2-TNATA:C60 정공 주입층을 이용한 유기발광다이오드의 성능 향상 연구

박소현; 강도순; 박대원; 최영선; Sohyun Park; Do soon Kang; Dae-Won Park; Youngson Choe

Polymer(Korea), Vol.32, No.4, 372-376, July, 2008

Export Citation

2-TNATA:C60 정공 주입층을 이용한 유기발광다이오드의 성능 향상 연구

Enhanced Efficiency of Organic Electroluminescence Diode Using 2-TNATA:C60 Hole Injection Layer

박소현, 강도순, 박대원 , 최영선 ^†

부산대학교 화학공학과

Sohyun Park, Do soon Kang, Dae-Won Park , and Youngson Choe^†

Department of Chemical Engineering, Pusan National University, Busan 609-735, Korea

E-mail:

초록

유기발광소자(OLED)에서 정공 주입층으로 사용되는 4,4′,4″-tris(N-(2-naphthyl)-N-phenylamino)-triphenylamine(2-TNATA)가 전극으로 사용되는 ITO(indium tin oxide)와 홀 수송층(hole transport layer, HTL)사이에 박막으로 진공 증착되었다. 공증착에 의해 C60이 약 20 wt% 도핑된 2-TNATA:C60 층을 제조하였으며, AFM과 XRD를 이용하여 2-TNATA:C60 박막의 분자 배향성 및 토폴로지를 관찰하였다. 또한, 다층 소자의 J-V, L-V 및 전류 효율 특성이 고찰되었다. C60은 분자 배향성을 가지고 있으나, 2-TNATA:C60 박막은 C60 분자의 균일한 분산에 의해 분자 배향성이 확인되지 않았다. C60의 도핑에 의해서 2-TNATA 박막이 더욱 조밀해지고 균일해지는 것을 확인하였으며, 이로 인하여 박막 내의 전류 밀도가 증가됨을 확인하였다. 2-TNATA:C60 하이브리드 박막을 이용하여 ITO/2-TNATA:C60/NPD/Alq3/LiF/Al 다층 소자를 제조하였을 때 소자의 휘도가 향상 되었으며 소자 효율도 약 4.7에서 약 6.7 cd/A로 증가하였다.

Vacuum deposited 4,4′,4″-tris(N-(2-naphthyl)-N-phenylamino)-triphenylamine (2-TNATA), used as a hole injection (HIL) material in OLEDs, is placed as a thin interlayer between indium tin oxide(ITO) electrode and a hole transporting layer (HTL) in the devices. C60-doped 2-TNATA:C60 (20 wt%) film was formed via co-evaporation process and molecular ordering and topology of 2-TNATA:C60 films were investigated using XRD and AFM. The J-V, L-V and current efficiency of multi-layered devices were characterized as well. Vacuum-deposited C60 film was molecularly oriented, but neither was 2-TNATA:C60 film due to the uniform dispersion of C60 molecules in the film. By using C60-doped 2-TNATA:C60 film as a HIL, the current density and luminance of a multi-layered ITO/2-TNATA:C60/NPD/Alq3/LiF/Al device were significantly increased and the current efficiency of the device was increased from 4.7 to 6.7 cd/A in the present study.

Keywords:2-TNATA;OLED;C60 doping;current efficiency;vacuum deposition

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Chen BJ, Sun XW, Wong TKS, Hu X, Uddin A, Appl. Phys. Lett., 84, 063505 (2005)
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Yuan YY, Han S, Grozea D, Lu ZH, Appl. Phys. Lett., 88, 093603 (2006)
Hawkridge AM, Pemberton JE, J. Am. Chem. Soc., 125(3), 624 (2003)
Oh S, Kang DS, Choe Y, J. Korean Ind. Eng. Chem., 17(6), 591 (2006)
Kang DS, Choe Y, J. Korean Ind. Eng. Chem., 18(5), 506 (2007)
Choe Y, Park S, Park D, J. Chem. Eng. Jpn., 38(8), 600 (2005)
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[2] Askari SH, Rughooputh SD, Wudl F, Synth. Met., 29, 129 (1989)

[3] Brandon KL, Bently PG, Bradley DDC, Dunmur DA, Synth. Met., 91, 305 (1997)

[4] Jung ES, Cho EH, Chung PJ, J. Korean Ind. Eng. Chem., 9(4), 548 (1998)

[5] El-Nahass MM, El-Gohary Z, Soliman HS, Opt. Laser Technol., 35, 523 (2003)

[6] Yuan Y, Grozea D, Lua ZH, J. Appl. Phys., 86, 143509 (2005)

[7] Khrishnakumar KP, Menon CS, Mater. Lett., 48, 64 (2001)

[8] Yanagiya S, Nishikata S, Sazaki G, Hoshino A, Nakajima K, Inoue T, J. Cryst. Growth, 254(1-2), 244 (2003)

[9] Boamfa MI, Christianen PCM, Maan JC, Engelkamp H, Nolte RJM, Physica B, 294, 343 (2001)

[10] Ji ZG, Wong KW, Tse PK, Kwok RWM, Lau WM, Thin Solid Films, 402(1-2), 79 (2002)

[11] Iebeler C, Antoniadis H, Bradley DDC, Shirota Y, J. Appl. Phys., 85, 1608 (1999)

[12] Chen BJ, Sun XW, Wong TKS, Hu X, Uddin A, Appl. Phys. Lett., 84, 063505 (2005)

[13] Burroughes JH, Bradley DDC, Brown AR, Marks RN, MacKay K, Freind RH, Burn PL, Holmes AB, Nature, 347, 539 (1990)

[14] Lee JY, Jang HK, J. Appl. Phys., 88, 183502 (2006)

[15] Yuan YY, Han S, Grozea D, Lu ZH, Appl. Phys. Lett., 88, 093603 (2006)

[16] Hawkridge AM, Pemberton JE, J. Am. Chem. Soc., 125(3), 624 (2003)

[17] Oh S, Kang DS, Choe Y, J. Korean Ind. Eng. Chem., 17(6), 591 (2006)

[18] Kang DS, Choe Y, J. Korean Ind. Eng. Chem., 18(5), 506 (2007)

[19] Choe Y, Park S, Park D, J. Chem. Eng. Jpn., 38(8), 600 (2005)

[20] Shukla VK, Kumar S, Appl. Surf. Sci., 253(16), 6848 (2007)

[21] Chen BJ, Sun XW, Li YK, Appl. Phys. Lett., 82, 3017 (2003)

[22] Tang CW, Van Slake SA, Appl. Phys. Lett., 51, 913 (1987)