Large n-heteroacene derivaties : synthesis, characterization and application as n-type and ambipolar semiconductos

• Main Author: Wang, Zilong
• Other Authors: Zhang Qichun
• Format: Theses and Dissertations
• Language: English
• Published: 2018
• Subjects: DRNTU::Science::Chemistry::Organic chemistry::Aromatic compounds; DRNTU::Engineering::Materials::Microelectronics and semiconductor materials::Nanoelectronics and interconnects
• Online Access: http://hdl.handle.net/10356/73485
• Institution: Nanyang Technological University

Organic π-conjugated materials have attracted much attention in recent years because these materials have already shown several great advantages over inorganic semiconductors, such as low-cost, flexibility, and variability of the properties. This is why organic low-bandgap compounds have been considered to be next generation semiconductors. Although great achievement in developing p-type organic semiconductors have been witnessed, the progress in searching n-type and ambipolar organic semiconductors has fallen behind the p-type ones. Thus, developing n-type and ambipolar organic semiconductors is of great significance. N-heteroacenes, derived from the classic p-type semiconductors called oligoacenes, have been proven to be an efficient pathway to approach novel n-type and ambipolar organic semiconductors. Especially large N-heteroacene derivatives with longer conjugations can provide more possibilities for strong π-π interactions, and have come into the sight of scientists, recently. However, the research of large N-heteroacene derivatives is still far from sufficient to verify the potential and possibilities. Thus, this thesis mainly focuses on the research of large N-heteroacene derivatives, and it contains the following parts: Firstly, two large N-heteroacene derivatives were designed and synthesized through employing a pyrene bridge and triisopropylsilyl substituents. These as-prepared two large N-heteroacene derivatives are easy to crystallize and have good stability as well as solubility. They show n-type semiconductor behaviors in photoelectrochemical (PEC) cells. Secondly, a pyracyclene unit was employed as the bridge to build up stable large N-heteroacene derivative. This N-heteroacene derivative shows ambipolar semiconductor behaviors in the PEC cells for water splitting. Thirdly, two extra-long large N-heteroacene derivatives were designed and synthesized with fifteen and twenty six-membered rings annulated in one row, respectively. The fifteen-ring one has been successfully confirmed by single crystal X-ray diffraction. Fourthly, a quinone unit is employed as the bridge to extend the conjugation of the large N-heteroacene derivatives. Two large N-heteroacene derivatives are designed and synthesized with six and seven six-membered rings conjugated in one row. The extended conjugation can greatly change the molecules stacking structure without changing the molecular orbital energy levels. They have deep LUMO energy levels and show n-type semiconductor behavior in thin film transistors. Finally, some reconnaissance research is also introduced in the last chapter. Some ideas and prospects are also presented. In conclusion, this thesis focuses on the design and synthesis of large N-heteroacene derivatives and the characterization. Especially through the single crystal X-ray diffraction method, molecular structures, molecules stacking modes and the relationship between molecular structure and properties are well studied. As n-type or ambipolar semiconductors, the behaviors of the N-heteroacene derivatives in organic field-effect transistor and photoelectrochemistry cells are explored.