含并二噻吩液晶分子之合成與鑑定及其在有機薄膜電晶體之應用

Abstract

本研究合成出平面并二噻吩為中心的六環液晶分子，簡稱為C12-PTTT。分子設計上以噻吩為中心核，最外側則設計苯環加烷氧基延長共軛長度，以及增加分子柔軟度。所合成之液晶分子以旋轉塗佈製備有機薄膜電晶體，在未修飾自組裝層前，其元件電荷遷移率最高為6.14 × 10-4 cm2V-1s-1。修飾三種自組裝層OTS、ODTS、HMDS後，以OTS之修飾對於材料C12-PTTT之載子遷移率提升最大，其提高至2.44 × 10-3 cm2V-1s-1。 為求提升載子遷移率，本論文研究兩個不同於傳統製程方式，其一為應用為在介電層二氧化矽上刷一層聚酰亞胺，以此方法製作之有機薄膜電晶體其載子遷移率提升至1.88 × 10-2 cm2V-1s-1 。另外的方式為於二氧化矽介電層上製備聚二甲基矽氧烷微流管道，並搭配材料液晶之特性製備薄膜電晶體元件，以C12-PTTT材料製備之元件其載子遷移率高達3.51 × 10-2 cm2V-1s-1；此外以同樣的方法，使用另一雙噻吩蒽為中心核之液晶材料，簡稱12PADT，其所製備之微流道薄膜電晶體載子遷移率由傳統旋轉塗佈元件之 2.77 × 10-2 cm2V-1s-1提升至1.31 cm2V-1s-1。

In this study, we synthesized a planar liquid crystal based on thieno [3,2-b] thiophene which added a phenyl and a thiophene unit to extend conjugated length (C12-PTTT) . In addition, two alkoxy groups were added to aromatic ring to gain additional liquid crystal phase and increase solubility. The obtained C12-PTTT compound was used to fabricate organic field effect transistor (OFET) devices. For the OFET device with self-assembled monolayers, its mobility increases from 6.14 × 10-4 cm2V-1s-1 to 2.44 × 10-3 cm2V-1s-1. Besides the traditional spin coating process, two methods were used to enhance the mobility of OFET device. The first method was applying a rubbed polyimide on the top of SiO2 layer. For this method, the mobility of its OFET device is enhanced to reach 1.88 × 10-2 cm2V-1s-1. The other method was using polydimethylsiloxane (PDMS) mode to fabricate microchannel on the top of SiO2 layer. The mobility of the OFET device based on C12-PTTT is further enhanced to reach 3.51 × 10-2 cm2V-1s-1 which is highest value for the OFET devices based on C12-PTTT. We also used microchannel method to fabricate a OFET device using another anthracenedithiophene-based liquid crystal compounds, i.e.,12PADT. It’s mobility reach the highest value of 1.31 cm2V-1s-1 which is much higher than that (2.77 × 10-2 cm2V-1s-1) of its traditional OFET device fabricated by spin coating process.