Design and Synthesis of New Green Dopants for Electroluminescence

• Main Authors: Zong-Wei Tsai, 蔡宗韋
• Other Authors: Chin Hsin Chen
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/72711292597887553122

碩士 === 國立交通大學 === 應用化學系 === 88 === Coumarin-6 is one of the well-known green laser dyes which has a fluorescence emission peaked around 510 nm. For display application, it is desirable to have a green emission slightly shifted to the red. This can be achieved by substituting a julolidyl moiety at the C-7 position of coumarin ring. But, most of these emissions tend to shift further to the red at high concentration due to molecular aggregation. One of the ways to alleviate this concentration broadening effect is to increase the steric bulkiness of the dye. Part I of the thesis deals with the design and attempted synthesis toward one such sterically bulky molecule, 10-(3,3-dimethyl-3H-2-indol- yl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrid-o[3,2,1-ij]quinolin-11-one. In the synthesis of the target compound, the intermediate, ethyl 2-(3,3-dimethyl-2,3-dihydro-1H-2-indolylidenyl)acet- ate, was tautomerized to the more stable form, ethyl 2-(3,3-dimethyl-2,3- dihydro-1H-2-indolylidenyl)acetate. Although tried with many different conditions, it did not lead to the compound as expected. This result led us to propose another synthetic scheme which might circumvent the tautomerism problem. Part II of the thesis is focused on the design and synthesis of a new functionalized green fluorescent coumarin (C-545TPhBr), for the purpose of end capping the PF8 blue fluorescent polymer to study its energy transfer. In order to maintain the emissive characteristics of the host polymer, the conjugation between the dopant molecule and the polymer has to be disrupted. Unfortunately, free rotation of the phenyl group on the designed molecule led to a much reduced fluorescence emission. Introduction of substituent to prevent free rotation of the phenyl group is proposal for enhancing the fluorescence quantum efficiency of this new dopant.