Ët œ ® o° Ë Ñ host ö n Úù m Ç MADN8 ý ° Ë Ñ] K ¡X ì Ä V R Ëù m Ç

Y V

Ët œ  ®  o° Ë Ñ host ö n Úù m Ç MADN8 ý ° Ë Ñ] K ¡X ì Ä V R Ëù m Ç

ƒ

‘ š' å r )



Å Ò@ /† < Ɠ §
” ¸·& ñ ˜ ÐÖ 6 x ½ + Ël Õ ü tƒ  ½ ¨™ è, à º" é ¶ 443-749



™ » ÷ 7 B) o 



Å Ò@ /† < Ɠ § \  -t r Û ¼% 7 ›† < Æ Ò, à º" é ¶ 443-749

T

) Ö < G ž B ^∗ · z £ Ó 



Å Ò@ /† < Ɠ § \  -t r Û ¼% 7 ›† < Æ Ò,
” ¸·& ñ ˜ ÐÖ 6 x ½ + Ël Õ ü tƒ  ½ ¨™ è, à º" é ¶ 443-749 (2008¸   4 Z 4 8{ 9  ~ à Î6 £ §)

Ñ þ

˜Ò  o OLED_  ' õ AÒ  o µ 1 Ï F  g — ¸ (host) Ó ü t| 9 – РŠҖ Ð  6   x ÷ &  H î ß –& ñ & h “   µ 1 Ï F  gÓ ü t| 9 – Ð" f „   ü < € ª œ/ B N (hole) _  s 1 l x5 Å q • ¸  _  ° ú  “ É r Ä »l $ ì  r   Ó ü t| 9  MADN (2-methyl-9,10-di (2-naphthyl)-anthracene) r

« Ñ\  ¦ \ P 7 £ x ‚ à Ìl \  ¦ s 6   x # Œ 2.0 × 10

⁻⁶

Torr _  ”  / B N › ¸| \ " f 1.0 ˚ A/sec _  5 Å q • ¸– Ð _ þ t  s × ¼Ä »o l  ó

ø Í0 A\  é ß –{ 9 ~ à Ì} Œ •Ü ¼– Ð 7 £ x ‚ Ã Ì % i  . 7 £ x ‚ Ã Ì  ) a ~ à Ì} Œ •\  @ / # Œ ì  rF  g+ þ AF  g > \  ¦  6   x # Œ 8 £ ¤& ñ ô  Ç PLE Û ¼& 7 ˜ à

Ô! 3 _  4 Ÿ x Ä ºo ü < þ j& h ´ ú » ¡ § Ü ¼– Ð ì  r K   ) a PL Û ¼& 7 ˜à Ô! 3 _  4 Ÿ x Ä ºo ç ß – ç ß –  s  @ /| Ä Ì& h Ü ¼– Ð { 9 u    H  Ö  ¦



© œ`  ¦ ˜ Ð% i  . Õ ªo “ ¦ ì  rF  gF  g • ¸> Z O Ü ¼– Ð 300 ∼ 800 nm   © œ % ò % i \ " f È Òõ Ö  ¦ õ  ì ø Í Ö  ¦ Û ¼& 7 ˜à Ô! 3 `  ¦ ì 

r$ 3  # Œ F  g † < Æ © œÃ º_  ° ú כ`  ¦   & ñ % i  . ì  r$ 3 \   H Jellison Modine ì  r í ß – › ' a > d ” \  Õ ªo × ¼ „ à Ðt  (grid search) ì  r$ 3  ~ ½ ÓZ O `  ¦  8 # Œ Bruggeman_  Ä »´ òB | 9 s  : r õ   8Ô  ¦ # Q  6   x % i Ü ¼ 9, ³ ð€    } 9 l \  ¦ “ ¦



9 # Œ / B N l /~ à Ì} Œ •+/ B NF G (void)/ ~ à Ì} Œ •/l 8 £ x _  4 © œ>  — ¸4 S q`  ¦ & h 6   x % i  .   & ñ  ) a F  g † < Æ © œÃ º_  & ñ S X ‰$ í “ É r f

 ¨ à º> à º_  „  í ß –r Ð 3 x õ  PLE (photoluminescence excitation) 8 £ ¤& ñ   õ _  q “ §– РÒ'  S X ‰ “   % i  .

PACS numbers: 74.25.Gz, 78.20.Ci, 78.55.-m

Keywords: Ä »l µ 1 Ï F  g  s š ¸× ¼, MADN, F  g µ 1 Ï F  g, F  g † < Æ © œÃ º

I. " e  ] Ø

Ä

»l µ 1 Ï F  g  s š ¸× ¼ (OLED : Organic Light Emit- ting Diodes)  H 21 [ jl  ' ‘ é ß –í ß –\ O  r @ /_  n Û ¼e  ¦ Y Us 

™

è \  כ ¹½ ¨÷ &  H : £ ¤$ í [ þ t`  ¦ ¿ ºÀ Ò ° ú Æ ғ ¦ e ” # Q TFT ü

< LCD\  ¦ @ /^ ‰½ + É  © œ Ä »} © œô  Ç [ j@ / n Û ¼e  ¦ Y Us 

–

Ð [ j> & h  Å Ò3 l q`  ¦ ~ à Γ ¦ e ”  . OLED_  µ 1 Ï F  g8 £ x Ó ü t

| 9

“ É r $ ì  r  ü < “ ¦ì  r  – Ð @ /Z > ÷ & 9, l ‘ : r& h Ü ¼– Ð ' õ A Ò 

o, & h Ò  o, 0 l qÒ  o µ 1 Ï F  gÓ ü t| 9 `  ¦ s 6   x # Œ n Û ¼e  ¦ Y Us _  Ò 

o› ¸³ ð‰ & ³s  0 p x  . s  ×  æ ' õ AÒ  oµ 1 Ï F  g Ä »l $ ì  r  Ó ü t

| 9

– Ѝ  H DABPV-ph (1,4-bis[4

⁰

diphenylaminobiphenyl-4- yl]vinyl]benzene), DPVBi (4,4

⁰

-bis (2,2-diphenylethen- 1- yl)-diphenyl), MADN (2-methyl-9,10-di (2-naphthyl)- anthracene) 1 p x s  e ”   [1]. ' õ AÒ  oµ 1 Ï F  g “ ¦ì  r  – Ѝ  H PPP (poly (p-phen ylene)), PF (polythiophene) 1 p x s  e ”   [2].

OLED _  > hµ 1 ϓ É r y n C_  3" é ¶Ò  o\  K { © œ   H é ß –Ò  o OLEDü <

∗

E-mail: [email protected]

Ñ þ

˜Ò  o OLED (WOLED) ×  æd ” Ü ¼– Ð > hµ 1 Ïs  ”  ' Ÿ ÷ &# Q „  Ò  o (full color) OLED – Ð S X ‰  © œ÷ &% 3  . { 9 ì ø Í& h Ü ¼– Ð OLED_  µ

1 Ï F  g“ É r µ 1 Ï F  g8 £ x \   6   x ÷ &  H Ä »l Ó ü t _  : £ ¤$ í \  _ K    & ñ

 )

a  .  € ª œô  Ç Ò  o © œ_  OLED › ¸" î \ • ¸ 6 £ x6   x| ¨ c à º e ” t  ë

ß – WOLED  H n Û ¼e  ¦ Y Us , Ñ þ ˜ s à Ô, › ¸" î 1 p x 6 £ x6   xì  r  

 F  g# 3 0 A # Œ  © œ ×  æ כ ¹ô  Ç ™ è – Ð “  d ” ÷ &“ ¦ e ”  .

Ä

»l µ 1 Ï F  g ™ è _  1 l x  Œ • ´ òÖ  ¦`  ¦ † ¾ Ó © œr v l  0 AK " f  H “ ¦

´

òÖ  ¦ µ 1 Ï F  gÓ ü t| 9 _  s 6   x õ   8Ô  ¦ # Q ™ è _  „  l & h ·F  g † < Æ& h  1

l

x  Œ •`  ¦ “ ¦ 9ô  Ç ™ è ½ ¨› ¸_  þ j& h  o € 9 כ ¹  .  8 £ x ½ ¨

›

¸– Ð s À Ò# Q”   OLED_  F  g : £ ¤$ í “ É r  ×  æ ç ß –[ O `  ¦ “ ¦ 9ô  Ç Fresnel d ” Ü ¼– Ð
 è ­ q à º e ” Ü ¼Ù ¼– Ð, ™ è \  ¦ ½ ¨$ í   H y Œ • Ó

ü t| 9 [ þ t _  F  g † < Æ © œÃ ºë ß – · ú ˜“ ¦ e ” Ü ¼€   ™ è  ? / Ò\ " f ë ß –[ þ t

#

Q”   y n C`  ¦ þ j@ /ô  Ç ã ¼| 9 # Q è ­ q à º e ”   H F  g ½ ¨› ¸ [ O >   0

p

x  . ~ à Ì} Œ •_  F  g † < Æ © œÃ º   & ñ “ É r F  g † < Æ& h  8 £ ¤& ñ x 9  ì  r$ 3 `  ¦ :

Ÿ

x K  0 p x  9 [3–5], Ò  oí  H • ¸ Z  }“ É r “ ¦´ òÖ  ¦ _  ™ è \  ¦ ] j



Œ

• l  0 AK  F  g † < Æ& h  / B N”  ½ ¨› ¸ (microcavity structure)\ 

@

/ô  Ç ´ ú §“ É r ƒ  ½ ¨ ”  ' Ÿ ÷ &“ ¦ e ”   [6,7].

-133-

OLED \  @ /ô  Ç F  g † < Æ& h  / B N”  ½ ¨› ¸\  ¦ ½ ¨‰ & ³ # Œ Z  }“ É r Ò  oí  H

•

¸ x 9  “ ¦´ òÖ  ¦ _  ™ è \  ¦ ½ ¨‰ & ³ l  0 AK " f  H ™ è  ] j Œ •\ 

€ 9

כ ¹ô  Ç µ 1 Ï F  g8 £ x _  ¿ ºa 
 F  g † < Æ © œÃ º 1 p x`  ¦ p o    & ñ # Œ

„

 í ß –r Ð 3 x`  ¦ : Ÿ x ô  Ç þ j& h _  › ¸| `  ¦ ¹ 1 Ô ? /  H õ & ñ s  ‚  ' Ÿ ÷ &

#

Q  l \  ‘ : r ƒ  ½ ¨\ " f  H þ j   H WOLED \ " f — ¸ Ó ü t| 9 

–

Ð y Œ • F  g`  ¦ ~ à Γ ¦ e ”   H ' õ AÒ  o µ 1 Ï F  g Ó ü t| 9 _  
“   MADN_  F 

g † < Æ © œÃ º   & ñ x 9  l œ í F  g † < ƃ  ½ ¨\  ¦ r ' Ÿ  % i  . é ß –1 l q µ 1 Ï F 

gÓ ü t| 9 – Ð  6   x r  ´ òÖ  ¦ s  b  # Q4 R WOLED_  ' õ AÒ  o µ 1 Ï F  g

—

¸ Ó ü t| 9 – РŠҖ Ð  6   x ÷ &  H î ß –& ñ & h “   µ 1 Ï F  gÓ ü t| 9 – Ð" f „   ü <

€

ª œ/ B N _  s 1 l x5 Å q • ¸  _  ° ú  “ É r Ä »l $ ì  r   Ó ü t| 9  MADN [8–10] \  @ /ô  Ç È Òõ Ö  ¦ õ  ì ø Í Ö  ¦`  ¦ 8 £ ¤& ñ · ì  r$ 3    H ì  rF  g F 

g • ¸> Z O `  ¦ G × þ ˜ % i   [11].

ì

 r$ 3  r  Jellison Modine_  ì  r í ß –d ”  [12]`  ¦ ë ß –7 á ¤ ô  Ç “ ¦

& ñ “ ¦ Õ ªo × ¼ „ à Ðt  (grid search)~ ½ ÓZ O  [13]`  ¦  8 # Œ Bruggeman _  Ä »´ òB | 9   H   (Effective Medium Approx- imation : EMA) [14]\  ¦  8Ô  ¦ # Q  6   x   H þ j& h ´ ú » ¡ § ì  r$ 3 

~

½ ÓZ O `  ¦ G × þ ˜ % i   [15, 16].   & ñ  ) a F  g † < Æ © œÃ º_  & ñ S X ‰$ í

“ É

r ™ è F  g > à º– РÒ'  > í ß –  ) a f  ¨ à º> à ºü < # Œl  F  g \  -t \ 



 É r µ 1 Ï F  g _  þ j@ /° ú כÜ ¼– Ð f  ¨F  g • ¸ Û ¼& 7 ˜à Ô! 3 \  ï  r   H 8 £ ¤

&

ñ   õ \  ¦ ˜ Ð# ŒÅ ҍ  H F  g µ 1 Ï F  g # Œl  (photoluminescence ex- citation : PLE) _  q “ §– Ð  Ž 7 £ x % i  . Õ ªo “ ¦  ½ ™× ¼Ì “ s˜ Ð



 Z  }“ É r \  -t _  y n C`  ¦ f  ¨ à º # Œ l $  © œI – Ð [  t  ° ú ˜ M : y n

CÜ ¼– Ð ~ ½ ÓØ  ¦   H F  g µ 1 Ï F  g (photoluminescence : PL) Û ¼& 7 ˜ à

Ô! 3 _  4 Ÿ x Ä ºo  Ä ºÛ ¼† < Êà º (Gaussian function)`  ¦ ë ß – 7

á

¤ ô  Ç “ ¦ & ñ “ ¦ š ¸o ”   ! Q„   7.5\  ¦ s 6   x # Œ þ j& h ´ ú 

»

¡

§ # Œ PLEü < q “ § % i  .

II. ÷ m Ç] M ö U ê s0 n É

1. M “ ˜ m Ç U ØR  õ m Í ‰ ˜ mø m ÇU c lT c l ” Ö «Y c l

é

ß –{ 9 ~ à Ì} Œ • 7 £ x ‚ à Ì\   6   x| ¨ c l ó ø Í[ þ t“ É r  6 £ § _  õ & ñ `  ¦   5

g ï  r q  % i  . €  $ , 1 inch × l inch ß ¼l – Ð   É r _ þ t   s

× ¼Ä »o  ³ ð€  _  Ô  ¦í  HÓ ü t`  ¦ | 9 ™ è– Ð ± ú ˜ 2 ; Ê ê  [ j— : r, IPA, 7

£

x À Óà º_  í  H " f– Ð y Œ • 5ì  rm ”  œ í6 £ §   [ j' ‘ ô  Ç Ê ê,  t } Œ •Ü ¼

–

Ð | 9 ™ è Û ¼– Ð ³ ð€  _  Ó ü t`  ¦ ] j  % i  . ï  r q   ) a l ó ø ͓ É r

| 9

™ è ì  r 0 Al _  glove boxî ß –\  ~ à Ì} Œ • ] j Œ •`  ¦ 0 AK  V , # Q ¿ º

% 3  .

\

 -t  ½ ™× ¼Ì “ s (E

g

) s  3.0 eV, Ä »o „  s “ : r • ¸ (T

^g

)  120

◦

C – Ð „   ü < € ª œ/ B N _  s 1 l x5 Å q • ¸  _  ° ú  “ É r Ä »l $ ì  r   Ó

ü t| 9  MADN r « Ñ\  ¦ ï  r q  % i   [5,6,10,17]. r « Ñ_  7 £ x ‚ à Ì

\

  H Fig. 1 \ 
  · p \ P 7 £ x ‚ à Ìl  (thermal evaporator)\  ¦ s

6   x, MADN À Ò\  ¦ $ 3 % ò • ¸m \  40 mg | ¾ Ó { Œ ™  7 £ x

‚ Ã

Ì % i   (Fig. 1). 7 £ x ‚ à Ìl  ? / Ò\   H Fig. 1 \ " fü < ° ú   s

 5> h_  ˜ Ðà Ô e ”  . MADN é ß –{ 9 ~ à Ì} Œ •“ É r 1   ˜ Ðà Ô\ " f 2.0 × 10

⁻⁶

Torr _  ”  / B N › ¸| \ " f 1.0 ˚ A/sec _  5 Å q • ¸– Ð _ þ t



s × ¼Ä »o l ó ø Í0 A\  50 nm_  ¿ ºa – Ð 7 £ x ‚ Ã Ì % i  .

Fig. 1. Glove box and inner schematic of thermal evap- orator equipment.

Fig. 2. Comparison of typical PL (left) and PLE (right) spectra. We were able to fit the measured PL spectrum using four Gaussian peaks (dot-dash lines) that have their respective centers at xc

1

, xc

2

, xc

3

, and xc

4

. Xc

1

, Xc

2

, Xc

3

, and Xc

4

are the positions of corresponding features in the PLE spectra.

2. ° Ë Ñ] K ¡ • ¤X N Ë

_ þ

t  s × ¼Ä »o l ó ø Í0 A\  7 £ x ‚ Ã Ì  ) a MADN é ß –{ 9 ~ à Ì} Œ •\  @ /

# Œ ì  rF  gF  g • ¸>  (Spectrophotometer, Jasco model V-

570)\  ¦  6   x # Œ È Òõ Ö  ¦ õ  ì ø Í Ö  ¦`  ¦ 8 £ ¤& ñ % i “ ¦, 150

W Xenon lamp\  ¦ # Œl  F  g " é ¶ Ü ¼– Ð   H ì  rF  g+ þ AF  g >  (spec-

trofluorometer, Jasco model FP-6500)\  ¦  6   x # Œ PL x 9 

PLE [ jl \  ¦ 8 £ ¤& ñ % i  . PL 8 £ ¤& ñ r  # Œl   © œ“ É r 8 £ ¤& ñ  ) a

Fig. 3. The measured (symbols) and the best-fit (solid lines) transmittance and reflectance spectra measured by spectroscopic photometer of MADN. The inset was chemical structure of MADN.

Fig. 4. Optical constants spectra of MADN correspond- ing to the respective best-fit spectra in Fig. 3 The inset was presented Tauc’s plot for MADN film.

È

Òõ Ö  ¦ õ  ì ø Í Ö  ¦ – РÒ'  > í ß –  ) a f  ¨ à ºÖ  ¦ (A=100-T-R) _  4

Ÿ

x Ä ºo  ×  æ 
“   384 nm_    H % ƒ“   385 nm– Ð # Œ 8 £ ¤& ñ

% i “ ¦, PLE 8 £ ¤& ñ r  µ 1 Ï F  g   © œ“ É r MADN _  PL 4 Ÿ x Ä ºo 



 H % ƒ“   440 nm– Ð # Œ 8 £ ¤& ñ % i  . 8 £ ¤& ñ  ) a PLE 4 Ÿ x Ä ºo 



 H PL 4 Ÿ x Ä ºo  ì  r K    õ ü <_  q “ §ü <   & ñ  ) a F  g † < Æ © œÃ º_ 

&

ñ S X ‰$ í `  ¦  Ž 7 £ x   H X < s 6   x % i  .

III. ÷ m Ç] M ö+ s ÇÊ Ý õ m Í Ä Z ØV Ä

Fig. 2  H MADN é ß –{ 9 ~ à Ì} Œ •_  PLõ  PLE [ jl \  ¦ ì  rF  g + þ

AF  g > \  ¦  6   x # Œ 8 £ ¤& ñ ô  Ç   õ \  ¦
  · p Û ¼& 7 ˜à Ô! 3 s  .

#

Œl  F  g  \  -t \  ¦ 3.22 eV (: 385 nm)– Ð # Œ 8 £ ¤& ñ ô  Ç PL Û ¼& 7 ˜à Ô! 3 _  4 Ÿ x Ä ºo   H 2.80 eV (: 443 nm)\ " f ˜ Ð# Œ F 

g † < Æ& h   ½ ™× ¼Ì “ ss  €  • 2.80 eVe ” `  ¦ · ú ˜ à º e ” % 3   (Fig. 2).

Fig. 2 _  PL Û ¼& 7 ˜à Ô! 3 `  ¦ s 6   x # Œ ½ ¨ô  Ç Ò  oý a³ ð  H CIEx

= 0.146, CIEy = 0.090 s % 3 “ ¦, z  ´] j MADN`  ¦ µ 1 Ï F  g8 £ x

Fig. 5. Comparison of the measured PLE (symbol) with the calculated absorption coefficient (solid line) spectra of MADN.

Ü

¼– Ð “ITO/PeDot:PSS (55 nm)/NPB (60 nm)/MADN (60 nm)/LiF (1 nm)/ Al (100 nm)” ½ ¨› ¸_  OLED\  ¦ z  ´ +

« >z  ´\ " f f ” ] X  ] j Œ • # Œ EL Û ¼& 7 ˜à Ô! 3 `  ¦ 8 £ ¤& ñ K  ‘ : r   õ  4

Ÿ

x Ä ºo  2.74 eV (: 452 nm)\ " f ˜ Ð# Œ PL 4 Ÿ x Ä ºo  2.80 eV ˜ Ð  $ \  -t A á ¤ Ü ¼– Ð s 1 l x   H ‰ & ³ © œ`  ¦ ^  ¦ à º e ” % 3  .

6

f• ¸ 1,000 cd/m

²

\  @ / # Œ 8 £ ¤& ñ  ) a Ò  oý a³ ð  H CIEx = 0.15, CIEy = 0.11 [18] – Ð ‰ & ³F  $ ì  r   ' õ AÒ  oÄ »l µ 1 Ï F  g ™ è



\  s 6   x ÷ &  H Idemitsu Kosan  _  CIE Ò  oý a³ ð (0.15, 0.12) ü < q “ § # Œ  _  { 9 u    H  כ Ü ¼– Ð
 z Œ ¤ . 2.82 eV (: 440 nm)\  ¦ µ 1 Ï F  g \  -t – Ð # Œ 8 £ ¤& ñ ô  Ç Fig. 2 Ä º 8

£

¤ _  PLE Û ¼& 7 ˜à Ô! 3 “ É r 3.07 eV ü < 3.23 eV\ " f  H 4 Ÿ x Ä ºo 

\

 ¦ ˜ Ð% i “ ¦, 3.37 eVü < 3.59 eV\ " f €  •ô  Ç 4 Ÿ x Ä ºo  + þ AI \  ¦

˜

Ð# Œ 4> h_  PLE 4 Ÿ x Ä ºo \  ¦ ”    כ Ü ¼– Ð
 z Œ ¤ . PLE 4

Ÿ

x Ä ºo ç ß – ç ß –  “ É r 0.16, 0.14, 0.22 eV% i  . Fig. 2 ý a8 £ ¤ _

 PL Û ¼& 7 ˜à Ô! 3 “ É r 4 Ÿ x Ä ºo  + þ AI  Ä ºÛ ¼† < Êà º\  ¦ ë ß –7 á ¤ ô  Ç



“ ¦ & ñ “ ¦ ™ èá Ôà ÔJ ?# Q š ¸o ”   ! Q„   7.5\  ¦ s 6   x, \ 



-t \  @ / # Œ þ j& h ´ ú » ¡ § [19,20] # Œ ì  r K ô  Ç  כ s  . PL Û

¼& 7 ˜à Ô! 3 “ É r 4 > h_  4 Ÿ x Ä ºo – Ð ì  r K ÷ &% 3 “ ¦,   õ  þ j& h ´ ú » ¡ §

 )

a 4 Ÿ x Ä ºo   H y Œ •y Œ • 2.39, 2.61, 2.75, 2.87 eV– Ð 4 Ÿ x Ä ºo ç ß – ç

ß –  s  0.22, 0.14, 0.12 eV– Ð PLE_  4 Ÿ x Ä ºo  ç ß –  õ  @ /

| Ä

Ì& h Ü ¼– Ð q 5 p w ô  Ç  Ö  ¦  © œ`  ¦ ˜ Ð% i  . “ ¦^ ‰ © œI _  ~ à Ì} Œ •s 



 ˜ Ðm  Û ¼à ÔY UÛ ¼ 1 p x s   Œ •6   x # Œ 6   xÓ  o © œI \ " f% ƒ! 3  ì  r K

  ) a PL 4 Ÿ x Ä ºo  ç ß –  s  & ñ S X ‰ ô  Ç  Ö  ¦  © œ“ É r  m % 3 Ü ¼
, l 

$

 © œI ü < # Œl  © œI  ï  r 0 A[ þ t ç ß –_  ç ß –  s  q 5 p w † < Ê`  ¦ · ú ˜ à º

 e ” % 3   [21–23]. ì  r K   ) a PL [ jl _  q   H $ \  -t Â Ò '

 0.0015, 0.1858, 0.1497, 0.0717– Ð ì  r$ 3 ÷ &% 3 “ ¦ 2.61 eV (: 475 nm)\ " f  © œ y © œô  Ç [ jl \  ¦ ˜ Ð% i  .

Fig. 3“ É r MADN _   o† < ƽ ¨› ¸ü < MADN é ß –{ 9 ~ à Ì} Œ •\  @ /

# Œ 300 ∼ 800 nm_    © œ% ò % i \ " f ì  rF  gF  g • ¸> \  ¦  6   x

# Œ 8 £ ¤& ñ ô  Ç È Òõ Ö  ¦ õ  ì ø Í Ö  ¦ _  Û ¼& 7 ˜à Ô! 3 `  ¦ þ j& h  ´ ú » ¡ § ô

 Ç   õ \  ¦
  · p  כ s  . ì  rF  gF  g • ¸> Z O Ü ¼– Ð 8 £ ¤& ñ ° ú כ\ 

@

/ô  Ç þ j& h  ´ ú » ¡ § r  / B N l /~ à Ì} Œ •+/ B NF G/ ~ à Ì} Œ •/l 8 £ x _  4 © œ> 

—

¸4 S q`  ¦ & h 6   x % i   H X <, EMA 8 £ x“ É r MADN ~ à Ì} Œ •_  ³ ð€  



} 9 l \  ¦ “ ¦ 9 l  0 Aô  Ç  כ s   (Fig. 3).

È

Òõ Ö  ¦ õ  ì ø Í Ö  ¦ Û ¼& 7 ˜à Ô! 3 _  þ j& h  ´ ú » ¡ §“ É r Levenburg- Marquadt · ú ˜“ ¦o 7 £ §`  ¦ s 6   x ô  Ç ‚  + þ A r) ì  r$ 3 `  ¦ : Ÿ x # Œ



© œl  4 © œ>  — ¸4 S q\     > í ß –  ) a È Òõ Ö  ¦ õ  ì ø Í Ö  ¦ Û ¼& 7 ˜à Ô

!

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È

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\

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Optical Properties of a Blue Light-emitting Host Material, MADN

Myung Hee Park

NT·IT Fusion Technology Institute, Ajou University, Suwon 443-749

Yong Seok Kim

Division of Energy Systems Research, Ajou University, Suwon 443-749

Soonil Lee

^∗

and Ken Ha Koh

Division of Energy Systems Research, NT·IT Fusion Technology Institute, Ajou University, Suwon 443-749 (Received 8 April 2008)

The optical properties of blue-light-emitting 2-methyl-9,10-di (2-naphthyl)-anthracene (MADN), which has emerged as a promising host material for a white OLED because of its stability and bipolar charge transport characteristics, were studied. MADN thin films were deposited on glass substrates at a rate of 1.0 ˚ A/sec by using a thermal evaporator at a base pressure of 2 × 10

⁻⁶

Torr.

The photoluminescence-excitation (PLE) spectra of the as-deposited films showed distinct sub- peak features, and a deconvolution analysis of the corresponding photoluminescence (PL) spectra based on Gaussian functions resulted in four-peak mirror images. The optical constants of MADN in the wavelength range of 300 ∼ 800 nm were determined through simultaneous fittings of the transmittance and the reflectance spectra. In our analysis, a Jellison-Modine dispersion function, which was used to parametrize the optical constants of MADN, was used in combination with a grid search method and Bruggeman’s effective medium approximation. A four-phase model of air/film+void/film/substrate was assumed to take the surface roughness into consideration. The accuracies of the determined optical constants were confirmed through a comparison of the measured PLE spectrum of a MADN film with the simulated absorption coefficients calculated from the fitting-produced extinction coefficients.

PACS numbers: 74.25.Gz, 78.20.Ci, 78.55.-m

Keywords: Organic light emitting diodes, MADN, PL, Optical constant

∗

E-mail: [email protected]