Synthesis、Characterization and Simulation of Novel Carbazole Derivative Organic Dyes

本研究以donor-π bridge-acceptor為主要的設計架構，合成出一系列的有機染料－NW、NHW、NS與NHS。Donor以carbazole為主，共軛長度的延伸以thiophene為主，搭配強拉電子基benzothiadiazole，最後以常見的cyanoacetic acid當作注入基團。合成之中間體與化合物以核磁共振儀與質譜儀鑑定其分子結構，搭配紫外光-可見光光譜儀與循環伏安法量測染料分子的吸收係數、最大吸收波長、能隙值與HOMO、LUMO的能階值。最後以理論基礎DFT和TD-DFT輔助分析染料的光學與電化學性質，結構最佳化構形和分子軌域電荷分佈情形。 吸收光譜的表現上，染料的確隨著共軛長度的延伸而使得吸收譜線愈紅位移，能隙值愈小。導入推電子基carbazole也會使得吸收譜線愈紅位移。從CV圖可以發現，在不延伸共軛長度的前提下(NHW與NHS)，推電子基carbazole對於HOMO能階值的提升很有限，因為carbazole不是一個強推電子基，不過還是可以看到HOMO值有些微的提升，LUMO值有些微的下降。在延伸共軛長度的前提下(NW與NS)，HOMO值雖然也有些微的提升，但LUMO值隨著能隙變得更小而降低。從以上的結果得知延伸共軛長度，能有效的縮減能隙，讓分子的LUMO值隨之降低。理論計算出的結果，可以發現不管是導入donor或是延伸共軛長度，皆可以提升HOMO值，與有效的降低能隙，達到更紅位移的效果。吸收光譜的理論計算波長相對大小與實驗值實際測得的數據相對大小趨勢一致。A series of new organic dyes, 2-cyano-3-(5-(7-(5-(9-ethyl-9H-carbazol-3-yl) thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)acrylic acid (NW), 3-(5- (7-(5-(9H-carbazol-9-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-2-cyanoacrylic acid (NHW), 2-cyano-3-(5-(7-(5''-(9-ethyl-9H-carbazol-3-yl) -3''-hexyl -2,2''-bithiophen-5-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)acrylic acid (NS) and 3-(5-(7-(5''-(9H-carbazol-9-yl)-3''-hexyl-2,2''-bithiophen 5-yl)benzo[c][1,2,5] thiadiazol-4-yl)thiophen-2-yl)-2-cyanoacrylic acid (NHS), were designed and synthesized based on the structure of donor-π bridge-acceptor. Herein, carbazole, benzothiadiazole and cyanoacetic acid were used as donor, acceptor and anchoring group, respectively, in these dye molecules. All intermediates and final products were fully characterized using 1H-NMR, 13C-NMR and ESI mass. UV-vis spectrometer was employed to measure the extinction coefficient, absorption spectrum, and optical bandgap of N series organic dyes. The energy levels of HOMO and LUMO were also determined by cyclic voltammetry. Experimental results clearly indicated that the extension ofπ-conjugation length and the incorporation of carbazole as donor red-shifted the absorption spectrum and lowered the optical bandgap. Both NHW and NHS have similar conjugation length but the incorporation of carbazole in them had little effect on up-shifting the HOMO level. This is probably because carbazole is not a strong donor group. Moreover, comparing NW and NS showed the increment of conjugation length mainly down-shifted the LUMO level but kept HOMO almost unchanged, thus leading to the decrease in bandgap. Additionally, the theoretical calculations of these dye molecules were performed in vacuum system. All the electronic absorption characteristics and HOMO, LUMO energy level were calculated by TD-DFT- B3LYP/ 6-31G / + / (d ) level of theory. We V can get the optimized structure and molecular orbital about electron distribution condition of the ground state and exicted state. The calculated HOMO level would be raised by inducing donor and extending the conjugation length. The absorption spectrum is in consistent with the experiment data