A simple route to fabricate defect-free Ag-nanoparticle-carbon-nanotube composite-based high-resolution mesh flexible transparent conducting electrodes (FTCEs) is explored. In the selective photonic sintering-based patterning process, a highly soft rubber or thin plastic substrate is utilized to achieve close and uniform contact between the composite layer and photomask, with which uniform light irradiation can be obtained with diminished light diffraction. This well-controlled process results in developing a fine and uniform mesh pattern (≈12 μm). The mesh patternability is confirmed to be dependent on heat distribution in the selectively light-irradiated film and the pattern design for FTCE could be adopted for more precise patterns with desired performance. Moreover, using a very thin substrate could allow the mesh to be positioned closer to the strain-free neutral mechanical plane. Due to strong interfacial adhesion between the mesh pattern and substrate, the mesh FTCE could tolerate severe mechanical deformation without performance degradation. It is demonstrated that a transparent heater with fine mesh patterns on thin substrate can maintain stability after 100 repeated washing test cycles in which a variety of stress situations occurring in combination. The presented highly durable FTCE and simple fabrication processes may be widely adoptable for various flexible, large-area, and wearable optoelectronic devices.

We develop a facile route to the scalable fabrication of flexible reattachable ionomer nanopatterns (RAINs) by continuous nanoinscribing and low-temperature roll imprinting, which are repeatedly attachable to and detachable from arbitrarily shaped surfaces. First, by sequentially performing continuous nanoinscribing over a polymer substrate along the multiple directions, we readily create the multidimensional nanopattern, which otherwise demands complex nanofabrication. After its transfer to an elastomer pad for use as a soft nanoimprinting stamp, we then conduct a low-temperature roll imprinting of the ionomer film to fabricate a flexible and highly transparent RAIN. Reversible loosening of ionic units in the ionomer material at the mild temperature as low as ∼60−70 °C enables the faithful nanopatterning over thermosensitive organic compounds and fragile materials under a slight pressure. The excellent adhesion purely emerging from ionic interactions uniquely realizes the conformal attachability and clean detachability of RAINs for universal targets in ambient conditions, particularly beneficial for individual wearable and mobile devices requiring the userspecific "on/off" of the nanopattern-driven functionalities. As one vivid example, we demonstrate that a single light-emitting device can be switched from the focused pointer to the widespread flashlight depending on the RAIN application upon user's purpose.

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Temperature of Ag NWs on ultrathin plastic substrate under various energy conditions are numerically analyzed, and guidelines for designing effective IPL irradiation processes to induce NW welding without thermal damage to the substrate are derived.

Figure 5. Device structure and performance of R2R RO Ag mesh-based and ITO-based OLED. a) Schematic of a flexible OLED structure using inverted architecture. b) Device characteristics of current density versus voltage. The inset shows a photograph of a flexible OLED device in operation. Device characteristics such as c) luminance versus voltage and d) current efficiency versus current density of OLED.

Plasmonic color printing has received significant attention owing to its advantages such as nonfading and nontoxic color expression, without necessitating the use of chemical dyes. Recently, color generation from laser-induced plasmonic nanostructures has been extensively explored because of its simplicity, cost-effectiveness, and large-scale processability. However, these methods usually utilize a top-down method that causes unexpected background colors. Here, we proposed a novel method of plasmonic color printing via a bottom-up type laser-induced photomodification process. In the proposed method, selective silver nanoparticles (Ag NPs) structure could be fabricated on a transparent substrate through a unique organometallic solution-based laser patterning process. A set of color palettes was formed on the basis of different processing parameters such as laser fluence, scanning speed, and baking time. This color change was verified by finite-difference time-domain (FDTD) simulations via monitoring the spectral peak shift of the localized surface plasmon resonance (LSPR) at Ag NPs. It was also confirmed that the colors can be fabricated at a relatively high scanning speed (≥10 mm/s) on a large substrate (>300 mm2). Since semitransparent color images can be patterned on various transparent substrates, this process will broaden the application range of laser-induced plasmonic color generation.

The flashlight annealing process has been widely used in the field of flexible and printed electronics because it can instantly induce chemical and structural modifications over a large area on an electronic functional layer in a subsecond time range. In this study, for the first time, we explored a straightforward method to develop strong self-adhesion on a metal nanowire-based flexible and transparent conductive film via flashlight irradiation. Nanowire interlocking, for strong mechanical bonding at the interface between the nanowires and polyamide film, was achieved by simple hot pressing. Then, by irradiating the nanowire-impregnated film with a flashlight, several events such as interdiffusion and melting of surface polymers could be induced along with morphological changes leading to an increase in the film surface area. As a result, the surface of the fabricated film exhibited strong interfacial interactions while forming intimate contact with the heterogeneous surfaces of other objects, thereby becoming strongly selfadhesive. This readily achievable, self-attachable, flexible, and transparent electrode allowed the self-interconnection of a lightemitting diode chip, and it was also compatible for various applications, such as defogging windows and transparent organic lightemitting diodes.

In article number https://doi.org/10.1002/smll.201800676, Kyoohee Woo, Jooho Moon, and co‐workers describe a simple, large area‐compatible, intense light‐induced patterning process to fabricate Ag nanoparticle–carbon nanotube‐based defect‐free, highly conductive, mesh transparent electrodes with exceptional durability after 100 washing test cycles, in which a variety of stress situations such as rubbing, folding, and crumpling occurs in combination.