Synthesis, Properties and Applications of Novel π-Conjugated Materials with Coplanar Core

寡聚噻吩(α-oligothiophene)是常用於有機光電材料的化合物，但由於噻吩環間的翻轉常造成吸收波長無法有效紅移以及分子間π-π作用力的降低；在本論文中，我們利用簡易的合成方法成功得到一系列以碳原子橋接的寡聚噻吩化合物，由X-ray晶體結構可發現此類分子具有高度共平面性；藉由該系列的TT分子作為核心進行衍生化，可順利得到新染料TT1N；雖然新染料在吸收特性上較類似結構YY1有明顯提升，但HOMO能階過高以及缺乏疏水性長碳鏈的存在，造成元件表現不如染料YY1，未來在芴基上官能化長碳鏈，應該能夠提升元件效率；另一方面，藉由此系列的平面結構BTB進行對稱性衍生化，可得到雙酸基化合物BTB-1；此分子具有立體空間龐大、吸收光譜廣泛…等特色，雖然不具有強推電子基，但太陽能電池表現上仍相當不錯，為目前少數非胺類有機染料具有高效率的例子。 最後一部分，我們利用類似想法，成功的將多電子性噻吩環引入三聚茚(truxene)的共軛中心，並進一步合成出一系列新型之C3對稱化合物。透過測量化合物之光物理、熱穩定和電化學性質與純碳氫骨架之三聚茚T1比較，可進一步探討分子結構與性質間的關係。α-Oligothiophenes are one of the most prominent organic semiconducting materials and have been widely studied in electronic devices. However, deviation from planarity may decrease conjugation in oligothiophenes through torsion about single bonds or S-syn defects. Furthermore, theoretical studies predict that the molecular packing is not optimized for maximum charge carrier mobility. Herein, we report unprecedented synthetic routes for the synthesis of a novel class of carbon bridged oligothiophenes with coplanar molecular configuration. We characterized the nearly flat molecular structures of TT and TTB by using X-ray crystallography. These coplanar cores have also been functionalized as metal-free organic sensitizers TT1N and BTB-1 used for dye-sensitized solar cells (DSSCs) and given PCEs of 4.29% and 5.83%, respectively. On the other hand, we utilized similar idea to synthesize a novel class of star-shaped coplanar molecules with C3 symmetry. To the best of our knowledge, this is the first report about the synthesis of truxene analogues embedding thiophene rings as functional constituents. We anticipate that this new C3-symmetric molecule would drastically reconstitute the properties of its hydrocarbon parent due to the presence of electron-rich thiophene rings