Synthesis And Characterization Of N-heteropentacenes For Organic Semicoductors

A series of π-conjugated N-hetero-pentacene derivatives were designed and synthesized successfully. The OFET properties for these N-hetero-pentacene molecules were also studied. The main purpose of this research is to understand the effects of nitrogen atoms introduced into the TIPS-pentacene skeleton, and halogen atoms attached around the periphery of the TIPS-pentacene on the properties of different organic semiconductors. The effects of the number, position of the nitrogen and halogen atoms are investigated. Theoretical calculations were used to provide insights to the role of different parameters to the OFET properties of the synthesized molecules. The main contents of this thesis include:1. Pyrazine rings were introduced into the pentacene terminal rings to give the new7V-hetero-pentacene compounds, including6,13-bis-(triisopropylsilylethynyl)-1,4-diazapentacene and6,13-bis-(triisopropylsilylethynyl)-1,4,8,11-tetrazapentacene. The structure and property relationships have been studied. These molecules show good stability and layered π-π stacking in their single-crystals. Compared with TIPS-pentacene, the HOMO and LUMO energy levels of these molecules are significantly lowered, while the energy gap remain almost the same. The OTFT results showed that the electron mobilities of these molecules are increased dramatically; however, the hole mobilities are decreased.2. A comparative study on a series of nitrogen containing pentacenes were conducted. Theoretical investigations provide insights to their structure-property relations. We calculated the energy level, reorganization energy (λ), ionization energy (IE) and electron affinities (EA) by using DFT-based methods. The result showed that the λ, IE, EA increased with the increasing number of nitrogen and halogen atoms. The findings of this work provides a general guideline for designing stable ambipolar and n-type organic semiconductors materials.