有機材料及無機奈米粒子之氫鍵超分子作用於光電材料之應用

Abstract

本論文研究方向為探討一系列包含有機材料及無機奈米粒子之氫鍵超分子作用 在有機光電材料為研究主軸。 第一部分，兩種主鏈包含2,7-carbazole和 fused-dithienothiophene環的共軛高分子在側邊懸掛acid-protected 和 benzoic acid 官能基 (PCA 和 PCB)，此系列高分子的吸收範圍約在300 nm-580 nm， 以作為太陽能電池的應用。此外也合成氧化鋅奈米粒子, 和表面改質含有吡啶官能基(ZnOpy)，大小約3-4奈米。ZnOpy奈米粒子當電子接受者取代部分PCBM，不但透過氫鍵與高分子PCB的benzoic acid產生超分子作用力，而且增加ZnOpy 奈米粒子在高分子PCB均勻的分散性。因此，在複合系統中， PCB/ ZnOpy/PCBM在重量1:0.05:1混摻時，在AM 1.5的標準太陽光照射下，最佳元件效率可達到0.55%，Jsc=2.11 mA/cm2，Voc=0.88 V，FF=29.4 %。 第二部分，我們利用Suzuki coupling reaction合成了以2,7-carbazole及fused dithienothiophene單元為分子主鏈的共軛型高分子(PCA, PCB, 和PCC ) ，此系列高分子的吸收範圍約在300 nm-550 nm。其中PCB主鏈側邊修飾有酸的保護基,而PCB的主鏈側邊修飾有酸的官能基,相互作為研究氫鍵效應的對照組,而且PCA, PCB, 和PCC 在電化學實驗氧化過程中有電致變色的性質，PCB有明顯的顏色變化(由橘變黑) ， X光繞射光譜儀(XRD)也可觀察到PCB的氫鍵結構有較高的結晶度，在小角度繞射區段可觀察到高分子主鏈層的層間距。且當與PCBM重量比 1：1混摻時，在AM 1.5的標準太陽光照射下，最佳元件效率可達到0.61%，Jsc= 2.26 mA/cm2，Voc=0.9 V，FF=29.8%。相較於高分子PCA 無氫鍵形成， PCB含有氫鍵結構其熱穩定性，結晶度，電致變色及太陽能電池轉化效率都因為PCB含有氫鍵結構而提高其性質。

第三部分,合成鑑定四個高分子(P1-P4)包含aryl-imidazo-phenanthrolines (AIP) 敖合基，其中修飾含有phenyl 和 fused-thiophene。高分子(P1-P4)在電化學氧化過程中顯示有電致變色的性質，另外，四個高分子(P1-P4) ，其中P3-P4高分子側邊修飾含有carboxylic acid的官能基和表面改質吡啶的氧化鋅奈米粒子混摻以形成奈米複合材料加以討論氫鍵效應。利用紫外光光譜儀(UV) ，螢光光譜儀(PL) ， 時間解析光激螢光光譜儀(TRPL) ， X光繞射光譜儀(XRD) ， 穿透式電子顯微鏡(TEM)加以分析氫鍵的效應。P3/ZnOpy, P4/ZnOpy 奈米複合材料因為氫鍵結構顯示有較高的結晶度，此外，由於氧化鋅和高分子的超分子作用力，從TEM圖可得知含有氫鍵的奈米複合材料(P3/ZnOpy, P4/ZnOpy)其分散性較好。 最後一個部份，本研究中擬開發新的非金屬系(metal-free)有機光敏化染料，所設計的染料分子是以tris-dodecyloxyphenyl-與cyanoacrylic acid為電子予體與受體，而主要是合成修飾不同的電子予體或電子予體與電子受體間之共軛橋樑(conjugated spacer)。在共軛橋樑設計上，主結構是以dithieno[3,3-b:2’,3’-d] thiophene，其中再分別含有dithiophene以及bithiazole來延長共軛系統長度，以提升電荷轉移的能力和加強吸收光譜的強度和範圍。由於含有液晶性質的分子，具有較良好的分子排列性，藉由引入一般運用在液晶上的片段液晶分子結構trioxyphenyl-，加上共平面性較好的融合環dithieno[3,3-b:2’,3’-d] thiophene，來探討所設計的分子在染料敏化型太陽能電池上的應用與特性。其中所設計的染料分子化合物16其光轉換效率為3.72% (Voc = 0.58V, Jsc=9.98 mA/cm2, FF =0.65)，在相同條件下，已可達N719效率(7.04%)的53%，雖然效率不及以往文獻triarylamine為電子予體的效率，但成功的開發出新一系列不同於以往的電子予體染料分子，未來可在分子的設計上，對於電子予體上做取代基的轉換，以利於光轉換效率的提升。

First, Two kinds of novel conjugated polymers containing 2,7-carbazole, thiophene, and fused-dithienothiophene rings as backbones bearing acid-protected and benzoic acid pendants (PCA and PCB, respectively) were utilized for organic solar cell applications. The absorption spectra of these polymers (in both solutions and solid films) showed an absorption range at 300–580 nm. Furthermore, ZnO nanoparticles were synthesized and surface-modified with pyridyl surfactants (ZnOpy) to be ca. 3–4 nm. The pyridyl surfactants of ZnOpy nanoparticles (as electron acceptors to partially replace expensive electron acceptor PCBM) not only induce supramolecular interactions with benzoic acid pendants of polymer PCB via H-bonds, but also enhance the homogeneous dispersions of ZnOpy nanoparticles in polymer PCB. Thus, the ternary systems of PCA,PCB/ZnOpy/PCBM in weight ratios of 1:0.05:1 and 1:0.1:1 were investigated in bulk heterojunction polymer solar cells (PSCs). Under the standard illumination of AM 1.5, 100 mW/cm2, the best power conversion efficiency (PCE) of the PSC cell containing a polymer blend of PCB/ZnOpy/PCBM=1:0.05:1 reached PCE=0.55%, with Jsc=2.11 mA/cm2, Voc=0.88 V, and FF=29.4%. Second, Three kinds of dithienothiophene/carbazole-based conjugated polymers (PCA, PCB, PCC), which bear acid-protected and benzoic acid pendants in PCA and PCB, respectively, were synthesized via Suzuki coupling reaction. Interestingly, PCA, PCB, and PCC exhibited reversible electrochromism during the oxidation processes of cyclic voltammogram studies, and PCB (with H-bonds) revealed the best electrochromic property with the most noticeable color change. According to powder X-ray diffraction (XRD) analysis, these polymers exhibited obvious diffraction features indicating bilayered packings between polymer backbones and π-π stacking between layers in the solid state. Compared with the XRD data of PCA (without H-bands), H-bonds of PCB induced a higher crystallinity in the small-angle region (corresponding to a higher ordered bilayered packings between polymer backbones), but with a similar crystallinity in the wide angle region indicating a comparableπ-πstacking distance between layers. Moreover, based on the preliminary photovoltaic properties of PSC devices (PCA, PCB, and PCC blended individually with PCBM acceptor in the weight ratio of 1:1), PCB (with H-bonds) possessed the highest power conversion efficiency of 0.61% (with Jsc = 2.26 mA/cm2, FF = 29.8%, and Voc = 0.9 V). In contrast to PCA (without H-bands), the thermal stability, crystallinity, and electrochromic along with photovoltaic properties of PCB were generally enhanced due to its H-bonded effects. Third, Four novel metallo-polymers (P1-P4) containing aryl-imidazo-phenanthrolines (AIP) ligands (incorporated with phenyl and fused-thiophene cores) were synthesized and characterized. Interestingly, P1-P4 exhibited electrochromism during the oxidation processes of cyclic voltammogram studies. In addition, P1-P4 were blended with surface-modified pyridyl-ZnO nanoparticles (ZnOpy as proton acceptors) to form nanocomposites, where P3-P4 were functionalized with carboxylic acid pendants (as proton donors) on the polymer backbones to study for the H-bonded effects on surface-modified ZnOpy nanoparticles. In order to investigate the nanocomposites containing metallo-polymers P1-P4 and surface-modified ZnOpy nanoparticles, nanocomposites P1-P4/ZnOpy were characterized by UV-visible (UV) absorption spectra, Fourier transform infrared (FTIR), photoluminescence (PL) spectra, time-resolved photoluminescence decays, X-ray diffraction (XRD) measurements, and transmission electron microscopy (TEM) analyses. In contrast to nanocomposites P1/ZnOpy and P2/ZnOpy, higher crystallinities with a distinct layered-structure of H-bonded nanocomposites P3/ZnOpy and P4/ZnOpy in XRD measurements were induced by the introduction of surface-modified ZnOpy nanoparticles to metallo-polymers P3 and P4, correspondingly. Furthermore, due to the supramolecular interactions of surface-modified ZnOpy nanoparticles with metallo-polymers P3-P4, TEM images verified that ZnOpy nanoparticles were more homogeneously distributed in nanocomposites P3-P4/ZnOpy (with H-bonds) than those in P1-P2/ZnOpy (without H-bonds), respectively. Finally, In this study we synthesized three metal-free organic dyes (Cpd11, Cpd16, and Cpd22) featuring 3,4,5-tris(dodecyloxy)phenyl and cyanoacrylic acid moieties as electron-donor and electron-acceptor/anchoring units, respectively, linked through various dithienothiophenyl conjugated spacers. Cpd16 exhibits mesomorphic properties, confirmed through polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction (XRD), due to the appropriate ratio of the lengths of its flexible chain to its rigid core. Molecular modeling of Cpd16, and its d-spacing determined from XRD data, verified the existence of a tilt angle in the SmC phase. Among these metal-free organic dyes, a dye-sensitized solar cell incorporating Cpd16 exhibited the best performance, presumably because of its better packing and its mesomorphic properties; the power conversion efficiency was 3.72% (Voc = 0.58 V; Jsc = 9.98 mA cm–2; FF = 0.65) under simulated AM 1.5 irradiation (100 mW cm–2).