Two-dimensional distribution of local electronic structure of inhomogeneous organic thin film under operating state

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05050
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thin film/Surface and interfacial physical properties
• Research Institution: Chiba University
• Principal Investigator: Okudaira Koji 千葉大学, 大学院工学研究院, 准教授 (50202023)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 有機デバイス / 非均一系 / 分子配向 / イオン化ポテンシャル / 有機薄膜

Outline of Final Research Achievements

We determined not only the average value of the molecular orientation but also the ratio of crystalline and amorphous parts of the polymer type organic semiconductor (P3HT-PCBM system) by using grazing incident x-ray diffraction and near-edge x-ray absorption fine structure. Furthermore, the molecular orientation, including the rotation angle of the molecule as well as molecular tilt angle of organic semiconductor (DNTT) thin film on SiO2 and copper (oxide), which constitute the substrate of the bottom type organic field transistors, were precisely determined. It was clarified that P3HT-PCBM, DNTT/SiO2, and DNTT/Cu are heterogeneous systems in which crystalline part and near amorphous part coexist and two-dimensional distribution of ionization potential would be observed.

Free Research Field

物理化学

Academic Significance and Societal Importance of the Research Achievements

有機半導体デバイスの電荷の移動層は，結晶質領域と非晶質領域が共存しており，それぞれの領域のモルフォロジーだけでなくイオン化ポテンシャルが異なる2次元不均一系である。本研究では，代表的な有機高分子系であるP3HT－PCBM薄膜や，本来結晶性が高いと考えられるDNTTなどの小分子量有機半導体薄膜の分子配向を異なる手法で精密に調べ，その結果から結晶領域と非晶質領域の膜作成プロセスによる変化に関する知見を得ることができた。本研究の結果は，有機デバイスの電荷移動機構に関する知見を与えるだけでなく，より高移動度の有機デバイス作成プロセスへの指針を与えるものと考えている。