Optoelectronic properties of polyfluorene derivatives and their blends with π-conjugated polymers = 폴리플루오렌계 고분자 및 폴리플루오렌을 포함한 공액계 고분자 블렌드의 광전자적 특성

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Optoelectronic properties of polyfluorene derivatives and their blends with PVK (or PSi8CNPV) have been studied in this dissertation. Firstly, suppression of secondary emission (excimer) of PDHBF was observed by a blend of newly synthesized polyfluorene (PDHBF) and PVK. PDHBF has a featureless and broad emission which is originated from an excimer at around 520nm even though it has bulky cyclohexyl butyl group at C-9 position of PDHBF. The Forster-type energy transfer was occurred from PVK to PDHBF because one of the conditions for the energy transfer, the spectral overlap between the emission of PVK and the absorption of PDHBF, could be satisfied. Photoluminescence excitation spectra (PLE), photoluminescence at low temperature, and fluorescence decay time measurements in PVK/PDHBF blends were performed to prove the energy transfer. In particularly, the PLE peak of PVK was not observed when the emission was fixed at 520nm (excimer emission). However, the PLE peaks of PVK were observed when the emission was fixed at the main emission of PDHBF. From these results, the excimeric emission of PDHBF is able to be much more suppressed in PVK/PDHBF (90/10, w/w). The chromophores generating the excimeric emission are formed when the chromophores are photoexcited above the critical energy level of an excited state. The chromophores formed by the energy transfer have lower energy than the critical energy and therefore fail to form the excimers. In addition, the dilution effect and the fast fluorescence decay time (~200ps) of PDHBF may explain the suppression of excimeric emission, too. Fluorescence life time (decay time) measurement was performed to investigate the effect of side-chain length of polyfluorene in PVK/polyfluorene and polyfluorene/PSi8CNPV blends. The fluorescence decay time of polyfluorenes and PVK was in the range of 150 ~ 220ps and 12ns. However, the decay time of PVK/polyfluorenes (9010) was varied as the side-chain length of polyfluorene. As the side-ch...
Advisors
Chung, In-Jae정인재
Description
한국과학기술원 : 생명화학공학과,
Publisher
한국과학기술원
Issue Date
2005
Identifier
244871/325007  / 020015143
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2005.2, [ xvii, 176 p. ]

Keywords

Electroluminescence; Fluorescence decay time; Polyfluorene; Polymer Light-Emitting Diode; Nanocomposite; 나노복합체; 전기발광; 형광소멸시간; 폴리플루오렌; 고분자 발광소자

URI
http://hdl.handle.net/10203/28952
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=244871&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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