Optical memories based on photoresponsive organic field-effect transistors (OFETs) are of great interest due to their unique applications, such as multibit storage memories and flexible imaging circuits. Most studies of OFET-type memories have focused on the photoresponsive active channels, but more useful functions can be additionally given to the devices by using floating gates that can absorb light. In this case, effects of photoirradiation on photoactive floating-gate layers need to be fully understood. Herein, we studied the photoinduced erasing effects of floating-gate interlayers on the electrical responses of OFET-type memories and considered the possible mechanisms. Polymer/C composites were inserted between pentacene and SiO to form photoresponsive floating-gate interlayers in transistor memory. When exposed to light, C generated excitons, and these photoexcited carriers contributed to the elimination of trapped charge carriers, which resulted in the recovery of OFET performance. Such memory devices exhibited bistable current states controlled with voltage-driven programming and light-driven erasure. Furthermore, these devices maintained their charge-storing properties over 10 000 s. This proof-of-concept study is expected to open up new avenues in information technology for the development of organic memories that exhibit photoinduced recovery over a wide range of wavelengths of light when combined with appropriate photoactive floating-gate materials.

Photoresponsive transistor memories that can be erased using light-only bias are of significant interest owing to their convenient elimination of stored data for information delivery. Herein, we suggest a strategy to improve light-erasable organic transistor memories, which enables fast "photoinduced recovery" under low-intensity light. CdSe quantum dots (QDs) whose surfaces are covered with three different organic molecules are introduced as photoactive floating-gate interlayers in organic transistor memories. We determine that CdSe QDs capped or surface-modified with small molecular ligands lead to efficient hole diffusion from the QDs to the conducting channel during "photoinduced recovery", resulting in faster erasing times. In particular, the memories with QDs surface-modified with fluorinated molecules function as normally-ON type transistor memories with nondestructive operation. These memories exhibit high memory ratios over 10 between OFF and ON bistable current states for over 10 000 s and good dynamic switching behavior with voltage-driven programming processes and light-assisted erasing processes within 1 s. Our study provides a useful guideline for designing photoactive floating-gate materials to achieve desirable properties of light-erasable organic transistor memories.

Self‐healable and stretchable energy‐harvesting materials can provide a new avenue for the realization of self‐powered wearable electronics, including electronic skins, whose main materials are required to be robust to and stable under external damage and severe mechanical stresses. However, thermoelectric (TE) materials showing both self‐healing properties and stretchability have not yet been demonstrated despite their great potential to harvest thermal energy in the human body. As most existing TE materials are either mechanically brittle or unrecoverable after being subjected to damage, a novel approach is necessary for designing such materials. Herein, self‐healable and stretchable TE materials based on all‐organic composite system wherein polymer semiconductor nanowires are p‐doped with a molecular dopant and embedded in a thermoplastic elastomer matrix are reported. The polymer nanowires are electrically percolated in the matrix, and the resulting composite materials exhibit good TE performance. The composites also exhibit both excellent self‐healing properties under mild heat and pressure conditions and good stretchability. It is believed that this work can be a cornerstone for the design of self‐healable and stretchable energy‐harvesting materials as it provides useful guidelines for imparting electrical conductivity to insulating thermoplastic elastomers, which typically possess versatile and useful mechanical properties.

Hybrid carbon nanotube composites with two different types of fillers have attracted considerable attention for various advantages. The incorporation of micro-scale secondary fillers creates an excluded volume that leads to the increase in the electrical conductivity. By contrast, nano-scale secondary fillers shows a conflicting behavior of the decreased electrical conductivity with micro-scale secondary fillers. Although several attempts have been made in theoretical modeling of secondary-filler composites, the knowledge about how the electrical conductivity depends on the dimension of secondary fillers was not fully understood. This work aims at comprehensive understanding of the size effect of secondary particulate fillers on the electrical conductivity, via the combination of Voronoi geometry induced from Swiss cheese models and the underlying percolation theory. This indicates a transition in the impact of the excluded volume, i.e., the adjustment of the electrical conductivity was measured in cooperation with loading of second fillers with different sizes.

A water washing process can effectively reduce the presence of residual lithium with minimal effect on lithium‐ion battery cell performance. We investigated the effects of varying the amount of water used for washing and the temperature used to evaporate the water on Li1.00Ni0.80Co0.15Mn0.05O2. The residual lithium decreased and the cell performance deteriorated as the amount of water used for washing was increased from 0.7 to 5 times the amount of active material. The temperature at which the active material was dried after washing had a considerable effect on the reformation of the residual lithium layer after heat treatment. A ratio of water/active material of 1:1 and a drying temperature of 120 °C were selected as the optimal washing conditions, achieving a residual lithium content of less than 1000 ppm with minimum deterioration in cell performance; as a result of the treatment, the total volume of gas evolution was reduced by 25 %.