9:30 AM - 11:30 AM
▲ [26a-P04-9] Charge Transport Anisotropy of Oriented Semiconducting Polymer Films Grown at Liquid/Air Interfaces
Keywords:Organic Field Effect Transistors, Orientation, Polymer Semiconductor
Semiconducting Polymers (SCPs) are emerging as material for the active layer of organic field-effect transistors (OFETs). Various methods have been proposed to orient SCPs as the OFET mobility can be improved by aligning the polymer backbone along the current direction. However, difficulty in multilayer film coating by various methods to orient polymer is still a major limitation because of the unavailability of orthogonal solvents for a majority of the SCPs. The unidirectional floating film transfer method (UFTM) is an efficient film fabrication technique to prepare oriented film. In UFTM, film preparation is isolated from the device substrate; therefore, structural order and thickness can be independently controlled. Most of the reports in UFTM and related method utilizes polarized UV-vis absorption spectroscopy to evaluate the dichroic ratio (DR) and air interface of the films are transferred at the dielectric interface of bottom-gated top-contact (BGTC) OFETs. Optical anisotropy is not surface sensitive and probes the absorbance throughout the bulk (including liquid and air interface). Since the orientation in UFTM is supposed to occur due to frictional force arising from the viscous liquid substrate, it is important to investigate charge transport anisotropy at both the interfaces as the structural order of the SCPs can change through the thickness direction. Orientation of SCPs results in a large charge transport anisotropy of which value is determined within a few nm of the thin film of SCP near the dielectric interface. Therefore, we examined charge transport anisotropy in UFTM films by different OFET geometry and SCP thickness utilizing different interfaces. High charge transport anisotropy was confirmed at both the interfaces even when the thickness changes from 5.5 nm to 30 nm. These results suggest that the orientation distribution of SCPs in UFTM is almost uniform throughout film thickness. These results will be presented in detail.