二維分子αβ-和βα-四噻吩萘異構物之分子的合成設計和性質與有 機太陽能電池之應用

Abstract

本論文成功設計出一種新穎的二維平面分子之合成方法，並成功地合成出六環熔合二維平面分子αβ-tetrathienonaphthalene (αβ-TTN) 與βα-tetrathienonaphthalene (βα-TTN)。透過選擇性地導入烷基側鏈於α-或β-aNDT結構片段上，並先後經由PtCl2催化分子內單邊合環反應，再與DDQ進行Scholl氧化合環反應，於錫化後即可得到電子予體Sn-αβ-TTN與Sn-βα-TTN。其分別與含電子受體之單體Br-DTFBT 及Br-DTDPP在鈀金屬催化下進行Stille聚合反應，可得到四種新穎的低能隙共軛高分子P-αβ-TTNDTDPP、P-αβ- TTNDTDTFBT、P-βα-TTNDTDPP與P-βα-TTNDTFBT，並應用於有機高分子太陽能電池。四種低能隙高分子中，αβ-TTN系列與βα-TTN系列之高分子之平均分子量及溶解度有很大的差異，其可能與分子間的堆疊有關。在光學性質上，我們發現αβ-TTN系列相較於βα-TTN系列的高分子有較低的光學能隙值 (P-αβ-TTNDTDPP = 1.46 eV V.S. P-βα-TTNDTDPP = 1.48 eV, P-αβ-TTNDTFBT = 1.71 eV V.S. P-βα-TTNDTFBT = 1.75 eV)。另一方面，電學性質上電學能隙質亦顯現出相同的趨勢 (P-αβ-TTNDTDPP = 1.40 eV V.S. P-βα-TTNDTDPP = 1.48 eV, P-αβ-TTNDTFBT = 1.67 eV V.S. P-βα-TTNDTFBT = 1.70 eV)。太陽能電池元件應用上，P-βα-TTNDTDPP有較優良的元件表現，其電子元件為正結構 (ITO/PEDOT:PSS/Active layer/Ca/Al)。在加入3 v%的DIO作為添加劑以優化元件效率後，Jsc值可從1.66 mA/cm2有效提升至6.00 mA/cm2，並得到Voc為0.64 V與FF為68.5 %，達到提升2.6倍之光電轉換效率2.63 %，由此可看出DIO在元件的表現上扮演了很重要的角色。

We have successfully developed a novel synthetic method for preparing two-dimensional and planar molecules. Coplanar αβ-tetrathienonaphthalene (αβ-TTN) and βα-tetrathienonaphthalene (βα-TTN) with two-dimensional and six-fused-aromatic-ring frameworks were thus stnthesized. Installation of alkyl groups on α-aNDT or β-aNDT moieties were carried out, followed by PtCl2-catalyzed intramolecularcyclization and DDQ-promoted Scholl oxidative cyclization. Subsequent to stannylation, Sn-αβ-TTN and Sn-βα-TTN were obtained successfully. Both compounds were copolymerized with Br-DTFBT and Br-DTDPP respectively by Pd-catalyzed Stille co-polymerization to furnish 4 low band-gap copolymers, P-αβ-TTNDTDPP, P-αβ-TTNDTDTFBT, P-βα-TTNDTDPP, and P-βα-TTNDTFBT. αβ-TTN-based copolymers all have lower optical band-gap than βα-TTN-based copolymers. (P-αβ-TTNDTDPP = 1.46 eV V.S. P-βα-TTNDTDPP = 1.48 eV, P-αβ-TTNDTFBT = 1.71 eV V.S. P-βα-TTNDTFBT = 1.75 eV) A similar trend was also found for the electrical band-gap. (P-αβ-TTNDTDPP = 1.40 eV V.S. P-βα-TTNDTDPP = 1.48 eV, P-αβ-TTNDTFBT = 1.67 eV V.S. P-βα-TTNDTFBT = 1.70 eV). When employed in solar cell applications, P-βα-TTNDTDPP exhibited a Jsc of 6.00 mA/cm2, a Voc of 0.64 V, an FF of 68.5%, and the best PCE value of 2.63% (ITO/PEDOT:PSS/Active layer/Ca/Al) with DIO as a processing additive. The comparison device without treatment of DIO showed a low PCE of 0.73% and a low Jsc of 1.66 mA/cm2. Therefore, the presence of DIO plays a significant role in enhancing the device performance.