Bio‐Inspired Controllable Liquid Transfer: From Fundamentals in Micro‐Patterning to Applications in Optoelectronics

Abstract

Solution‐processed micro‐patterning is a crucial process for making high‐performance optoelectronic devices, since the carrier transfer behavior is closely related to the uniformity, orientation, and resolution of micro‐patterns. Developing solution processes with good controllability has thus attracted increasing research interest in the last decade. Inspired by Chinese brushes, a fibrous‐guided direct‐writing strategy is recently developed that enables controllable liquid transfer for making micro‐patterns, which is systematically reviewed from viewpoints of both the fundamentals in liquid manipulation and the applications in optoelectronics. First, a model structure of dual‐conical fibers (CFs) is proposed, whose capacity in liquid transfer is featured as the dynamic liquid balance and the uniform liquid film. On the basis, triple‐ and multi‐ CFs are developed for transferring liquid onto the target substrate in a controllable manner, where the tri‐phase contact line can be finely tuned. Thereafter, micro‐patterns with µm‐scale resolution, cm‐scale uniformity, and molecular‐scale orientation can be achieved, as is demonstrated by the as‐prepared ultrasmooth quantum dot films, highly aligned silver nanowires films, and wrinkle‐free reduced graphene oxide films, respectively. The high‐performance optoelectronic devices, including quantum dot light‐emitting diodes, flexible transparent electrodes, and pressure sensors, are demonstrated. Perspectives for solution‐processed micro‐patterning in optoelectronics are also suggested.