本論文探討共軛高分子聚3-己基噻酚(Poly(3-hexylthiophene-2,5 -diyl, P3HT)的高分子奈米薄膜，在溶劑蒸氣退火的同時透過光罩照光，當共軛高分子在受到光激發後，會產生構型以及物理性質的改變，在亂度與自由能驅使下，形成可控制之薄膜內照光區與非照光區之間的分子流動現象。
我們以厚度為50 nm的雜接型P3HT(regiorandom, 簡稱RRa-P3HT)薄膜，在光學顯微鏡下，以線性圖樣的光罩進行光照，並同時施以甲苯溶劑之退火處理。我們藉由光學顯微鏡(optical microscopy, OM)及原子力顯微鏡(atomic force microscope, AFM)，觀察到此奈米薄膜在照光後，薄膜內高分子由亮區流到暗區，局部厚度會依光罩上的圖像而進行改變。因此我們可以利用光罩控制照光範圍和位置，藉由照光與非照光區間物理性質與亂度上的差異，形成光罩上所指定的特定圖樣。
除了厚度的變化之外，我們發現在溶劑退火前期，位在RRa-P3HT薄膜亮暗交界附近，會形成特異的高分子雙峰堆積或匱乏的厚度分布，而後隨著退火時間增長，共軛高分子會遷移到暗區中央形成較為單純的單峰分佈。我們首先改變照光過程中光學顯微鏡的對焦位置，驗證退火前期厚度分布的變異並非對焦造成的現象。針對雙峰分布的原因，我們量測雙峰圖樣表面積，並在體積守恆條件下計算中央區域假想單峰的表面積，比較兩者之差異。我們發現退火初期(2小時)雙峰轉換為假想單峰僅需1.54 nJ/m。而更長退火時間 (16小時)後，由單峰轉為假想雙峰則需要37.59 nJ/m，較前期趨往假想單峰所需的驅動力大了24倍。因此驗證雙峰形成的原因是表面能的驅動所致。更深入解釋，退火初期雙峰之形成，主要是推動亮區高分子移往暗區的驅動力，在高分子跨過暗區後消失，而在暗區內沒有高分子濃度的差異，不會有濃度擴散效應，所以在介面形成分子的堆積。但是此時高分子的運動仍能受毛細力驅動，由簡單表面積的計算，足證此毛細力作用的存在。另外，退火初期在接近邊界處的暗區所形成一個下陷的匱乏厚度分布曲線，乃因高分子鏈在進入暗區後，其構型由僵直化轉為柔軟，擴散移動能力增加，較堆積在邊界上正進入暗區的高分子移動速度較快，所以造成暫時性的局部分子匱乏現象。
此外，我們發現高分子薄膜在經由照光溶劑退火後有聚集而形成細小顆粒的現象：此種細小顆粒會隨著退火時間增長，其平均粒徑與高度會增加。但更進一步退火後，聚集顆粒的平均粒徑與高度反而減少。對於此聚集現象，我們認為高分子在受到照光激發後，主鏈鍵角扭轉，構型呈現僵直化，使得在高分子鏈移動過程中，易因分子鏈間的”碰觸”，藉著- interaction而”黏結”，又因高分子間的鏈交纏，累積為巨大的分子聚集結構，成為我們觀察到的細小顆粒。但這高分子鏈黏結所形成的分子聚集，其間的作用力小於如結晶高分子之間的鍵結作用，因此在溶劑的塑化過程中會因亂度效應而消解。所以隨著溶劑退火時間增長，此等暫態的分子聚集會逐漸減少，因而聚集顆粒在退火後期會消退甚至消失。
我們另以齊接式P3HT(regioregular, 簡稱RR-P3HT)進行相同實驗。由於RR-P3HT具高度規則性，其分子間立體障礙小、作用力強，排列較為緊密，溶劑分子不易進入RR-P3HT高分子間，因此在相同退火時間點下，高分子在亮暗區之間的移動，遠較分子結構雜亂的RRa-P3HT為慢。在光學顯微鏡及原子力顯微鏡觀察之下，發現退火時間要長達24小時後，薄膜上才有較明顯的光罩條紋。
此外，我們簡單探討當RRa-P3HT薄膜內混摻光惰性高分子(如聚苯乙烯，Polystyrene, PS)時，高分子在亮/暗區之間的運動。我們以膜厚70 nm的90% RRa-P3HT/10% PS薄膜進行研究。理論上我們預期混摻薄膜中有三類同時進行的分子流動：第一種是RRa-P3HT高分子因光激發引起自由能上升而由亮區移往暗區的流動；另外兩種則是因為亮區RRa-P3HT僵直化，使得退火處理時局部溶劑吸收量較暗區為多，高分子濃度下降，形成高分子(RRa-P3HT以及PS)由暗區往亮區的費克(Fickean)分子流。實驗結果發現高分子薄膜也會複製光罩的圖樣產生局部厚度變化，但和未摻雜PS薄膜不同的是，在此系統，亮區的厚度較高。參照以前陳威群和潘志華學長對MEH-PPV系統的研究結果，在摻雜系統的實驗中分子流動現象乃由PS由暗區流向亮區的分子流所壟斷。這是因為亮區僵直化的RRa-P3HT移動速度較暗區未受光激發的RRa-P3HT大幅下降，同時對於暗區RRa-P3HT，亮區是高自由能的區域，所以這兩種分子流遠小於PS分子流。此外，我們觀察到暗區有聚集現象產生的細小顆粒，在亮、暗區邊界處更為密集，其原因可能為上述三種分子流動在邊界產生分子局部沾黏與交纏的機率較高所造成。
最後，我們利用共軛焦螢光光譜儀，探討共軛高分子RRa-P3HT在照光溶劑退火下的流動對螢光光譜的影響。我們發現不論是暗區或亮區，PL強度在經過溶劑退火曝光處理2小時後，皆劇烈下降—亮區PL強度降為原始薄膜的12.6%，暗區則約為25.2% —並隨著實驗時間增長，PL強度持續下降；當退火時間長達16小時，亮、暗區PL強度分別僅剩原始薄膜的2.9%及0.8%，亮區PL強度略高於暗區的PL強度，其原因可能是亮區的高分子鏈段在受到照光後尚存有應力所致。同時，在退火處理下， PL也可能藍位移：在2小時退火後，亮區的PL波峰相較原始薄膜有明顯藍移約53 nm，在暗區則在退火8小時約有藍移36 nm。藉由共軛焦拉曼光譜看局部區域C=C訊號變化，我們發現退火2小時後亮區C=C訊號約為原始薄膜的42.6%；暗區則約為原始薄膜的83.4%，亮區高分子會因直接曝光造成裂解發生，使得C=C訊號劇烈下降，暗區雖沒有直接受到照光影響，但會受到高分子由亮區移往暗區的分子流動影響，使得C=C訊號下降。因此我們認為在亮區高分子會因曝光使得分子裂解的可能性大。而暗區C=C訊號的下降，可能是由亮區移入的RRa-P3HT所致。此外，參照以前劉奇京學長的研究論文結果，薄膜在經由溶劑退火後，其PL強度會因殘留應力下降而大幅下降，所以分子應力鬆弛效應，有可能也是退火處理後薄膜PL強度下降的另一個可能原因。

In this thesis, we explored the molecular behavior of conjugated polymer P3HT (Poly(3-hexyl thiophene-2,5-diyl) in nanofilms that underwent conformational and physical variations upon solvent annealing under light exposure through an optical mask so that molecular flows could form in a controllable fashion between the lighted and dark regions as driven by local free energy and the molecular entropy.
The experiments were conducted by using 50 nm thin films of regiorandom P3HT (RRa-P3HT) illuminated under an optical mask of line patterns in an optical microscopy, with the film simultaneously annealed in toluene vapor at room temperature. Employing an optical microscopy (OM) and atom force microscope (AFM), we observed that the RRa-P3HT molecules flowed from the lighted regions to dark regions and underwent local thickness changes in accordance to those on the optical mask. Hence, by lowering the molecular entropy of conjugated polymer with light absorption, we can produce specific patterns on ultrathin films by controlling the positions and areas with optical masks.
Other than changes of average thicknesses in the lighted or dark areas, we observed in early annealing of the unique topographic profiles of double peaks or local depression, arising from molecular pile-up or depletion, at the vicinities of the boundaries between the lighted and dark regions. These features, however, evolved with the annealing time into central single peaks as the polymer molecules moved into the centers of the dark regions. After excluding, with defocusing experiments, the effect of beam focusing for the double-peak distributions we contemplated its connection with surface tension by calculating the surface energies of the observed topographic profiles of single or double peaks and their corresponding hypothetical ones of the same volume. We found that in the early stage double peaks indeed had the lower surface energy, but by a mere ~1.54 nJ/m than the corresponding single peak at 2 hrs. At longer times, however, the situation reversed and the single peak became favorable with the energy difference widening to ~37.59 nJ/m at 16 hrs. Therefore, the formation of double peaks and their evolution were deemed to be resulted from the effect of surface energy. In further details, the initial double peaks were resulted from the local pileup of molecules created principally due to the lack of driving forces to bring the polymer further into the dark regions. Within the dark regions, the entropy forces that had brought the molecules to the boundaries had ceased to exist and there were no concentration gradients to sustain any Fickean flows. Nevertheless, as shown above, capillary forces still influenced the free energy inasmuch to drive the molecules into single peaks in the dark regions in order for favorable surface energies. By the same token, the depression at the edge of the dark region due to molecular depletion was due to a transient velocity difference between the light-rigidified polymer molecules that had not yet completely entered the dark region, which are sluggish, and those that had entered entirely and regained backbone flexibility for swift molecular movements.
Interestingly, we also observed the emergence of tiny molecular aggregates that grew in size with annealing time. These aggregates, however, diminished eventually. These transient aggregations were believably formed between polymer chains that had segments, or sections of segments, bounding with each other by the - interaction energy after the molecules went into contacted during the molecular exodus. The entangling long chain structures of the polymer molecules may effectively accumulate such polymer molecules into aggregates to the extent large enough to be observable. The molecules within each aggregate, however, were bounded only by weak forces and hence may dissolve again so that the aggregates subsided during further solvent annealing.
We also conducted similar experiments using the regioregular P3HT (RR-P3HT). Due to the tight packing between the stereo-regular molecules, plasticization by solvent became much more difficult and hence the flows between the lighted and dark regions were much slower. The topographic patterns were observable only after 24 hours annealing.
A diluted system of RRa-P3HT with optically inert polystyrene (PS), 90%:10%, was also investigated. Thicker films (70 nm) were used here for the sake of preventing disturbance by dewetting that prevailed in thinner, diluted films and may interrupt the molecular flows during the solvent annealing. Theoretically, there would be three types of molecular flows in this system: the first being the flows of the optically induced rigidified RRa-P3HT from the lighted regions to the dark, and the other two the Fickean flows of PS and RRa-P3HT, both from the dark regions to the lighted, arising from the concentration gradients due to enhanced solvent absorption in the lighted regions caused by light-induced entropy reduction. In this case, the nanofilms also underwent local thickness changes in mimicking the mask patterns, only that the molecules flows were reverse from that in the pristine RRa-P3HT, moving from the dark regions to the lighted. In fact, this was consistent with prior observations by Chen and Pan from our lab for which MEH-PPV, instead, was used for the similar experiment and it was concluded that the observed molecular flows were dominated by that of the PS molecules. The dominance by the optically inert PS, clearly, was due to the substantially reduced diffusion velocity of the rigidified RRa-P3HT and the higher free energy in the lighted regions for the RRa-P3HT. Moreover, tiny aggregates were prevalently observed in the dark regions and in the boundaries, which were believably arising from the greater probabilities of inter-chain interactions in the interplay of the three types of molecular flows.
Finally, we examined, by using a confocal spectrometer, the effects of the molecular flows on fluorescence behavior of the RRa-P3HT. Firstly, the photoluminescence (PL) intensity was found decreased substantially in both the lighted and dark regions, to 12.6% (lighted regions) and 25.2% (dark regions), after 2 hrs annealing, of that before the annealing. The decreases continued to only 2.9% (lighted regions) and 0.8% (dark regions) at 16 hrs. For sufficiently long annealing times, blue shifts were found accompanying the PL decreases: 53 nm (lighted regions after 2 hrs) and 36 nm (dark regions after 8 hrs). Further revealed by confocal Raman spectra, at 2 hrs annealing the C=C signal decreased to 42.6% (lighted regions,) and 83.4% (dark regions) of that before the annealing. The decreases of C=C bonding in the lighted regions, obviously, were caused by light-induced degradation. However, the decreases in the dark region were intriguing, but it may be influenced by the RRa-P3HT molecules diffused from the lighted regions. Moreover, as reported before by Liu from our group, the PL decreases may also be contributed from reduction of the residual stresses from solvent annealing. Likewise, the stronger emissions in the lighted regions at very long annealing times (16 hrs) were likely arising from the increases of segmental stresses of the light-rigidified RRa-P3HT chains.

摘要 I
Abstract VI
誌謝 VI
目錄 XII
圖目錄 XV
表目錄 XXI
第一章 簡介 1
第二章 文獻回顧 3
2-1旋轉塗佈 3
2-2 超薄膜的殘留應力 4
2-3高分子薄膜的除潤現象(dewetting) 10
2-4 共軛高分子除潤與發光行為影響 11
2-5 共軛高分子 12
2-5-1共軛高分子的電子結構及導電機制 13
2-5-2 Exciton、Excimer、Exciplexes和Polaron pair 16
2-5-3共軛高分子P3HT 18
2-5-4共軛高分子P3HT的拉伸 21
2-6光致變色材料介紹 24
2-6-1 光致變色物質的應用 26
第三章 實驗設置 27
3-1實驗材料 27
3-2實驗架構 29
3-3-1溶液的配製 31
3-3-2薄膜製備 31
3-3-3 照光溶劑退火實驗 32
3-3-4 試片封裝 32
3-4 儀器介紹與分析 35
3-4-1光學顯微鏡 35
3-4-2原子力顯微鏡 (Atomic Force Microscopy) 36
3-4-3 原子力顯微鏡整合共軛焦螢光光譜儀及偏極化拉曼光譜系統 38
3-4-4 共軛焦微拉曼光譜系統 40
第四章 結果與討論 43
4-1 照光影響 43
4-2 光罩實驗 47
4-2-1 光罩50 m照光的溶劑蒸氣退火實驗 47
4-2-2 雙峰現象的驗證 54
4-2-3 光罩5 m照光的溶劑蒸氣退火實驗 58
4-2-4 照光區域的aggregation探討 65
4-2-5 RRa-P3HT/PS混摻薄膜照光溶劑退火實驗 69
4-3薄膜樣貌之峰型變化的原因探討 71
4-3-1 原始峰型的函數回歸 72
4-3-2 假想峰型的函數表示 74
4-3-3單/雙峰轉換所需的表面張力計算 76
4-4 RR-P3HT光罩5 m照光的溶劑蒸氣退火實驗 83
4-5 共軛高分子RRa-P3HT的螢光光譜分析 85
第五章 結論 89
第六章 參考文獻 92
附錄 96

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