有機太陽能電池用―含5,6-雙氟-2,1,3-苯并噻二唑拉電子基與噻吩、呋喃及硒吩推電子基之共聚合物及其含紫質側鏈之共聚合物之合成與鑑定

Abstract

本研究致力於研究低能隙共軛高分子材料，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)。本研究提出兩個不同的低能隙高分子設計方法，分別為非共價鍵作用力探討及同族元素之影響兩個部分。 本研究第一部分將氟導入2,1,3-苯并噻二唑 (BT) 的5,6號位置，如此可以大幅提升分子間非共價鍵的作用力，進而提升固態分子間堆疊的規則性。將其與四噻吩 (quaterthiophene, Th4) 共聚所得低能隙共軛高分子在固態也顯現規則的固態堆疊。用此高分子所做的太陽能元件之光電轉換效率為6.82%及有機場效電晶體之電荷遷移率為0.29 cm2V−1s−1，為目前2,1,3-苯并噻二唑與四噻吩所形成共聚合物中表現最好的材料。 本研究第二部分將呋喃、噻吩及硒吩分別導入共軛高分子中，分別導入共軛高分子中，研究同族元素對於共軛高分子之影響。結果發現主要的影響為高分子的能隙大小及高分子之結晶性，隨著原子序變大，能隙有縮小及結晶性上升的情況，因此三個高分子之中以含有硒吩 (PTh2SeFBT) 元件表現最好，其電荷遷移率為0.36 cm2V−1s−1及光電轉換效率為7.34%。

This research is aimed to enhance the performances of low band gap (LBG) polymer in the optoelectronic applications, such as organic field-effect transistors (OFETs) and organic polymer photovoltaics (OPVs). Two strategies were used to design high performance LBG polymers, including promoting of the intermolecular non-covalent interaction strength and effect of congeners of the state-of-art LBG polymers. In the first part of this study, 5,6-difluoro-benzo-2,1,3-thiadiazole acceptor unit was copolymerized with quaterthiophene donor unit (PTh4FBT). This fluorinated unit was used to enhance the non-covalent interaction and the packing order of polymer chains in the aggregation state. The best OPV device based on this obtained polymer shows the power conversion efficiency (PCE) value of 6.82% and its OFET mobility of 0.29 cm2v-1s-1. In the second part of this study, furan and selenophene units were used to replace two thiophene units in the copolymers to study the effect of congeners. Other two copolymers (PTh2OFBT and PTH2SeFBT) were synthesized. Reduction of the bandgap and increase of crystallinity were observed in the selenophene containing polymer. Therefore, the device performances of PTh2SeFBT were the highest among the three polymers. The OPV and OFET devices based on PTh2SeFBT reveals the PCE value of 7.34% and 0.36 cm2v-1s-1. However, PTh2OFBT shows increase of the bandgap and reduction of crystallinity. So the OPV and OFET devices based on PTh2OFBT shows PCE value of 0.21% and mobility of 10-3 cm2v-1s-1.