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標題: | 支鏈效應於予體-受體交替共軛高分子的物理性質以及形態學之研究 Side Chain Effects on the Physical Properties and Morphologies of Donor-Acceptor Alternating Conjugated Polymers |
作者: | Chien-An Chen 陳建安 |
指導教授: | 童世煌 |
關鍵字: | 予體-受體,奈米微結構,堆疊方向,支鏈工程,寡聚醚,自組裝,結晶, donor-acceptor,nanostructure,packing orientation,side chain engineering,oligo(ethylene glycol),self-assembly,crystallization, |
出版年 : | 2019 |
學位: | 博士 |
摘要: | 予體-受體交替共軛高分子被廣泛應用於各種光電元件,諸如高分子太陽能電池、有機場效應電晶體、有機發光二極體。對於這些應用來說,予體-受體交替共軛高分子的電荷遷移率與元件效率表現呈現高度正相關的關係。有兩個關鍵因素影響著電荷遷移率,“奈米微結構的規整度”以及“高分子堆疊方向”。支鏈工程被認為是一種非常有力的技術以創造高度規整奈米微結構的高分子以及調控高分子的堆疊方向。此技術通常涵蓋以下三種參數:(1)支鏈長度(2)支鏈位向(3)支鏈種類。雖然已有大量的支鏈效應的研究對於各種予體-受體交替共軛高分子,但是這些個別的支鏈效應研究是由不同的研究團隊所執行而且難以進行比較。因此,提供一個全面的支鏈效應研究包含上述的三種支鏈參數是非常必要的。在本論文中,我們不僅提供了一個全面的支鏈效應研究還展示了兩種策略透過合理的高分子結構設計利用支鏈工程得到高度規整奈米微結構的高分子以及調控高分子的堆疊方向。
為了執行全面的支鏈效應研究以及創造擁有高度規整奈米微結構的高分子,我們成功合成了八種寡聚噻吩-噻吩并吡咯二酮(3T-TPD)的共軛高分子伴隨著不同的支鏈位向(朝外以及朝內)、支鏈種類(十二碳鏈以及四乙二醇(TEG))、支鏈長度(八碳鏈、六碳鏈、四碳鏈)。這些高分子的光學性質、電化學性質、熱性質以及自組裝行為被系統性地討論。對於這些3T-TPD的共軛高分子來說,擁有支鏈朝外的高分子展現較優異的π-π堆疊相較於支鏈朝內的高分子,導致支鏈朝外的高分子堆疊形成層板(LAM)結構。然而,支鏈朝內的高分子伴隨著差的主鏈平面性堆疊出極為罕見的六角最密堆積(HEX)結構。對於支鏈種類效應來說,不論是支鏈朝外的高分子以及支鏈朝內的高分子具備TEG支鏈展示出較長波長的紫外-可見光吸收光譜以及更高度規整的奈米微結構相較於具備十二碳支鏈的高分子。這些結果指出較為柔軟的TEG支鏈可以有效提升高分子的自組裝行為表現。對於支鏈長度效應來說,越長的支鏈越能幫助支鏈朝外的高分子排列成越高度規整的LAM結構。相反地,越短的支鏈越適合支鏈朝內的高分子自組裝成越高度規整的HEX結構。 更進一步,為了深入研究寡聚醚(OEG)支鏈效應,我們成功合成一系列寡聚噻吩-異靛藍素高分子,P3TI以及P4TI,具備不同數量以及位置的OEG支鏈。這些高分子的光學性質、熱性質以及自組裝行為被系統性地討論。我們發現PnTI的高結晶性是源自於堆疊良好的寡聚噻吩單元。對於僅具備碳鏈支鏈的高分子而言,P3T(R8)I(Rb-16) 以及 P4T(R8)I(Rb-16),這些高分子展現出最高的結晶性但是最大的dπ-π相較於其他具備寡聚醚支鏈的高分子。這些高分子的π-π堆疊行為是由寡聚噻吩單元所主導,因為在異靛藍素上體積龐大的碳鏈(Rb-16)阻礙了異靛藍素的緊密堆疊。當這個異靛藍素上體積龐大的碳鏈(Rb-16)被柔軟且體積小的OEG支鏈取代後,例如P3T(R8)I(E)、P3T(E)I(E)、P4T(R8)I(E)以及P4T(E)I(E),這些高分子的π-π堆疊行為轉變成為異靛藍素單元主導,因為體積小的OEG可以使得異靛藍素堆疊得比寡聚噻吩更緊密,最終犧牲了原本堆疊良好的寡聚噻吩單元。因此,即使這些高分子展現出較小的dπ-π,他們的結晶性也是相對的弱。除此之外,我們發現了OEG支鏈的重要功能-藉由調控高分子的結晶性進而調控高分子的堆疊方向。舉列來說,OEG支鏈成功使得P3TI高分子從輕微緣向排列(edge-on oreintation)改變為完全面相排列(face-on oreintation),此完全面向排列的高分子非常適合應用於太陽能電池。 我們的研究不僅提供了策略以設計具備高度規整奈米微結構的予體-受體交替共軛高分子亦提供了一個方針以調控高分子的堆疊方向,我們期望此研究能對於發展高效能的高分子光電元件有所幫助。 Donor-acceptor alternating conjugated polymers (D-A CPs) are widely used in optoelectronic devices, such as polymer solar cells (PSCs), organic field-effect transistors (OFETs), and organic light emitting diodes (OLEDs). For those applications, charge mobility of D-A CPs and device performance are in high-positive correlation. There are two critical factors influence the charge mobility, “regularity of nanostructure” and “polymer packing orientation”. Side chain engineering is a powerful technique to create polymers with highly ordered nanostructure and to control the polymer packing orientation. The technique usually involves three parameters: (1) side chain length, (2) side chain location and (3) side chain type. Although there are lots of side chain effect studies in D-A CPs, those studies are carried out from different research groups and each individual side chain effect study is difficult to do comparison. Therefore, to provide a comprehensive side chain effect study including three parameters is necessary. In this dissertation, we not only provided a comprehensive side chain effect study but also demonstrated two strategies to obtain the polymer with highly ordered nanostructure and to control the polymer packing orientation respectively through rational design of polymer using side chain engineering. In order to do a comprehensive side chain effect study and to create polymers with highly ordered nanostructure, we successfully synthesized eight oligothiophene-thienopyrroledione (3T-TPD) based CPs with different side chain location (outward and inward), type (dodecyl and tetraethylene glycol (TEG)), and length (octyl, hexyl, and butyl). Those polymer’s optical properties, electrochemical properties, thermal properties, and self-assembly behavior had been systematically studied. For 3T-TPD based CPs, outward series polymers show better π-π stacking than inward series polymers, leading to pack into lamellae (LAM) structure. However, inward series polymers with poor coplanarity of backbone pack into rarely found hexagonal (HEX) structure. For side chain type effect, both the outward series polymers and inward series polymers with TEG chains show longer wavelength of λmax of UV-Vis absorption and higher order of the nanostructure than the polymers with dodecyl chains. These results reveal that the more flexible TEG chain can enhance the self-assembly behavior of the polymers. For side chain length effect, the outward series polymers have higher order of LAM with longer side chain. On the contrary, shorter side chain is more suitable for inward series polymers to self-assemble into higher order of HEX. Furthermore, in order to investigate oligo(ethylene glycol) (OEG) side chain effect in depth, we successfully synthesized a series of oligothiophene-isoindigo based polymers, P3TI and P4TI, by varying amount and location of OEG side chain. Their optical properties, thermal properties, and morphologies are systematically studied. High crystallization capability of PnTI polymers is mainly contributed from the stable stacking of oligothiophene unit. For the polymers with all alkyl side chains, P3T(R8)I(Rb-16) and P4T(R8)I(Rb-16), they show the highest crystallinity but the largest dπ-π among each series polymers. Their π-π stacking behavior is dominated by oligothiophene unit because the bulky alkyl side chains (Rb-16) on isoindigo unit prohibit close packing of isoindigo unit. As the bulky Rb-16 side chains on isoindigo unit are replaced by linear and flexible OEG side chains, i.e. P3T(R8)I(E), P3T(E)I(E), P4T(R8)I(E), and P4T(E)I(E), their π-π stacking behavior is dominated by isoindigo unit because isoindigo unit with small size of OEG side chains can stack more closely than oligothiophene unit, resulting in a sacrifice for stable stacking of oligothiophene unit. Therefore, even though they show relatively short dπ-π, their crystallinity is relatively low. In addition, OEG side chains are capable of controlling the packing orientation of the polymers by adjusting the crystallinity of the polymers. For instance, OEG side chains change the packing orientation of P3TI polymers from slightly edge-on orientation of P3T(R8)I(Rb-16) to fully face-on orientation of P3T(R8)I(E) and P3T(E)I(E) which is suitable for polymer solar cell application. Our studies not only provide a strategy to design a D-A CPs with highly ordered nanostructure but also provide a guide to control the polymer packing orientation for potential application in high performance optoelectronic devices. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/7740 |
DOI: | 10.6342/NTU201904150 |
全文授權: | 同意授權(全球公開) |
電子全文公開日期: | 2024-10-17 |
顯示於系所單位: | 高分子科學與工程學研究所 |
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ntu-108-1.pdf 此日期後於網路公開 2024-10-17 | 11.73 MB | Adobe PDF |
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