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

Abstract

as well as their application in organic optoelectronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and other devices. [3][4][5][6][7][8][9][10][11] OFET is one of the basic devices to characterize electrical properties of OSCs and also has wide applications as the core component of organic electronic products, such as organic sensors, organic electronic circuits, wearable electronic devices, and so on. [12] Over these years, the performance of OSCs and their OFETs has been continuously improved, with the high carrier mobilities of transistors (µ) > 1-10 cm 2 V −1 s −1 . [13] In addition to optimizing the molecular structures and characteristics of OSCs (typically main-chain engineering and side-chain engineering), [14][15][16] another key factor in developing high-performance semiconductors and transistors is the processing technology. [17] It is well known that the electrical properties of OSCs not only depend on the molecular structures, but also are closely on the aggregation structures of the semiconductor thin films, resulting in two carrier transport modes: intramolecular band transport and intermolecular hopping transport. The carrier mobilities of the same OSC with different aggregated structures may differ by 10 or even 100 times, because the microstructure and the morphology of OSC films are influenced by many factors, such as intermolecular interaction, external forces, annealing, molecular self-assembly, and so on. [18][19][20] The common processing technologies of OSC thin films are mainly vacuum vapor deposition and solution processing. Vacuum deposition is only suitable for some small molecule semiconductors, and requires large equipments and high temperatures. So far, a great variety of solution processing methods [21] have been adopted to deposit semiconductor thin films, and spin coating is the most commonly used method in the laboratory. The process of spin coating is simple and suitable for small-area, but hard to prepare large-area uniform films, and more than 95% of the materials are wasted. [22] In addition, the orientation degree of the thin films prepared by spin coating is not high, and it is easier to form small-size spherulite crystals. Finally, the shear stress distribution is uneven during the spin-coating process, which makes it difficult to control the film morphology. [7] 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 fieldeffect transistors. In this review, the types of MGC techniques are first listed and the relevant mechanisms (wetting mechanism, fluid...

How Anionic Dopants Impact the Electrochemical Additive Manufacturing of Polypyrrole

“…The control of pressures in the electrolytic cell allows driving the electrolyte from the tip of pipettes, without causing the collapse of the meniscus Figure C shows the curved surface of the meniscus at the interface of the substrate and the pipette due to the balance of forces, including capillary forces, electrostatic interactions, and gravitational forces . The properties of deposited materials are governed by the meniscus formation, as it affects the amount and distribution of electrolytes .…”

Review of recent advances and sensing mechanisms in solid-state organic thin-film transistor (OTFT) sensors

“…80,83 A recent review by Wu and coworkers highlights many available techniques and materials for meniscus guided coating. 93 Zhu and coworkers reported highlysensitive NH 3 sensors with a solution-sheared ultrathin 1,4bis((50-hexyl-2,20-bithiophen-5-yl)ethynyl)benzene (HTEB) film as the semiconductor with a S of 41% and a LOD of 100 ppb for films of 1-2 monolayers thick (Fig. 8A).…”

Elucidating Morphology‐Mobility Relationships of Organic Thin Films Through Transfer Learning‐Assisted Multiscale Simulation

“…Several empirical models have been proposed to establish relationships between processing conditions and device performance. [17][18][19] However, obtaining molecular-level insights into the mechanism solely through experimental approaches is challenging, necessitating the use of multiscale simulations. Multiscale simulation techniques have been employed to investigate the morphology and electrical properties of solutionprocessed films.…”