Demand For Flexible Electronics Research Articles

High-quality VO2 films synthesized on polymer substrates using room-temperature pulsed laser deposition and annealing

With the growing trend towards portable and adaptable devices in various fields, the demand for flexible electronics and coatings utilizing phase transition materials like VO2 as a functional layer is rising. However, depositing high-quality crystalline VO2 films directly onto polymer substrates remains challenging due to the thermosensitivity of such materials being barely compatible with usual VO2 deposition methods. In this study, we present a simple method for directly growing VO2 on Kapton substrates. VOx films were first deposited onto the Kapton substrate at room temperature using pulsed laser deposition and subsequently annealed in an oxygen atmosphere at 390 °C. The electrical and optical properties of the VO2/Kapton samples with different film thicknesses were investigated. The 200 nm-thick vanadium dioxide films exhibit the best resistivity contrast with 3.1 orders of magnitude (OOM), while the 50 nm-thick films show the best transmittance change of 54 % at 2500 nm. The switching performances are comparable or even superior to those achieved previously using more complicated synthesis processes such as film transfer, introduction of buffer layers, and ink injection. Additionally, by coupling W elemental doping and thin film strain, we successfully tuned the VO2 transition temperature to room temperature with a dopant concentration of only 1.1 at.% while maintaining a high electrical contrast (2 OOM). The impressive electrical and optical transition performance of the VO2/Kapton samples, combined with their tunable transition temperature, makes them promising candidates for flexible electronic devices and thermochromic smart coatings.

Selective detection of microcracks under the surface of glass substrates by non-contact stress-induced light-scattering method with temperature variations

Demand for flexible electronics is increasing due to recent global movements related to IoT. In particular, the ultra-thin glass substrate can be bent, its use is expanding for various applications such as thin liquid crystal panels. On the other hand, fine-polishing techniques such as chemical mechanical polishing treatments, are important techniques in glass substrate manufacturing. However, these techniques may cause microcracks under the surface of glass substrates because they use mechanical friction. We propose a novel non-contact thermal stress-induced light-scattering method (N-SILSM) using a heating device for inspecting surfaces to detect polishing-induced microcracks. In this report, we carry out the selective detection of microcracks and tiny particles using an N-SILSM with temperature variation. Our results show that microcracks and tiny particles can be distinguished and measured by an N-SILSM utilizing temperature change, and that microcrack size can be estimated based on the change in light-scattering intensity.

Process converts wood into a squishy sensor

Carbon-based materials that bounce back when you press them are in demand for flexible electronics and energy storage devices alike. Most of the available options have limitations, though: They come from nonrenewable sources, have inferior electrical properties, or are difficult to manufacture on scale. Now, researchers have revealed a compressible material with promising electrical properties from a sustainable, if somewhat surprising, source: wood. University of Maryland, College Park, engineer Liangbing Hu presented the work last week at the ACS national meeting in New Orleans. To make the spongy material, Hu, postdoctoral researcher Chaoji Chen, and colleagues were inspired by honeycombs, which have a wavy lattice that stands up to compression. They hypothesized they might be able to chemically change wood’s architecture to achieve a similar effect. Indeed, by stripping away lignin and hemicellulose from a block of balsa wood, they transformed the wood’s rigid, boxlike cell walls into a lattice

Synthesis of Silver Nanoparticles at the Liquid–Liquid Using Ultrasonic Wave

The high demand of flexible electronics and the miniaturization of electronic components have been increasing very rapidly. Nanotechnology and in particular nanoparticles have become very important for the development of new technologies and applications which depend on the synthesis and characterization of nanoparticles with specific properties. Significant attention has been focused on the characteristics of the nanoparticles since their properties, particle size and shape are very different when compared to those of the bulk materials. In order to produce nanoparticles with more efficient structures and electronic properties for nano ink, it is necessary to control the particle size to avoid agglomeration. Currently, the nanoparticle size and its agglomeration is controlled by surfactants, but some studies have shown that adding surfactants have negative effects on the conductivity of the nanoparticles along with the high curing temperatures of nano-ink. In this study, silver nanoparticles were synthesized by adding methanol to water instead of surfactants in order to control the silver nanoparticle size. The water and methanol solution was prepared by using different ratios v/v of water/methanol obtaining a liquid–liquid interface and forming a molecular–molecular interface restricting the silver ion movement in the solution. In addition to the liquid–liquid interface, the ion concentration and movement were also restricted through a spraying mist by using ultrasonic waves. The silver ion and the reducing agent were found to have a difference in concentration by the spraying mist method. The movement of the silver ions and the reducing agents were controlled by the difference in concentration. It was observed that the control of the nanoparticles and ion movement was more efficient by spraying silver ion solution than using a reducing agent solution. We confirmed that by increasing the volumetric ratios of methanol the silver nanoparticle size also increased. The mist particle size and the concentration were also calculated at different volumetric ratios of methanol.