Approaches to Stretchable Polymer Active Channels for Deformable Transistors

The fabrication of deformable devices has been explored by interconnecting nonstretchable unit devices with stretchable conductors or by developing stretchable unit devices consisting of all stretchable device components such as electrodes, active channels, and dielectric layers. Most researches have followed the first approach so far, and the researches based on the second approach are at the very beginning stage. This paper discusses the perspectives of the second approach, specifically focusing on the polymer semiconductor channel layers, that is expected to facilitate high density device integration in addition to large area devices including polymer solar cells and light-emitting diodes. Three different routes are suggested as separate sections according to the principles imparting stretchability to polymer semiconductor layers: structural configurations of rigid semiconductors, two-dimensional network structure of semiconductors on elastomer substrates, and ductility enhancement of semiconductor films. Each section includes two subsections divided by the methodological difference. This Perspective ends with discussion on the future works for the routes and the challenges related to other device components.112417Ysciescopu

Flexible, Highly Efficient All-Polymer Solar Cells

All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymeracceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C 61 -butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared withpolymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices.ope

Full-Field Subwavelength Imaging Using a Scattering Superlens

Light-matter interaction gives optical microscopes tremendous versatility compared with other imaging methods such as electron microscopes, scanning probe microscopes, or x-ray scattering where there are various limitations on sample preparation and where the methods are inapplicable to bioimaging with live cells. However, this comes at the expense of a limited resolution due to the diffraction limit. Here, we demonstrate a novel method utilizing elastic scattering from disordered nanoparticles to achieve subdiffraction limited imaging. The measured far-field speckle fields can be used to reconstruct the subwavelength details of the target by time reversal, which allows full-field dynamic super-resolution imaging. The fabrication of the scattering superlens is extremely simple and the method has no restrictions on the wavelength of light that is usedclos

Highly Reversible, Grain-Directed Zinc Deposition in Aqueous Zinc Ion Batteries

Achieving highly reversible Zn metal anodes is a crucial step in advancing the performance of aqueous zinc ion batteries. However, despite the relative stability of Zn metal in aqueous environments, Zn metal is plagued by deterrents such as dendritic growth, H-2 evolution, and corrosion. This mainly stems from the absence of a stable solid-electrolyte interphase (SEI), an inevitable consequence of moderate concentration aqueous electrolytes. In response to such issues, herein, an artificial SEI formed from cross-linked gelatin is introduced by coating the surface of Zn metal. The presence of the gelatin layer significantly changes the deposition morphology of Zn, where its plated surface is much more uniform and dense compared to bare Zn metal. Interestingly, grain-directed electrodeposition can be observed in which the crystallographic orientation of the underlying Zn metal substrate determines the directionality of electrochemically plated Zn. This mode of growth results in a highly uniform and dense surface, translating to enhanced electrochemical stability.

Cationic Additive with a Rigid Solvation Shell for High-Performance Zinc Ion Batteries

Despite substantial progresses, in aqueous zinc ion batteries (AZIBs), developing zinc metal anodes with long-term reliable cycling capabilities is nontrivial because of dendritic growth and related parasitic reactions on the zinc surface. Here, we exploit the tip-blocking effect of a scandium (Sc3+) additive in the electrolyte to induce uniform zinc deposition. Additional to the tri-valency of Sc3+, the rigidity of its hydration shell effectively prevents zinc ions from concentrating at the surface tips, enabling highly stable cycling under challenging conditions. The shell rigidity, quantified by the rate constant of the exchange reaction (k(ex)), is established as a key descriptor for evaluating the tip-blocking effect of redox-inactive cations, explaining inconsistent results when only the valence state is considered. Moreover, the tip-blocking effect of Sc3+ is maintained in blends with organic solvents, allowing the zinc anode to cycle reliably even at -40 degrees C without corrosion.N

Enhanced Air Stability of Polymer Solar Cells with a Nanofibril-Based Photoactive Layer

In spite of the rapid increase in the power conversion efficiency (PCE) of polymer solar cells (PSCs), the poor stability of the photoactive layer in air under sunlight is a critical problem blocking commercialization of PSCs. This study investigates the photo-oxidation behavior of a bulk-heterojunction (BHJ) photoactive film made of single-crystalline poly­(3-hexlythiophene) (P3HT) nanofibrils and fullerene derivatives [phenyl-C₆₁-butyric methyl ester (PCBM), indene-C 60 bisadduct (ICBA)]. Because the single-crystalline P3HT nanofibrils had tightly packed π–π stacking, the permeation of oxygen and water into the nanofibrils was significantly reduced. Chemical changes in P3HT were not apparent in the nanofibrils, and hence the air stability of the nanofibril-based BHJ film was considerably enhanced as compared with conventional BHJ films. The chemical changes were monitored by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and UV–vis absorbance. Inverted PSCs made of the nanofibril-based BHJ layer also showed significantly enhanced air stability under sunlight. The nanofibril-based solar cell maintained more than 80% of its initial PCE after 30 days of continuous exposure to sunlight (AM 1.5G, 100 mW/cm²), whereas the PCE of the conventional BHJ solar cell decreased to 20% of its initial PCE under the same experimental conditions

Effect of PEDOT Nanofibril Networks on the Conductivity, Flexibility, and Coatability of PEDOT:PSS Films

The use of poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS) in electrodes and electrical circuits presents a number of challenges that are yet to be overcome, foremost amongst which are its relatively low conductivity, low coatability on hydrophobic substrates, and decreased conductivity at large strains. With this in mind, this study suggests a simple way to simultaneously address all of these issues through the addition of a small amount of a nonionic surfactant (Triton X-100) to commercial PEDOT:PSS solutions. This surfactant is shown to considerably reduce the surface tension of the PEDOT:PSS solution, thus permitting conformal coatings of PEDOT:PSS thin film on a diverse range of hydrophobic substrates. Furthermore, this surfactant induces the formation of PEDOT nanofibrils during coating, which led to the high conductivity values and mechanical stability at large strains (ε = 10.3%). Taking advantage of the superior characteristics of these PEDOT:PSS thin films, a highly flexible polymer solar cell was fabricated. The power conversion efficiency of this solar cell (3.14% at zero strain) was preserved at large strains (ε =7.0%)

Network Pharmacological Analysis on the Herbal Combinations for Mitigating Inflammation in Respiratory Tracts and Experimental Evaluation

The regulation of inflammatory mediators, such as TNF-α, IL-6, IL-1β, and leukotriene B4, could play a crucial role in suppressing inflammatory diseases such as COVID-19. In this study, we investigated the potential mechanisms of drug combinations comprising Ephedrae Herba, Schisandra Fructus, Platycodonis Radix, and Ginseng Radix; validated the anti-inflammatory effects of these drugs; and determined the optimal dose of the drug combinations. By constructing a herb-compound-target network, associations were identified between the herbs and tissues (such as bronchial epithelial cells and lung) and pathways (such as the TNF, NF-κB, and calcium signaling pathways). The drug combinations exerted anti-inflammatory effects in the RAW264.7 cell line treated with lipopolysaccharide by inhibiting the production of nitric oxide and inflammatory mediators, including TNF-α, IL-6, IL-1β, and leukotriene B4. Notably, the drug combinations inhibited PMA-induced MUC5AC mRNA expression in NCI-H292 cells. A design space analysis was carried out to determine the optimal herbal medicine combinations using the design of experiments and synergy score calculation. Consequently, a combination study of the herbal preparations confirmed their mitigating effect on inflammation in COVID-19

Tuning Mechanical and Optoelectrical Properties of Poly(3-hexylthiophene) through Systematic Regioregularity Control

While the regioregularity (RR) of conjugated polymers is known to have a strong influence on their inherent properties, systematic study of the RR effect has been limited due to the lack of a synthetic methodology. Herein, we successfully produced a series of poly(3-hexylthiophene)s (P3HTs) having a wide range of RR from 64 to 98%. Incorporation of controlled amounts of head-to-head (H-H) coupled dimer in modified Grignard metathesis polymerization allows a facile tuning of the RR of the P3HTs with comparable molecular weight and low polydispersity. Then, we investigated the effect of RR on structural, electrical, and mechanical properties of P3HTs in which a higher content of H-H regio-defects, namely lower RR, systematically lowered the degree of crystallinity. Although high RR P3HT (98%) had higher charge carrier mobility (1.81 x 10(-1) cm(2) V-1 s(-1)), its strong crystallinity induced high brittleness and stiffness, resulting in device failure under a very small strain, as shown in tensile and bending tests. The tensile modulus was reduced significantly from 287 MPa (RR 98%) to 13 MPa (RR 64%), and also the RR 64% P3HT film had much better mechanical resilience with an order of magnitude higher elongation at break than that of the RR 98% polymer. Our findings suggest that the mechanical and electrical properties of conjugated polymers can be systematically tuned by controlling the RR to meet the purposes of various organic electronic applications, i.e., flexible portable devices vs high-performance panelsclose1

Self-Seeded Growth of Poly(3-hexylthiophene) (P3HT) Nanofibrils by a Cycle of Cooling and Heating in Solutions

In spite of the recent successes in transistors and solar cells utilizing poly­(3-hexylthiophene) (P3HT) nanofibrils, systematic analysis on the growth kinetics has not been reported due to the lack of analytical tools. This study proposed a simple spectroscopic method to obtain the crystallinity of P3HT in solutions. On the basis of the analytical approach, we found that the crystallinity hysteresis upon temperature is a simple function of the solubility parameter difference (Δδ) between the P3HT and the solvents. When Δδ ≥ 0.7, a cooling (−20 °C)-and-heating (25 °C) process allowed the preparation of solutions including 1D crystal seeds dispersed in the solution. Simple coating of the seeded solutions completed the growth of the seeds into long nanofibrils at the early stage of the coating and thereby achieved almost 100% crystallinity in the resulting films without any postannealing process. The existence of PCBM for bulk-heterojunction (BHJ) solar cells did not affect the nucleation and growth of the nanofibrils during the cooling-and-heating process. The solar cells prepared from the solutions with Δδ ≥ 0.7 had solar conversion efficiencies higher than the conventional thermally annealed cells