화학공학소재연구정보센터
Journal of the Korean Industrial and Engineering Chemistry, Vol.9, No.5, 710-714, October, 1998
PPV 발광층 및 전자 수송층을 가진 이종 접합구조 EL 소자의 제작 및 특성
Fabrication and Characteristics of Hetero-junction EL Devices Containing Electron Transport Layer and PPV as Emitting Layer
초록
Poly(p-phenylene vinylene), PPV를 발광층으로 하고 전자수송층(electron transport layer, ETL)이 도입된 이중 접합구조 유기 전기발광소자(electroluminescence device, ELD)를 제작하고 전기 발광 특성을 조사하였다. 전자 수송제로는 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole(PBD)를 사용하고 이를 분산시킬 기재 고분자(matrix polymer)로는 stilbene계 공단량체를 포함하는 poly(styrene-co-p-vinyl-trans-stilbene (PVTS)), poly(styrene-co-MeO-PVTS) 및 poly(styrene-co-MeO-ST)를 합성하였다. 이들 재료를 이용하여 이종 접합구조 ELD를 제조하였으며 poly(styrene-co-PVTS)를 기재 고분자로 쓴 EL 소자가 최대의 휘도를 나타냄을 확인하였다. Poly(styrene-co-MeO-PVTS) 및 poly(styrene-co-MeO-ST) 등 전자 주게 성질을 가진 methoxy기를 함유하는 기재 고분자를 쓴 EL 소자는 전자 수송층이 없는 ITO/PPV/Mg 단층 소자와 휘도가 유사 혹은 낮게 나타났다. Poly(styrene-co-PVTS)를 ETL에 쓴 EL 소자에 있어서 styrene보다 긴 conjugation 길이의 증가가 EL 발광 스펙트럼에 미치는 영향은 크지 않고 실제 발광은 PPV에 의해 주로 일어남이 관찰되었다.
Organic eletroluminescence devices (ELD) with hetero-junction structure were fabricated utilizing poly(p-phenylne vinylene) (PPV) as emitting layer and electron transport layer (ETL). 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) was used as an electron transport agent. Copolymers with stilbene type comonomers, such as poly(styrene-co-PVTS), poly(styrene-co-MeO-PVTS) and poly(styrene-co-MeO-ST) were synthesized to be used as a matrix polymer to disperse electron transport agent (PBD). Among the hetero-junction EL devices fabricated with the above materials, the device with poly(styrene-co-PVTS) as matrix polymer for ETL gave the highest luminance (120.7 cd/m(2), 13 V). EL devices made with poly(styrene-co-MeO-PVTS) or poly(styrene-co-MeO-ST) matrix exhibited lower luminance than the one with polystyrene matrix and the single layer EL (ITO/PPV/Mg) device.
  1. Tang CW, VanSlyke SA, Appl. Phys. Lett., 51, 913 (1987) 
  2. Tang CW, VanSlyke SA, Chen CH, J. Appl. Phys., 65, 3610 (1989) 
  3. Okii H, Hara H, Ohba Y, Jpn. J. Appl. Phys., 31, L416 (1992) 
  4. Adachi C, Tsutsui T, Saito S, Appl. Phys. Lett., 55, 1489 (1989) 
  5. Tsutsui T, Adachi C, Saito S, Synth. Met., 41-43, 1193 (1991)
  6. Ohmori Y, Fujii A, Uchida M, Morishima C, Yoshino K, Appl. Phys. Lett., 62, 3250 (1993) 
  7. Kido J, Kimura M, Nagai K, Science, 267(5202), 1332 (1995) 
  8. Burroughes JH, Bradley DDC, Brown AR, Marks RN, MacKay K, Friend RH, Burns RL, Holmes AB, Nature, 347, 539 (1990) 
  9. Braun D, Heeger AJ, Appl. Phys. Lett., 58, 1982 (1991) 
  10. Zhang C, Seggern HV, Pakbaz K, Kraabel B, Schmidt HW, Heeger AJ, Synth. Met., 62, 35 (1994) 
  11. Greenham NC, Moratti SC, Bradly DDC, Friend RH, Holmes AB, Nature, 365, 628 (1993) 
  12. Park LS, Shin KS, Park SK, Mol. Cryst. Liq. Cryst., 295, 43 (1997)
  13. Park LS, Shin KS, Kim SJ, Shin DS, Polym.(Korea), 21(4), 590 (1997)
  14. Park LS, Kim SJ, Han YS, Shin DS, Mol. Cryst. Liq. Cryst., to submitted
  15. Gagnon DR, Capistran JD, Karasz FE, Renz RW, Polymer, 28, 56 (1987)
  16. Mcelhanon JP, Escober H, Wu MJ, Chaudry U, Hu CL, McGrath DV, J. Org. Chem., 62, 908 (1997) 
  17. Holmes AB, Bradley DDC, Brown AR, Burn PL, Burroughes JH, Friend RH, Greenhna NC, Gymer RW, Halliday DA, Jackson RW, Kraft A, Martens JHF, Pichler K, Samuel IDW, Synth. Met., 55-57, 4031 (1993)