理論計算探討分子設計：苊衍生物為基本結構之高效能P型有機半導體材料

Density-Functional Theory Calculation: High Performance p-Channel Organic Semiconducting Materials Based on Aacenaphthene Derivatives

劉威賜(Wei-Szu Liu)

指導教授 ： 郭明裕

國立暨南國際大學/科技學院/應用化學系/碩士(2009年)

摘要

本篇利用密度泛函定理(DFT)理論計算的方式研究發展有機半導體材料，以苊(Aacenaphthene)為基礎，設計一系列苊的衍生物，根據描述電荷傳輸的Marcus理論計算其分子的重排能、電荷耦合值、游離能及其電荷遷移率。其中，以 Benzo[1,2-k;4,5-k’]difluoranthene (BDF)為基礎結構的衍生物最具有潛力，在針對這些分子探討鹵素取代基對分子重排能的影響，並作分子軌域模型、鍵長變化量的分析，讓我們可以更清楚了解分子在電荷傳輸時的特性。另外，在分子重排能的部分，由於外部重排能較接近實際電荷傳輸的情況，因此我們在本篇研究中加入外部重排能的探討，發現周遭分子的作用力會因為侷限的效應降低分子重排能。
由於本篇目標是發展穩定、可溶、高效能的P型有機半導體材料，以利於應用在液相製程的有機場效電晶體，目前有Triethylsilyl-Anthradithiophene (TES-ADT)和Difluorine-Triethylsilyl-Anthradithiophene (DF-TES-ADT)等分子材料達到這樣目標，因此將本篇研究的分子材料與之比較，由電子結構分析研究結果發現DH-BDF的分子重排能非常小，僅僅只有86meV，主要是因為分子具有較多未鍵結(non-bonding)的特性。從游離能的計算結果與TES-ADT和DF-TES-ADT比對，DH-BDF很可能也是可於空氣中穩定操作的P型半導體材料，而且DH-BDF本身也有烷基長碳鏈取代，因此，DH-BDF也可以液相製程達成為穩定且高效能的P型有機半導體材料。

關鍵字

有機半導體材料 ； 電荷傳輸 ； 鹵素取代基 ； 分子軌域模型 ； 重排能 ； 電荷耦合值 ； 有機場效電晶體

並列摘要

Charge transport of organic semiconductors for a series of acenaphthene derivatives was theoretically studied using Marcus theory, the internal reorganization energies (λ+) associated with the transfer of holes in a series of acenaphthene derivatives were calculated to investigate the influence of substituents. The Ionization potentials (IP) were examined because they are relevant to the stability of the hole. The electronic coupling (t) and charge mobility (μ) of acenaphthene derivatives is also estimated based on the single crystal structure. And then, we can make more understanding the effect of halogenation for the electronic character from the result of frontier orbital and bond length analyses. The goal of this work is developing novel, soluble, stable and π-stacked organic semiconductors for the solution processing OFET. The internal reorganization energies (λ+) for hole transfer in BDF is 86 meV. Frontier orbital analyses demonstrated that the small λ+ values are due to the nonbonding character of the BDF frameworks. As well as the λ+ values, the calculated adiabatic IPs indicate that these frameworks are p-type air-stable materials. A comparison with silylethynylated ADTs indicates that DH-BDF may be air-stable. Of these, DH-BDF with two hexyl side chains and π-stacking promises to be soluble, stable and high-performance p-channel organic semiconductor for solution processing OFET.

並列關鍵字

organic semiconductors ； charge transfer ； frontier-orbital models ； halogenation ； reorganization energies ； electronic coupling ； OFET

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