Fibrous controllable liquid transfer:

towards high-performance thin-film devices

Huan Liu*

School of Chemistry, Beihang University, Beijing, 100191, China.

E-mail: liuh@buaa.edu.cn

In nature, various biological fibrous systems exhibit unique dynamic wetting properties, which has shown many advantages in inhabiting local environments. However, controllable liquid transfer by an open fibrous system is still poorly understood and remains a challenge, because capillary coalescence is frequently encountered when fiber array interacted with a liquid. Here, we revealed the fundamental of the Chinese brush for its capability in controllable liquid transfer: the unique anisotropic multi-scale structure of the freshly emergent hairs. Drawing inspirations, we developed model devices with flexible conical fibers that allows for direct writing functional micro-lines with 10 µm resolution and nano-thin films, with well-defined profile and uniform distribution on diverse substrates. To be noticed, the fibers-guided directional liquid transfer enables fine controlling the liquid/solid/gas tri-phase contact line under multiple directional stresses. Taking advantages, highly oriented polymer thin film and aligned AgNWs film were fabricated in large scale, based on which high performance of polymer TFTs devices and the anisotropic flexible conductive electrode were developed, respectively. We also demonstrated that the conical fiber array enables direct preparing ultra-smooth QD micro-patterns, and thus a high-performance QLED devices was allowed. We envision that the controllable liquid transfer guided by the conical fibers will shed light on the novel template-free printing of functional photoelectric devices.

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