| Budget Amount *help |
¥8,400,000 (Direct Cost: ¥8,400,000)
Fiscal Year 2002: ¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2001: ¥4,500,000 (Direct Cost: ¥4,500,000)
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| Research Abstract |
This research was carried out to investigate the photodynamics for white luminescence in organic thin films composed of DCM, Alq, and PBD (or PPCP), which exhibit red, green, and blue luminescence, respectively. The results are summarized as follows;
1. HOMO-LUMO levels of PBD, Alq, and DCM possess type-I energy lineup, while those of PPCP and Alq type-II lineup.
2. Mechanism of white luminescence in PPCP/Alq double layer EL device was investigated, and a new device structure utilizing red photoluminescence (PL) of DCM is proposed.
3. PBD layers codoped with Alq and DCM exhibit white luminescence depending on the composition. The mechanism of white luminescence has been found to be energy transfer from PBD to Alq and to DCM, and also from Alq to DCM. Time constants for some of the above energy transfer were obtained.
4. Time-resolved PL was measured under the resonant excitation of the incident laser to the absorption of PBD or Alq. The result shows that for the more pure white luminescence the luminescence of DCM derived by the energy transfer from Alq is desirable.
5. Luminescence from DCM has been attributed to the relaxation from Alq with short time constant and from PBD at longer time constant.
6. No remarkable energy transfer has been recognized from PBD to Alq. When bothe PBD and Alq are excited, the molecule contribute to blue and green luminescence, respectively, and then the energy transfer to DCM results in red luminescence. DCM cannot be efficiently excited by photo irradiation.
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