Transparent electrodes that can maintain their electrical and optical properties stably against large mechanical deformations are essential in numerous applications of flexible and wearable electronics. In this paper, we report a comprehensive analysis of the electrical, optical, and mechanical properties of hybrid nanostructures based on graphene and metal nanotrough networks as stretchable and transparent electrodes. Compared to the single material of graphene or the nanotrough, the formation of this hybrid can improve the uniformity of sheet resistance significantly, that is, a very low sheet resistance (1 Ω/sq) with a standard deviation of less than ±0.1 Ω/sq, high transparency (91% in the visible light regime), and superb stretchability (80% in tensile strain). The successful demonstration of skin-attachable, flexible, and transparent arrays of oxide semiconductor transistors fabricated using hybrid electrodes suggests substantial promise for the next generation of electronic devices.

Uncontrolled growth of insulating lithium sulfide leads to passivation of sulfur cathodes, which limits high sulfur utilization in lithium-sulfur batteries. Sulfur utilization can be augmented in electrolytes based on solvents with high Gutmann Donor Number; however, violent lithium metal corrosion is a drawback. Here we report that particulate lithium sulfide growth can be achieved using a salt anion with a high donor number, such as bromide or triflate. The use of bromide leads to ~95 % sulfur utilization by suppressing electrode passivation. More importantly, the electrolytes with high-donor-number salt anions are notably compatible with lithium metal electrodes. The approach enables a high sulfur-loaded cell with areal capacity higher than 4 mA h cm−2 and high sulfur utilization ( > 90 %). This work offers a simple but practical strategy to modulate lithium sulfide growth, while conserving stability for high-performance lithium-sulfur batteries.

Despite the theoretically high energy density, the practical energy density of Li-S batteries at the moment does not meet the demand due to low sulfur (S) loading (<2 mg cm −2 ), large electrolyte amount (electrolyte/sulfur ratio >20 µL mg −1 ), and excess lithium (Li) metal use (>10 times excess). [5] In particular, large electrolyte usage (flooding) greatly diminishes the practical energy density of Li-S batteries. Due to the intrinsic solution-based redox chemistry, however, many of the challenges arise from minimizing the electrolyte/ sulfur ratio (E/S ratio). Since soluble lithium polysulfide (LiPS, Li 2 S x when 2 < x ≤ 8) intermediates are self-redox mediating, the decrease in the LiPS dissolution causes a sluggish sulfur conversion and high polarization. [6] Next, the morphology of lithium sulfide (Li 2 S) electrodeposition and the kinetics of the re-oxidation are affected by the sulfur species solubility as well. [7] Hence, uncontrolled precipitation and continual accumulation of Li 2 S limit the discharge capacity and further passivate the cathode interface throughout the cycling. [8] Reducing the electrolyte volume exacerbates not only the cathode performance but also the anode stability. A high reactivity and an infinite volume change of the Li metal anode cause the incessant decomposition of the electrolyte. Therefore, the lean electrolyte condition accelerates the increase of the cell resistance and provokes earlier performance failure compared to the flooding electrolyte system. [9] Manipulating electrolyte materials (solvents, salt anions, and additives) has a considerable impact on the electrochemical performance of Li-S batteries. There have been studies in which solvents with high Gutmann donor numbers (DNs) form strong interactions with lithium ions (Li + ) and promote the solvation of polysulfide (PS) anions. The increased LiPS solubility facilitates the solution-mediated reaction pathway, enabling fast reaction kinetics and high sulfur utilization. [10] Furthermore, the same merits can also be achieved with salt anions having high-DNs [11] or additives promoting ionic solvation. [12] Under a lean electrolyte regime, the role of highly solvating electrolytes becomes more prominent because of the limited solubility of sulfur species. For example, high-DN solvents can enhance the sulfur utilization under the reduced electrolyte amount by promoting the charge/discharge reactions. [13] Despite this fact, the Minimizing electrolyte use is essential to achieve high practical energy density of lithium-sulfur (Li-S) batteries. However, the sulfur cathode is more readily passivated under a lean electrolyte condition, resulting in low sulfur utilization. In addition, continuous electrolyte decomposition on the Li metal anode aggravates the problem, provoking rapid capacity decay. In this work, the dual functionalities of NO 3 − as a high-donor-number (DN) salt anion is presented, which improves the sulfur utilization and cycling stability of lean-electrolyte Li-S batteries. The NO 3 − anion eleva...

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Influence of carrier conductivity and injection on efficiency and chromaticity in small-molecule white organic lightemitting diodes based on 4 , 4 ′ -bis ( 2 , 2 ′ -diphenylvinyl ) -1 , 1 ′ -spirobiphenyl and rubrene

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In this work, we report a freeform shaped active‐matrix organic light‐emitting diode (AMOLED) display based on low‐temperature polycrystalline silicon technology. It was found that our AMOLED, developed with a unique pixel structure, can withstand in various desired shapes featuring its stretchable property with no degradation of image quality and device characteristics. We demonstrated unprecedented convex/concave shape of the 9.1‐inch AMOLED display by low‐temperature thermoforming process. The AMOLED display with freeform design is promising for future display applications such as automotive, Internet of things devices, and wearable electronics.