent group derived from & 5- or G-rnembered monecyciic
`ring or from a compound having 2 to 5 concansed rings. Exaniples of the ring structures include banzene, aaphthalane,
`anthracene, phenanthrene, perylene, tetranene, pyrane, benzpyrene, chrysene, tiphenylene, acenaphihene and fua-
`tine. Of these ring structures, particularly preferable are univalent groups originating from benzene, naphthalene, phen-
`anthrene, pyrene arid fluorene, because trey are chamically stable and heat-resistant,
`{(O08t} As aromatic heterooyclic grup is preferred a univalent group derived fromS- or B-rnemberad monocyolic ring
`or from: a compound having 2 te 4 condensed rings. Examples of the ning structures inchide furan, benzofuran, thiophen,
`benzothiophen, pyrrole, pyrazole, triazole, imidazole, oxadiazals, indole, carbazole, pyrralaimidazole, pyrralapyrazole,
`pyrrolopyroale, thienopynrole, ivenothionhen, furosyrrole, furofuran, ihenofuran, benzcisoxazole, benzoisottiazaie, ber-
`Zoimidazele, nyridine, pyrazine. pyridazine, pyrimicine, viazine, quinoline, isoquinoline, cinnoline, quinoxaline, phen-
`anthriding, benzolmidazole, perimidine, quinazolina and azgutene. Of these ring structures, particulary preferable are
`UnivValent groups arighnading from pyriding, pyrazine, pyrimitiine, triazine, quinoline, isoquinoline, quinoxaline and phen-
`anthridine, because they are chemically stable, heat-resistant and capable of delocalizing negative charge efficiently.
`[8052] Aromatic hydrocarbon groun and aromatic heterncyvelic group, exemplified as Ar’ -Ar*, may carry substituents
`insofar as they do rot depart from the scope of the present rwention, There is no special imitation on the kind of the
`substituent and any substituent is possible. However, fis preferable that itis an electron-aocepting group.
`[2053] An electron-accepting group preferable as substituent of Ar“ -Ar’includes following examples: halogen atom
`auch as fluorine stem, chiarine atarn and bramine aterm; cyano group; thlocyane group, nth group, alkyisulfeny) group
`such as mesy] group; aryleuifonyt group such as tosyt group: aoyi Group having usually one or more carbon atoms and
`usually 12 orlass, preferably 6 or less. carbon atoms such as formyd groun, acatyl droup and benzoyl group; alkoxycarbonyt
`group having usually 2 or more carbon atoms and usually 10 or lass, preferably 7 ar jess carbon ators such as meth-
`oxycarbonyl group and ethoxyecarbonyl group; aryloxycarbony! group containing aromatic hydrocarhon group or aromatic
`heterocyclic Group having usually 3 or more, preferably 4 or more carbon atoms and usually 25 or less, preferably 16
`oy jass carbon atams, such as shenoxwycarhony! group and pyridyioxycarbany! group, arrinecarbanyl group: aminesul-
`
`ideegroup: haloaiky! group with straightchain, branched chain or cyclic alkyl group having usually one or mare, usually
`
`10 of less, preferably 6 or kess carbon atoms and having halogen substiivent tke Puorine or chlorine, such as trifluor-
`omethy! group and pentafluorerhy! group.
`[8054]
`In particular, if is preferable that at least one group of Ar’?-Ar?s has one or marefluorine or chlorine atoms as
`substituent. itis mostprsteratiie thet all the hydrogen atoms af Art-Art are replaced with Huorine atoms giving perflucroary!
`qroup, frarn the stacdpoist of efficiant delocalization of negative cheage and sutable sublimation propery. As axanipies
`of perflueroary! group can becited pentafluorepheny! group, heptefiuarc-2-naphtyl greup and tetraflvero--+-pyridyl group.
`[8055]
`Furthermore,it is preferable that Ar?!-Ar74 have a substituent represented by the formula (7) befow.
`
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`
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`
`iChemical Formula 5]
`
`

`

`EP 1725 O78 Ai
`
`Ar’®
`
`Ar’?
`
`Gi the formula (75, E® renresents an etement which oelongs ta group 13 of the tong form poriodic table and Ar >-Ar??
`represent, independenity of cach other, an arommahe hydrocarbon group that may have substituenis or an aromatic
`hsterecyclic group that may Nave substhuents.}
`{8056]
`In the formula (79, ES represents, independently of each other, an element which belongs to group 13 af the
`long form periodic table. Preferable is a boren atom, alurainum atom or galiurn aterm. Particularly preferable is a boron
`atom, because the compound is then chemically stable, easy to synthesize and easy to punhy.
`[8057]
`In the formuda (7°), Ar?5-Ar’? reorasant, indapendantly of aach other, an aramatic hydrocarban graup that may
`have substituents oy an arometic heterocyclic group that may have substituents. Conerate axamples, prefecabie exam-
`ples, examples of substituents and preferable examples of substituents are the same as those descrihad above for
`Ar? Arta,
`
`ft is preferable that a counter anian represented by tie formula (7} has, in ib: structure, two or more partial
`{8058}
`structures represenied by the formufa (7°). When it possesses bye or more such partial structures, they may be either
`two differant structures ar the sania structure. Preferably, they are co the searstrumture.
`{(O059} The moleasar weight of Ar’l-Ar?4 inchiding their substituents, is usually within the range of 1000 or amatler,
`oreferably G00 or amadier, mare preferably 300 or smaiier.
`[8060] Themoimcular weight of a counter anion is usually 100 of largar, preferably 200 or larger. more preferably 300
`of larger. lf is usuadiy 4000 ar smaier preferably 2000 or srnalier, more preferably 1000 or amatier.
`IF the molecular
`weight of a counter anion is too small, delocalization of negative charge is inaufficient anc interaction with a cation is
`too strang, leading to lower charge transporting capacity.
`lf the molecutar weight of a counter anion is too large, the
`counter anion Heeli may hinder charge transport.
`fO064]}
`In the present invention, the expression “may have substituents” means “may have at least one substituent’.
`[B062] A courter anion, which is an anion of an ion radical compound of the present invention. wil be axemplified
`below, if is te be understocedthat they are cited as examphes end by no means restrictive.
`
`{Chemical Formula 6]
`
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`

` =
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`EP 1725 O78 Ai
`
` 1
`
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`
`no-f S-e-Con wcoc~f}-a--4")-coct,
`a
`a
`)
`cl
`cl
`oN
`OCHS
`
`on}-8-tip
`a
`
`NO
`
`i-2. Cation radical of a hole-transporting compound]
`
`[8063] The cation radical of a hole-transparting compound, which is a cation of an ion radical compound af the present
`inveriion, ig a chemical spaci