含共軛吡啶質子受體懸掛基氫鍵側鏈高分子之超分子組裝於有機光電材料之應用

Abstract

本論文研究方向為探討一系列包含共軛吡啶質子受體氫鍵側鏈高分子之合成，利用超分子組裝的特性，在三大方向在有機光電材料為研究主軸。 第一個部份，成功的聚合出以Sonogashira coupling 和Wittig-Horner反應合成出的兩種發光吡啶單體，進而將發光高分子與不同的質子予體錯合形成超分子側鏈與交聯高分子錯合物，而此氫鍵高分子錯合物之液晶及發光性質可以被吡啶共軛段及不同質子予體所調整。然而，含有較小pKa 值的質子予體可以讓氫鍵高分子錯合物得到紅位移的發光。 第二個部份，成功的將吡啶單體與苯酸同分異構物（即，para-、meta-、和ortho-）共聚出液晶及發光氫鍵高分子。藉由FTIR、DSC、XRD鑑定其氫鍵的形成。此外，此氫鍵高分子與其錯合物之液晶及發光性質不但與氫鍵效應有關，也被共聚不同位置的苯酸同分異構物所影響。接著，結合不同改質的奈米金球（酸或無酸改質），隨著加入的奈米金球濃度變化，自身氫鍵（含有吡啶與酸）與無自身氫鍵高分子（含有吡啶與酸保護）的奈米複合材料，其PL發光強度將有不同程度的驟息。進一步，利用TEM觀察自身氫鍵與無自身氫鍵高分子混合改質奈米金球，而其微觀現象和PL驟息程度相互呼應，解釋了自身氫鍵高分子的酸與改質金球的酸相互競爭所造成。 第三個部份，描述兩種不同吡啶基比例系列的發光高分子超分子奈米複合材料，即，側面甲基高分子和側面甲氧基高分子，進而與質子予體的奈米粒子發展出可區分的聚集現象在TEM影像裡。質子受體高分子不但顯示了高程度聚集，而且可以使質子予體的奈米粒子均勻分散。並且，酸表面改質的奈米金球與側面甲氧基的高分子之間的氫鍵作用力，比起無酸表面改質的奈米金球更有效的影響了發光驟息的現象。此外，與側面甲基高分子比起來，側面甲氧基高分子更容易的捕捉酸表面改質的奈米金球在超分子組裝的奈米複合材料裡。吡啶基質子受體高分子與質子予體的奈米粒子的氫鍵作用力可以解釋相似的發光驟息效應。我們以實驗數據建立了在不同的吡啶基高分子的指數方程式，進而可以預測Stern-Volmer常數。發展了多種奈米複合材料包含兩種發光高分子(甲氧基和甲基高分子)與表面改質的奈米金球(酸和無酸改質)，進而展示出差異性的聚集現象在TEM影像。未來我們可以基於奈米金球發光驟息的回復性，在化學感測與生醫感測研究領域作進一步的發展。 最後一個部份，氫鍵側鏈高分子與染料型質子予體結合（含末端氰酸基）。氫鍵高分子錯合物得到了從440至462 nm寬廣的吸收能帶，且其光學能隙大約在2.11-2.25 eV之間。結果發現，在AM 1.5G、100 mW/cm2的模擬太陽光下，將合成出之氫鍵高分子錯合物與PCBM（[6,6]-phenyl C61-butyric acid methyl ester）混合為主動層材料，成功地以1:1 w/w的混合比例得到一具有短路電流3.17 mA/cm2、開路電壓0.47 V、填充因子34%及最高之光電轉換效率0.50%之有機太陽能電池。

First, two H-bonded acceptor polymers and were successfully prepared by polymerization of fluorescent pyridyl monomers, which were synthesized via Sonogashira coupling and Wittig-Horner reactions. Supramolecular side-chain and cross-linking polymers (i.e., H-bonded polymer complexes) were obtained by complexation of light-emitting H-acceptor polymers with various proton donor (H-donor) acids. Mesogenic and photoluminescent (PL) properties of light-emitting H-acceptor polymers can be adjusted not only by the central structures of the conjugated pyridyl cores but also by their surrounding non-fluorescent H-donor acids. Redder shifts of PL emissions in H-bonded polymer complexes occurred when the light-emitting H-acceptor polymers were complexed with H-donors having smaller pKa values. Second, a series of PL and liquid crystalline (LC) self-H-bonded side-chain copolymers consisting of pyridyl H-acceptors and isomeric acid H-donors (i.e., para-, meta-, and ortho-benzoic acids) were synthesized. Supramolecular H-bonded complexes were also obtained by mixing the photoluminescent H-acceptor homopolymer with isomeric H-donor homopolymers. The formation of H-bonds was confirmed by FTIR, DSC, and XRD measurements. Moreover, PL and LC properties of the H-bonded copolymers and complexes were affected not only by the H-bonding effect of the supramolecular structures but also by the acid-substituted positions of isomeric H-donors. In combination with different functionalized gold nanoparticles (which bear acid or acid-free surfactants), the emission intensities of nanocomposites containing self-H-bonded copolymer (bearing both H-acceptor and H-donor moieties) and non-self-H-bonded copolymer (bearing acid-protected moieties), respectively, were quenched to different extents by varying the concentration of gold nanoparticles. The copolymeric H-acceptors and surface-modified gold nanoparticles demonstrated diverse morphological and PL quenching effects on the supramolecular architectures of nanocomposites, which result from competition between the H-donors from the acid pendants on copolymers and the acid surfactants on gold nanoparticles. Third, this approach is exploring hydrogen-bonded (H-bonded) suparmolecular assembled behavior via both TEM and fluorescence quenching studies through organic solvent dissolving and evaporating processes. Different lateral methyl- and methoxy-substituted groups with pyridyl terminus of fluorescent side-chain polymers, it performed that the H-bonded interactions affect the fluorescence quenching effectively upon the addition of surface-modified gold nanoparticles bearing acid and acid-free surfactants in the fluorescence titrations experiments. We demonstrated that homopolymer PBOT1 has the highest Ksv constant in the compared fluorescent side-chain polymers. In addition, we established the exponential equation to predict Stern-Volmer constant in various pyridyl units of polymers from the experimental information. TEM studies displayed that interesting H-bonded suparmolecular behavior of addition into the carboxylic acid units of surface-modified gold nanoparticles. It is clearly observed that homogeneously gold nanoparticles distributions are on the fluorescent side-chain polymers. Thus, the TEM morphologies of H-bonded architectures demonstrate the versatility of the self-assembled processes in supramolecular nanocomposites of H-acceptor polymers and surface-modified gold nanoparticles. Finally, novel supramolecular side-chain polymers were constructed by complexation of H-acceptor polymers, i.e., side-chain conjugated polymers containing pyridyl pendants, with low-band-gap H-donor dyes (bearing terminal cyanoacrylic acids) in a proper molar ratio. H-bonded polymer complexes exhibited broad absorption peaks in the range of 440-462 nm with optical band-gaps of 2.11-2.25 eV. The PSC device containing H-bonded polymer complex blended with PCBM (1:1 w/w) gave the best preliminary result with an overall power conversion efficiency (PCE) of 0.50%, a short-circuit current of 3.17 mA/cm2, an open-circuit voltage of 0.47 V, and a fill factor of 34%.