In a new paper published February 26 in the journal Nature Energy, a University of Colorado Boulder researcher and his international collaborators unveiled an innovative method to manufacture the new solar cells, known as perovskite cells, an achievement critical for the commercialization of what many consider the next generation of solar technology.

Today, nearly all solar panels are made from silicon, which boast an efficiency of 22%. This means silicon panels can only convert about one-fifth of the sun’s energy into electricity, because the material absorbs only a limited proportion of sunlight’s wavelengths. Producing silicon is also expensive and energy intensive.

Enter perovskite. The synthetic semiconducting material has the potential to convert substantially more solar power than silicon at a lower production cost.

“Perovskites might be a game changer,” said Michael McGehee, a professor in the Department of Chemical and Biological Engineering and fellow with CU Boulder’s Renewable & Sustainable Energy Institute.

Scientists have been testing perovskite solar cells by stacking them on top of traditional silicon cells to make tandem cells. Layering the two materials, each absorbing a different part of the sun’s spectrum, can potentially increase the panels’ efficiency by over 50%.

“We’re still seeing rapid electrification, with more cars running off electricity. We’re hoping to retire more coal plants and eventually get rid of natural gas plants,” said McGehee. “If you believe that we’re going to have a fully renewable future, then you’re planning for the wind and solar markets to expand by at least five to ten- fold from where it is today.”

To get there, he said, the industry must improve the efficiency of solar cells.

But a major challenge in making them from perovskite at a commercial scale is the process of coating the semiconductor onto the glass plates which are the building blocks of panels. Currently, the coating process has to take place in a small box filled with non-reactive gas, such as nitrogen, to prevent the perovskites from reacting with oxygen, which decreases their performance.

“This is fine at the research stage. But when you start coating large pieces of glass, it gets harder and harder to do this in a nitrogen filled box,” McGehee said.

McGehee and his collaborators set off to find a way to prevent that damaging reaction with the air. They found that adding dimethylammonium formate, or DMAFo, to the perovskite solution before coating could prevent the materials from oxidizing. This discovery enables coating to take place outside the small box, in ambient air. Experiments showed that perovskite cells made with the DMAFo additive can achieve an efficiency of nearly 25% on their own, comparable to the current efficiency record for perovskite cells of 26%.

The additive also improved the cells’ stability.

Commercial silicon panels can typically maintain at least 80% of their performance after 25 years, losing about 1% of efficiency per year. Perovskite cells, however, are more reactive and degrade faster in the air. The new study showed that the perovskite cell made with DMAFo retained 90% of its efficiency after the researchers exposed them to LED light that mimicked sunlight for 700 hours. In contrast, cells made in the air without DMAFo degraded quickly after only 300 hours.

While this is a very encouraging result, there are 8,000 hours in one year, he noted. So longer tests are needed to determine how these cells hold up overtime.

“It’s too early to say that they are as stable as silicon panels, but we’re on a good trajectory toward that,” McGehee said.

The study brings perovskite solar cells one step closer to commercialization. At the same time, McGehee’s team is actively developing tandem cells with a real-world efficiency of over 30% that have the same operational lifetime as silicon panels.

McGehee leads a U.S. academic-industry partnership called Tandems for Efficient and Advanced Modules using Ultrastable Perovskites (TEAMUP). Together with researchers from three other universities, two companies and a national laboratory, the consortium received $9 million funding from the U.S. Department of Energy last year to develop stable tandem perovskites that can feasibly be used in the real world and are commercially viable. The goal is to create tandem more efficient than conventional silicon panels and equally stable over a 25-year period.

With higher efficiency and potentially lower price tags, these tandem cells could have broader applications than existing silicon panels, including potential installation on the roofs of electric vehicles. They could add 15 to 25 miles of range per day to a car left out in the sun, enough to cover many people’s daily commutes. Drones and sailboats could also be powered by such panels.

After a decade of research in perovskites, engineers have built perovskite cells that are as efficient as silicon cells, which were invented 70 years ago, McGehee said. “We are taking perovskites to the finish line. If tandems work out well, they certainly have the potential to dominate the market and become the next generation of solar cells,” he said.

As the Dartmouth-based website about prosopometamorphopsia explains, “‘Prosopo’ comes from the Greek word for face ‘prosopon’ while ‘metamorphopsia’ refers to perceptual distortions.”’ Specific symptoms vary from case to case and can affect the shape, size, color, and position of facial features. The duration of PMO also varies; it “can last for days, weeks, or even years.”

A new Dartmouth study published in the “Clinical Pictures” section of The Lancet reports on a unique case of a patient with PMO. The research is the first to provide accurate and photorealistic visualizations of the facial distortions experienced by an individual with PMO.

The patient, a 58-year-old male with PMO, sees faces without any distortions when they are viewed on a screen and on paper, but he sees distorted faces that appear “demonic” when viewed in-person. Most PMO cases however, see distortions in all contexts, so his case is especially rare and presented a unique opportunity to accurately depict his distortions.

For the study, the researchers took a photograph of a person’s face. Then, they showed the patient the photograph on a computer screen while he looked at the real face of the same person. The researchers obtained real-time feedback from the patient on how the face on the screen and the real face in front of him differed, as they modified the photograph using computer software to match the distortions perceived by the patient.

“In other studies of the condition, patients with PMO are unable to assess how accurately a visualization of their distortions represents what they see because the visualization itself also depicts a face, so the patients will perceive distortions on it too,” says lead author Antônio Mello, a PhD student in the Department of Psychological and Brain Sciences at Dartmouth. In contrast, this patient doesn’t see distortions on a screen. This means that the researchers were able to modify the face in the photograph, and the patient could accurately compare how similar his perception of the real face was to the manipulated photograph. “Through the process, we were able to visualize the patient’s real-time perception of the face distortions,” says Mello.

In their research with other PMO cases, the co-authors state that some of their PMO participants have seen health professionals who wanted to help but diagnosed them with another health condition, not PMO.

“We’ve heard from multiple people with PMO that they have been diagnosed by psychiatrists as having schizophrenia and put on anti-psychotics, when their condition is a problem with the visual system,” says senior author Brad Duchaine, a professor of psychological and brain sciences and principal investigator of the Social Perception Lab at Dartmouth.

“And it’s not uncommon for people who have PMO to not tell others about their problem with face perception because they fear others will think the distortions are a sign of a psychiatric disorder,” says Duchaine. “It’s a problem that people often don’t understand.”

Through their paper, the researchers hope to increase public awareness of what PMO is.

Jupiter, Saturn, Uranus and Neptune, on the other hand, contain mostly gas. But scientists also have known for a long time that planet-forming disks start out with 100 times more mass in gas than solids, which leads to a pressing question: When and how does most of the gas leave a nascent planetary system?

A new study led by Naman Bajaj at the University of Arizona Lunar and Planetary Laboratory, published in the Astronomical Journal, provides answers. Using the James Webb Space Telescope, or JWST, the team obtained images from such a nascent planetary system — also known as a circumstellar disk — in the process of actively dispersing its gas into surrounding space.

“Knowing when the gas disperses is important as it gives us a better idea of how much time gaseous planets have to consume the gas from their surroundings,” said Bajaj, a second-year doctoral student at UArizona’s Lunar and Planetary Laboratory. “With unprecedented glimpses into these disks surrounding young stars, the birthplaces of planets, JWST helps us uncover how planets form.”

During the very early stages of planetary system formation, planets coalesce in a spinning disk of gas and tiny dust around the young star, according to Bajaj. These particles clump together, building up into bigger and bigger chunks called planetesimals. Over time, these planetesimals collide and stick together, eventually forming planets. The type, size and location of planets that form depend on the amount of material available and how long it remains in the disk.

“So, in short, the outcome of planet formation depends on the evolution and dispersal of the disk,” Bajaj said.

At the heart of this discovery is the observation of T Cha, a young star — relative to the sun, which is about 4.6 billion years old — enveloped by an eroding circumstellar disk notable for a vast dust gap, spanning approximately 30 astronomical units, or au, with one au being the average distance between the Earth and the sun.

Bajaj and his team were able, for the first time, to image the disk wind, as the gas is referred to when it slowly leaves the planet-forming disk. The astronomers took advantage of the telescope’s sensitivity to light emitted by an atom when high-energy radiation — for example, in starlight — strips one or more electrons from its nucleus. This is known as ionization, and the light emitted in the process can be used as a sort of chemical “fingerprint” — in the case of the T Cha system, tracing two noble gases, neon and argon. The observations also mark the first time a double ionization of argon has been detected in a planet-forming disk, the team writes in the paper.

“The neon signature in our images tells us that the disk wind is coming from an extended region away from the disk,” Bajaj said. “These winds could be driven either by high-energy photons — essentially the light streaming from the star — or by the magnetic field that weaves through the planet-forming disk.”

In an effort to differentiate between the two, the same group, this time led by Andrew Sellek, a postdoctoral researcher at Leiden University in the Netherlands, performed simulations of the dispersal driven by stellar photons, the intense light streaming from the young star. They compared these simulations to the actual observations and found dispersal by high-energy stellar photons can explain the observations, and hence cannot be excluded as a possibility. That study concluded that the amount of gas dispersing from the T Cha disk every year is equivalent to that of Earth’s moon. These results will be published in a companion paper, currently under review with the Astronomical Journal.

While neon signatures had been detected in many other astronomical objects, they weren’t known to originate in low-mass planet-forming disks until first discovered in 2007 with JWST’s predecessor, NASA’s Spitzer Space Telescope, by Ilaria Pascucci, a professor at LPL who soon identified them as a tracer of disk winds. Those early findings transformed research efforts focused on understanding gas dispersal from circumstellar disks. Pascucci is the principal investigator on the most recent observing project and a co-author on the publications reported here.

“Our discovery of spatially resolved neon emission — and the first detection of double ionized argon — using the James Webb Space Telescope could become the next step towards transforming our understanding of how gas clears out of a planet-forming disk,” Pascucci said. “These insights will help us get a better idea of the history and impact on our own solar system.”

In addition, the group has also discovered that the inner disk of T Cha is evolving on very short timescales of decades; they found that the spectrum observed by JWST differs from the earlier spectrum detected by Spitzer. According to Chengyan Xie, a second-year doctoral student at LPL who leads this in-progress work, this mismatch could be explained by a small, asymmetric disk inside of T Cha that has lost some of its mass in the short 17 years that have elapsed between the two observations.

“Along with the other studies, this also hints that the disk of T Cha is at the end of its evolution,” Xie said. “We might be able to witness the dispersal of all the dust mass in T Cha’s inner disk within our lifetime.”

Co-authors on the publications include Uma Gorti with the SETI Institute, Richard Alexander with the University of Leicester, Jane Morrison and Andras Gaspar with the UArizona’s Steward Observatory, Cathie Clarke with the University of Cambridge, Giulia Ballabio with Imperial College London, and Dingshan Deng with the Lunar and Planetary Laboratory.

A collaborative research team comprising Professor Jong Kyu Kim, Jaerim Kim, a Ph. D. candidate, Professor Yong-Tae Kim, and Doctor Sang-Mun Jung from the Department of Materials Science and Engineering at the POSTECH has succeeded in developing an economical and efficient water electrolysis catalyst that overcomes the limitations of conventional catalysts by using an oblique angle deposition method and nickel (Ni). The research has been recognized for its excellence and published as an inside front cover article in the international journal Advanced Materials.

The water-electrolysis processes employ costly precious metals like platinum as catalysts for hydrogen production, rendering the process excessively costly. Furthermore, the use of conventional thin-film catalysts often results in inadequate separation of hydrogen bubbles, leading to blockages in the catalyst’s active sites or hindering reactant movement, ultimately diminishing process efficiency.

In response to these challenges, the research team opted for oblique angle deposition and nickel. This technique involves tilting the substrate during deposition to easily create diverse nanostructures of the material, offering a straightforward and inexpensive solution. Moreover, nickel stands out as an abundant non-precious metal catalyst on Earth, demonstrating relatively high efficiency in hydrogen generation.

The team utilized an oblique angle deposition method to synthesize nickel featuring finely crafted, vertically aligned nanorods protrusions. In contrast to conventional nanostructures that merely augment the catalyst’s surface area, the researchers engineered highly porous nickel nanorods array, presenting a unique superaerophobic surface properties to solve the hydrogen adherence issues. Experimental results revealed that hydrogen bubbles generated during the electrolysis process exhibited the accelerated separation of hydrogen bubbles from the superaerophobic surface. The team’s superaerophobic three-dimensional nickel nanorods catalyst, with effective pore channels, demonstrated a remarkable 55-fold improvement in hydrogen production efficiency compared to an equivalent amount of nickel in a traditional thin film structure.

Professor Jong Kyu Kim and Ph. D. Jaerim Kim, leading the research, explained, “By enhancing the efficiency of the water electrolysis process for green hydrogen production, we are advancing towards a hydrogen economy and a carbon-neutral society.” They added, “This breakthrough not only benefits water electrolysis but also holds promise for various other renewable energy applications where surface reactions play a crucial role, such as carbon dioxide reduction and light energy conversion systems.”

This study was sponsored by the Hydrogen Energy Innovation Technology Development Program, the Program for Establishing an International Cooperation Foundation, the Future Innovation Infrastructure Research for Radiology Program, and the Future Material Discovery Program of Korea.