State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, and Graduate School of the Chinese Academy of Sciences, Changchun 130022, People's Republic of China.
Phys Chem Chem Phys. 2012 Aug 7;14(29):10279-84. doi: 10.1039/c2cp41248a. Epub 2012 Jun 27.
The growth process and phase state of 5,5''-bis(3'-fluoro-biphenyl-4-yl)-2,2' : 5',2''- terthiophene (m-F2BP3T) thin films were investigated by atomic force microscopy (AFM), in-plane and out-of-plane X-ray diffraction (XRD), and selected area electron diffraction (SAED). Two meso-phases (thin film phases) of m-F2BP3T films on SiO(2) surface were obtained in the early stages. The m-F2BP3T films initially exhibited two-dimensional (2D) layers (≤4 ML) followed by three-dimensional (3D) island growth. The film structure evolved two thin film phases in the first four layers and the bulk phase was formed from the fifth layer, which occurred concomitantly with the change of the growth mode. Moreover, the variation of weak epitaxy growth behavior of ZnPc from 2D to 3D growth further reflects that the phase state of the first three layers is different from that of the fourth layer, in spite of ZnPc crystals showing just one orientation corresponding to commensurate epitaxy. The novel phase behavior is closely related to the synergistic effects of the outstanding soft matter properties, limited elasticity of organic molecules, and strain originating from the SiO(2) substrate. This study investigates novel phase behavior in organic thin films and provides significant insight into the mechanism of the phase transition.
采用原子力显微镜（AFM）、面内和面外 X 射线衍射（XRD）和选区电子衍射（SAED）研究了 5,5''-双（3'-氟联苯-4-基）-2,2'：5',2''-三联噻吩（m-F2BP3T）薄膜的生长过程和相态。在早期阶段，获得了 SiO2 表面上 m-F2BP3T 薄膜的两种介相（薄膜相）。m-F2BP3T 薄膜最初表现出二维（2D）层（≤4 ML），随后是三维（3D）岛状生长。在最初的四层中，膜结构演变为两个薄膜相，而从第五层开始形成体相，这与生长模式的变化同时发生。此外，ZnPc 从二维到三维生长的弱外延生长行为的变化进一步表明，前三层的相态与第四层不同，尽管 ZnPc 晶体仅显示出一个对应于共格外延的取向。这种新的相态行为与出色的软物质性质、有机分子有限的弹性以及源自 SiO2 衬底的应变的协同效应密切相关。本研究调查了有机薄膜中的新相态行为，并为相转变机制提供了重要的见解。
