Low-Temperature Alignment of Conjugated Polymers by Plasticizer-Aided Physical Rubbing.

Rubbing-induced alignment of conjugated polymers is systematically investigated in terms of intra- and inter-molecular interaction. Various polymer films with a broad range of polymer chain rigidity are rubbed, and the degree of polymer chain alignment is quantitatively characterized. The rubbing technique effectively aligns crystalline domains in conjugated polymer films when the temperature approaches the critical rubbing temperature ( ), at which the rearrangement and the slip of polymer chains are possible.

Tailored Uniaxial Alignment of Nanowires Based on Off-Center Spin-Coating for Flexible and Transparent Field-Effect Transistors.

The alignment of nanowires (NWs) has been actively pursued for the production of electrical devices with high-operating performances. Among the generally available alignment processes, spin-coating is the simplest and fastest method for uniformly patterning the NWs. During spinning, the morphology of the aligned NWs is sensitively influenced by the resultant external drag and inertial forces.

Anisotropy of Charge Transport in a Uniaxially Aligned Fused Electron-Deficient Polymer Processed by Solution Shear Coating.

Precise control of the microstructure in organic semiconductors (OSCs) is essential for developing high-performance organic electronic devices. Here, a comprehensive charge transport characterization of two recently reported rigid-rod conjugated polymers that do not contain single bonds in the main chain is reported. It is demonstrated that the molecular design of the polymer makes it possible to achieve an extended linear backbone structure, which can be directly visualized by high-resolution scanning tunneling microscopy (STM).

Charge-Transfer-Controlled Growth of Organic Semiconductor Crystals on Graphene.

Controlling the growth behavior of organic semiconductors (OSCs) is essential because it determines their optoelectronic properties. In order to accomplish this, graphene templates with electronic-state tunability are used to affect the growth of OSCs by controlling the van der Waals interaction between OSC ad-molecules and graphene. However, in many graphene-molecule systems, the charge transfer between an ad-molecule and a graphene template causes another important interaction.

Motion-Programmed Bar-Coating Method with Controlled Gap for High-Speed Scalable Preparation of Highly Crystalline Organic Semiconductor Thin Films.

Solution-processed organic semiconductor thin films with high charge carrier mobility are necessary for development of next-generation electronic applications, but the rapid processing speed demanded for the industrial-scale production of these thin films poses a challenge to control of their thin-film properties, such as crystallinity, morphology, and film-to-film uniformity. Here, we show a new solution coating method that is compatible with a roll-to-roll printing process at a rate of 2 mm s by using a gap-controllable wire bar, motion-programming strategy, and blended active inks. We demonstrate that the coating bar, the horizontal motion of which is repeatedly brought to an intermittent standstill, results in an improved vertically self-stratified structure and a high crystallinity for organic active inks comprising a semiconducting small molecule and a semiconducting polymer.

Negative Transconductance Heterojunction Organic Transistors and their Application to Full-Swing Ternary Circuits.

Multivalued logic (MVL) computing could provide bit density beyond that of Boolean logic. Unlike conventional transistors, heterojunction transistors (H-TRs) exhibit negative transconductance (NTC) regions. Using the NTC characteristics of H-TRs, ternary inverters have recently been demonstrated.

Bar-Coated Ultrathin Semiconductors from Polymer Blend for One-Step Organic Field-Effect Transistors.

One-step deposition of bi-functional semiconductor-dielectric layers for organic field-effect transistors (OFETs) is an effective way to simplify the device fabrication. However, the proposed method has rarely been reported in large-area flexible organic electronics. Herein, we demonstrate wafer-scale OFETs by bar coating the semiconducting and insulating polymer blend solution in one-step.

Nanopatched Graphene with Molecular Self-Assembly Toward Graphene-Organic Hybrid Soft Electronics.

Increasing the mechanical durability of large-area polycrystalline single-atom-thick materials is a necessary step toward the development of practical and reliable soft electronics based on these materials. Here, it is shown that the surface assembly of organosilane by weak epitaxy forms nanometer-thick organic patches on a monolayer graphene surface and dramatically increases the material's resistance to harsh postprocessing environments, thereby increasing the number of ways in which graphene can be processed. The nanopatched graphene with the improved mechanical durability enables stable operation when used as transparent electrodes of wearable strain sensors.

Chemical Vapor Deposition of Bernal-Stacked Graphene on a Cu Surface by Breaking the Carbon Solubility Symmetry in Cu Foils.

The synthesis of Bernal-stacked multilayer graphene over large areas is intensively investigated due to the value of this material's tunable electronic structure, which makes it promising for use in a wide range of optoelectronic applications. Multilayer graphene is typically formed via chemical vapor deposition onto a metal catalyst, such as Ni, a Cu-Ni alloy, or a Cu pocket. These methods, however, require sophisticated control over the process parameters, which limits the process reproducibility and reliability.

Side-Chain-Induced Rigid Backbone Organization of Polymer Semiconductors through Semifluoroalkyl Side Chains.

While high-mobility p-type conjugated polymers have been widely reported, high-mobility n-type conjugated polymers are still rare. In the present work, we designed semifluorinated alkyl side chains and introduced them into naphthalene diimide-based polymers (PNDIF-T2 and PNDIF-TVT). We found that the strong self-organization of these side chains induced a high degree of order in the attached polymer backbones by forming a superstructure composed of "backbone crystals" and "side-chain crystals".