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 Z†rg âæ® :ÿªV ÒÖ r2n:.

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School of Materials Science and Engineering, Seoul National University, San 56-1, Shillim-dong, Kwanak-gu, Seoul 151-744, Korea (Received February 15, 2005;accepted June 14, 2005)

ÿW’² zF†V B¾r î&b-š&b® ² Z†rg 6Úæ:š Wittig g¿š Ê ¿‡®V:. ¿‡r 6Úæ:– Òn v† ÿ:& ᖠÿʇš JV6 400 × k® ^†ÚÊ~– 200 × Z® è– vZÊ~

Ò V&’²¾ JW žk‡Ê : 袚 «Î®V:. WW® 6Úæê ÿ·R šÚ2&r þ¦ zF†® Ú

& ®Ê K·ŽÊV =šn³ UV ·n– rg úïRÊ >bû’² Ê/®V6 ÊÒ Ê zF†V þ~W

’² rgbûš r®ê ٚ «Î®V:. B² CVwkR ʶWÎ š Ê Z沪V Æ zF†& ® Êr ¿‡r 6Úæ:® HOMO e LUMO &^ VZV VW’² š&’²¾ âæ® Z†rg‡Ê û

~š «Î®V:.G

Abstract:As a new class of electroluminescent (EL) polymers, PPV-based polymers containing sulfone group in the main chain were synthesized through Witting polymerization reaction to control π-conjugation length and energy levels for predictable light emission and enhanced device performance. These EL polymers showed good solubility in common organic solvents and high thermal stability with initial decomposition temperature of ca. 400 × and glass transition temperature around 200 ×. Emission colors were tuned from green to deep blue by reducing π-conjugated length between sulfone groups. It was also noted from the cyclic voltammetry (CV) measurements and semiempirical calculations that sulfone group with high electron affinity effectively lowered HOMO-LUMO energy levels to enhance EL device performance.

Keywords: electroluminescence, sulfone, charge carrier balance, PPV.

†To whom correspondence should be addressed. E-mail: [email protected]

Ê V²WÊÒ ¶ n Þ:.⁷NBî ÒnW’² ÊB² ŽV® † N‡ûš >Ò 6Úæ ÂÆ&r †V®†ê : ‹† ¢Ž& : r² 6Úæ "V LEDî kJjúb^Ê& ÿn† ZÊr r gâæ® 6‡R ¾. rg þ~® ûš èÒ n Þê ë:

Ê :WW’² FÂnª:.^8,9

Ê ÒnW π-K· 6ÚæV lê š¦W – Z沪{&r ^n ê j– oÊ kKÊ ZæJ:ê Óâ Ê/²:ê BB V :.W óÆV Þ:.^10,11ÊJ  6Úæ k ® kK® Ê/ÆV Z WC&r Òîâ nêÆ ÊB² ZO ÖR– B†æ® šrg â ÎÊ $Ê r3nê WCʲ à ÊB² Zæ– kK® Ê/

~Êê âæ® çæþ~š þ~â r:. †Òr âæþ~® û

š ZÊrê 6Úæ k ²® Zæ, kK® RÛR Ê/& 6 kš Ö®ê ÙÊ šê®:. ÊWÎ Z†rg âæê çO e ¢O

^ã:® Fermi VZ Ò¾n– 6Úæ® HOMO(highest occupied mole- cular orbital) e LUMO(lowest unoccupied molecular orbital) VZV WW Ò®®B næ RÛ® &^ ûÊ ³ ®ê ÙÊ:. ʖ

o– Vf&r âæ® çæþ~š óV2ú† Z² ë– Â⠎ VV ÞêÆ
ÞN ë– Òî(Ca)Êî Nzî(Mg)R o–

Ò¾nV ç– ^㚠ÿ®B 6Úæ® LUMO VZ– ¢O® Fermi VZÒ 4êê ÙÊ:.¹²NBî, Ò¾nV ç– ^㖠K†î 

†& Ó² ¾š V6 Þr ÿ& rӚ qê:. ¦ÞN  ë– Š2ƒÊ ʲ ¦ r Ê® 6ÚæÒ ¾r ÊÛ g¿ ÂÆ

® :‹k âæÒ "2ê ÙÊ:.^13,14ÊB² ÊÛ g¿ ÂÆ® 

& B†æ® 3‡WCÊ rg‹R Zæn÷‹ Ê Rî² 6kn ZO Rî&r® B†æ® šrg âÎÊ Z:Æ, kKÊ Ê&

ëW~’²¾ Zæn÷‹&rֆ gR®ê Zæ® kKR® "þ Ê J: þRW’² Ê>6 B² /2& Ê ÖR&r r3®ê KZ Z®û® Wû’² ¢O’²Ö†® Zæ® RÛÊ ÿÊÊê ÖnWÎ þR Þâ r:. NBî ÊF :‹ g¿ ÂÆ® âæê 6Úæ®  R² ú–ª[& ®Êr Ê>† ¢Ž& Óâ r 箆 ‹:ê rÓÊ †Î:. ŽÞN ë– ¢>NÚ(Al)R o–

^㚠¢O’² ÿ®Êr Z沪{Ê Æ -CN,^15,16 -F,^17,18 oxadia- zole¹⁹G® †û‡†Ò lê rg6ÚæÒ ÿ®ê ÙÊ:. ÊB² 6 Úæ:– Z沪V Æ çÿ†:š 6Úæ& Û®ê ÙÊ ÒnWÊÆ CN-PPV– oÊ PPV® R& †Ò Û®B 6Úæ® LUMO VZÒ PPV& šÊ 0.9 eV k ú’²¾ Zæ

– Òîš ÿ²  Æ® š ² çæ þ~š JΠٚ N

^² : n Þ:.¹⁵NBî ʖ o– Z沪V Æ çÿ†Ò 6Ú æ& Û®ê &ê :r rgbûÊ ûbû ’² Ââ Ê /®† ¢Ž& þ~Ê è–  rg® 6ÚæÒ †&ê ²V Þ:.

†Òr N FÂ&rê PPV® R& Z沪V Æ zF†Ò

Û¾’²¾ kKR Zæ® RÛ® &^ VZÒ Æ^®6 B² z F†® ÚÂÆÒ ®B :WÎ π-K·ŽÊÒ Æ^®B rgbû

‡š Ús®6æ ®V:. ÊÒ Z®B zF†Ò gB’² π-K·ŽÊ Ò Æ^² 6ÚæÒ WW ¿‡®B Figure 1&r– oÊ PPVS0, PPVS1, PPVS2Ò ÛÛ®V6 PPVS2® gZ& †V B¾r

6ÚæÒ PPVS2CNÊÒ ÛÛ®V:.

2. /

2.1 !ÿ£ ´|

Bis(bromomethyl-p-phenyl)-sulfone (1): p-tolyl sulfone(10 g, 41 mmol) R N-bromosuccinimide(22 g, 123 mmol)Ò 250 mL® CCl⁴& ÏÊ6 benzoyl peroxide(0.1 g, 0.41 mmol)Ò ‚Û®V:. Ê ÿ·š 242Z /ž ®®¦n²  W2†:. f« BR& ®Ê  ÿ·š

R® ’² Žï®6 anhydrous magnesium sulfate² ÊƲ  ÿ

krRkÊ :¢ >® n§& ÿn:. ¹H NMR (CDCl3, 300 MHz) 7.91 (d, 4H), 7.53(d, 4H), 4.46(s, 4H); IR(KBr, cm^-1) 1303(SO), 1151(SO).

Bis(formyl-p-phenyl)-sulfone (2): 1(5 g, 12.4 mmol)R hexamethylene- tetramine(5.2 g, 37.2 mmol)š ʲ²BÚ 80 mL& ÏÊ6 122Z /

ž ®®¦n®V:. ~’² W²  n§’š BR®B Æ®

saltÒ :. KÊƆ&r ®>Ò ÊƲ saltÒ H²O/acetic acid(1/1, v/v) 60 mL& ÏÊ6 242Z /ž ®®¦n²  5 mL® HClš ‚ Û®V:. 12Zš ª n§²  ~’² W®6 R® ’& ¾ Z2†:. ÊÒ 1 N® NaOH ÿ·’² gª®6 ʲ²Bښ ÿ

®B êò®V:. f«®& ʲ²Bښ rÆ®6  3‡’š

column chromatography(silica gel, ethyl acetate/n-hexane1/1)² kr®B 0.48 g(Y14%)® Æ 6 2Ò :. ¹H NMR(DMSO-d6, 300 MHz) 10.09(s, 2H), 8.23(d, 4H), 8.13(d, 4H); IR(KBr, cm^-1) 1710(CO), 1330(SO), 1157(SO); Elem anal. Found(Calcd) : C, 61.65(61.30); H, 3.57(3.67).

Bis(bromomethyl-p-phenyl)-sulfone triphenyl phosphonium salt(3): 1 (5 g, 12.4 mmol)R triphenyl phosphine(9.6 g, 37.2 mmol)š 30 mL®

DMF& ÏÊ6 22Z /ž ®®¦n®V:. ~’² W2þ  Ê Ùš ¦nn6 Þê 300 mL® &¢Ê& rrÞ Ö ¾Zš r32

S O O

n S

O O

n

S O O

n

S O

O

NC

n ww}zW

ww}zX

ww}zY

ww}zYju

S O O

n S

O O

n

S O O

n

S O

O

NC

n ww}zW

ww}zX

ww}zY

ww}zYju

Figure 1. Electroluminescent polymers with sulfone group in the main chain.

†:. ÊÒ BR®B – ^® 6Ò R® &¢Ê² Žï² 

&‚² k®B 7 g(Y60%)® ÎÖ 6 3š ân®V:.

1H NMR(CDCl3, 300 MHz) 7.38-7.80(m, 38H), 5.58(d, 4H); IR (KBr, cm^-1) 1442(P-CH2); Elem anal. Found(Calcd) : C, 63.91(64.66); H, 4.26(4.56).

(4-Methyl-benzyl)-phosphonic acid diethyl ester (4): 4-methylbenzyl bromide(12 g, 64.8 mmol)Ò triethyl phosphite(20 mL, 117 mmol)& ÏÊ 6 100 ×&r 122Z /ž ¦n2†:. n§®  – triethyl phos- hite

ª Ê® krRk Ê :¢ >& ÿn:. ¹H NMR(CDCl3, 300 MHz) 7.18(d, 2H), 7.11(d, 2H), 3.95(q, 4H), 3.15(s, 1H), 3.08(s, 1H), 2.32(s, 3H), 1.25(t, 6H).

1,2-Di-p-tolyl-ethene (5) THF/DMF(4/1, v/v) 100 mL& sodium hy- dride(60% oil-dispersed, 3.6 g, 90 mmol)š Ú2ú6 4(15.7 g, 64.8 mmol)Ò ‚Û®V:. B†& p-tolualdehyde(7.81 g, 65 mmol)š ‚Û

®6 55 ײ ~²  12Z /ž n§2†:. ~’² W²

 ’ 500 mL& ¾Z®B 1 N® HCl nÿ·’² gª®V:. 3‡

r 6Ò BRÒ Ê ân®6 R® ’² Žï®V:. ÊÒ K ÊƆ&r ÊÆ2þ  &‚² k®B 8.2 g(Y61%)® Æ

kš :. ¹H NMR(DMSO-d6, 300 MHz) 7.47(d, 4H), 7.18(d, 4H), 7.15(s, 2H), 2.31(s, 6H); IR(KBr, cm^-1) 1516(CC); Elem anal. Found (Calcd) C, 91.60 (92.26); H, 6.23 (7.74).

1,2-Bis-(4-bromomethyl-phenyl)-ethene (6): CCl4 150 mL& 5(3.0 g, 14.4 mmol)Ò ÏÊ6 B†& N-bromosuccinimide(7.7 g, 43.2 mmol)

– benzoyl peroxide(0.14 g, 0.56 mmol)Ò ‚Û®V:. Ê ÿ·š 242 Z /ž ®®¦n²  W2ú6 BR& ®Ê  ÎÖ® · Ò R® ’² Žï®V:. ÊÒ ÊÆ®6 ÿ:Ò rÆ®B ÎÖ

§& ÿn:. ¹H NMR(DMSO-d6, 300 MHz) 7.65(d, 4H), 7.49(d, 4H), 7.47(s, 2H), 4.73 (s, 4H).

1,2-Bis-(4-bromomethyl-phenyl)-ethene triphenyl phosphonium salt (7):

6(5.6 g, 15.3 mmol)R triphenyl phosphine(12.0 g, 46 mmol)š DMF 40 mL& ÏÊ6 22Z /ž ®®¦n®V:. ~’² W2þ  n

§·š ¦nn6 Þê 400 mL® &¢Ê& rrÞ Ö ¾Zš r 32†:. ÊÒ BR®B – ^® 6Ò R® &¢Ê² Žï

²  &‚² k®B 2.9 g(Y21%)® ^ 6 7š :.

1H NMR(DMSO-d6, 300 MHz) 6.93-7.91(m, 40H), 5.15(d, 4H); IR (KBr, cm^-1) 1516(CC), 1443(P-CH²); Elem anal. Found (Calcd): C, 67.34(70.12);

H, 4.94 (4.98).

2,3-Di-p-tolyl-acrylonitrile (8): 180 mL® tert-butanol& potassium tert- butoxide(10.1 g, 90 mmol)Ò Ú2ú6 B†& 4-methylbenzyl cyanide(8 g, 61 mmol)– p-tolualdehyde(8.4 g, 70 mmol)Ò ‚Û²  55 ײ 

~®V:. 22Z /ž n§²  R® ’& ¾Zš r32ú6 1 N® HCl nÿ·’² gª®V:. BRÒ Ê 3‡r 6Ò ân®

6 ÊƲ  &‚² k®B 7.8 g(Y55%)® 8š ân®

V:. ¹H NMR (DMSO-d6, 300 MHz) 7.95(s, 1H), 7.84 (d, 2H), 7.65(d, 2H), 7.35(d, 2H), 7.32(d, 2H), 2.37(s, 6H); IR(KBr, cm^-1) 2218(nitrile), 1516(CC); Elem anal. Found(Calcd): C, 86.83(87.52); H, 5.00(6.48); N, 5.98 (6.00).

2,3-Bis-(4-bromomethyl-phenyl)-acrylonitrile (9) CCl⁴ 50 mL& 8(3.0 g, 12.9 mmol)š ÏÊ6 B†& N-bromosuccinimide(6.9 g, 38.7 mmol)–

benzoyl peroxide(0.12 g, 0.5 mmol)Ò ‚Û®B 242Z /ž ®®¦

n2þ  W2†:. BRÒ Êr – ·Ò R® ’² Ž ï®6 ÊÆ®V:. f«®& ÿ:Ò rÆ®B ÎÖ® 6Ò 

6 ª Ê® krRk Ê :¢ >® n§& ÿn:. ¹H NMR (DMSO-d6, 300 MHz) 8.08(s, 1H), 7.96(d, 2H), 7.91(d, 2H), 7.61(d, 2H), 7.59(d, 2H), 4.76(s, 4H).

2,3-Bis-(4-bromomethyl-phenyl)-acrylonitrile triphenyl phosphonium salt(10): DMF 30 mL& 9(4 g, 10.2 mmol)– triphenyl phosphine(8.1 g, 31 mmol)š ÏÊ6 22Z /ž ®®¦n®V:. ~’² W2þ

CH3 S

O O

CH3 BrCH2 S

O O

CH2Br NBS, BPO

CCl4

1

1) HMTA in CHCl3 2) H2O, H⁺

1 _OHC ^O_S

O

CHO

2

P(Ph)3 DMF

PH2C S O O

CH2P

3 3

+ +

Br Br

_ _

1

3

triethyl phosphite

CH₃ CH₂Br CH₃ CH₂P(OEt)₂

O

4

OHC CH₃

CH₃

CH₃

BrCH₂

CH₂Br

5

NBS, BPO CCl₄

CH₂P PCH₂

3

3 +

+ Br

Br _ _

6

7

P(Ph)₃ DMF

CH2P PCH2

3

3 +

+ Br

Br _ _

CN CH3 CH2CN

OHC CH3

BrCH2

CH2Br CN

9

CH3

CH3 CN

8

NBS, BPO CCl4

10

P(Ph)3 DMF

Scheme 1. Synthetic scheme of monomers.

 300 mL® &¢Ê& rrÞ Ör ¾Zš 3‡2ú6 BRÒ 

&‚² k®B 2.3 g(Y25%)® ÎÖ 6 10š :. ¹H NMR (DMSO-d6, 300 MHz) 7.07-7.97(m, 39H), 5.24(d, 4H); IR(KBr, cm^-1) 2214(nitrile), 1516(CC), 1439(P-CH²); Elem anal. Found(Calcd):

C, 67.23(69.52); H, 4.10(4.73), N, 1.68(1.53).

2.2 \´

Bis(formyl-p-phenyl) sulfone (2) (0.6 g, 2.1 mmol)R bis(bromomethyl- p-phenyl)-sulfone triphenyl phosphonium salt (3) (2.0 g, 2.1 mmol)š Ê

²²BÚ/&‚(v/v, 2/1) ’¿ÿ:& ÏV:. ⠆®®&r po- tassium tert-butoxide(0.6 g, 0.5 mmol)Ò &‚ 20 mL& ÏB ÊÒ Ê²²BÚ 20 mL– ¾. n§·& rrÞ W®®V:. ~&r 12 2Z /ž ¦n2r g¿n§š nß²  500 mL® ª‚& Ö â® THF& ÏÎ  ª‚& ¾Z®ê Rkš 3â nK®V:.

Ê]â Êr g¿ PPVS0Ò 0.39 g(Y77%)š ’Æ PPVS1, PPVS2, PPVS2CN G® :Î 6Úæ: ʖ v®â g¿®V:

(Scheme 2).

2.3 SOG#HO#'£#gÜ#Z#l`#

ÿ·2&r® photoluminescence(PL)ê 1,1,2,2-tetrachloroethaneš

ÿ:² ®B W g¿® 10^-4 M® ÿ·š ": wk®V:. šÚ

2® PL– W g¿Ò 1,1,2,2-tetrachloroethane& 1.5 wt%² ÏÎ

 Êٚ 0.2 µm syringe filter² BR®6 BR·š quartz ²Ê Z&

ú–ª[®B wk®V:. EL wk– ITO(indium-tin-oxide)V ÛV

v ²Ê Z& 6Úæÿ·š ú–ª[®B šÚš 6 B†& ¢

>Nښ Kó®B ZO® >ÊWÊ Ú 1 mmÎ >‹ ELâæ Ò rç®V:.

PLR EL® wk&ê monochromator(Spex 270M)– current/voltage source(Keithley 236), optical powermeter(Newport 818-SL)Ò ÿ®V

’Æ þ6 :.– ~&r ßn:.

2.4 F|folf#Yrowdpphwu|+FY,#l`#

g¿:® Ê~ª&^ê EG&G Princeton Applied Research®

model 362Ò Êÿ®B Ag/AgCl ZOR Jk²V2"² ferrocene/

ferrocenium redox system(-4.8 eV)š ÿ®B ~&r 20 mV/s® scan rate² wk®V:.

3. ûG Z ë«

3.1 \´ Z ?L |

WW® >:& V² ¿‡– ¹H NMR, FT-IR,&âÚsR 

Ús Gš Ê «Î®V6 >:® g¿– î ¢z Wittig g

~– 11² ®V6, ÿ:²ê ʲ²BÚ/&‚(v/v, 4/3) ’¿ÿ:

Ò ÿ®V:. Þ PPVS2CN®  n§‡Ê Æ †V g¿

Rk & þšÞ¢š IR² «Î®V’Æ(Figure 2), ¹H NMR®  – phosphonium salt:® phosphine proton ’ÂV Òê ٚ Ê

:â þŽr ʲ²BÚ, šŽú, &‚ G&ê Ï  ®’Æ, THF, DMF, DMSO G&ê ÖÚW’² Ï®:. NBî, NMP– 1,1,2,2-te- trachloroethane&ê ÿÊ‡Ê ášr ÿ·š "2ê ÙÊî 6Úæ

šÚš êÆê ŽrV :. GPC(gel permeation chromatography) Ò Êÿ®B Úæš wk®V6 Ê& V² RÒ Table 1& k

®V:. ¿‡r g¿:® Úæ– ®’î ú–ª[š Êr 6Ò² g¯W ‚Û‡š lê 6Úæ šÚš †&ê ÿÚ®V:.

V:. TGA(thermogravimetric analysis) wk2 ^†ÚÊ~(T^d)V Ó 400 × k² : è– JW žk‡š V&š «Î®V6 DSC(di- fferential scanning calorimetry) wkš ² vZÊ~(T^g) 180 × Ê® è– hš JBR:. :r Z†rgâæ® ç/2 Z(Joule) J® r3’² ÎÊ âæžk‡Ê 6Úæ® JWžk‡& $– W ûš qê:ê ٚ 6zÊ R¢ N FÂ&r ¿‡r 6Úæ:®

Z†rgâæÿ 6Úæ²r® öW n‡š «Î¶ n Þ:.²⁰ 3.2 \´ÿ£ \¤L |

Figure 3– rg6Úæ® ÿ·2&r® UV ·núïRš J BV:. ÿ·2® úïRš JÊ PPVS0&r PPVS2² VÊr : r K·ŽÊV îîÊr λmax– λcut-offV ûbû ’² Ó 30 nm

OHC CHO

+

+

+ 2 +

3

2

2

3

7

10

PPVS0

PPVS1

PPVS2

PPVS2CN

Scheme 2. Polymerization of EL polymers with sulfone group. 7333#6833#6333#5833#5333#4833#4333# 833# Wavenumber(cm^-1)

Transmittance(a.u.)

O=S=O PPVS2

PPVS2CN

CN

O=S=O

Figure 2. IR spectra of PPVS2 and PPVS2CN.

Table 1. Summary of Polymerization Results

PPVS0 PPVS1 PPVS2 PPVS2CN

Yield(%) 77 42 60 69

Mn 1700 2000 6200 2100

Mw 2400 3500 8200 4700

PDI 1.41 1.75 1.30 2.23

Table 2. Thermal Properties of EL Polymers

PPVS0 PPVS1 PPVS2 PPVS2CN

Tg(×) 198 180 187 198

Td(×) 407 420 414 410

k Ê/®ê ٚ V†¶ n Þ:. ÊÒ Ê rg® †N>Z V nê î&b-š&b® K·ŽÊV 6ÚæR& Ûr zF

†& ®Êr þRW’² rn¢š ¢ n Þ:. ʖ o– û

‡– šÚ2® wk&r š ®â î’Æ λ^cut-offê Ó 10 nm k óV² hš JV:. PPVS2CN® &ê vÂÆÎ PPVS2& š®B λmax– λcut-offV >bû ’² n nm Ê/®ê Ù Ê V†nêÆ Êٖ †® ے² ÿ·&rê stilbene ÂÆ® ʇ(planarity)Ê fâ®B :r² vþ² K·ŽÊV Z 6 Ù& †Î®Æ Êٖ ʶWÎ &r «În:.

PL® & V² UV ·núïR&r– o– û‡š

JV’Æ ²V rgbû– 400 nm® deep blueֆ 530 nm® green&

Êʆ¢ K·ŽÊV Ž&& †Ò ûbû ’² Ê/®V:

(Table 3). B² +W’² vibronic ’Â:Ê V†nêÆ(Figure 4)

Êٖ 6Úæ® π-K·¿ &^ VZ® vibronic structure& †Î ®ê ْ² Ûg& ®Ê B†r ZæV B†2® Vû –

/&^ VZ²Ö† †V2® BB V r² :Î /&^

Þ:.²¹ ÿ·2&rê PPVS0– PPVS1® rgbû® ~Ê& šÊ r PPVS1R PPVS2® K·ŽÊ& †Î rgbû® ~ÊV Æ®

êÆ Êٖ PPVS2®  zF† Ê® î&b-š&b†:Ê PPVS1& šÊ J: Æ âZ šʇš VŽ :r þRWÎ K·

ŽÊÒ fâ2þ ْ² 3Wr:. Ê& šÊr šÚ2&r® r gbû ~Êê Ââ óV®êÆ ÿ·2&r æv²Ê âZ®V

® ÚæÊ Ê®ê Úæ& ®Ê Wûš q¢’²¾ N æ vÒ Ùڎ:6 ¶ n Þ:. ÊB² Rê šÚ2&r®

úïRÊ ÿ·2&rJ: CÊ i– Ù&r «ÎÊ R n ÞêÆ ÿ·2®  >Ò  – 6 r>® Ògà B

†æ(singlet exciton)V âÎnÊr rgÊ Òî" šÚ® &

ê ÚæZ® Žçÿ& ®Ê J: – &^2&r B†n†

¢ŽÊ:.^22-24 EL úïR– PPVS1R PPVS2®  W g¿® š Ú2® PL(Table 3)R š ² ²V rgbûš JV’î PPVS2CN

® &ê PL& šÊ ûbû ’² Ó 60 nm k® Æ Ê/š J BR:(Figure 5). Ê]â PLR EL® úïRÊ :Î Z– æ

†·n(self absorption)– vibronic transition& ®² þR² Êsn6 Þ

:.^25-27 :r² Vwnê – PPVS0, PPVS1, PPVS2, PPVS2CNÊ

WW deep blue, blue, green, yellowV:.

3.3 \´ÿ£ O{L |

WW® 6Úæ® †^W Z†rg‡š V®† Z®B Z®–

Z«Z® VÒ Ús®V:. âæê ITO(çO)– Al(¢O)& rû Z«š V®Vš ¢ ÎVnê Z«Ê óV~& †Ò Z®V švk W’² óV®ê Z†rgâæ® ZkWÎ Z†‡š V†¶ n Þ:. þ6 âæ&r V2WÎ Z†rgš Vw¶ n Þ’Æ âæ® ²V ÎÖçæþ~– PPVS2®  5.0Ý10^-4%² š ²  Ʈ PPVâæ– š¦Ê J®š¢ :r zF†& ®² Z†rg‡

û ûš «Î¶ n Þ:.²⁸ W âæ® Z†rgÊ Òîê electric field h– PPVS0®  2.5 MV/cm² Vû è®6, PPVS2CN®

V 1.9 MV/cm² Vû ®’Æ PPVS1R PPVS2® ê WW 2.1 MV/cm– 2.0 MV/cmV:. ÊB² û‡– W g¿V lê HOMO– LUMO® &^ VZ– ZOÊ lê Fermi VZZ® &

^ û~ʲ zÛ¶ n Þ’Æ ÊÒ ZÊr :r :.š ²

&^ VZ® wkR ʶW š ß®V:. :r :.WÎ &^

 VZ š Z®B cyclic voltammetry wkš Êr HOMO V

.0 .2 .4 .6 .8

.0 PPVS0

PPVS1 PPVS2 PPVS2CN 413#

31;#

319#

317#

315#

313#

Absorbance(a.u.)

# 633# 733# 833# 933# :33# Wavelength(nm)

Figure 3. UV-Vis. spectra of polymers in solution.

Figure 4. PL spectra of polymers in solution.

413 31;

319 317 315 313

PL intensity(a.u.)

#683# 733# 783# 833# 883# 933# 983# :33# Wavelength(nm)

350 400 450 500 550 600 650 700

.0 .2 .4 .6 .8

.0 PPVS0

PPVS1 PPVS2 PPVS2CN Table 3. Summary of Optical Properties for EL Polymers

UV-Vis. Abs. PL

Solution(λ^max) (nm)

Film(λ^max) (nm)

Solution(λ^max) (nm)

Film(λ^max) (nm)

EL(λ^max) (nm)

PPVS0 324 326 400 449 -

PPVS1 358 360 452 472 478

PPVS2 384 384 450 526 528

PPVS2CN 378 376 463 522 586

Figure 5. EL spectra of polymers.

413 31;

319 317 315

313733# 833# 933# :33# ;33# Wavelength(nm)

0 2 4 6 8

0 PPVS1

PPVS2 PPVS2CN

EL Intensity(a.u.)

ZÒ ¢š6 šÚ2&r® UV ·n úïR® λ^cut-offn®Ò

&^ VZÒ ¢š:. ʶW š ZÊrê PM3 parameter Ò ÿ®B n.W(semiempirical) Úæúš nß¾’²¾ N û‡š ʶW’² ^w®V’Æ(>, 3® rӇ’² HOMO e LUMO® ^VWÎ h– :rWÎ wk®–ê :Ê:) N

RÒ Table 4& k®V:. ÊÒ JÊ PPVS0, PPVS1, PPVS2® r r² HOMO– LUMO VZV þ¦ f~ èšêÆ Êê Z沪

V Æ zF† Ê® K·ŽÊÒ k®ê î&b-š&b†® n V f~² îîÊr r3®ê ْ² bandgap energyV WW 3.20, 2.79, 2.54 eV® n®Ò JÊÆ r~W’² fânê Ù B² o–

Êv² zÛr:. PPVS2CN® &ê Z沪V Æ 

†V êV² Ûn† ¢Ž& HOMO– LUMO VZV PPVS2&

šÊ þ¦ š¢’î HOMO VZV PPVS2& šÊ š&’²¾ kK® RÛÊ z"Ž PPVS2& šÊ – rg‡š JBR

:(Figure 6).

B² R& ®Êr PPVS2CN® †Ò gB’² ² stilbeneÂÆ® Ê‡Ê fâ®ê Êv² :r vþ² π-K·ŽÊV Z<’²¾ bandgap energyV N vÂÆÎ PPVS2& šÊ :

ê ٚ V†¶ n Þ:. ÊB² ÂÆ& †Î &^ VZª®  û‡– n.W ® R&r NV² î:. g¿® †

®¯WÎ k2& V² †® Wû– n.W ’² :2

«Î®V’Æ PPVS2CN®  †Ò gB’² ç ® π-K·

ÂÆV Ó 60° k úzÞ¢š ¢ n Þ:.

4. û«

N FÂ&rê Z沪V Æ zF†Ò Êÿ®B 6Úæ® K

·ŽÊÒ Æ^®6 ÊÒ Ê rgbûš þ~W’² r¶ n Þ ê Z†rg 6ÚæÒ ¿‡®6 N ‡š V®V:. :r² ¿

‡r 6Úæ:– n² JW ‡R rg‡š JBR’Æ Z

†W ‡V– ʶW š ®B zF†Ò ¾v®ê 6Úæ V ¿‡® ÿʇ, rgbû® r, n² JW ‡ G® ûfR

¾. þ~WÎ Z†W ‡š lê ² Z†rgÿ 6Úæ²r ÿÚ² Vû‡Ê Þ¢š ¢ n Þ:.

[÷£ KÜN FÂê R¯†vÖ® National Research Laboratory (NRL) programR ²ÃR¯>(CRM-KOSEF)& ®Êr ÒÖ &

n†& f2:.

ƒ+S

1. B. E. A. Saleh and M. C. Teich, Fundamentals of Photonics, John Wiely &

Sons, New York, 1991.

2. W. J. Mooney, Optoelectric Devices and Principles, Prentice Hall, New Jersey, 1991.

3. P. Bhattacharya, Semiconductor Optoelectronic Devices, Prentice Hall, New Jersey, 1994.

4. J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H. Friend, P. L. Burn, and A. B. Holmes, Nature, 347, 539 (1990).

5. N. Tessler, G. J. Denton, and R. H. Friend, Nature, 382, 695 (1996).

6. J. Lu, Y. Tao, M. D’iorio, Y. Li, J. Ding, and M. Day, Macromolecules, 37, 2442 (2004).

7. A. Kraft, A. C. Grimsdale, and A. B. Holmes, Angew. Chem. Int. Ed., 37, 402 (1998).

8. J. Salbeck, Ber. Bunsenges. Phys. Chem., 100, 1667 (1996).

9. K. A. Killeen and M. E. Thomson, J. Appl. Phys., 91, 6717 (2002).

10. H. Antoniadis, M. A. Abkowitz, and B. R. Hsieh, Appl. Phys. Lett., 65, 2030 (1994).

11. D. W. M. Blom, M. J. M. Dejong, and J. J. M. Vleggaar, Appl. Phys. Lett., 68, 308 (1996).

12. I. D. Parker, J. Appl. Phys., 75, 1656 (1994).

13. A. C. Fou, O. Onitsuka, M. Ferreira, M. F. Rubner, and B. R. Hsieh, J.

Appl. Phys., 79, 7501 (1996).

14. M. Strukelj, R. H. Jordan, and A. Dodabalapur, J. Am. Chem. Soc., 118, 1213 (1996).

15. N. C. Greenham, S. C. Moratil, D. D. C. Bradley, R. H. Friend and A. B.

Holmes, Nature, 365, 628 (1993).

16. S. H. Jin, D. S. Koo, C. K. Hwang, J. Y. Do, Y. I. Kim, Y. S. Gal, J. W. Lee, and J. T. Hwang, Macromol. Res., 13, 114 (2005).

17. I. D. Parker, Q. Pei, and M. Marrocco, Appl. Phys. Lett., 65, 1272 (1994).

18. Y. Jin, J. Kim, S. H. Park, K. Lee, and H. Suh, Bull. Korean Chem. Soc., 26, 795 (2005).

19. J. H. Kim and H. Lee, Bull. Korean Chem. Soc., 25, 652 (2004).

20. T. Zyung, S. Jung, and D. H. Hwang, Synth. Met., 117, 223 (2001).

21. M. Klessinger and J. Michl, Excited States and Photochemistry of Organic Molecules, VCH, 1995.

22. D. R. Baigent, A. B. Holmes, S. C. Moratti, and R. H. Friend, Synth. Met., 80, 199 (1996).

23. S. A. Jenekhe, Adv. Mater., 7, 309 (1995).

24. M. A. Fox and S. Farid, Science, 226, 917 (1984).

25. C. Zhang, D. Braun, and A. J. Heeger, J. Appl. Phys., 73, 5177 (1993).

26. S. Tasch, A. Niko, G. Leising, and U. Scherf, Appl. Phys. Lett., 68, 1090 (1996).

27. M. Berggren, G. Gustafsson, O. Inganas, M. R. Andersson, O. Wennerstrom, and T. Hjertberg, Adv. Mater., 2, 488 (1994).

28. D. H. Hwang, I. N. Kang, M. S. Jang, H. K. Shim, and T. Zyung, Polym.

Bull., 36, 383 (1996).

Table 4. Summary of Energy Levels for EL Polymers

PPV S0 PPV S1  PPV S2 PPV S2C N C alcd. Exp. C alcd. Exp. C alcd. Exp. C alcd. Exp.

LU M O (eV ) -1.47 -3.03 -1.47 -2.90 -1.44 -2.84 -1.57 -3.16 bandgap (eV ) 7.92 3.20 7.34 2.79 7.10 2.54 7.31 2.67 H O M O (eV ) -9.39 -6.23 -8.81 -5.69 -8.54 -5.38 -8.88 -5.83

Figure 6. I-L characteristics of PPVS2 and PPVS2CN.

73 63 53 43

3# 3# 433# 533# 633# 733# 833# 933# Current density(mA/cm²)

0 0 0 0 0

PPVS2 PPVS2CN

EL Intensity(a.u.)