Meniscus-Guided Deposition of Organic Semiconductor Thin Films: Materials, Mechanism, and Application in Organic Field-Effect Transistors.

Solution-processable organic semiconductors are one of the promising materials for the next generation of organic electronic products, which call for high-performance materials and mature processing technologies. Among many solution processing methods, meniscus-guided coating (MGC) techniques have the advantages of large-area, low-cost, adjustable film aggregation, and good compatibility with the roll-to-roll process, showing good research results in the preparation of high-performance organic field-effect transistors. In this review, the types of MGC techniques are first listed and the relevant mechanisms (wetting mechanism, fluid mechanism, and deposition mechanism) are introduced. The MGC processes are focused and the effect of the key coating parameters on the thin film morphology and performance with examples is illustrated. Then, the performance of transistors based on small molecule semiconductors and polymer semiconductor thin films prepared by various MGC techniques is summarized. In the third section, various recent thin film morphology control strategies combined with the MGCs are introduced. Finally, the advanced progress of large-area transistor arrays and the challenges for roll-to-roll processes are presented using MGCs. Nowadays, the application of MGCs is still in the exploration stage, its mechanism is still unclear, and the precise control of film deposition still needs experience accumulation.