本論文主要利用雙層薄膜拉伸法，進行機械應力與形變對共軛高分子光電性質影響之研究。所謂雙層薄膜拉伸法，乃指利用可進行局部頸縮形變的玻璃態高分子薄膜做為基材，上疊欲進行拉伸研究之共軛高分子薄膜，雙層薄膜經妥善界面接合後一起拉伸，利用合適的厚度比例，可使上層之高分子薄膜因下層薄膜的局部形變，而能進行大尺度的局部應力拉伸探討。實驗中，下層層薄膜為Polystyrene(PS)或是Polycarbonate(PC)，而上層薄膜為1.以不同濃度摻雜於PS之共軛高分子MEH-PPV，及2.具有不同側鏈的聚噻吩共軛高分子P3HT、P3EHT、P3BT，以探討分子間作用力對機械應力促進共軛高分子光致發光增益的作用。從實驗結果可以看到，共軛高分子薄膜的發光增益隨著局部應力上升而大約成指數上升。當1%MEH-PPV混摻99%PS的薄膜局部應力達220MPa時，纖化區內的發光增益可達89倍。P3EHT有著聚噻吩共軛高分子系列中最小的分子間作用力而在受力拉伸後有最高的26倍發光增益。應力的施加使得共軛高分子鏈段處於拘束的狀態，局部形變區內共軛高分子鏈的電荷捕捉能力下降，亦即應力抑制了charge-phonon coupling，因此我們可以看到發光增益。接著我們利用共軛焦微螢光光譜儀觀察受拉伸薄膜的各個區域，發現MEH-PPV和聚噻吩共軛高分子在局部形變區域中有著截然不同的行為。隨著MEH-PPV/PS比例變大，局部形變區相對於彈性形變區的藍位移也越大。我們則在聚噻吩系列的共軛高分子樣品中看不到此藍位移。最後我們利用飛秒時間解析上轉換系統，反推薄膜在不同區域中皮秒時間尺度的時間解析光譜。從重建的時間解析光譜我們可以看到不管100%MEH-PPV或是70%MEH-PPV/30%PS，發光峰隨時間紅移的速度皆隨著所受應力的增加而減緩。另外從delay time 對強度關係進行fitting後的結果發現MEH-PPV具有至少兩個能量逸散的機制，且較短時間的decay constant很明顯地隨著應力的增加而上升。上述兩點也呼應前面提到拉伸應力的施加使得高分子鏈處於拘束的狀態，進而抑制了電荷的捕捉和non-radiative relaxation的發生。

In order to have a better knowledge of the impact of mechanical stress and deformation on optoelectronic behavior of conjugated polymers, “two-layer structure stretching” is used in this thesis. In “two-layer structure stretching”, glassy state polymer is used as a substrate which can undergo local necking deformation. The substrate is then topped with polymers we are interested in. Not until these two layers are firmly attached to each other are we going to stretch this structure. With some adequate thickness ratios, top layer is greatly stretched due to the deformation of bottom layer. In our experiments, polystyrene and polycarbonate were used as a substrate. We top the substrate with (1) different ratio of MEH-PPV to PS (2) polythiophenes with different side chains. 89 times of PL enhancement was recorded as stress goes up to 220MPa for 1%MEH-PPV /99% PS case. P3EHT has the weakest intermolecular interaction among P3EHT, P3HT, and P3BT, thus it has the highest PL enhancement. It is the suppression of electron-phonon interaction of molecular segments that leads to the huge PL enhancements. A significant difference between MEH-PPV and polythiophene series is found under the confocal PL. We observe PL peak shifts in film and craze region for MEH-PPV cases, whereas we see no PL peak shifts for polythiophene series. We then use time-resolved up-conversion technique in probing different region of MEH-PPV/PS films, so that we can rebuild the time-resolved PL spectrum on a picosecond timescale. From the time-resolved spectrum, we observe a decrement of the rate of red-shift no matter in 100% MEH-PPV or 70% MEH-PPV/30% PS. We found at least two energy decay mechanism from the fitting curve of delay time versus intensity. The shorter decay time constants increase dramatically in highly stretched region comparing to longer ones. These two phenomenon are both the evidence of the suppression of charge trapping and non-radiative relaxation.

目錄 8
圖目錄 12
第一章 簡介 20
第二章 文獻回顧 22
2-1 共軛高分子介紹 22
2-1-1 共軛高分子介紹 22
2-1-2 共軛高分子的摻雜效應 23
2-2 高分子薄膜機械性質和形變機制 26
2-1-1 高分子的彈性形變區 26
2-1-2 高分子的纖化區 27
2-1-3 高分子的微頸縮機制 28
2-3拉伸對共軛高分子發光行為的影響 30
2-4 MEHPPV超快時間解析光譜 31
第三章 實驗方法 33
3-1實驗材料 33
3-1-1 高分子 33
3-1-2 有機溶劑 35
3-2雙層結構薄膜製備 37
3-2-1不同濃度系統 雙層結構薄膜 MEH-PPV/PS + PS 37
3-2-2不同濃度系統 雙層結構薄膜MEH-PPV/PS + PC 38
3-2-3 高濃度系統雙層結構薄膜P3HT、P3EHT、P3BT+PS 40
3-3拉伸模具和實驗方法 41
3-4 封裝製程 42
3-5儀器介紹與分析 44
3-5-1光學顯微鏡 (OPTICAL MICROSCOPY) 44
3-5-2螢光光譜儀(PHOTOLUMINESCENCE SPECTROMETER) 45
3-5-3原子力顯微鏡 (ATOMIC FORCE MICROSCOPY) 46
3-5-4共軛焦螢光光譜儀、飛秒時間解析螢光上轉換系統 48
3-6高分子薄膜微觀機械性質計算 51
3-7 不同區域之光致發光增益分析 58
第四章 結果與討論 60
4-1雙層高分子薄膜結構拉伸試驗 61
4-1-1巨觀雙層結構表面形貌 62
4-1-3雙層結構局部形變區深寬比和上層薄膜膜厚的改變 66
4-2雙層結構薄膜在局部形變區的機械性質探討 71
4-3 拉伸共軛高分子之發光性質探討 75
4-3-1-1 不同濃度MEH-PPV/PS薄膜受拉伸處理引起之光致發光增益 75
4-3-1-2聚噻吩共軛高分子P3HT、P3EHT、P3BT薄膜受拉伸處理引起之光致發光增益 81
4-3-2-1 MEH-PPV/PS薄膜局部形變區之光致發光增益分析 84
4-3-2-2聚噻吩共軛高分子P3EHT、P3HT、P3BT薄膜局部形變區之光致發光增益分析 87
4-5共軛焦微螢光光譜 89
4-5-1不同濃度MEH-PPV/PS雙層結構薄膜之共軛焦微螢光光譜 92
4-5-2 MEH-PPV/PS共軛焦微螢光光譜的分峰-探討分子團聚情形 96
4-5-2聚噻吩共軛高分子P3EHT、P3HT、P3BT雙層結構薄膜之共軛焦微螢光光譜 101
4-6 MEH-PPV分子團聚強度及P3EHT、P3HT、P3BT單位晶格強度討論 102
4-7 雙層高濃度系統與過往單層摻雜系統的比較 107
4-8-1雙層結構薄膜經拉伸之後的飛秒時間解析(TIME-RESOLVED)光譜 111
4-8-2由時間上轉換方法測不同區域之exciton生命週期 119
第五章 結論 126
第六章 參考文獻 128

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