Percolation networks of silver nanowires (AgNWs) are commonly used as transparent conductive electrodes (TCEs) for a variety of optoelectronic applications, but there have been no attempts to precisely control the percolation networks of AgNWs that critically affect the performances of TCEs. Here, we introduce a capillary printing technique to precisely control the NW alignment and the percolation behavior of AgNW networks. Notably, partially aligned AgNW networks exhibit a greatly lower percolation threshold, which leads to the substantial improvement of optical transmittance (96.7%) at a similar sheet resistance (19.5 Ω sq(-1)) as compared to random AgNW networks (92.9%, 20 Ω sq(-1)). Polymer light-emitting diodes (PLEDs) using aligned AgNW electrodes show a 30% enhanced maximum luminance (33068 cd m(-2)) compared to that with random AgNWs and a high luminance efficiency (14.25 cd A(-1)), which is the highest value reported so far using indium-free transparent electrodes for fluorescent PLEDs. In addition, polymer solar cells (PSCs) using aligned AgNW electrodes exhibit a power conversion efficiency (PCE) of 8.57%, the highest value ever reported to date for PSCs using AgNW electrodes.

Electronic skin (e-skin) technology is an exciting frontier to drive the next generation of wearable electronics owing to its high level of wearability, enabling high accuracy to harvest information of users and their surroundings. Recently, biomimicry of human and biological skins has become a great inspiration for realizing novel wearable electronic systems with exceptional multifunctionality as well as advanced sensory functions. This review covers and highlights bioinspired e-skins mimicking perceptive features of human and biological skins. In particular, five main components in tactile sensation processes of human skin are individually discussed with recent advances of e-skins that mimic the unique sensing mechanisms of human skin. In addition, diverse functionalities in user-interactive, skinattachable, and ultrasensitive e-skins are introduced with the inspiration from unique architectures and functionalities, such as visual expression of stimuli, reversible adhesion, easy deformability, and camouflage, in biological skins of natural creatures. Furthermore, emerging wearable sensor systems using bioinspired e-skins for body motion tracking, healthcare monitoring, and prosthesis are described. Finally, several challenges that should be considered for the realization of next-generation skin electronics are discussed with recent outcomes for addressing these challenges.

Stimuli-responsive colorimetric sensors are promising for various industrial and medical applications due to the capability of simple, fast, and inexpensive visualization of external stimuli. Here we demonstrate a thermoresponsive, smart colorimetric patch based on a thermoresponsive plasmonic microgel embedded in a stretchable hydrogel film. To achieve a fast and efficient thermoresponsive color change, raspberry-shaped plasmonic microgels were fabricated by decorating gold nanoparticles (AuNPs) on poly(N-isopropylacrylamide) (PNIPAM) microgels, which exhibit reversible and strain-insensitive color shifts (between red and grayish violet) in response to a temperature change. The smart colorimetric patch containing a plasmonic microgels exhibits a significant extinction peak shift (176 nm) in a short time (1 s), with a temperature-sensing resolution of 0.2°C. Moreover, the transition temperature of the plasmonic microgel can be finely tuned by additives and comonomers, so that the exquisite temperature visualization can be conducted over a wide temperature range of 25-40°C by assembling plasmonic microgel films with different transition temperatures into an array patch. For proof-of-concept demonstrations, a freestanding smart colorimetric patch was utilized as a spatial temperature scanner and a colorimetric thermometer for a thermoresponsive actuator, which is potentially applicable in smart, wearable sensors and soft robotics.

No abstract

Improved performance in plasmonic organic solar cells (OSCs) and organic light-emitting diodes (OLEDs) via strong plasmon-coupling effects generated by aligned silver nanowire (AgNW) transparent electrodes decorated with core-shell silver-silica nanoparticles (Ag@SiO NPs) is demonstrated. NP-enhanced plasmonic AgNW (Ag@SiO NP-AgNW) electrodes enable substantially enhanced radiative emission and light absorption efficiency due to strong hybridized plasmon coupling between localized surface plasmons (LSPs) and propagating surface plasmon polaritons (SPPs) modes, which leads to improved device performance in organic optoelectronic devices (OODs). The discrete dipole approximation (DDA) calculation of the electric field verifies a strongly enhanced plasmon-coupling effect caused by decorating core-shell Ag@SiO NPs onto the AgNWs. Notably, an electroluminescence efficiency of 25.33 cd A (at 3.2 V) and a power efficiency of 25.14 lm W (3.0 V) in OLEDs, as well as a power conversion efficiency (PCE) value of 9.19% in OSCs are achieved using hybrid Ag@SiO NP-AgNW films. These are the highest values reported to date for optoelectronic devices based on AgNW electrodes. This work provides a new design platform to fabricate high-performance OODs, which can be further explored in various plasmonic and optoelectronic devices.