Search

Herein, flexible circuits with enhanced adhesion and antibending resistance are fabricated by heat‐assisted direct ink writing. The experimental parameters are explored under different nozzle sizes, angles, heights, direct writing speeds, and heating temperatures by selecting an appropriate extrusion speed. The solvent evaporation caused by heating temperature enables the metal particles to densify quickly to form a conductive path. This method is suitable for fabricating devices on polyimide (PI) with appropriate direct writing parameters and is simple to operate. A flexible Ag circuit with a resistivity of 4.31 × 10−8 Ω m and good resistance after 20 000 consecutive bending cycles is fabricated with a nozzle size of 32G, a nozzle height of 10 μm, a nozzle angle of 90°, an extrusion speed of 5 μm min−1, a substrate heating temperature of 70 °C, and a direct writing speed of 1 mm s−1. Large‐area complex flexible display LED arrays are fabricated using thermally assisted direct ink writing. [ABSTRACT FROM AUTHOR]

As a critical part of flexible electronics, flexible circuits inevitably work in a dynamic state, which causes electrical deterioration of brittle conductive materials (i.e., Cu, Ag, ITO). Recently, gallium‐based liquid metal particles (LMPs) with electrical stability and self‐repairing have been studied to replace brittle materials owing to their low modulus and excellent conductivity. However, LMP‐coated Ga2O3 needs to activate by external sintering, which makes it more complicated to fabricate and gives it a larger short‐circuit risk. Core–shell structural particles (Ag@LMPs) that exhibit excellent initial conductivity(8.0 Ω sq−1) without extra sintering are successfully prepared by coating nanosilver on the surface of LMPs through in situ chemical reduction. The critical stress at which rigid Ag shells rupture can be controlled by adjusting the Ag shell thickness so that LM cores with low moduli can release, achieving real‐time self‐repairing (within 200 ms) under external destruction. Furthermore, a flexible circuit utilizing Ag@LMPs is fabricated by screen printing, and exhibits outstanding stability and durability (R/R0 < 1.65 after 10 000 bending cycles in a radius of 0.5 mm) because of the functional core–shell structure. The self‐repairable Ag@LMPs prepared in this study are a candidate filler for flexible circuit design through multiple processing methods. [ABSTRACT FROM AUTHOR]

Abstract: The transfer of synthesized large‐area 2D materials to arbitrary substrates is expected to be a vital step for the development of flexible device fabrication processes. The currently used hazardous acid‐based wet chemical etching process for transferring large‐area MoS2 films is deemed to be unsuitable because it significantly degrades the material and damages growth substrates. Surface energy‐assisted water‐based transfer processes do not require corrosive chemicals during the transfer process; however, the concept is not investigated at the wafer scale due to a lack of both optimization and in‐depth understanding. In this study, a wafer‐scale water‐assisted transfer process for metal–organic chemical vapor‐deposited MoS2 films based on the hydrofluoric acid treatment of a SiO2 surface before the growth is demonstrated. Such surface treatment enhances the strongly adhering silanol groups, which allows the direct transfer of large‐area, continuous, and defect‐free MoS2 films; it also facilitates the reuse of growth substrate. The developed transfer method allows direct fabrication of flexible devices without the need for a polymeric supporting layer. It is believed that the proposed method can be an alternative defect‐ and residue‐free transfer method for the development of MoS2‐based next‐generation flexible devices. [ABSTRACT FROM AUTHOR]

Flexible EMMO IGZO TFTs fabricated on 20 µm thick PI film are reported here. The utilized technology results in high electrical stability, of devices, combined to high robustness against mechanical deformation down to 3%. [ABSTRACT FROM AUTHOR]

Sorting of semiconducting single-walled carbon nanotubes (SWNTs) by conjugated polymers has attracted considerable attention recently because of its simplicity, high selectivity, and high yield. However, up to now, all the conjugated polymers used for SWNT sorting are electron-donating (p-type). Here, a high-mobility electron-accepting (n-type) polymer poly([N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)) (P(NDI2OD-T2)) is utilized for the sorting of high-purity semiconducting SWNTs, as characterized by Raman spectroscopy, dielectric force spectroscopy and transistor measurements. In addition, the SWNTs sorted by P(NDI2OD-T2) have larger diameters than poly(3-dodecylthiophene) (P3DDT)-sorted SWNTs. Molecular dynamics simulations in explicit toluene demonstrate distinct linear or helical wrapping geometry between P(NDI2OD-T2) and different types of SWNTs, likely as a result of the strong interactions between the large aromatic core of the P(NDI2OD-T2) backbone and the hexagon path of SWNTs. By using high-mobility n-type P(NDI2OD-T2) as the sorting polymer, ambipolar SWNT transistors with better electron transport than that attained by P3DDT-sorted SWNTs are achieved. As a result, flexible negated AND and negated OR logic circuits from the same set of ambipolar transistors are fabricated, without the need for doping. The use of n-type polymers for sorting semiconducting SWNTs and achieving ambipolar SWNT transistor characteristics greatly simplifies the fabrication of flexible complementary metal-oxide-semiconductor-like SWNT logic circuits. [ABSTRACT FROM AUTHOR]

Despite significant progress in the field of wearables and flexible electronics, there are hardly any reports describing the overall implementation of these systems, from the design of electrical interconnects and substrates to the choice of electronic components. Researchers working on materials for flexible electronics are sometimes disconnected from those designing the electronic circuits for such applications. Herein, an overview of the essential design requirements for flexible electronics is presented. It includes discussions regarding communication protocols, design and implementation of electrical interconnects, choice and fabrication of substrates, and choice of electronic components for flexible systems. The functionalities of these electronic components are comprehensively discussed with consideration of the energy budget, in terms of power consumption, also presented. Additionally, the components of power generation and storage are explored with respect to their market accessibility. The field of wearable electronics is highly interdisciplinary and such information is essential for eventual standardization of the field. [ABSTRACT FROM AUTHOR]