New alternating conjugated copolymer (PFTT) comprised of 9,9´-dioctylfluorene and thienothiophene has been synthesized by palladium-catalyzed Suzuki coupling reaction. The synthesized polymer could be well characterized by $^1H-NMR, ^13C-NMR$, and elemental analysis.
Not only did it show high thermal stability, but also PFTT displayed a unique phase transition behavior between crystalline state and liquid-crystalline (LC) state. In proof of its LC property, the film of polymer showed a birefringent fluid phase as annealed above its melting temperature ($T_Cr-LC$). In addition, owing to its relatively high characteristic temperatures, the fluorene-based copolymer PFTT is expected to be used as semiconducting layers in organic field-effect transistors (OFETs).
Light-emitting diode (LED) device fabricated with ITO/PEDOT/PFTT/LiF/Al configuration revealed pure green light emission with a maximum EL peak at 515 nm. Such emission corresponded to the CIE coordinates (0.29, 0.63), which close to standard green used in national television system committee (NTSC). As the controlled HOMO and LUMO energy levels conduced toward enhanced hole and electron injection, PFTT exhibited high electroluminescent performances better than the other similar copolymer (e.g, PFT2), which demonstrated the superiority of PFTT in LEDs.
New alternating conjugated copolymer (PFTT) comprised of 9,9´-dioctylfluorene and thienothiophene has been synthesized by palladium-catalyzed Suzuki coupling reaction. The synthesized polymer could be well characterized by $^1H-NMR, ^13C-NMR$, and elemental analysis.
Not only did it show high thermal stability, but also PFTT displayed a unique phase transition behavior between crystalline state and liquid-crystalline (LC) state. In proof of its LC property, the film of polymer showed a birefringent fluid phase as annealed above its melting temperature ($T_Cr-LC$). In addition, owing to its relatively high characteristic temperatures, the fluorene-based copolymer PFTT is expected to be used as semiconducting layers in organic field-effect transistors (OFETs).
Light-emitting diode (LED) device fabricated with ITO/PEDOT/PFTT/LiF/Al configuration revealed pure green light emission with a maximum EL peak at 515 nm. Such emission corresponded to the CIE coordinates (0.29, 0.63), which close to standard green used in national television system committee (NTSC). As the controlled HOMO and LUMO energy levels conduced toward enhanced hole and electron injection, PFTT exhibited high electroluminescent performances better than the other similar copolymer (e.g., PFT2), which demonstrated the superiority of PFTT in LEDs.
New alternating conjugated copolymer (PFTT) comprised of 9,9´-dioctylfluorene and thienothiophene has been synthesized by palladium-catalyzed Suzuki coupling reaction. The synthesized polymer could be well characterized by $^1H-NMR, ^13C-NMR$, and elemental analysis.
Not only did it show high thermal stability, but also PFTT displayed a unique phase transition behavior between crystalline state and liquid-crystalline (LC) state. In proof of its LC property, the film of polymer showed a birefringent fluid phase as annealed above its melting temperature ($T_Cr-LC$). In addition, owing to its relatively high characteristic temperatures, the fluorene-based copolymer PFTT is expected to be used as semiconducting layers in organic field-effect transistors (OFETs).
Light-emitting diode (LED) device fabricated with ITO/PEDOT/PFTT/LiF/Al configuration revealed pure green light emission with a maximum EL peak at 515 nm. Such emission corresponded to the CIE coordinates (0.29, 0.63), which close to standard green used in national television system committee (NTSC). As the controlled HOMO and LUMO energy levels conduced toward enhanced hole and electron injection, PFTT exhibited high electroluminescent performances better than the other similar copolymer (e.g., PFT2), which demonstrated the superiority of PFTT in LEDs.
스쯔끼 (Suzuki) 중합 경로를 통하여 C-9 위치에 옥틸기를 갖는 플루오렌기와 접합된 (fused) 싸이오펜기를 갖는 새로운 공중합체 PFTT를 합성하였다. 이 고분자의 수 평균 분자량은 13 000으로 $^1H-$ 및 $^13C-NMR$ 분광법과 원소분석을 통해 성공적인 교대 고분자의 합성이 확인되었다. 이 고분자는 분해온도가 387℃ 에 이르는 높은 열 안정성을 보였을 뿐 아니라 DSC 분석을 통하여 독특한 상 변이 현상이 관찰되었는데 161℃ 에서의 결정화와 243℃ 에서의 액정화가 그것이다. 더 나아가 X-선 회절 및 PLM 측정을 통해 PFTT가 녹는점 이상으로 가열했을 시 액정상에서 자발적인 분자배향을 갖는 열방성 (thermotropic) 액정 고분자임이 밝혀졌다.
ITO/PEDOT/고분자/LiF/Al 의 적층구조를 가진 전기발광소자로부터 515 nm에서 최대발광 파장을 나타내는 순수 녹색광을 얻었고, 이는 NTSC의 녹색기준에 매 우 근접한 (0.29, 0.63)의 색좌표를 나타내었다. 플루오렌 주사슬에 전자가 풍부한 싸이오펜기를 도입함으로써 폴리플루오렌 동종중합체 (homopolymer) 보다 공중합체의 HOMO 에너지 준위는 높아지고, LUMO 에너지 준위는 낮아지게 되었고, 이로부터 각 전극으로부터의 정공과 전자의 주입이 용이해져, 높은 최대 양자효율을 보였다.
