[25a-E205-1~9] 12.1 Fabrications and Structure Controls

▼ [25a-E205-5] Large-area Oriented Films of Semiconducting Polymers by Unidirectional Floating Film Transfer Method

〇MANISH PANDEY¹, Jumpei Toyoda¹, Yuya Sugita¹, Masakazu Nakamura¹ (1.NAIST)

Keywords:Polymer Orientation, Anisotropy, OFETs

Solution processable semiconducting polymers (SCPs) have made the fabrication of active layer of organic field-effect transistors (OFETs) easy and cost-effective. Improvement in charge transport in semiconducting polymers has been well studied in the recent past by orienting the main chains along the channel direction of OFETs. However, the inevitability of pre-aggregation in solution and difficulty in layer-by-layer film coating of films by various methods to orient SCPs is still a major limitation for their use in large-area fabrication of thin films for high-performance printed electronics with adequate repeatability. The unidirectional Floating film transfer method (UFTM) is an efficient film fabrication method to solve the above issue. In this technique, one drop of SCP ink is placed on the orthogonal viscous liquid, and SCP solution spreads on it. Viscous drag arising from the liquid substrate continuously acts opposite to the SCP film expansion direction, resulting in orientation of SCP perpendicular to the film expansion direction. At the same time, simultaneous solvent evaporation results in solid-oriented floating films of SCPs at the liquid-air interface, which can be transferred to any desired substrate. UFTM possesses various advantages, such as minimum material wastage and high performance due to polymers' uniaxial orientation. In addition, layer-by-layer film fabrication is possible in UFTM as the film preparations are done on the liquid substrate and then transferred on actual device substrates. We have actively worked on this method. Large-area (40 cm²) of ribbon-shaped films using 10 μl of the polymer ink can be prepared using UFTM. Recent progress in UFTM will be presented in this work, which includes the orientation of different kinds of SCPs like p-type and n-type, and orientation distribution of SCPs throughout the film thickness will also be discussed.