| Project/Area Number |
17350092
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional materials/Devices
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
ADACHI Chihaya Kyushu University, Center for Future Chemistry, Professor, 未来化学創造センター, 教授 (30283245)
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| Co-Investigator(Kenkyū-buntansha) |
SASABE Hiroyuki Chitose Institute of Science and Technology, Faculty of Photonics Science, Professor, 光科学部, 教授 (20015126)
徳丸 克己 筑波大学, 名誉教授 (60011491)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,700,000 (Direct Cost: ¥15,700,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥14,600,000 (Direct Cost: ¥14,600,000)
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| Keywords | Organic LED / Phosphorescence / transient photoluminescence / Ir complex / Temperature dependence / 三重項励起子 / Triplet-triplet annihilation / 濃度消光 / イリジウム錯体 |
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| Research Abstract |
We established an absolute PL quantum efficiency measurement system using an integrating sphere. We carefully measured absolute PL quantum efficiency and internal system crossing (ISC) efficiency of Ir complexes which are useful for organic light emitting diodes. In particular, we clarified non-radiative decay process from the triplet excited state to the ground state.
We observed that green emitting Ir(ppy)_3 has PL quantum efficiency of η_<PL>=89±2%, and blue emitting FIrpic has η_<PL>=89±2%, indicating suppression of non-radiative decay processes in their doped films. On the other hand, red emitting Btp_2Ir(acac) showed rather low η_<PL>=32±3%. In order to clarify the non-radiative deactivation process, we measured the ISC efficiency by photoacoustic spectroscopy (PAS). As a result, Btp_2Ir(acac) was revealed to have nearly 100% of ISC efficiency, and we concluded that non-radiative deactivation efficiency from the triplet level is 64%.
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