5,6-雙氟-2,1,3-苯并硒二唑拉電子基與噻吩推電子基之共聚合物及其隨機共聚合物之合成與鑑定及其在有機太陽能電池之應用

Abstract

本研究致力於合成低能隙共軛高分子材料，研究其材料之光學、電化學及分子間堆疊特性，並將其應用於有機半導體元件，如有機場效電晶體 (OFET) 與有機薄膜高分子太陽能電池 (OPV)。 本研究第一部分將5,6-雙氟-2,1,3-苯并噻二唑中的硫取代成硒原子，合成出5,6-雙氟-2,1,3-苯并硒二唑，並將其與四噻吩 (quaterthiophene, Th4) 共聚得低能隙共軛高分子。藉由如此清楚比較在高分子中硒原子與硫原子對其之性質差異。此高分子在光學及電化學分析上皆可測量到擁有較窄的能隙，而用此高分子所做的太陽能元件之光電轉換效率為6.06%及有機場效電晶體之電荷遷移率為0.12 cm2V−1s−1，為目前含2,1,3-苯并硒二唑之高分子表現最好的材料。 本研究第二部分將5,6-雙氟-2,1,3-苯并噻二唑與5,6-雙氟-2,1,3-苯并硒二唑結合，並使用多種單體比例合成出多個共聚物，並分析單體比例對高分子性質、分子間排列及元件表現之影響。結果發現隨著5,6-雙氟-2,1,3-苯并硒二唑在高分子中比例上升可得到較窄的能隙，而在分子排列上，雖然多單元共聚物之lamellar stacking下降，但由於原子大小與電負度的差異使得多單元共聚高分子擁有較好的π-π stacking，最後用P1和P2所做的太陽能元件之光電轉換效率分別為5.20%及5.63%，有機場效電晶體之電荷遷移率分別為0.46 cm2V−1s−1及0.32 cm2V−1s−1。

In this study, we synthesized low band gap (LBG) polymers and study their optical, electrochemical and molecular packing. The obtained polymers were used for optoelectronic applications, such as organic field-effect transistors (OFETs) and organic polymer photovoltaics (OPVs). In the first part of this study, we replaced the sulfur atom in 5,6-difluoro-benzo-2,1,3-thiadiazole (FBT) with the selenium stom. The synthesized 5,6-difluoro-benzo-2,1,3-selenadiazole (FBSe) was copolymerized with quaterthiophene (Th4) unit.The obtained polymer possesses lower bandgap deduced from CV analysis. The best OPV device based on this polymer showed the power conversion efficiency (PCE) value of 6.02 % and its OFET mobility of 0.12 cm2v-1s-1. In the second part of this study, we combine two acceptor units, FBT and FBSe. A series of copolymers base on FBSe, FBT and Th4 units were synthesized to investigate the inflences of FBSe:FBT ratio on polymer properties, solid-state morphology and device performance. Copolymers with higher FBSe ratios were found to have narrower Eg. Because of size and electronegativitydifferences of selenium and sulfir atoms, the FBSe : FBT ratio further affects the structural regularity of the conjugated chains, and their self-assembly behaviors. The random ternary copolymers degrade the order of the lamellar stacking, but possess more ordered π-π stacking. The OPV devices based on P1 and P2 show PCE value of 5.20 % and 5.63 %. The OFET devices show the mobilities of 0.46 and 0.32 cm2v-1s-1.