| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 봄 (04/14 ~ 04/15, 전경련회관) |
| 권호 | 30권 1호, p.49 |
| 발표분야 | 유기반도체 |
| 제목 | Exciton Dynamics of π-conjugated Polymers doped with phosphorescent Emitters |
| 초록 | While the phenomenon of electroluminescence (EL) from organic, polymeric or small molecular light-emitting diodes (LEDs) is qualitatively understood, a quantitative assessment of the microscopic processes is still sparse. Targets of interest are the kinetics of the pathways by which the generated or injected excitations decay to the ground state within π-conjugated polymers doped with phosphorescent emitters. Those blending systems are now crucial for OLEDs due to their higher triplet emission efficiency. Actually, relatively long-lived phosphorescence compare to fluorescence is a typical feature of molecular organic solids. It is caused by spin-forbidden radiative decay from the lowest triplet state (T1) populated via intersystem crossing (ISC) from the lowest excited singlet state (S1). Since ISC is a forbidden process by spin selection rules, its probability is typically 1-2 % in π-conjugated polymers, unless a heavy metal atom with high spin-orbit coupling is incorporated. To overcome this limitation and obtain higher triplet emissive decay ratio, heavy metal containing triplet emitters are often doped into π-conjugated polymers. Figure 1 Time dependence of the phosphorescence from PtOEP in a semilogarithmic plot for 1 wt.-% PtOEP in MeLPPP(circles) and polystyrene film(triangles) and 1 wt.-% PtOEP in PhPPV film(rectangles) both measured at 4.2 K. The films were excited at 2.32 eV. In this presentation, various aspects of triplet decay kinetics will be shown. Used blend systems are typical π-cojugated polymers, such as polyphenylenevinylene (PPV) derivatives or polyfluorene (PF) derivatives doped with phosphorescent chromophores like octaethylporphyrine derivatives with various heavy metal cores. Those blend systems are investigated mainly with optical density, photoluminescence (PL) and photoluminescence excitation spectroscopy both for dilute solutions and spincasted films. To trace exact triplet decay kinetics, time-resolved PL technique is used. |
| 저자 | 임찬 |
| 소속 | 건국대 |
| 키워드 | organic optoelectronics; triplet exciton dynamics; energy transfer; electron transfer; organic diodes; organic semiconductor; pi-conjugated polymers |
