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Friction Force Mapping of Molecular Ordering and Mesoscopic Phase Transformations in Layered-Crystalline Organic Semiconductor Films.
Miyata, Ryo; Inoue, Satoru; Nikaido, Kiyoshi; Nakajima, Ken; Hasegawa, Tatsuo.
Afiliación
  • Miyata R; Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
  • Inoue S; Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
  • Nikaido K; Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
  • Nakajima K; Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan.
  • Hasegawa T; Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
ACS Appl Mater Interfaces ; 16(30): 39701-39707, 2024 Jul 31.
Article en En | MEDLINE | ID: mdl-39013158
ABSTRACT
It is critical to understand molecular ordering processes in small-molecule organic semiconductor (OSC) films in optimizing electronic device applications, although it is difficult to observe and investigate the ordering characteristics at a mesoscopic or device scale. Here, we report that friction force microscopy (FFM) allows visualizing the ordering transformation process from a thermodynamically metastable phase to a stable phase at a mesoscopic scale. We utilized 2-octyl-benzothieno[3,2-b]naphtho[2,3-b]thiophene (2-C8-BTNT) as a typical highly layered-crystalline OSC. We found that the friction force between an AFM tip and spin-coated OSC films significantly depends on whether local film states are in metastable monolayer phase or stable bilayer-type herringbone (b-LHB) phase that exhibits high carrier mobility. The formation of the stable b-LHB phase leads to lower friction than the metastable monolayer phase, clearly visualizing the molecular order. Force map (Fmap) analysis indicates that the lower friction in the b-LHB phase should be associated with the reduction of interfacial adhesion force. Notably, the observed results demonstrate that the spin-coated thin film changes from continuous film with the monolayer phase to rugged microcrystal grains with the b-LHB phase when left at ambient conditions. By contrast, an appropriate post-thermal annealing process facilitates the phase transformation without inducing such morphological changes. The technique provides a unique and effective tool for revealing the relationship between processing conditions and device performance in polycrystalline OSC films.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: ACS Appl Mater Interfaces Asunto de la revista: BIOTECNOLOGIA / ENGENHARIA BIOMEDICA Año: 2024 Tipo del documento: Article País de afiliación: Japón Pais de publicación: Estados Unidos
Texto completo
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Imprimir
XML
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: ACS Appl Mater Interfaces Asunto de la revista: BIOTECNOLOGIA / ENGENHARIA BIOMEDICA Año: 2024 Tipo del documento: Article País de afiliación: Japón Pais de publicación: Estados Unidos