研究生: |
鄭元瑋 Cheng, Yuan-Wei |
---|---|
論文名稱: |
分子機械應力對共軛小分子與高分子光電及拉曼光譜行為之影響 The influence of mechanical stresses on photoluminescence and Raman polarization behavior of conjugated small molecules Rhodamine 6G and polymer MEH-PPV |
指導教授: |
楊長謀
Yang, Chang-Mou |
口試委員: |
戴子安
Dai, Chi-An 蔣酉旺 Chiang, Yeo-Wan 郭昌恕 Kuo, Chang-shu |
學位類別: |
碩士 Master |
系所名稱: |
工學院 - 材料科學工程學系 Materials Science and Engineering |
論文出版年: | 2017 |
畢業學年度: | 105 |
語文別: | 中文 |
論文頁數: | 93 |
中文關鍵詞: | 共軛高分子 、光致發光 、機械應力 、電子與聲子的交互作用 、分子拘束 、濃度淬滅 |
外文關鍵詞: | conjugated polymers, photoluminescence, mechanical stress, electron-phonon interactions, molecular constraints, concentration quenching |
相關次數: | 點閱:5 下載:0 |
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由最近的研究中發現,共軛高分子分子鏈在拉伸後,會因為分子鏈處於分子拘束的狀態,而能有效地降低分子鏈上的電荷捕捉能力,使電子和聲子的交互作用減少,造成螢光效率大幅的上升。本研究延用此方法在發光小分子Rhodamine 6G (R6G)上,將R6G製成薄膜後,利用雙層分子極限拉伸法,探討小分子的機械拉伸對光電效率的影響。我們發現在分子拉伸後,小分子R6G的螢光PL強度仍然有上升,但是沒有高分子這麼顯著,原因是小分子容易由拉伸狀態鬆弛,造成分子上的應力,無法有效的累積,以達到分子拘束的效果。由濃度效應和微觀拉曼光譜的研究,我們發現外加機械應力在低濃度小分子R6G上的效果,和作用在高分子上相似,但當濃度提高時,小分子的concentration quenching逐漸上升,而我們所觀察到高濃度R6G之PL發光增益,是因為拉伸造成局部濃度下降,減低concentration quenching所引起的。
The molecular confinement effect via mechanical stretching of producing dramatic PL enhancements as recently observed in conjugated polymers was examined for one of the small molecule counterpart, the rhodamine 6G (R6G). By invoking a special two-layer stretching method on copper grids with molecular-scale stress analysis, we found that R6G, upon mechanical stretching, exhibited only small enhancements of the PL efficiency. At low concentration, this effect was attributed to suppression of electron-phonon interactions. At high concentration, the enhancements were arising from decreases of concentration quenching rather than suppression of electron-phonon coupling that dominates in the molecularly confined conjugated polymers. This work hence concludes that simple mechanical stretching is incapable to produce for small molecules the sufficient segmental stresses required for reduced electron-phonon coupling for the enhancements of optoelectronic efficiencies.
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