WO2006075905A1

WO2006075905A1 - Phosphors with high luminous efficiency and display device containing them

Info

Publication number: WO2006075905A1
Application number: PCT/KR2006/000179
Authority: WO
Inventors: So-Young Jung; Kyu-Sung Cho; Kyung-Hoon Choi; No-Gill Park; Bong-Ok Kim; Sung-Min Kim; Seung-Soo Yoon
Original assignee: Gracel Display Inc.
Priority date: 2005-01-17
Filing date: 2006-01-17
Publication date: 2006-07-20
Also published as: KR20060083520A; CN101891770A; US20100121065A1; CN101115818A; CN101891770B; CN101115818B; KR100734500B1

Abstract

The present invention relates to a novel organic electrophosphorescent compounds and a display device comprising the same. The electroluminescent iridium compounds described above can be employed as a light emitting substance having a molecular structure which gives high efficiency in a blue phosphor material.

Description

PHOSPHORS WITH HIGH LUMINOUS EFFICIENCY AND DISPLAY

DEVICE CONTAINING THEM

[Technical Fieldl The pre sent invent ion relates to electrolumines cent iridium compounds and di splay devi ces employing the same as a l ight emitt ing dopant . More speci fical ly, it relates to novel i ridium compounds which have blue elect rolumine scent property of high e ffi ciency and can be used as a subs tance to form a light emitting layer of a l ight emitting device , and di splay devi ces employing the compounds as a l ight emitt ing dopant .

[Background Art]

Among di splay devi ces , electroluminescence ( EL ) devi ces , being sel f- luminous type di splay devi ces , have advantages of wide vi sual angle , exel lent cont rast as we l l as rapid response rate . Meanwhi le , Eastman Kodak firstly developed an organic EL device employing low molecular aromatic di amine and aluminum complex as a subs tance for forming a l ight emitting layer , in 1987 [Appl . Phys . Le tt . 51 , 913 , 1987 ] . The most important factor to determine luminous e ffi ciency in an organic EL device i s l ight emitt ing material . Though fluorescent material s have been wide ly used up to the pre sent as the l ight emi tt ing mate rial , deve lopment of phosphor material , from the aspect of the mechani sm of electroluminescence , i s one of the best ways to improve the luminous effi ciency up to 4 folds , theoreticall y .

Up to the present , i ridium ( I I I ) complexes have been widely known as phosphorescent l ight emitting mate rial : ( acac ) I r (btp ) ₂ , I r ( ppy ) ₃ and Firpic or the l i ke having been known as RGB , re spectively [ Baldo et a l . , Appl . Phys . Lett . , VoI 75 , No . 1 , 4 , 1999 ; WO 00 / 70 655 ; WO 02 /7 492 ; Korean Patent La id-Open No . 2004 - 14346 ] . Various phosphors have been researched in Japan , Europe and America l , in part icular .

( acac ) I r ( btp ) 2 I r ( ppy ) ₃ Firpic I rppz Though a few excel lent conventional iridium complexes have been reported for red l ight emitting subs tances or green light emitting substances up to the present , only Firpic or I rppz represented by the Formulas above has been reported a s a pos s ible subs tance for blue light emitt ing substance . However , the technical level i s an early stage for mas s product ion because the compounds have cons iderably short l i fetime as compa red to other l ight emitt ing substance s . In particular , the pos s ibi li ty of ma s s product ion of a blue phosphor i s very low unl es s a hos t which can lead maximum performance of the blue phosphors i s developed .

[Disclosure] [Technical Problem!

The obj ect of the present invention i s to overcome above-mentioned problems and to provide a blue phosphor compound having qui te di fferent concept from convent ional blue phosphors . Other obj ects of the present invention are to provide a phosphor compound which has excel lent l i fet ime compared to conventional blue phosphor compounds so that it i s advantageous to be commonly employed, and ha s l ight emitting property of hi gh efficiency even in a low doping concentrat ion, and to provide a di splay device employing the nove l blue phosphor compound as a l ight emitting dopant .

[Technical Solution]

As a result of intens ive researches to solve the problems of prior art , the present inventors invented blue electroluminescent compounds having l ight emitting property of high effi ciency even in a low doping concentration , and a di splay device employing the compound as a l ight emitt ing dopant .

The pres ent invention relates to a phosphor compound repre sented by Chemical Formula 1 : [ Chemi cal Formula 1 ]

wherein , L is selected from the l igands of fol lowing formulas :

n i s 2 or 3 , A i s selected from the groups of fol lowing formulas :

R¹ or R² independently represent s hydrogen , linear or branched C₁-C₂₀ a l kyl group or al koxy group with or without halogen subs tituent ( s ) , halogen or cyano group ; each one o f groups from R³ to R¹⁴ independently represents hydrogen , l inear or branched C1-C20 al kyl group or al koxy group wi th or without halogen substi tuent ( s ) , halogen , phenyl group , ketone group , cyano group or C₅-C₇ cycloal kyl , or groups from R³ to R¹⁴ a re l inked vi a al kylene or al kenylene each other to form a C₅-C₇ spi ro-ring or a

C5-C9 fused ring , or l inked with R¹ or R' via al kylene or al kenylene to form a C₅-C₇ fused ring .

The novel i ridium complexes according to the pre sent invention are blue electrolumines cent compounds having excel lent l i fe span and l ight emit ting propertie s with high efficiency even in low doping concent ration .

Novel phosphor compounds according to the pres ent invent ion ( compounds of Chemical Formula 1 ) include compounds having the structures of Chemi cal Formula 2 to Chemical Formula 4 :

[ Chemical Formula 2 ]

Chemical Formula 3]

[Chemical Formula 4]

In the compounds of Chemical Formula 2 to Chemical Formula 4 , R¹ or R² independently represents hydrogen , methyl , ethyl or halogen ; each one of groups from R³ to R¹⁴ independent ly represents hydrogen , l inear or branched Ci-C₅ al kyl , halogen , or groups from R³ to R¹⁴ are linked each other via al kylene or a l kenylene to form a C₅-C₆ spiro-ring or a C₅-Cg fused ring , or l inked with R¹ or R² via al kylene or al kenylene to form a C₅-C₆ fused ring .

The compounds represented by Chemical Formul a 2 include compounds represented by one of Chemi cal Formulas 5 to 9 :

[ Chemical Formula 5 ]

[ Chemical Formula 6 ]

[Chemical Formula 7]

[Chemical Formula 8]

[Chemical Formula 9]

I n the Chemical Formulas 5 to 7 , R³ and R⁴ independently represent hydrogen , methyl , ethyl , n- propyl , i-propyl or fluorine , p , q or r represent s 1 or 2 , and the dotted l ine means a s ingle bond or a double bond .

The compounds represented by Chemi cal Formula 3 include compounds represented by one of Chemical Formulas 10 to 15 :

[ Chemical Formula 10 ]

[ Chemical Formula 11 ]

₃-n

[ Chemical Formula 12 ]

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

In the Chemi cal Formulas 10 to 15 , R to R independently represent hydrogen , methyl , ethyl , n- propyl , i-propyl or fluorine , p , q or r repre sent s 1 or 2 , and the dotted l ine means a s ingle bond or a double bond .

The compounds represented by Chemical Formula 4 include compounds represented by one o f Chemi cal Formulas 16 to 21 :

[ Chemical Formula 16 ]

[ Chemical Formula 17 ]

₃-n

[ Chemical Formula 18 ]

[Chemical Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

In the Chemical Formulas 16 to 21 , R⁹ to R¹⁴ independently repre sent hydrogen , methyl , ethyl , n- propyl , i -propyl or fluorine , p , q or r represent s 1 or 2 , and the dotted l ine means a s ingle bond or a doub le bond .

The novel electrolumines cent compound according to the pre sent invention i s speci fi cal ly selected from the compounds repre sented by fol lowing formulas :

_3-n

S ince phosphors are very de l icate in terms of li fe span , in genenal , tris-chelated complexes in which n is 3 i s pre ferred according to the present invention . However , pos s ible structure of the phosphor may have one ore more auxil iary ligand ( s ) ( that i s , n=l or 2 ) , of which fol lowing auxi liary l igands are preferable .

The pyridinyl derived l igands which const itute the electroluminescent compounds according to the pres ent invention can be prepared by adopting the preparation proces s i l lustrated in Reaction Scheme 1 to Reaction Scheme 4 : [ React ion Scheme 1 ]

As shown in Reaction Scheme 1 , the l igand can be prepared by deleting the act ivated hydrogen at the benzyl pos ition from a benzylpyridine derivat ive , a s an eas i ly available start ing material , and subs titut ing i t wi th halogenated al kyl or the l i ke . [ Reaction Scheme 2 ]

As il lustrated by Reaction Scheme 2 , the l igand can be prepared by replacing a substituent at the activated benzyl position of 2-phenyl - l-pyridin- 2 - yl -ethanone or 2 -phenyl- l-pyridin-2 -yl -propanone as a starting material , subj ecting it to a nucleophi l ic reaction with al kyl l ithium or the li ke , converting the hydroxyl group of the re sultant compound to a leaving group, and performing a coupl ing reaction . Alternatively, the corresponding pyridinyl derived l igand can be prepared by directly removing the carbonyl group of said ethanone derivat ive by us ing a reductant such as l ithium aluminum hydride . [ Reaction Scheme 3 ]

As shown in Reaction Scheme 3 , a pyridinyl derived compound containing a corre sponding spi ro ring can be prepared from cyclopropanone via nucl eophi l ic reaction or substitution with phenyl l ithium and a 2-lithiuated pyridine derivat ive . [ Reaction Scheme 4 ]

The compound which forms a fused ring with a phenyl group or a pyridine group can be prepared, a s i l lustrated in Reaction Scheme 4 , by deleting the act ivated hydrogen at the benzyl pos ition of IH- indene as s tarting materi al and performing a coupl ing react ion with bromobenz ene or the li ke .

The proces s for preparing novel pyridinyl derived ligands according to the present inventi on i s not restricted to one of the proces ses i l lustrated by Reaction Scheme s 1 to 4. In addition , one of the proce sses according to React ion Scheme 1 to Reaction Scheme 4 may be adapted, or any preparing proces s via othe r route may be carried out . Since the preparation can be performed without di fficulties by a person having ordinary s ki l l in the art by us ing conventional methods o f organi c synthes i s , it i s not des cribed here in detai l .

From the novel pyridinyl derived l igands , iridium complexe s can be prepared via the proces s of Reaction Scheme 5 :

[ React ion Scheme 5 ]

I ridium trichloride ( I rCl₃ ) and the pyridinyl derived l igand thus prepared are mixed in a molar rati o of 1 : 2 ~ 3 , preferably in a molar ratio of about 1 : 2.2 in the presence of a solvent and the mixture i s heated under reflux to i solate di i ridium dimer . The solvent used in thi s reaction stage i s preferably alcohol or alcohol /water mixed solvent , for example 2 -ethoxyethanol or 2 -ethoxyethanol /water mixed solvent .

The i sol ated diiridium dimer i s mixed with auxi l iary ligand L and organic solvent and heated to prepare e lectrolumine scent iridium compound as the fina l product . The molar ratio of pyridinyl derived l igand and other ligand L to be reacted i s dete rmined according to the compos ition rat io of the fina l product . At this time , AgCF₃SO₃ , Na₂CO₃ , NaOH or the l i ke i s reacted as be ing mixed wi th 2 - ethoxyethanol or diglyme a s organic solvent .

[Description of Drawings]

Fig . 1 i s a cross- sectional view of an organic EL device ,

Fig . 2 is an electrolumine scence spectrum of a mCP : [ BO l ( M ) - 0 ] complex ,

Fig . 3 is a graph showing the property of current dens ity-voltage-luminance of a mCP : [ BO l ( M) - 0 ] device ,

Fig . 4 is a graph showing the property of luminance-voltage- luminance of a mCP : [ BO 1 ( M ) - 0 ] devi ce , and

Fig . 5 is a graph showing the property of luminous e fficiency of a mCP : [ BO l (M ) - 0 ] device .

<Description of symbol s of s igni ficant parts of the drawings > 1 : a glas s for organic EL 2 : a transparent electrode ITO thin fi lm 3 : a hole transport layer 4 : a l ight emitting layer 5 : a hole blocking layer 6 : an electron transport layer 7 : an electron inj ect ing layer 8 : a cathode

Other and further obj ect s , features and advantages of the invention wil l appear more ful ly from the fol lowing de scription .

[Mode for Invention]

Now, the pre sent invent ion i s described as re ferring to exemplary proces ses for preparing the nove l e lectrolumine scent compounds according to the pres ent invention by way of Examples . The se Example s , however , are intended to provide better unde rstanding of the invention , and it should be understood that the scope of the invention i s not re st ricted the reto .

Examples

The ligands employed in the fol lowing Examples are des ignated as abbreviations a s de fined in Table 1 :

[ Table 1 ]

[Example 1]

Preparation of [ B01 ( R=H ) ] ₃I r

I ridium chloride ( I I I ) ( 0.40 g , 1.37 mmol ) and benz yl pyridine (purchased from Aldri ch ) a s l igand BO l ( R=H ) ( 0.90 g , 5.33 mmol ) were added to 20 mL of 2 -ethoxyethnol , and the mixture was heated under re flux under nitrogen atmosphere for 16 hours . At ambi ent temperature , water ( 50 πiL ) wa s poured into the reaction mixture , and the solid produced was fi ltered and washed with cold methanol to give μ- dichloro di iridium intermediate ( 0.52 g , yie ld : 45 % ) as yel low crys tal s .

To 5 mL of diglyme , added we re μ-dichloro di i ridium int ermediate ( 0.52 g , 0.31 mmol ) thus obta ined, ligand BO l ( R=H ) ( 0.12 g , 0.73 mmol ) and

AgCF₃SO₃ ( 0.19 g ) , and the resultant mixture was heated at 110 ^°C under nitrogen atmosphere for 24 hours . At ambient temperature , 50 mL of water was poured thereto . After fi l tering the sol id produced, extracting with methylene chloride , and recrystal l i z ing from a mixed solution of methylene chloride-methanol , 0.11 g ( yield : 20 % ) of tit le compound was obtained .

¹H NMR ( 200MH z , CDCl₃ ) : δ 4.2 ( s , 6H ) , 7.05 - 7.3 (m, 18H ) , 7.6- 7.9 (m, 6H )

MS /FAB : 700 ( found ) , 699.88 ( calculated )

[ Example 2 ]

Preparation of [ BO l ( R=methyl ) ] ₃1 r Benzyl pyridine ( 1.0 g , 5.9 mmol ) was di s solved in 20 iriL of THF under nitrogen atmosphere , and phenyl l ithium solution ( 6.5 mmol ) was added thereto at - 78 °C . After standing for 20 minutes , methyl iodide ( 0.92 g , 6.5 mmol ) together with 5 mL of THF was s lowly added to the reaction mixture , and the resultant mixture was stirred for one hour . The react ion tempe rature was rai sed to room temperature , and the mixture stirred for 2 hours . After quenching the reaction , the product was extracted to obtain 0.86 g of the product having a methyl subs tituent as oil . Methyl substituted product thus obta ined ( 0.86 g , 4.7 mmol ) was again di s solved in 20 mL of THF under nitrogen atmosphere , and reacted with phenyl l ithium and methyl iodide in the same manner . After puri fication by s i l ica gel column chromatography , pure benzyl pyridine having two methyl subst ituents at the benzyl pos it ion

( BO l ( R=methyl ) ) ( 0.61 g , 3.1 mmol , yield : 53 % ) was obta ined .

By us ing dimethyl l igand BO 1 ( R=methyl ) ( 0.61 g , 3.1 mmol ) thus obtained, the same procedure as de scribed in Example 1 was repeated to give the titl e compound , tri-chelated iridium complex ( 0.31 g , 0.40 mmol , yie ld : 39% ) .

BO l ( R=methyl )

¹H NMR ( 200MHz , CDCl₃ ) : δ 1.65 ( s , 6H ) , 7.05-7.23 (m, 7H ) , 7.62 - 7.7 ( q, IH ) , 8.62 ( d, IH ) [ BO l ( R=methyl ) ] ₃I r

¹H NMR ( 200MHz , CDCl₃ ) : δ 1.7 ( s , 18H ) , 7.05-7.3 (in, 18H ) , 7.6- 7.9 (m, 6H )

MS /FAB : 785 ( found ) , 784.05 ( cal culated )

[ Example 3 ]

Preparation of [ BO 1 ( R=ethyl ) ] ₃I r

By us ing ethyl iodide , the same procedure a s described in Example 2 was repeated to give the title compound, diethyl l igand BO l ( R=ethyl ) ( yield : 46% ) .

By the use of dimethyl l igand BO l ( R=ethyl )

( 0.8 g, 3.55 mmol ) thus obtained, the same procedure as des cribed in Example 1 was repeated to give tri- chelated iridium complex ( 0.37 g , 0.43 mmol , yield : 36% ) .

BO l ( R=ethyl )

¹H NMR(200MHz, CDCl₃) : δ 1.0 (t, 6H) , 1.9 (q, 4H) , 7.05-7.23 (m, 7H) , 7.62-7.7 (q, IH) , 8.62 (d, IH) [BOl (R=ethyl) ] ₃Ir

¹H NMR ( 200MHz , CDCl₃ ) : δ 0.95 ( t , 18H ) , 1.9 ( q, 12H ) , 7.05 -7.3 (m, 18H ) , 7.6-7.9 (m, 6H )

MS / FAB : 869 ( found ) , 868.21 ( cal culated )

[ Example 4 ]

Preparation of [ B03 ] ₃I r

In 20 mL of ether , 2 -phenyl- 1-pyridin-2 -yl - ethanone ( 1.0 g , 5.07 mmol ) was di s solved, and l ithium aluminum hydride ( 1.0 M solution in ether 10 inL ) was s lowly added thereto at -78 ^°C . After stirring the react ion mixture for one hour or more , the temperature was rai sed to ambient temperature , and the react ion continued for two hours or more . Afte r quenching by us ing ethanol and treatment of acid-base , ligand B03 ( 0.79 g , 4.31 mmol , yield : 85 % ) was obtained by extract ion .

By the use of l igand B03 ( 0.79 g , 4.31 mmol ) thus obtained, the same procedure as described in Example 1 was repeated to give tri-chelated iridium complex ( 0.35 g , 0.47 mmol , yield : 33 % ) .

B03

¹H NMR(200MHz, CDCl₃) : δ 2.88 (t, 2H) , 3.21 (t, 2H) , 7.05-7.23 (m, 7H) , 7.62-7.7 (q, IH) , 8.62 (d, IH )

[ B03 ] ₃I r

¹H NMR ( 200MHz , CDCl₃ ) : δ 2.9 ( t , 6H ) , 3.22 ( t , 6H ) , 7.05- 7.3 (m, 18H ) , 7.6- 7.9 (m, 6H ) MS /FAB : 742 ( found ) , 741.97 ( calculated )

[ Example 5 ]

Preparation of [B07 ] ₃Ir

Cyclopentanone ( 2.1 g , 25.0 mmol ) and 1.1 equivalent of phenyl l ithium ( 2.75 mmol ) were added to THF solvent at -78 ^°C , and the temperature was rai s ed to ambient temperature , to carry out the reaction for 2 to 4 hours . Again, at a temperature of - 78 °C , 2 - lithiuated pyr idine ( 27.5 mmol , 1.1 equivalent ) was added . After reacting for 2 to 4 hour s as rai sing the temperature to ambient temperature , l igand B07 ( 1.2 g , yi eld : 21 % ) was obta ined .

By the use of ligand B07 ( 1.0 g , 4.48 mmol ) thus obtained, the same procedure as described in Example 1 was repeated to give tri-chelated i ridium complex ( 0.54 g , 0.63 mmol , yield : 42 % ) .

B07

¹H NMR ( 200MHz , CDCl₃ ) : δ 1.5 ( t , 4H ) , 2.1 ( t , 4H ) , 7.05-7.3 (m, 5H ) , 7.5 -7.7 ( m, 2H ) , 8.6 ( d , IH ) [ B07 ] ₃ I r

¹H NMR ( 200MHz , CDCl₃ ) : δ 1.5 ( t , 12H ) , 2.1 ( t , 12 H ) , 7.05-7.3 (m, 18H ) , 7.6-7.9 (m, 6H ) MS / FAB : 863 ( found ) , 862.16 ( calculated )

[ Example 6 ]

Preparation of [ BO 9 ] ₂ [ acac ] Ir

Under ni trogen atmosphere , lH-indene ( 1.0 g , 8.6 mmol ) was dis solved in 20 mL of THF, and n-butyl l ithium ( 2.0 M solution in hexane 5 mL ) was added thereto at - 78 ^°C . After standing for 20 minutes , 2 - bromopyridine ( 1.4 g , 8.86 mmol ) together with 5 mL of THF wa s s lowly added to the reaction mixture , and the resultant mixture was sti rred for one hour . The reaction tempe rature was rai sed to room temperature , and the mixture stirred for 2 hours . After quenching the reaction, the product was extracted to obta in indene having a pyr idinyl substituent as oi l . Pyridinyl indene thus obtained was again di s s olved in THF, and reacted with n-butyl l ithium ( 10 mmol ) and methyl iodide ( 1.3 g , 9.2 mmol ) at - 78 ^°C under nitrogen atmosphere in the same manne r , to prepare pyridinyl indene ( B12 ) having a methyl subst ituent . The l igand ( B12 ) thus prepared was reacted wi th exce s s amount of sodium borohydride in the pre sence of ethanol , to give l igand ( B09 ) . After puri fication by s ilica gel column chromatography, pure l igand ( B09 ) ( 0.63 g , 3.0 mmol , yield : 35% ) was obta ined .

By us ing l igand B09 ( 0.63 g , 3.0 mmol ) thus obta ined, the same procedure a s de scribed in Example 1 was repeated to give μ-dichloro di iridium intermediate , which was then di s solved in 10 mL of 2 -ethoxyethanol and reacted with 2 , 4 -pentanedione at 130 ^°C for 12 hours , to obtain the t itle compound ( 0.03 g , 0.035 mmol , yield : les s than 5 % ) .

B09 ¹H NMR ( 200MHz , CDCl₃ ) : δ 1.5 ( t , 4H ) , 2.1 ( t , 4H ) , 7.05 - 7.3 (m, 5H ) , 7.5 -7.7 (m, 2H ) , 8.6 ( d , IH )

[ B09 ] 2 [ acac ] I r

¹H NMR ( 200MHz , CDCl₃ ) : δ 1.5 ( t , 12H ) , 2.1 ( t , 12H ) , 7.05-7.3 (m, 18 H ) , 7.6-7.9 (m, 6H ) MS /FAB : 863 ( found ) , 862.16 ( calculated )

[ Example 7 ] Manufacture of OLED An OLED device is manufactured by us ing the l ight emitting substance prepared from one of Examples 1 to 6 as a light emitt ing dopant .

A transparent electrode I TO thin fi lm ( 15Ω/D) obta ined from glas s for OLED (manufactured from Samsung-Corning ) was subj ected to ultrasonic washing sequent ial ly with trichloroethylene , acetone , ethanol and di stil led water , and stored in i sopropanol .

Then , an ITO subs tate i s equipped on a subs trate folder of vacuum vapor deposition device , and 4 , 4 ' , 4 "-tri s ( N , N- ( 2 -naphthyl ) - phenylamino ) triphenylamine ( 2 -TNATA) was charged in a cel l of the vacuum vapor depos ition devi ce . After vent i lation to reach the degree of vacuum in the chamber of 10^{~ 6} torr , elect ric current was applied to the cell to evaporate 2 -TNATA to vapor-depos it a hole inj ecting layer on the ITO substrate with 60 nm of thickness .

2 -TNATA

Then , N , N ' -bi s ( α-naphthyl ) -N , N' -diphenyl- 4 , 4 ' - diamine ( NPB ) was charged in another cell of sa id vacuum vapor depos ition devi ce , and electri c current was appl ied to the cel l to evaporate NPB to vapor- depos it a hole transport layer on the hole inj ect ing laye r with 20 nm of thicknes s .

NPB

Further , 4 , 4 ' -N, N ' -dicarbazole-bipheny1 ( CBP ) as a l ight emitting host substance was charged in another cel l of the vacuum vapor depos ition device , while the l ight emitting substance prepared from each one of Examples 1 to 6 in stil l another cel l . The two substances were doped by evaporating them in di fferent rates , to vapor depos it a l ight emitting laye r ( 4 ) having 30 nm of thicknes s on the hole transport laye r .

The doping concentrat ion of 4 to 10 mol l was appropriate on the bas is of CBP . Bes ides CBP , 1 , 3- bi s ( N-carbazol yl ) benzene (mCP ) or 4 , 4 ' -N , N ' - dicarba zole- 3 , 3 ' -dimethyl-biphenyl ( CDBP ) was empl oyed as a l ight emitting host substance , depending upon the EL l ight emitting wave length . The doping concentration of 4 to 10 % was again appropriate .

CBP

mCP

CDBP

Then , in the same manner as in the case of NPB , bi s ( 2 -methyl- 8 -quinol inato ) (p- phenylphenolato ) aluminum ( I I I ) ( BAIq) a s a hole bloc king layer wa s vapor depos ited with a thickne s s of 10 nm on the l ight emitting layer , and subs equent ly tri s ( 8-hydroxyquinol ine ) a luminum ( I I I ) (AIq ) as an electron transport layer was vapor depo s ited with a thicknes s of 20 nm . Lithium quinolate ( Liq ) a s an electron inj ect ing layer was then vapor depos ited with a thickne s s of 1 to 2 nm, and Al cathode was vapor deposited with a thickne s s fo 150 nm by us ing another vapor deposition device , to manufacture an OLED .

BAIq

AIq

Liq

[ Example 8 ]

Evaluation of optical propert ies of l ight emitting substances

The complexes having high synthetic yie ld among the subs tances were purified by vacuum subl imati on unde r 10^{~ 6} torr , and used as a dopant of an OLED light emitting layer . With respect to the subs tance s having low synthetic yie ld , only the l ight emitt ing peak was checked . The l ight emitting peak was measured by preparing a methylene chloride solution having the concentration of 10^~4 or les s .

At the time of measuring l ight emi s s ion of every subs tance , the excitation wavelength wa s 250 nm . Luminous efficiencies of the OLEDs were measured at 10 mA/cm² , and the properties of various electrolumines cent compounds according to the pres ent invent ion are shown in Table 2 :

[ Table 2 ]

[Industrial Applicability]

As described above , the nove l electrolumines cent iridium complexes according to the present invention are those subs tances showing blue l ight emitting property, that have exce llent l i fe span , and light emitting propert ies of high e ffi ciency even at a low doping concentration . The phosphors according to the present invention can prominently contribute to improve EL performance of organic EL devices , and particularly overcome the problem of ab sence of a blue substance , which has been an obstac le for selecting a phosphor .

Claims

[CLAIMS] [Claim 1] A phosphor compound represented by Chemical Formula 1 :

[Chemical Formula 1]

wherein , L is selected from the l igands of fol l owing formulas :

n i s 2 or 3 ,

A i s s ele cted from the groups of fol lowing formula s :

R¹ or R² independent ly repre s ent s hydrogen , l ine ar or branched Ci-C₂O a l kyl group or al koxy group wi th or wi thout ha l ogen subs t ituent ( s ) , ha l ogen or cyano group ; each one of groups from R³ to R14

independently repre s ent s hydrogen , l inea r or branched Ci-C₂O a l kyl group or al koxy group wi th or wi thout ha logen subs t i tuent ( s ) , ha logen , phenyl group , ketone group , cyano group or C₅-C₇ cycl oa l kyl , or groups from R³ to R¹⁴ are l inked via a l kylene or al kenyl ene each other to form a C₅-C7 spi ro- r ing or a C₅-C₉ fus ed ring , or l in ked wi th R¹ or R² vi a a l kylene or al kenylene to form a C₅-C₇ fus ed ring .

[Claim 2]

A phospho r compound according to claim 1 , whi ch i s repre sented by Chemi cal Formu la 2 : [ Chemi ca l Formula 2 ]

wherei n R¹ or R² independent ly repre s ent s hydrogen , methyl , ethyl or ha logen ;

R³ or R⁴ independent ly repres ent s hydrogen , l ine a r or branched Ci-C₅ a l kyl , ha logen , or R³ and R⁴ are l i nked each othe r vi a a l kylene or a l kenylene to form a C₅-C₆ spiro-ring, or linked with R¹ or R² via alkylene or alkenylene to form a C₅-C₆ fused ring.

[Claim 3]

A phosphor compound according to claim 1 , which i s represented by Chemical Formula 3 : [ Chemi cal Formula 3 ]

whe rein R^J or independent ly represents hydrogen , methyl , ethyl or halogen ; each one of groups from R⁵ to R⁸ independent ly represent s hydrogen , linear or branched C₁-C₅ al kyl , halogen , or groups from R⁵ to R⁸ are l inked each other via al kylene or al kenylene to form a C₅-C₆ spiro-ring or a C₅-C₉ fused ring , or l inked with R¹ or R² via al kylene or al kenylene to form a C5-C6 fused ring .

[ Claim 4] A phosphor compound according to claim 1 , which i s represented by Chemical Formula 4 : [ Chemi cal Formula 4 ]

wherein R or R independently represents hydrogen , methyl , ethyl or halogen ; each one of groups from R⁹ to R¹⁴ independent ly represent s hydrogen , linear or branched C_x-Cs alkyl , halogen , or groups from R⁹ to R¹⁴ are l inked each other via al kylene or al kenylene to form a C₅-C₆ spi ro-ring or a C₅-C₉ fused ring , or l inked with R¹ or R² via al kylene or al kenylene to form a C₅-C₆ fused ring .

[Claim 5] A phosphor compound according to claim 2 , which i s se lected from the compounds represented by one of Chemical Formulas 5 to 9 : [ Chemi cal Formula 5 ]

[Chemical Formula 6]

[Chemical Formula 7]

[ Chemical Formula 8 ]

[ Chemical Formula 9 ]

wherein R³ and R⁴ of Chemical Formulas 5 to 7 independently represent hydrogen , methyl , ethyl , n- propyl , i-propyl or fluorine , p , q or r represent s 1 or 2 , and the dotted l ine means a s ingle bond or a double bond .

[Claim 6]

A phosphor compound according to claim 3 , which i s s elected from the compounds represented by one of Chemical Formulas 10 to 15 :

[ Chemi cal Formula 10 ]

3-n

[ Chemical Formula 11 ]

[ Chemical Formula 12 ]

[Chemical Formula 13]

₃._n

[Chemical Formula 14]

[Chemical Formula 15]

wherein , R to R of Chemica l Formul a s 10 to 15 independently repre sent hydrogen , methyl , ethyl , n- propyl , i -propyl or fluorine , p , q or r repre sent s 1 or 2 , and the dotted l ine means a s i ngle bond or a doub le bond .

IClaim 71

A phosphor compound a ccording to cl a im 4 , whi ch i s s e lected from the compounds repre sented by one o f Chemi ca l Formu l as 16 to 21 :

[ Chemi cal Formula 16 ]

[ Chemical Formula 17 ]

[Chemical Formula 18]

[Chemical Formula 19]

[ Chemical Formula 20 ]

[Chemical Formula 21]

wherein , R⁹ to R¹⁴ of Chemical Formulas 16 to 21 independently represent hydrogen , methyl , ethyl , n- propyl , i -propyl or fluorine , p , q or r represent s 1 or 2 , and the dotted l ine means a s ingle bond or a doub le bond .

[ Claim 8]

A phosphor compound according to claim 1 , whi ch i s represented by one of the fol lowing chemical formulas :

[ Claim 9]

A display devi ce compri sing a phosphor compound according to one of claims 1 to 8.