Directional Solution Coating by the Chinese Brush: A Facile Approach to Improving Molecular Alignment for High‐Performance Polymer TFTs

Abstract

Directional solution coating by the Chinese brush provides a facile approach to fabricate highly oriented polymer thin films by finely controlling the wetting and dewetting processes under directional stress. The biggest advantage of the Chinese brush over the normal western brush is the freshly emergent hairs used, whose unique tapered structure renders a dynamic balance of the liquid within the brush by multiple forces when interacting with the liquid. Consequently, the liquid is steadily held within the brush without any unexpected leakage, making the liquid transfer proceed in a well-controllable manner. It is demonstrated that the Chinese brush coating enables the crystallization of the polymer and the self-assembly of conjugated backbones to proceed in a quasi-steady state via a certain direction, which is attributed to the controllable receding of the three-phase contact line during the dewetting process by the multiple parallel freshly emergent hairs. The as-prepared polymer thin films exhibit over six times higher charge-carrier mobility compared to the spin-coated films, which therefore provides a general approach for high-performance organic thin-film transistors.

High‐Performance Proximity Sensors with Nanogroove‐Template‐Enhanced Extended‐Gate Field‐Effect Transistor Configuration

“…A typical example is the development of so-called human-friendly robots that share the same workspace as and interact with humans. [15] Here, to further enhance the electrical mobility of the spin-coated organic semiconducting layer, friction-transferred polytetrafluoroethylene (PTFE) template was pre-deposited on SiO 2 /Si substrate before coating of the DPP-DTT layer in order to form the nanogrooved surfaces and thereafter to orient the growth of semiconducting film. However, proximity sensors are also highly desired to locate the wanted objects before further operation and to detect the controlled by their fabrication parameters.…”

Bioinspired Dynamic Wetting on Multiple Fibers

“…Mater. 2017, 29,1703042 Figure 3. a) Self-removal of droplets on water strider legs and the excellent antifogging property of artificial nanocone arrays. a 1 ) Water striders live on the water surface.…”

“…[29] Upon the use of the Chinese brush, the polymer crystallization proceeded in a quasi-steady state via the brushing direction, and the receding of the three-phase contact line (TCL) was well controlled by the multiple parallel FEhairs. The orientation of the polymer chains within the films was directly visualized using polarized light optical microscope images, and the color changed from dark (Figure 4c 3 ) to light (Figure 4c 4 ) when the optic axis was rotated from 0° to 45°.…”

“…P and A indicate the axis of the microscope polarizer and the light vibration plane, respectively. [29] c 5 ) Diagram of the OTFT device. c 6 ) Mobility distribution for the DPPDTT devices prepared by Chinese-brush-coating and spin-coating methods on different substrates (G-s: nanogrooved substrate; F-s: flat substrate).…”

“…c 3 -c 6 ) Reproduced with permission. [29] Copyright 2017, Wiley-VCH. is, the elementary unit of the sticking events, the increase in the height of the liquid, L wet , between the elastic lamella pair increased linearly with the withdrawal height, L, while the dry length, L dry = L − L wet , remained constant because of the balance between the capillarity and elasticity (Figure 6b 1 ).…”