Molecular dynamics simulations to elucidate the mechanism of the universal behavior of molecular assemblies observed in the processes of organic semiconductor thin film growth

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05253
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 35030:Organic functional materials-related
• Research Institution: Tohoku University
• Principal Investigator: Ikeda Susumu 東北大学, 材料科学高等研究所, 准教授 (20401234)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 有機半導体 / 分子動力学シミュレーション / 薄膜 / 核生成 / 臨界核 / 結晶成長 / ペンタセン

Outline of Final Research Achievements

Molecular dynamics (MD) simulations were applied to elucidate the mechanism of nucleation and growth of organic semiconductor thin films. In particular, the phenomenon which is universally observed in thin film growth of organic semiconductors, that is, rod-shaped molecules are aligned with standing manner on substrate surfaces, was focused on. Specifically, the stability of clusters (nuclei) comprising standing molecules of pentacene was investigated by MD simulations. In the simulations, the clusters consisting of more than ten standing molecules could stably exist, and furthermore, the stabilized clusters could grow by capturing additional molecules in MD simulations. The results of the simulations were compared with the results of theoretical calculations based on the classical nucleation theory, and their consistency led us to understanding the stochastic behavior which critical nuclei show.

Free Research Field

材料科学、有機半導体、薄膜成長

Academic Significance and Societal Importance of the Research Achievements

次世代電子デバイス用材料として期待される有機半導体には、物質固有のキャリア移動度が無機半導体に比べ小さいという問題があるが、薄膜化してデバイスに用いる場合、粒界や分子配列の乱れによって移動度は更に小さなものとなる。移動度最大の高品質薄膜を得るためには、核生成、薄膜成長のプロセスを完全に制御する必要があり、その基礎として、分子レベルのメカニズム解明が必須となる。本研究では、棒状の有機半導体分子が基板表面上で立った状態で配列するという普遍的な現象に着目し、その要因を分子動力学シミュレーションによって明らかにした。有機エレクトロニクスによる社会貢献の基盤となる基礎的知見を提供するものである。