2007 Fiscal Year Final Research Report Summary
Multifunctional and highly efficient light emitting organic materials
| Project/Area Number |
17350090
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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 | Chiba University |
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Principal Investigator |
KARATSU Takashi Chiba University, Graduate Schoolof Engineering, Professor (70214575)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Light Emitteng Materials / Photochemistry / Photophysics / Organic Device / Light Source / Surface and Interface |
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| Research Abstract |
Organic materials for the organic devices were investigated Organic devices such as organic light emitting diode (OLED, organic elecholuminescence) are developing rapidly, and materials far such devices are increasing in importance. Here, three types of light emitting materials were investigated; 1. Fluorescent aromatic compounds containing organosilanes as substituents 2. Anthracene conjugates which have bulky substituents on a thread therefore stacking between two anthryl groups controlled by the thread; 3. Phosphorescent iridium (III) tris cyclometalated complexes. We have investigated photophysical characteristics such as radiative and nonradiative rate constants and intramolecular energy or electron transfer processes, and photochemistry such as photochemical cycloaddition or meridional-facial geometrical isomerization.
Here, item #3 is reported more details. Phosphorescent materials have attracted much attention as the material far the OLED because of their high performance of ele
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ctroluminescence. Especially, iridium (III) tris-cyckometalated complexes are just started to use fabrication of displays after pioneering work of the Thompson and Forrest group. Research interests have been focused on the facial (fad isomer that is easier to synthesize, and has higher phosphorescence quantum yield (Φp) and chemical stability. However, little is known far the meridional (mer) isomer. Thompson group and we have reported mer→fac photochemical one-way geometrical isomerization [1-3]. Recently, it is shown that synthetic importance of the merisomer that is synthesizable under mild condition to make facisomer of thermally unstable complex through photoisomerization Also, several merisomers are shown to be useful to fabricate OLED devices.
Our finding is indicating necessity of new mechanism to explain the mer→facgeometrical isomerization. That is quite different from the proposed mechanism far the thermochemical and photochemical mechanism proposed. We synthesized iridium(III) tris-1-phenylpyrazole (Ir(ppz)3). Ir(ppz)3 is interesting blue phosphorescent complex but mer and even facisomers do not give emission at ambient temperature in solution. If irradiate enantiomeric merΔ after optical resolution, only facΔ and-Λ isomers were generated, but no generation of mer Λ was observed. These finding is important not only practical purpose but also basic chemistry of such materials. These also contribute stability and lifetime of the materials, that is one of the most important point of practical utilization. Less
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Research Products
(42 results)
