論分子構形與末端取代基對固態結構的影響

Abstract

在有機共軛分子中，可分為三維 (3D) 共軛分子和一維 (1D) 共軛分子，其中，三維共軛分子是透過將共軛分子修飾到立體的球體分子 (核心) 外圍而成；一維共軛分子則是由共軛主鏈所構成。目前，三維共軛分子的研究著重在修飾不同特性的官能基於核心上，以得到各種性質的三維共軛分子，而較少對於三維共軛分子的構形與固態形貌進行研究；另外，至今，一維共軛分子已發展出許多體系，但如何有效且簡便地合成具有雙極性的一維共軛分子仍是個未解決的問題。因此，在本博士論文研究中，將針對三維共軛分子的構形對其固態形貌之影響進行研究。此外，發展出一簡便合成雙極性一維共軛分子的方法，並探究其分子之性質。 在第一部分的研究中，合成出富勒烯之六加成物 (C12T2-FHA, T2-FHA)，並探究其的構形傾向與固態形貌，發現三維共軛分子之外圍官能基的分子間作用力較弱時，傾向形成星形構形並自組裝成介穩態的蜂窩形陣列，反之，具有強分子間作用力的外圍官能基則傾向形成柱狀構形，和自組裝成具有六方晶格的樹枝狀晶體。第二部分，透過一簡便之合成策略，將 3-ethylrhodanine (RD) 修飾到 diketopyrrolopyrrole (DPP) 之共軛主鏈末端，得到一具有雙極性的一維共軛分子，並且此分子 (DPPT-RD) 可以形成高取向性且無結晶多型態的晶體陣列，其元件效率μh為 2.16 × 10-2 cm2/Vs、μe為 7.27 × 10-2 cm2/Vs。 最後，我們將 DPP 引用到三維共軛分子上，合成出DPPC6-FHA 及 DPPH-FHA，由於 DPP 的吸光範圍落在可見光，所以此分子為一可吸收可見光的巨球型分子 (吸光球型分子)，並且此吸光球型分子的形狀、大小與金奈米粒子相近，因此，可完全共混在一起，其薄膜態中無金奈米粒子之聚集產生。此外，從第一部分的研究得知：藉由溶劑焠火，可使三維共軛分子從星形構形的蜂巢狀結構轉變成柱狀構形的六方晶格之晶體。因此，此研究將透過此分子的構形改變，以期產生因分子形狀差異性之相分離，誘導出具有規則結構之金奈米粒子，以應用於高科技領域。

The organic conjugated molecules include 3D conjugated molecules which are constructed with a spherical core and peripheral arms and 1D conjugated small molecules which are built up with continuous conjugated backbone. Until now, a variety of 3D conjugated molecules have been developed, however, the conformational preferences and the solid-state structures of the molecules still is a complicate issue. Moreover, obtaining an ambipolar 1D conjugated small molecules by a simple way still is a challenging issue. Thus, in this study, we investigated the influences of molecular conformation of 3D conjugated molecules on supramolecular assembly structure. In addition, we develop a simple strategy to synthesize the 1D small molecules and investigated the solid-state morphology and charge transport properties of the molecules. First, our study reveals that the degree of intra-molecular interactions among the peripheral units will affect the conformation of 3D conjugated molecules. With weaker intra-molecular interaction of peripheral functional groups, the molecules keep star conformation and form metastable honeycomb array. On the contrary, with stronger intra-molecular interaction of peripheral functional groups, the molecules change into rod conformation and form a stable crystal with hexagonal lattice. Second, we develop a simple synthetic strategy that added dye units to the end of the conjugated backbone of diketopyrrolopyrrole (DPP). The 1D small molecules (DPPT-RD) was synthesized which has appropriate EHOMO and ELUMO for the hole and electron injection from the Au source-drain electrodes. Moreover, DPPT-RD can form crystal arrays with good lattice orientation and without polymorphism. Furthermore, DPPT-RD display ambipolar characteristic with μh and μe reaching 2.16×10-2 and 7.27×10-2 cm2 V-1 s-1, respectively. From these two experiments, we introduced the DPP unit to the peripheral of 3D conjugated molecules (DPPC6-FHA, DPPH-FHA). Since the absorbance range of DPP is on visible light, DPPC6-FHA and DPPH-FHA can be considered as absorbance giant spheres. Moreover, the shape and size of the molecules are similar to the gold nanoparticles, thus both can completely blended together. In addition, from previous study, the 3D conjugated molecules can form honeycomb arrays with star-conformation, after solvent annealing it can change into hexagonal lattice structure with rod-conformation. Thus, in this study, we use the property of conformation changeable of 3D conjugated molecules to induce regular packing gold nanoparticles.