Kumari Nikita, Pandey Manish, Nagamatsu Shuichi, Nakamura Masakazu, Pandey Shyam S
Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu, Kitakyushu 8080196, Japan.
Laboratory for Organic Electronics, Division of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan.
ACS Appl Mater Interfaces. 2020 Mar 11;12(10):11876-11883. doi: 10.1021/acsami.9b23345. Epub 2020 Feb 28.
Highly oriented thin films of poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) were prepared by friction-transfer technique followed by their characterization using polarized absorption spectroscopy, angle-dependent polarized Raman spectroscopy, and X-ray diffraction (XRD) techniques. Orientation in high-molecular-weight () polymers is hampered by chain folding or entanglements, which limit their macromolecular orientation. Interestingly, utilizing high-molecular-weight PBTTT ( > 50 kDa) and friction-transfer technique, successful fabrication of highly oriented thin films with very high dichroic ratio (∼30) was demonstrated. The role of the substrate's surface energy and its impact on the field-effect mobility (μ) of the oriented thin films were comprehensively investigated. The influence of annealing the thin films as prepared on the bare and self-assembled monolayer (SAM)-treated SiO surfaces exhibiting differential trends of μ was systematically investigated. This was explained by partial and complete conformational transformation of macromolecules on bare and SAM-treated SiO surfaces, respectively, after annealing them beyond liquid crystalline phase transition temperature, as revealed by in-plane and out-of-plane XRD results. On bare SiO, optimum μ up to 0.03 cm V s along the backbone orientation was obtained for the thin films annealed to 120 °C; whereas, it reached up to 0.36 cm V s on SAM-treated SiO after annealing at 200 °C. Finally, a charge transport mechanism was proposed taking evidence from the anisotropic optical and electrical characteristics of the friction-transferred PBTTT films into consideration.
通过摩擦转移技术制备了聚2,5-双(3-十四烷基噻吩-2-基)噻吩并[3,2-b]噻吩的高度取向薄膜，随后使用偏振吸收光谱、角度相关偏振拉曼光谱和X射线衍射(XRD)技术对其进行了表征。高分子量（）聚合物中的取向会受到链折叠或缠结的阻碍，这限制了它们的大分子取向。有趣的是，利用高分子量PBTTT（>50 kDa）和摩擦转移技术，成功制备了具有非常高二向色比（约30）的高度取向薄膜。全面研究了衬底表面能的作用及其对取向薄膜场效应迁移率（μ）的影响。系统研究了对在裸露和自组装单层（SAM）处理的SiO表面上制备的薄膜进行退火处理后，μ呈现不同趋势的影响。如面内和面外XRD结果所示，这分别是由于在高于液晶相变温度对裸露和SAM处理的SiO表面上的大分子进行退火后，大分子发生了部分和完全的构象转变。在裸露的SiO上，对于退火至120°C的薄膜，沿主链取向的最佳μ高达0.03 cm² V⁻¹ s⁻¹；而在SAM处理的SiO上，在200°C退火后，μ达到0.36 cm² V⁻¹ s⁻¹。最后，考虑到摩擦转移PBTTT薄膜的各向异性光学和电学特性，提出了一种电荷传输机制。
