November 20, 2019
Enjoy these interesting stories from the scientific community.
*-- New material to pave the way for lead-free solar panels --*
Scientists have developed a new material that could be used to make solar panels without lead.
Over the last decade, the quest to build a better, more efficient solar panel has centered on a mineral called perovskite. Solar panels made using the calcium titanium oxide mineral capture up to 28 percent of solar energy, while the best commercial panels boast efficiencies between 15 and 18 percent.
But building perovskite panels at scale has proven difficult. The material is unstable and contains water-soluble lead, a health hazard.
To build a safer solar panel, scientists developed a new hybrid material featuring organic and inorganic materials. The material's sandwich-like structure doesn't require lead and is much more stable.
Scientists described the new material this week in the journal Nature Chemistry.
"The energy and charge transfers between adjacent organic and inorganic layers are shown to be fast and efficient, owing to the atomically flat interface and ultrasmall interlayer distance of the perovskite materials," scientists wrote in their paper.
The study's authors suggest the new material could be used in a variety of electronic components and technologies.
"These structures are very exciting," Letian Dou, assistant professor of chemical engineering at Purdue University, said in a news release. "The sandwich structures are like semiconductor quantum wells that are widely used today in many electronic and optoelectronic devices, but they are much easier to produce and more tolerant to defects."
Dou and his colleagues previously used the organic-inorganic hybrid perovskite material to build a field effect transistor, a component in many electronic technologies that uses an electric field to control the flow of current.
According to Yao Gao, lead author of the new study and a postdoctoral fellow in Dou's research group at Purdue, the new material outperforms and is cheaper than a traditional inorganic semiconductor.
"Solar cells, as many people have demonstrated, can be highly efficient," Gao said. "With our new technology, we can make the hybrid perovskite materials intrinsically more stable. By replacing the toxic lead, these new materials are better for the environment and can also be safely used for bioelectronics sensors on the body."
*-- Astronauts conduct first spacewalk to fix cosmic particle detector on ISS --*
NASA astronaut Andrew Morgan and European Space Agency astronaut Luca Parmitano are back inside the space station after a spacewalk that lasted six hours and 39 minutes.
The spacewalk switched their spacesuits to battery power at 6:39 a.m. ET on Friday morning, starting the clock on the first in a series of challenging spacewalks. They returned to the space station and removed their spacesuits at 1:18 p.m.
During their time outside the International Space Station, Morgan and Parmitano began preliminary work related to the repair of the cosmic particle detector. Their efforts were broadcast live on NASA TV.
The duo didn't actually fix the device, but their work will make it possible to fix the detector during future spacewalk missions -- spacewalks that NASA says will be especially complicated.
Next Friday, Morgan and Parmitano will once again venture outside the space station, this time to -- according to NASA -- "access, cut, and label the stainless steel tubes that attach the current cooling system" to the cosmic particle detector.
"These spacewalks are considered the most complex of their kind since the Hubble Space Telescope servicing missions, which took place between 1993 and 2009," NASA reported last week.
The cosmic particle detector, officially named the Alpha Magnetic Spectrometer, is an experimental device designed to detect antimatter in cosmic rays. Data collected by the AMS could help scientists determine the mysterious makeup of dark matter, which accounts for most of the mass in the universe.
When engineers designed the device, they didn't conceive of in-service repairs. But the technology's cooling component is broken and needs to be replaced for the experiment to continue.
"When we first started this, we weren't really sure if we were going to be able to complete the repairs successfully," Tara Jochim, AMS spacewalk repair project manager at NASA's Johnson Space Center, said during a recent press briefing. "Usually when you go out for a spacewalk, you're working on a piece of hardware that was prepared for, on the ground, for a spacewalk."
The AMS was originally designed for a three-year mission, but the device has continued past its end date, and engineers want to prolong it further.
"More than 20 unique tools were designed for the intricate repair work, which will include the cutting and splicing of eight cooling tubes to be connected to the new system and reconnection of a myriad of power and data cables," according to NASA. "Astronauts have never cut and reconnected fluid lines during a spacewalk."
If the repair missions are successful, the AMS will be able to continue collecting data through 2030.
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