The findings could help lead to more stable and reliable wearables and flexible electronic devices — ScienceEach day
A workforce of Northwestern University supplies science researchers have developed a brand new technique to view the dynamic movement of atoms in atomically skinny 2D supplies. The imaging approach, which reveals the underlying trigger behind the efficiency failure of a extensively used 2D materials, could help researchers develop more stable and reliable supplies for future wearables and flexible electronic devices.
These 2D supplies — reminiscent of graphene and borophene — are a category of single-layer, crystalline supplies with widespread potential as semiconductors in superior ultra-thin, flexible electronics. Yet due to their skinny nature, the supplies are extremely delicate to exterior environments, and have struggled to show long-term stability and reliability when utilized in electronic devices.
“Atomically thin 2D materials offer the potential to dramatically scale down electronic devices, making them an attractive option to power future wearable and flexible electronics,” stated Vinayak Dravid, Abraham Harris Professor of Materials Science and Engineering on the McCormick School of Engineering.
The research, titled “Direct Visualization of Electric Field induced Structural Dynamics in Monolayer Transition Metal Dichalcogenides,” was revealed on February 11 within the journal ACS Nano. Dravid is the corresponding writer on the paper. Chris Wolverton, the Jerome B. Cohen Professor of Materials Science and Engineering, additionally contributed to the analysis.
“Unfortunately, electronic devices now operate as a kind of ‘black box.’ Although device metrics can be measured, the motion of single atoms within the materials responsible for these properties is unknown, which greatly limits efforts to improve performance,” added Dravid, who serves as director of the Northwestern University Atomic and Nanoscale Characterization (NUANCE) Center. The analysis permits a means to transfer previous that limitation with a brand new understanding of the structural dynamics at play inside 2D supplies receiving electrical voltage.
Building upon a earlier research during which the researchers used a nanoscale imaging approach to observe failure in 2D supplies brought on by warmth, the workforce used a high-resolution, atomic-scale imaging technique referred to as electron microscopy to observe the motion of atoms in molybdenum disulfide (MoS2), a well-studied materials initially used as a dry lubricant in greases and friction supplies that has lately gained curiosity for its electronic and optical properties. When the researchers utilized an electrical present to the fabric, they noticed its extremely cell sulfur atoms transfer repeatedly to vacant areas within the crystalline materials, a phenomenon they dubbed, “atomic dance.”
That motion, in flip, brought on the MoS2’s grain boundaries — a pure defect created within the area the place two crystallites throughout the materials meet — to separate, forming slim channels for the present to journey via.
“As these grain boundaries separate, you are left with only a couple narrow channels, causing the density of the electrical current through these channels to increase,” stated Akshay Murthy, a PhD scholar in Dravid’s group and the lead writer on the research. “This leads to higher power densities and higher temperatures in those regions, which ultimately leads to failure in the material.”
“It’s powerful to be able to see exactly what’s happening on this scale,” Murthy continued. “Using traditional techniques, we could apply an electric field to a sample and see changes in the material, but we couldn’t see what was causing those changes. If you don’t know the cause, it’s difficult to eliminate failure mechanisms or prevent the behavior going forward.”
With this new means to research 2D supplies on the atomic stage, the workforce believes researchers could use this imaging method to synthesize supplies which are much less prone to failure in electronic devices. In reminiscence devices, for instance, researchers could observe how areas the place data is saved evolve as electrical present is utilized and adapt how these supplies are designed for higher efficiency.
The approach could additionally help enhance a number of different applied sciences, from transistors in bioelectronics to mild emitting diodes (LEDs) in shopper electronics to photovoltaic cells that comprise photo voltaic panels.
“We believe the methodology we have developed to monitor how 2D materials behave under these conditions will help researchers overcome ongoing challenges related to device stability,” Murthy stated. “This advance brings us one step closer to moving these technologies from the lab to the marketplace.”