Phase Transitions and Formation of a Monolayer-Type Structure in Thin Oligothiophene Films: Exploration with a Combined In Situ X-ray Diffraction and Electrical Measurements

Nanoscale Research Letters

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[1] 0000 0001 0214 6706, grid.438275.f, Department of Engineering and Natural Sciences, Technical University of Applied Sciences Wildau, Hochschulring 1, 15745, Wildau, Germany;0000 0001 2242 8751, grid.5836.8, Department of Physics, University of Siegen, Walter-Flex-Strasse 3, 57072, Siegen, Germany;0000 0001 2242 8751, grid.5836.8, Department of Physics, University of Siegen, Walter-Flex-Strasse 3, 57072, Siegen, Germany;0000 0004 0385 8635, grid.496914.7, Aix Marseille University, University of Toulon, CNRS, IM2NP, Campus de St-Jérôme, 13397, Marseille, France;0000 0001 2242 8751, grid.5836.8, Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen, Adolf-Reichwein-Strasse 2, 57076, Siegen, Germany;0000 0001 2342 9668, grid.14476.30, Faculty of Fundamental Physical and Chemical Engineering, Lomonosov Moscow State University, GSP-1, Leninskie gory1, 119991, Moscow, Russian Federation;0000000092721542, grid.18763.3b, Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, 141700, Dolgoprudny, Russian Federation;0000 0001 2342 9668, grid.14476.30, Faculty of Fundamental Physical and Chemical Engineering, Lomonosov Moscow State University, GSP-1, Leninskie gory1, 119991, Moscow, Russian Federation;0000000092721542, grid.18763.3b, Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, 141700, Dolgoprudny, Russian Federation;0000 0004 0623 4449, grid.462057.2, Institut de Sciences des Matériaux de Mulhouse (CNRS UMR 7361), 15 rue Jean Starcky, B.P 2488, 68057, Mulhouse, France;0000 0001 2192 9124, grid.4886.2, Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432, Moscow region, Russian Federation;0000 0004 0494 6960, grid.465299.5, Enikolopov Institute of Synthetic Polymeric Materials of Russian Academy of Sciences, Profsoyuznaya st. 70, 117393, Moscow, Russian Federation;0000 0004 0494 6960, grid.465299.5, Enikolopov Institute of Synthetic Polymeric Materials of Russian Academy of Sciences, Profsoyuznaya st. 70, 117393, Moscow, Russian Federation;0000 0001 2342 9668, grid.14476.30, Chemistry Department, Lomonosov Moscow State University, Leninskie Gory 1-3, 119991, Moscow, Russian Federation;

关键词: Thin films;    Interfacial monolayers;    Oligomers;    Quarterthiophenes;    In situ GIXD;    Phase transitions;    Mesophase;   

DOI  :  10.1186/s11671-019-3009-8

来源: publisher

【 摘 要 】

A combination of in situ electrical and grazing-incidence X-ray diffraction (GIXD) is a powerful tool for studies of correlations between the microstructure and charge transport in thin organic films. The information provided by such experimental approach can help optimizing the performance of the films as active layers of organic electronic devices. In this work, such combination of techniques was used to investigate the phase transitions in vacuum-deposited thin films of a common organic semiconductor dihexyl-quarterthiophene (DH4T). A transition from the initial highly crystalline phase to a mesophase was detected upon heating, while only a partial backward transition was observed upon cooling to room temperature. In situ electrical conductivity measurements revealed the impact of both transitions on charge transport. This is partly accounted for by the fact that the initial crystalline phase is characterized by inclination of molecules in the plane perpendicular to the π-π stacking direction, whereas the mesophase is built of molecules tilted in the direction of π-π stacking. Importantly, in addition to the two phases of DH4T characteristic of the bulk, a third interfacial substrate-stabilized monolayer-type phase was observed. The existence of such interfacial structure can have important implications for the charge mobility, being especially favorable for lateral two-dimensional charge transport in the organic field-effect transistors geometry.

【 授权许可】

CC BY