| 摘要: | 近幾年來，有機材料由於製程容易、低成本、機械可撓性及可於室溫下鍍在不同的基材上等特性，在物理、化學、光學、工程領域方面有吸引相當多的研究投入。 現在有機半導體材料用於有機發光二極體(OLEDs)及有機太陽電池(OPV Cells)大部分都具有共軛π電子結構的特色，例如: 8-羥基喹啉鋁(Alq3)及碳六十(Fullerene)。 經過廣泛的文獻閱覽後，很少文獻將對掌性的影響帶入光電製程中。因此，我們選擇具有對掌性和可撓性的分子-消旋型聯二萘酚((R,S)-(±)-BINOL)及其左右旋型鏡像物((R)-(+)-BINOL, (S)-(-)-BINOL)，同時它也具備有共軛π電子結構可做為我們研究的對象。 利用結晶工程技術，如降溫方法及揮發方法，可用來製備聯二萘酚(BINOL)-二甲亞碸(DMSO)的包合物, 此包合物的形成是藉由主-客分子間的O-H…S=O氫鍵所產生。除此之外，經由溶劑篩選法找出幾乎不能溶解聯二萘酚的溶劑-水分子(H2O), 我們將消旋型聯二萘酚((R,S)-(±)-BINOL)或左旋型聯二萘酚((S)-(-)-BINOL)固體預先溶解於二甲亞碸(DMSO)溶劑中，然後每次加入0.2毫升的水(H2O)或0.2毫升二甲亞碸(DMSO)經過光激發光(Photoluminescence, PL)的測試, 發現當溶液中水含量增加時，光激發光強度(PL intensity)隨之下降，此結果顯示水含量增加導致大量的消旋型聯二萘酚((R,S)-(±)-BINOL)或左旋型聯二萘酚((S)-(-)-BINOL)分子聚集而造成濃度消光(Concentration Quenching). 在固態相中，我們發現消旋型和左右旋型聯二萘酚分子(BINOL)和二甲亞碸(DMSO)形成的包合物(Inclusion Compounds)可使光激發光的強度(PL Intensity)增加和放射波峰(Emission Peaks)往較大的波長遷移，還有使激發波長範圍(Excitation Wavelength Range) ii 變寬。這是因為二甲亞碸(DMSO)極性分子嵌入聯二萘酚(BINOL)晶格中改變聯二萘酚(BINOL)相鄰最近分子間的距離，使濃度消光(Concentration Quenching)減弱，且增加 偶極-偶極(Dipole-Dipole)間的作用力。 相較於一般半體導製程中常用的混摻法(Doping Method)和混合法(Blending Method)，結晶工程的技術 (Crystal Engineering Techniques)是一種同樣會在不改變主分子的情況下，微調放光性質(Emission Properties)的新技術。 另外，我們藉由量測結晶分子幾合參數，如: 分子間的距離 (Intermolecular Distances)、二面角(Diheral Angles)、及氫鍵的長度(Hydrogen Bonding Lengths)，量化及探究光激發光與晶體結構的關係。 In recent years, organic materials have attracted much research in many fields, including physics, chemistry, optics, and engineering. These novel materials have exceptional features such as easy processing, low cost, mechanical flexibility, and low temperature deposition on variety of substrate materials. Nowadays, most of organic semiconductors used for organic light emitting diodes (OLEDs) and organic photovoltaic (OPVs) have conjugated π systems, such as Alq3 and C60. After studying an extensive of references, few papers introduced the chiral effect on opto-electronic processes. Therefore, we simply chose chiral and flexible molecules with a conjugated π system, racemic form of 2,2'-dihydroxy-1,1'-dinaphthyl (BINOL) and its (R)-(+)- and (S)-(-)-enantiomers, as model compounds to this research. Using the crystal engineering methods, such as a cooling and an evaporation method, we could prepare inclusion compounds formed between the host BINOL and the guest dimethyl sulfoxide (DMSO) by the O-H…O=S hydrogen bonds. In addition, using water as a bad solvent, we could prepare solutions of (R,S)-(±)-BINOL or (S)-(-)-BINOL solids dissolved DMSO solvent in advance then with addition of either 0.2-ml water or 0.2-ml DMSO each time to make a photoluminescence test and observed the increase water fraction content of a solution, the decrease photoluminescence intensity of either (R,S)-(±)-BINOL or (S)-(-)-BINOL solids. This result only reveals that increasing water content resulted in larger BINOL molecules aggregation to cause the concentration quenching. iv In solid phase, we observed that the inclusion compounds of a racemic form and enantiomeric forms of BINOL with DMSO all revealed that the emission peaks moved toward longer wavelength and the intensities enhanced upon photoluminescence. It is the observation that changing the intermolecular distances among nearest BINOL molecules and inserting DMSO (a polar solvent molecule) in the crystal lattice to make the decrease of concentration quenching and the increase of dipole-dipole interaction. Crystal engineering techniques would be novel techniques to tune the emission wavelength without changing the host molecule as compared to the doping method and blending method used in organic semiconductors. In addition, we provide the insight to understand the relationship between photoluminescence spectra and crystal structures by measuring their molecular crystal geometrical parameters, such as intermolecular distances, dihedral angles, hydrogen bonding lengths. |
