Publication Highlight

To capture carbon from the environment, we need to first decarbonize the grid

Daniel Morton — Thu, 14 May 2026 16:50:20 +0000

To capture carbon from the environment, we need to first decarbonize the grid Daniel Morton Thu, 05/14/2026 - 10:50

Daniel Morton

Most carbon capture research focuses on the chemistry. A new study from CU 91��Ҹ� takes a big-picture look and asks hard questions about the whole system: what does it cost, at scale, and under real-world conditions?

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In 2024, global average temperatures exceeded 1.5 ^oC above pre-industrial levels for the first time. This threshold was set as an aspirational limit by the 2015 Paris Agreement and was considered a line beyond which the impacts of climate change on ecosystem and human vulnerability become stark. Crossing this threshold is a signal that reducing emissions alone will not be enough. Increasingly, scientists, engineers, and policymakers around the globe agree that we will need to actively pull carbon dioxide (CO₂) out of the atmosphere to help reduce the impacts of this pollutant. The scale of this task is vast. The International Energy Agency projections suggest that reaching net-zero emissions by 2050 will require removing around one billion tonnes of CO₂ from the atmosphere every year. A billion tonnes of CO₂ is roughly equivalent to the annual CO₂ output of the entire global aviation industry. This vast amount needs to not only be offset from the system but fully removed from it.

This is the problem that has inspired a collaborative team of researchers at RASEI, including RASEI Fellows Prof. Wilson Smith and Prof. Bri-Mathias Hodge, and is the subject of a recent collaborative report published in Joule.

Two ways to catch carbon

91��Ҹ�ers are exploring a number of ways to pull CO₂ directly from the environment, and this comparative study looks at two of them side-by-side. The first, direct air capture (DAC), draws air from the atmosphere through a liquid solution that absorbs CO₂, analogous to a large-scale filter. It is the more established of the two approaches, with the world’s largest DAC facility currently under construction, a plant in Texas designed to remove 500,000 tonnes of CO₂ per year. The second approach examined in this study, direct ocean capture (DOC), is less developed but works with a natural advantage: it is estimated that the oceans absorb around 30% of the CO₂ that human activity produces each year, meaning seawater is already rich in dissolved carbon that originated in the atmosphere. By extracting that carbon directly from seawater, DOC bypasses the need to process enormous volumes of air. In fact, this advantage is one of the main reasons why many researchers are evaluating the feasibility of DOC as a CO₂ removal solution.

Both approaches share a common challenge: once you have captured the CO₂ from air, you need to do something with it. The regeneration process releases concentrated CO₂ in a usable form, while also recovering the capture solvent. In most current DAC systems, this process requires heating the captured material up to around 900 ^oC, typically by burning natural gas. This process is energy-intensive and creates its own greenhouse gas emissions, somewhat undermining the overall carbon capture process.

To try and understand the impacts of this overall process, the RASEI team modeled what happens when you substitute the heat-based regeneration setup with an electricity-driven alternative called bipolar membrane electrodialysis, or BPMED. Instead of using heat to release the CO₂, BPMED uses electricity to shift the chemistry of the captured solution, enabling the release of CO₂ at ambient temperatures. The key question the team sought to answer was whether this substitution makes economic sense when integrated with DAC and DOC, and under what kinds of conditions.

Building the model

To assess the DAC and DOC pathways, the team built a portfolio of connected 91��Ҹ�, starting from the physics of how CO₂ is captured and released, moving through the energy demands of each step, all the way up to a full cost analysis. This kind of approach, known as a techno-economic analysis (TEA for short), links the technical performance of a process directly to its economics. A TEA allows you to not just explore whether something works but also gain insight into whether it is viable at scale and under real-world conditions.

A particular strength of this study is the level at which the 91��Ҹ� connect these dots. As lead author Dr. Hussain Almajed (who started an ORISE Postdoctoral fellowship at the National Energy Technology Laboratory in July of 2025 shortly after graduating with his PhD from CU 91��Ҹ�) puts it, the goal was to compare the two approaches “not to say which one is the winner, which one is the loser, but to highlight the trade-offs.” The team pulled data from the California electricity grid, modeled different power supply scenarios, and ran both the DAC-BPMED and DOC-BPMED systems through the same framework. This provided a side-by-side comparison, one that had not previously been explored, that produced some unanticipated observations.

Two technologies, two cost profiles

The comparative study revealed a foundational trade-off rooted in a fundamental difference between DAC and DOC: Concentration. Air contains about 120 times less carbon than seawater, requiring large volumes of air to be processed at every iteration. However, once the CO₂ is captured via a liquid solvent, typically a hydroxide, the comparison reverses. A typical liter of DAC solution contains 0.5 to 1.0 moles of dissolved carbon, which is roughly 160 to 320 times higher than the dissolved carbon in a liter of seawater. That means a DAC plant needs to process far less liquid to recover a given amount of CO₂ compared to DOC, but extracting carbon from such a concentrated solution requires running the BPMED part of the system at high intensity, at high electrical current, which consumes significant energy. The equipment footprint is relatively small, but the electricity bill is high.

DOC works the other way around. Because seawater holds less dissolved carbon compared to a DAC solution, a DOC plant must process vast amounts of seawater to recover the same amount of CO₂. The 91��Ҹ� estimate that DOC-BPMED would need roughly 20 times more membrane area than the equivalent DAC-BPMED system, representing a significant upfront investment. On the other hand, the electrically driven process can run at a much lower current when handling dilute seawater, using considerably less energy per tonne of CO₂ captured.

These differences are obvious in the cost estimates. For a plant capturing 100,000 tonnes of CO₂ per year, and connected to the current California electricity grid, the modeled cost of capture via DAC-BPMED came in at around $470 per tonne of CO₂ in the baseline case. For DOC-BPMED, the equivalent figure was around $1,500 per tonne, roughly three times higher. This is driven largely by the upfront cost of all the additional equipment, and not the energy use.

The authors are careful to state that these modeled estimates have a meaningful level of uncertainty built in, and they will shift as the underlying technologies mature. But the overall trends are clear. At present, and with the current equipment costs, DAC-BPMED has a significant cost advantage over DOC-BPMED under this electrically driven regeneration approach.

Unexpected potential routes to profitability

A finding that stood out from these 91��Ҹ� was an often overlooked commodity side product. The BPMED process works by using electricity to split a salt solution into an acidic stream, which is used to release CO₂, and a basic stream which produces sodium hydroxide (NaOH). Sodium hydroxide is a widely used industrial chemical, a commodity found in a range of industries such as paper manufacturing, water treatment, and chemical synthesis, with an established market value, averaged at around $450 per tonne.

In the DOC model, because the plant is processing such large volumes of seawater, it produces considerably more sodium hydroxide than it needs for its operation. The 91��Ҹ� show that selling that surplus could reduce the cost of the overall CO₂ capture process substantially. In a scenario projecting a largely decarbonized electricity grid by 2050, the revenue generated from sodium hydroxide sales was enough to fully offset the costs of the CO₂ capture process, and in the most optimistic scenario, the process showed a net profit.

The authors were candid about the limits of this finding. The global sodium hydroxide market, even accounting for projected growth, is not large enough to absorb the products from carbon capture at the scale required to make a meaningful dent in atmospheric CO₂ “Our brief market analysis showed that even if DOC-BPMED supplied 20% of the projected 2050 sodium hydroxide demand, it would still offset less than 0.1% of today’s global energy emissions.” Dr. Almajed said. But the principle illustrated by this finding has broader implications. Coupling carbon capture with the production of a valuable commodity, either carbon-based, or as a side-product, could be a viable route to improving the economics of the whole process. It is an approach that is already being pursued commercially, including by Travertine Tech, a company based in 91��Ҹ�, Colorado, which captures CO₂ while producing and selling phosphoric acid, gypsum, and cementitious materials.

The electricity issue

Because the BPMED regeneration process is driven entirely by electricity, the source of that electricity matters enormously. This impacts both the cost of the process, and whether it actually delivers a net reduction in atmospheric CO₂. A carbon capture plant powered by fossil-fuel generated electricity that itself emits CO₂ is self-defeating.

To explore how different electricity generation modes impact the overall process, the team modeled four power supply scenarios. The current California grid, a projected 2050 California grid operating at 95% decarbonization, and two off-grid options: dedicated wind and dedicated solar. Interestingly, the team found that connecting to the grid outperformed both off-grid renewable options on cost, in both the current and the projected scenarios. The authors suggest that in the model this is down to a matter of reliability, a grid-connected plant can essentially run continuously, spreading its capital costs across more operating hours. A plant running on dedicated solar or wind is constrained by intermittency, which can drive up the cost per tonne of CO₂ captured. Dr. Almajed highlights that this is an area of the model that could be expanded, “We just looked at solar or wind each by itself, we didn’t optimize the off-grid scenarios to include energy storage and batteries.”

The policy implication built from the observations across the model is clear, explains Dr. Almajed, “We need to really pursue grid decarbonization. We need cleaner energy to power technologies that are going to help address climate change.” Technologies, such as DAC- and DOC-BPMED do not operate in isolation from the broader energy system. The effectiveness of these technologies to help combat atmospheric pollution, both economically and technically, is critically dependent on the grid they are plugged into. Decarbonizing that grid is not a separate problem, it is a prerequisite.

The future of carbon capture

While there are a lot of valuable observations and ideas that have come out of this TEA, no model is perfect. The team was quick to clarify areas where their model could be refined as technologies and ideas evolve. “When technologies are in such a nascent stage, the analysis of these 91��Ҹ� should focus on qualitative, rather than quantitative, insights” explains Prof. Bri-Mathias Hodge. “While there are a number of areas where the model can be improved, it also suggests where efforts for improvements are best focused, particularly the aspect that have the largest impact on results.” This includes more detailed modeling of the membranes, better data on equipment costs as the technology matures and is more widely deployed, and a more complete optimization of how these carbon capture plants might interact with energy storage or hybrid power systems. Many of these are manageable problems, and work is already underway at RASEI to address some of these areas.

Sometimes, the real value in this kind of analysis is in what it reveals before such refinements are made. By mapping the full system, from the technical fundamentals through the macroscale economics, this study helps to identify where research effort is best directed. Enhancing the concentration of the dissolved carbon in the seawater fed into a DOC plant, for example, could reduce costs by 40-50% according to the study’s sensitivity analysis. As a technology that is beginning to be deployed and scaled, identifying areas where large improvements in process efficiency can be made could have significant energy, and cost savings. As Dr. Almajed notes, “The study generated a lot of insights that we didn’t even consider at the start of the project.”

Removing carbon from the atmosphere at the scale required to significantly impact global emissions is an interdisciplinary problem that spans chemistry, engineering, economics, and energy policy. Analyses such as this don’t necessarily resolve that complexity, but they do help to make it understandable, and act as a roadmap to focus efforts. Knowing where the bottlenecks are, and insights into what it would take to impact them, is a great way to start solving the problem.

May 2026

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Watching Carbon Capture in Action

Daniel Morton — Wed, 13 May 2026 21:00:48 +0000

Watching Carbon Capture in Action Daniel Morton Wed, 05/13/2026 - 15:00

Daniel Morton

Removing carbon dioxide (CO₂) directly from the air, a process called direct air capture (or DAC), is one of several approaches being developed to help reduce the concentration of this greenhouse gas in the atmosphere.

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Among the methods being scaled up, one of the more established involves exposing air to a strongly alkaline liquid, typically a solution of potassium hydroxide (KOH), commonly known as lye. The liquid chemically binds the CO₂, converting it into dissolved salts called carbonates and bicarbonates. Large facilities using this principle are already operating or under construction, with one plant in Texas that is currently under construction, designed to remove 500,000 tons of CO₂ per year.

Despite the maturity of the underlying chemistry, there has been a fundamental limitation in how well researchers can study it. Until now, the process has been something of a black box. Scientists could measure what went into a capture system and what came out, but the detailed chemistry happening inside, specifically in the thin zone where the air and liquid meet, was very difficult to observe directly. This is a meaningful gap, because what happens in that zone determines how efficiently the system works, and how it should be designed, especially for novel DAC liquids. As Jason Pfeilsticker (a Graduate Student in the group of RASEI Fellow Wilson Smith, and lead researcher on this project), explains, “This really is a case of if you want to know about something, just look at, really carefully, and in this case there was some work to do before we could take a detailed look”.

Think of it like medicine before medical imaging. For centuries, doctors understood that the body had internal structures and processes, but could only examine them indirectly, through symptoms, pulses, and what came out of the body. The development of X-rays and later MRI scanning did not change human biology, but it transformed what could be understood and acted upon. A diagnosis that once required guesswork could suddenly be made based on the information gained from mapping out the internal structures of the body. This study, just published in ACS Energy Letters, represents a similar shift for CO₂ capture: rather than inferring what is happening at the gas-liquid interface from indirect measurements, researchers in the group led by Wilson Smith at the 91��Ҹ� 91��Ҹ� have built an instrument that lets them watch it directly.

The instrument at the center of this work is a custom-designed laboratory flow cell. This device was designed and built specifically for this purpose and, to the teams’ knowledge, is the only one of its kind. “There were so many different variables that we wanted to explore, but in order to design a better process and or screen novel DAC solvents, we needed to have a better picture of what was going on” explains Pfeilsticker, “You can change the solvent, the pressures, the flow, the reactor design, all of which affect the microenvironment and thus the DAC performance ”. To get a clearer picture they set out to build a flow cell with built in features that enabled accurate spatial mapping of the kinetics of the reaction, in real time. Designing and building it required solving a series of practical problems. The cell needed to bring CO₂ gas into contact with flowing KOH liquid through a porous membrane, closely mimicking the interface in a real capture system. It needed to be optically clear and stable enough to allow laser-based measurements without bubbles, vibrations, or chemical interference disrupting the readings. The flow inside needed to be smooth and predictable, what scientists call laminar flow, so that the measurements could be interpreted meaningfully. Each of these requirements shaped the final design, from the choice of materials to the geometry of the flow channels. However, this oversimplifies the actual process, these lessons were learned as part of an extensive prototyping process.

“We made at least 60 or 70 iterations of this cell during the project” explains Jason. “I was drawn to this project because I really like to make things, and this looked like a challenge that would use a great combination of scientific investigation, detailed design and hands-on building”. Jason, who spends much of his free time working on motorcycles, or building electronics and musical instruments, knew he was going to need to iterate on the cell design. Early on the team considered getting design iterations professionally machined. But each of these would cost thousands of dollars to produce, and when you are learning what is important as you are designing, a small tweak here and there can become very expensive. A typical filament-based 3D printer would not be suitable for working with the chemicals involved in DAC. “We identified a resin that was chemically compatible with the base reagents we were using, and we found a cheap resin 3D printer online, that let us do some initial proof-of-principle work, then we upgraded to a better 3D printer for the project, and now we could print iterations for less than a dollar,” said Jason. This not only made the process cheaper but sped-up design development as well. The team identified three big challenges as they worked through the designs: good seals, bubbles, and smooth flow of the liquid. The solutions for these came from a number of inspirations, including sealing mechanisms borrowed from drumheads, reactor geometry angles to reduce bubble formation to enable effective laser probing, shaping of the flow inlets and outlets to ensure laminar flow, and flow dampener design.

To explore the reaction and map out the kinetics of the process the team used a technique called confocal Raman spectroscopy to make their measurements. This works by shining a laser at a point in the liquid and reading the light that scatters back; different chemical species produce distinct signatures, making it possible to identify and quantify them. By scanning the laser across the cell in a grid pattern while the process was running, the team built up two-dimensional chemical maps, essentially pictures showing where carbonates and bicarbonates were forming and accumulating across the contact zone, at the scale of fractions of a millimeter, in real time.

What those maps revealed was not what simple intuition would predict. “We saw that the equilibrium reaction is in effect going backwards near the surface” explained Pfeilsticker. When fresh KOH first contacts CO₂, the highly reactive hydroxide ions in the liquid rapidly consume the incoming CO₂, converting it to carbonate near the membrane. But this rapid reaction locally depletes the hydroxide supply right at the interface. As the liquid flows further through the channel and more CO₂ is absorbed, there are fewer hydroxide ions available near the membrane to drive the reaction forward. “Because it is laminar flow, there is no turbulent mixing” said Jason. The result is that a thin layer of bicarbonate, an intermediate chemical species in the conversion process, forms immediately next to the membrane, nestled between the membrane surface and the main hydroxide and carbonate-rich zone further into the liquid. This pattern becomes more pronounced further along the flow channel and represents a direct, spatial record of the chemistry unfolding in real time.

The team also found that operating conditions matter. Higher flow rates altered the shape and extent of the reactive zone, and doubling the concentration of KOH shifted the balance of products and appeared to reduce the hydroxide depletion effect near the membrane, potentially useful information for future system designs.

A key part of this work was the development of a computational model mirroring, and interpreting, what is going on inside the cell. Using the experimental observations to provide a framework to build the theoretical model allowed the team to effectively bound the scope and validate the model, in ways that would have been essentially impossible without the experimental data. The hope is that this model, which has now been validated with experimental data, in conjunction with flow cell maps can be used by future researchers as an initial screening tool in designing new DAC systems.

This work has the potential for significant impact. DAC Facilities using alkaline liquids are being built at the industrial scale. 91��Ҹ�ers are actively developing new and improved capture liquids to make the process more efficient, cheaper, and use less energy. With a cell design that enables accurate mapping, and a computational model that enables faster screening, the process of optimizing the carbon capture reactions can be accelerated. On an industrial scale even small improvements in reaction efficiency and cost can have huge savings on the system scale. Current approaches just look at the input and corresponding output of the cell, like judging a medical treatment by whether the patient recovered, without being able to examine what really happened inside the body.

This research describes a detailed, data-driven approach to answering the questions about what is really happening at the reactive center of DAC: how does a given liquid behave, what is happening at the interface where the chemistry is happening, how does varying the conditions impact the reaction? The combination of the experimental and theoretical tools disclosed by this work provides insight into how these processes work, and the key variables that can be used to optimize it.

The application of these tools can potentially extend beyond DAC. Wherever chemistry and transport interact at an interface, such as electrochemical systems that convert CO₂ into fuels or commodity chemicals, or in the separation of critical minerals. The design of this device was around one specific challenge, but has the potential for broad utility.

The transition from black box to observable system does not, by itself, solve the engineering challenges ahead. Models still need refinement, and scaling to industrial practice requires substantial research. But the ability to directly observe what is happening is a critical step in that process. What was previously assumed can now be tested. The reaction black box now has a window, that enables researchers to gain valuable insights into the inner workings of this critical process.

May 2026

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The solar cell that moonlights as an LED, and does both better

Daniel Morton — Mon, 27 Apr 2026 22:30:02 +0000

The solar cell that moonlights as an LED, and does both better Daniel Morton Mon, 04/27/2026 - 16:30

Daniel Morton

Imagine a display that harvests ambient light when it is not actively in use, offsetting some of its own energy consumption. The materials physics shows that this is possible, the same semiconductor material can, in principle, emit and absorb light efficiently. What has been missing is a device architecture that allows it to do both without reductions in efficiency of either application. A new study reports a perovskite diode that converts sunlight to electricity at 26.7% efficiency (a world record at the time of publication submission) and emits light at 31% efficiency, figures that would be high for a device designed to do only one of those things.

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Read the Article here

EurekAlert!

The Brighter Side

Metal-halide perovskites are a class of materials named for their distinctive crystal structure, that have emerged over the past decade as some of the most promising candidates for next-generation solar cells and light-emitting diodes (LEDs). They are relatively inexpensive to produce, can be tuned to absorb or emit different wavelengths of light, and have shown efficiency levels that rival far more costly semiconductor materials. Yet despite sharing the same underlying material, perovskite solar cells and perovskite LEDs have largely been developed as separate technologies, because the physical requirements of each push device design in opposite directions. A collaborative study published in Joule by a team led by Michael McGehee at the 91��Ҹ� 91��Ҹ�, and Jixian Xu at the University of Science and Technology of China, now demonstrates that this conflict can be resolved, and that resolving it improves both devices at once.

The challenge of doing two things at once

The tension between perovskite LEDs and solar cells comes down to a question of thickness. An effective LED needs an extremely thin, discontinuous layer of perovskite, typically around 50 nanometers (roughly one thousandth the width of a human hair), because thin, slightly uneven films naturally scatter light outward, helping photons escape the device. A solar cell, by contrast, needs a layer roughly sixteen times thicker to absorb enough incoming sunlight and convert it into electricity efficiently. For years, this meant that researchers optimizing a perovskite LED were building something poorly suited to harvesting solar energy, and vice versa. Thanks to these different needs the two applications have followed separate architectural paths, and devices that attempted to do both tended to do neither particularly well.

There is a further complication. Even in a well-made perovskite LED device, much of the light generated inside never escapes. When a photon (a particle of light) is produced inside the material, it travels outward and hits the surface. If it arrives at too steep an angle, it is reflected back inside rather than escaping, a phenomenon governed by the physics of how light moves between materials with different optical properties. Once trapped, that photon bounces around until it is absorbed by a microscopic defect in the material and converted to heat, essentially wasted energy. Reducing these losses requires both giving trapped photons a better route out and patching the defects that absorb them along the way. These have typically been treated as separate engineering problems.

A useful way to think about what the team describe in this research is to consider what a texture does to a pane of glass. Smooth, flat glass transmits light reasonably well in one direction, but offers little control over what happens to light approaching from awkward angles. Some passes through, some reflects, and the behavior is largely determined by the geometry. A textured or patterned surface changes this: by introducing deliberate variations in the surface structure, light arriving from many different angles can be redirected more usefully, whether that means bending it inward toward an internal target (for a solar cell) or redirecting it outward toward an observer (for an LED). The same surface feature serves both directions of travel. The team's approach works on a closely related principle, applied to structures far smaller than any surface texture visible to the naked eye, and with the added benefit that the material forming those structures also repairs the defects that were previously wasting energy as heat.

Building porous textured sponges

Building on earlier collaborative work published in Science in 2023, by McGehee and Xu, which demonstrated that porous alumina nanoplates (a form of aluminum oxide) could reduce energy losses at perovskite interfaces, the team set out to extend that principle into a more sophisticated architecture. The key advance was developing a method to assemble alumina nanoparticles into micrometer-sized islands (each around five micrometers across and half a micrometer tall) embedded within the perovskite device. The assembly process uses electrostatic attraction: two populations of alumina nanoparticles are given opposite surface charges, and when mixed, they cluster together naturally into porous, sponge-like islands. One population is treated with a negatively charged molecule (Me-4PACz) and the other population treated with a positively charged molecule (ODA). The team refer to these as e-Al₂O₃, where the "e" denotes “electrostatic” assembly.

The porous sponge-like structure is critical. Earlier approaches to introducing low-refractive-index materials (materials that are less optically dense than the surrounding perovskite) into LED devices tended to block the flow of electrical charge, undermining device performance. Because the e-Al₂O₃ islands are porous, the perovskite material can grow through them, maintaining electrical contact with the electrode beneath. The islands therefore redirect light without interrupting the charge transport the device depends on.

The surface treatments applied to the alumina nanoparticles were designed to serve a second, equally important function. The molecules used to give the particles their opposite charges are the same molecules known to passivate perovskite surfaces, essentially chemically neutralizing the defects where energy can be lost as heat. The surface recombination velocity, a measure of how quickly electrical charges are lost at interfaces, dropped from 20.2 cm/s in a flat control device to 1.4 cm/s in the e-Al₂O₃ device. This brings the rate of energy loss at the interface close to levels seen in high-performance silicon solar cells.

With defect losses suppressed to this degree, a useful secondary effect called photon recycling becomes significant. When a photon is generated inside the perovskite and would otherwise be trapped and lost, it now has a reasonable chance of being reabsorbed by the material and re-emitted, effectively getting a second, or third, attempt to find an exit. This would be counterproductive in a defect-rich material, because each reabsorption event would risk the photon being lost to heat. However, with defects minimized, photon recycling amplifies the benefit of the improved light routing, pushing external efficiency higher than the geometry of the device alone would predict.

Operated as a solar cell, the e-Al₂O₃ device achieved an externally certified stabilized power-conversion efficiency of 26.7%. At the time this work was submitted for publication this cell held the world record for the power conversion efficiency for perovskite devices (held between 05/2024 – 02/2025). Operated as an LED with the same 800 nm thick perovskite layer, the device reached an external quantum efficiency of approximately 31%, meaning roughly 31 out of every 100 injected electrons produced a photon that successfully escaped the device. Radiance (a measure of light output intensity) was nearly ten times higher than the flat control device. Across both operating modes, the e-Al₂O₃ devices also showed meaningfully improved long-term stability, retaining 95% of their initial solar cell efficiency after 1,200 hours of continuous operation, compared with 67% for the flat control.

The authors note that this combination of greater than 26% solar cell efficiency and greater than 30% LED efficiency in a single polycrystalline device is, across all photovoltaic materials, only the second time this has been demonstrated, the first being single-crystal gallium arsenide, a material that is substantially more expensive and more difficult to manufacture at scale.

The practical implication of a device that converts sunlight to electricity efficiently and emits light efficiently is not merely academic. Displays that harvest ambient light to extend battery life, or lighting systems that recover energy when not actively in use, become more plausible when the same device architecture serves both functions without meaningful compromise in either. More fundamentally, the work demonstrates that the long-standing separation between emissive and photovoltaic device design is not a physical inevitability but an engineering problem, one that careful co-optimization of optical and electronic properties can address.

April 2026

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The Physics That Hides in Plain Sight

Daniel Morton — Wed, 22 Apr 2026 15:30:34 +0000

The Physics That Hides in Plain Sight Daniel Morton Wed, 04/22/2026 - 09:30

Daniel Morton

Just published; a Perspective article by RASEI theorists raises new questions on what is hidden by quantum symmetry

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Check out the Perspective Here

Some of the most interesting actions happening inside a material are the things that, according to the rulebook, shouldn't be happening at all. In the world of quantum physics, that rulebook is written by symmetry, as encoded by the geometric arrangement of atoms in quantum matter. Essentially, how the atoms are stacked together in a solid. Symmetry sets strict rules about what physical effects are, and are not permitted. For decades, when experiments on certain materials produced results that symmetry said were impossible, the standard assumption was that something had gone wrong: a flawed measurement, or a contaminated sample. A new framework published by the group of Alex Zunger in the journal Matter suggests that in many of those cases, nothing had gone wrong at all. The effects were real. Indeed, they were just hidden—permitted by the local symmetry rules operating in small regions, or neighborhoods, not by the material's overall structure. Understanding where and how these hidden effects occur has practical consequences: the behavior of electrons in magnetic materials underpins technologies from computer hard drives to medical sensors, and knowing the full picture of what electrons can do can save us from discarding potentially critical new materials with hidden technological virtues.

Spin, and why it matters

To understand what this framework is doing, it helps to start with spin itself. Spin is a quantum property of electrons, one that has no obvious everyday analogy, but which causes electrons to behave, in some respects, like tiny magnets with a fixed orientation. In most materials, the spins of individual electrons point in random up or down directions and cancel each other out. But in certain materials, and under certain conditions, spins can be organized spatially and can be controlled. Moreover, even when spins cancel each other out over the global volume of a sample, the local rules operating in smaller regions can have a different spin symmetry, controlling the properties of the sample as a whole.

These unusual spin behaviors control the foundation of a field called quantum spintronics. Spintronics is, broadly, the use of electron spin rather than just electron charge to store, process, and transmit information. The hard drives in most computers already exploit this principle: the read heads that detect stored data work by sensing differences in how electrons with different spin orientations pass through a material. 91��Ҹ�ers are working towards spintronic devices that are faster, smaller, and more energy-efficient than what charge-based electronics alone can achieve.

The catch is that developing useful spin behavior out of a material requires the right conditions. This is where symmetry re-enters the picture. The chemical identity and spatial arrangement of atoms in a solid determine its overall properties. Change the atomic arrangement, and you change what spin can do. For this reason, identifying which materials have the right symmetry for a given spin effect has been central to the field. And for a long time, if a material's overall symmetry appeared to rule an effect out, that material was simply set aside.

Walking the streets: a new map of spin physics

The new framework addresses this directly. Rather than treating spin effects as simply present or absent in a given material, it draws a distinction between two types: apparent and hidden effects.

Apparent effects are those that follow directly from a material's overall atomic arrangement. If the global symmetry permits a spin effect, you expect to see it, and you do. Hidden effects are more subtle. They occur in materials where the overall atomic arrangement would, according to the current rulebook, forbid a given behavior, but where smaller, localized regions, or neighborhoods, within the material have their own legitimate symmetry that permits it. The global picture says no; the local picture says yes. The local picture wins. To comprehensively understand the potential spintronic virtues of a material, we need to also understand the mysteries of the local arrangements and symmetries of the spins.

A good way to think about this is to imagine judging a city's architecture and character purely from a satellite image. At that resolution, everything might look uniform and regular. Walk the streets, and observe the neighborhood at eye level, and an entirely different set of structures and interactions becomes visible. The framework outlined in this Perspective is insisting that materials physics needs to walk the streets, and that a great deal can be missed by staying at altitude.

To organize this, the framework described by the Zunger team sorts spin effects in magnetic and non-magnetic materials into distinct categories, determined by two key factors: whether the effect is apparent or hidden and whether the spin effect requires a help from a phenomenon called spin-orbit coupling (SOC)—an interaction emerging from relativistic theory of matter, in which an electron's motion through the electric field of an atomic nucleus influences its spin orientation. Some spin effects depend on this interaction; others do not, and this distinction has meaningful consequences for which materials can host them and how large the effects can be. Check out Box 1 for a deeper dive into these effects.

Box 1:

Apparent spin splitting induced in non-magnetic materials by relativistic SOC: The Rashba and Dresselhaus effect: Across all categories, the framework identifies both an apparent and a hidden version of each effect. The team helps provide understanding around this categorization by providing theoretical physics worked-out examples inspired by real, experimentally studied compounds. For example, in non-magnetic materials, well-known effects called the Rashba and Dresselhaus effects (both involving spin-orbit coupling) producing a separation of electron spin states, have previously overlooked hidden counterparts that can occur in materials whose overall symmetry would appear to rule them out. The framework points to the possibility that there can be materials that violate the nominal conditions for the (apparent) Rashba effect, but a hidden Rashba effect exists. For example, a hidden Rashba effect can show spin polarization even if the global symmetry violates the required broken inversion symmetry, but the structure consists of sectors that are individually non-symmetric. Predicted materials with hidden Rashba spin polarization pointed out by the new framework include tetragonal BaNiS₂ and tetragonal LaOBiS₂, whereas materials with hidden Dresselhaus spin polarization proposed theoretically exhibits local spin texture (the pattern of spin orientations across the material), but no spin splitting include hexagonal NaCaBi, cubic Si, and cubic Ge. This new perspective legitimizes the search for such materials that violate the (apparent) Rashba conditions yet show a (hidden) Rashba effect.

What can be hidden in magnetic materials?

In magnetic materials, hidden spin effects can arise not from the relativistic effect of spin-orbit coupling, but from the magnetic interactions between atoms. This means they can, in principle, be larger, and occur in materials containing lighter, more abundant elements. In both cases, the street-level view of the material is revealing structures and interactions that the satellite image simply could not see. You can find out more about examples of an apparent and a hidden SOC-independent effect in Box 2.

Controlling the electronics of materials

The practical significance of the framework extends beyond classification. The Perspective article explores whether hidden and apparent spin effects can be actively controlled, and, in certain materials, the answer is yes. In some antiferromagnetic compounds, switching between hidden and apparent spin states can be achieved using an electric field. This would be enabled if one could design a material that, in addition to (either apparent or hidden) spin-split AFM symmetry can have the added symmetry of polarity (how electrons are arranged across atoms). This will allow potential applications of the ability to switch spin states using only an electric field.

This is notable for a few reasons. Antiferromagnets carry some practical advantages over the ferromagnets (materials like iron, where all magnetic moments point the same way), that currently dominant magnetic technology. They produce no stray magnetic field, which reduces interference with neighboring components, respond rapidly to switching signals, and are robust against external magnetic disturbances. The ability to toggle spin effects electrically in these materials adds a further tool for device designers to work with.

Box 2:

Apparent, SOC-independent spin splitting in antiferromagnetic materials: Spin configurations consisting of alternation of spin-up layer followed by a spin-down layer are called antiferromagnets. For a long while it was textbook knowledge that electronic states in antiferromagnets would have the same energies for spin-up and spin-down layers (a behavior called “spin degeneracy”) in the absence of SOC. This is because it was assumed that the two atoms with opposite spins will compensate each other, giving rise to spin degeneracy. In 2020, the Zunger group with Emmanuel Rashba discovered the enabling symmetry conditions for the unusual case where electronic states in an antiferromagnets would have different energies for different spin (“spin-split antiferromagnets”) in the absence of SOC. Since this behavior follows the precise symmetry of the system it constitutes an apparent effect. Theorists soon pointed to real materials that would have such peculiar effects, including orthorhombic LaMnO_3, rhombohedral MnTiO₃, tetragonal KRu₄O₈, and tetragonal V₂Te₂Oand many others. This effect was later dubbed in the literature “altermagnetism” implying another form of magnetism.

Hidden, SOC-independent spin polarization in antiferromagnetic materials: In collinear antiferromagnets (collinear, meaning the psins all point along the same axis), this requires that (i) global system symmetry forbids SOC-independent spin splitting, but the (ii) local sectors break that symmetry. Predicted hidden spin polarization materials in magnetic AFM include tetragonal Ca₂MnO₄, La₂NiO₄, and MnS₂, and the following tetragonal compounds CoSe₂O₅, Fe₂TeO₆, K₂CoP₂O₇, LiFePO_4, Sr₂IrO₄, and SrCo₂V₂O₈.

Finding real materials with previously unsuspected hidden effects

The question is how one can use theoretical physics to search for specific materials with target spintronic properties? The history of material research and condensed matter physics has often proceeded via accidental discovery of materials with interesting physical properties—superconductors and light-emitting semiconductor. Yet, for many applications we know well what type of physical properties we want, but we do not know a material that has those target properties. An interesting advance was worked out in the research group of Alex Zunger: namely “Inverse Design”, where you find a material that has a specific, desired target property. The obvious obstacle is that there are innumerably many possible atomic structures that could, in principle, be made even from a few elements and we do not know which structure would have the desired target property. It turns out that modern atomic-resolution quantum mechanics (i.e., electronic structure theory) can now be combined with biologically inspired (evolutionary) “Genetic Algorithms” to scan a truly astronomic number of atomic configurations in genomic-like search of the one(s) that have desired, target materials properties. Once the number of configurations with target property is narrowed down to a few, laboratory synthesis becomes viable. Examples of specific compounds, known to exist but not known to be spintronic relevant were predicted theoretically as a result of this work.

A broad implication of this new framework is that the rulebook has been applied too rigidly. By demonstrating that hidden effects are real and systematic rather than accidental, the framework significantly expands the pool of materials worth investigating for spintronic applications. Materials that were previously set aside because their overall symmetry appeared to rule out useful spin behavior may, on closer, street-level, inspection, host exactly the effects that researchers are looking for, just in a form that requires a more careful look to find.

The Perspective also flags a subtler problem. Some of the theoretical tools routinely used to model materials are themselves guilty of the same “farsightedness” that causes hidden effects to be missed. Certain widely used approximations work at too coarse a resolution to detect local symmetry and therefore fail to predict effects that are genuinely present. Refining the theoretical toolkit is, as the authors suggest, as important as expanding the materials search.

Taken together, this framework offers a more complete account of what electrons can do inside a solid, and one that takes local structure seriously rather than assuming the view from altitude tells the whole story. The physics was there all along. It just required a closer look to find it.

April 2026

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Atomic Musical Chairs: How Tiny Nanocrystals Are Informing the Future of Energy-Efficient Electronics

Daniel Morton — Tue, 17 Mar 2026 19:43:33 +0000

Atomic Musical Chairs: How Tiny Nanocrystals Are Informing the Future of Energy-Efficient Electronics Daniel Morton Tue, 03/17/2026 - 13:43

Daniel Morton

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While most people, when asked about energy innovation, think about some of the "large" technologies, such as wind turbines, long transmission lines, or massive power plants, some of the most important advances in how we use energy are happening at a scale so small that millions of the "machines" involved could fit on the head of a pin.

New research from a team led by RASEI Fellow Gordana Dukovic, working in collaboration with RASEI Fellow Sadegh Yazdi and Prof. Dmitri Talapin from the University of Chicago, reveals new insights on a high-speed game of "atomic musical chairs." This collaboration involved two large teams working together. 91��Ҹ�ers from two United States National Science Foundation Science and Technology Centers (STCs) including IMOD and STROBE, employed cutting-edge microscopy techniques to directly visualize, for the first time at this scale, how atoms swap places inside tiny semiconductor nanocrystals, which is a crucial step toward understanding the composition, and ultimately the properties, of these materials.

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Science and Technology Centers are hubs for collaboration, bringing together multidisciplinary researchers from across the United States to solve large, challenging and complex problems. This article describes a space where two of these large networks worked together. STROBE, or Science and Technology Center on Real-Time Functional Imaging pushes the boundaries of microscopy to observe and understand materials at the atomic and nano-scales. IMOD, or The Center for Integration of Modern Optoelectronic Materials on Demand, focuses on making atomically precise semiconductors and integrating them into applications in VR displays, and devices for quantum communication and computing. This team leverages the expertise from both Centers to create new semiconductors and using cutting-edge microscopes to observe and understand them.

Almost all of our electronic devices are built from semiconductors. Whether it is the screen on your smartphone, the components in your car, or the microchips in your computer, these electronics rely on semiconductors. Traditionally, these materials are "grown" through rigid and often expensive processes. Tuning the properties of a semiconductor using this approach is not straightforward. If you want a specific color of light for a display, or a specific energy absorption profile for a solar panel, you often have to start from scratch with an entirely different material.

This is where semiconductor nanocrystals offer remarkable opportunities. The specific size, shape, and composition of these tiny nanocrystals determine the physical and electronic properties of the overall material. A particularly powerful process with such nanocrystals is called cation exchange. Instead of building a new crystal from scratch, you can take an existing one and swap out its internal atomic components to change its properties.

“This is a project that we have been working on for a long time” explains Ben Hammel, a graduate student in the Dukovic Group, and lead author on this research. “We have been looking at these materials from the Talapin Group for a long time”.

This work, just published in ACS Nano, focuses on what are called III–V nanocrystals, which are tiny, four-sided pyramids, or tetrahedrons, named for the groups of the periodic table their constituent elements come from (Group III includes elements like Indium, Gallium, and Aluminum; Group V includes Phosphorus, Arsenic, and Antimony). In this research, the nanocrystals are made of a mixture of Indium, Phosphorus, and Arsenic. To exert more control over the properties of these nanocrystals, the researchers introduced Gallium. Adding Gallium is like tuning a guitar string: it changes the energy of the crystal, influencing how it interacts with light.

“A lot of people have developed ways to make III-V bulk semiconductors, but the real challenge is making them into nanocrystals, where you have more control over their properties, and the Talapin Group have developed a really neat molten salt process to do this” explains Hammel. The molten salt work was published in Science in 2024.

Imagine the inside of one of these tiny crystals as a perfectly ordered lattice of "seats." There are two types of players: Anions (the Phosphorus and Arsenic atoms) and Cations (the Indium atoms). A key observation from the team was that the "house" never moves. The Anions are like the floor and the chairs, they stay perfectly still, maintaining the overall crystal framework. The Cations, on the other hand, are the players sitting in those chairs.

In this work, the nanocrystals were placed into a "hot bath" of molten Gallium salts, essentially starting the music on the game of atomic musical chairs. Previous work had shown that the atoms exchange, but there was not a lot of evidence for how this process worked. “Understanding how this works is very important, and finding out more about the local elemental composition, and how the Gallium atoms move can inform how we design these systems in the future” explains Hammel.

These nanocrystals are only 5 to 10 nanometers wide. A typical human hair is between 80,000 and 100,000 nanometers wide. These crystals are called "nano" for a reason! To observe this game of atomic musical chairs in action, the team used Scanning Transmission Electron Microscopy (STEM), an instrument that uses a focused beam of electrons to probe and image matter at the atomic scale. “Early on there were some signs that there was heterogeneity within the particles, but it was unclear, a big technical challenge we had to overcome was how we can actually measure the Gallium moving through the nanocrystal” said Hammel.

A key challenge they had to figure out was the sensitivity of the nanocrystals to the very tool being used to study them. The electron beam of the STEM, if used at high intensity, can damage the nanocrystals before a useful image can even be collected. To solve this, the team developed an innovative "statistical" imaging approach. Rather than blasting a single crystal with a high dose of electrons to get a sharp image, the researchers instead took many low-dose, and individually blurry, snapshots of hundreds of different crystals at different stages of the molten salt reaction. “We essentially stacked the data on top of each other” describes Hammel, “If I can add together 10 nanocrystals, I can get 10 times the signal”. Adding these kinds of signals together hadn’t been done before with semiconductor nanocrystals. “A lot of this came together from teamwork, I got a lot of really great suggestions from collaborators on how to collect and analyze this information. I used a suite of open source Python tools, which I was a little lost with until I met the researcher who developed them at a conference (Josh Taillon from NIST), who gave me some great suggestions and ideas” said Hammel. Using these advanced computer algorithms, they aligned and stacked hundreds of images on top of each other. Much like a long-exposure photograph of the night sky reveals stars the naked eye cannot see, this averaged stacked image revealed a detailed map of where the Gallium atoms were moving inside the nanocrystals. To the team’s knowledge, this signal-averaging approach for elemental mapping has not previously been applied to semiconductor nanocrystals.

The Gallium atoms rush in to claim “seats”, but not randomly. Gallium grabs the seats near the surface first. Because of the high surface-to-volume ratio of these tiny particles, this surface exchange causes a dramatic and rapid change in overall composition: within the first 15 minutes in the molten salt bath, the outside of the nanocrystals is substantially transformed. However, as the game goes on, it gets progressively harder. The Indium atoms sitting in the seats at the center of the nanocrystal are crowded in, and for a Gallium atom to reach the core, an Indium atom must fight its way out through an increasingly Gallium-rich lattice. This sets up a compositional gradient, essentially a smooth transition from a Gallium-rich exterior to an Indium-rich core, that persists even after 16 hours of reaction.

This new methodology, combining STEM with advanced computational image processing, is sensitive enough to detect and map the movement of atoms through individual nanocrystals. Applying it here directly revealed that the cation exchange process (Indium being replaced by Gallium) creates a graded composition rather than a simple sharp boundary between materials. The team also used computer simulations (finite element analysis in COMSOL) to model this exchange as a diffusion-limited process, finding that the rate of exchange slows dramatically as more Gallium enters the lattice, likely because the smaller Gallium atoms cause the lattice to contract, making it progressively harder for further exchange to occur.

Importantly, the methods developed in this work are broadly applicable and could be used to determine the elemental composition of many other types of nanocrystals that have previously been difficult to study due to their sensitivity to electron beams.

The ability to observe and better understand the cation exchange process in these semiconductor nanocrystals has significant implications for the development of next-generation materials. It has been suggested that graded compositions, like those observed here, could help suppress certain energy-loss processes in semiconductor devices, potentially enabling more efficient lighting and lower-power electronics. Whether these specific nanocrystals deliver on that promise remains an open and exciting research question, but this work provides the observational foundation needed to begin answering it. Additionally, the molten-salt synthesis approach that underpins this research is an active area of development as a potentially more versatile route to III–V semiconductor nanocrystals, materials that have historically been among the most challenging to synthesize with fine compositional control.

By developing new tools to better observe the game of "atomic musical chairs," the researchers are providing the field with insights into how to engineer materials at the atomic scale and revealing that the path from one material to another is more nuanced, and more interesting, than previously understood.

March 2026

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Investigating how political polarization impacts efforts to address climate change

Daniel Morton — Wed, 25 Feb 2026 19:22:40 +0000

Investigating how political polarization impacts efforts to address climate change Daniel Morton Wed, 02/25/2026 - 12:22

February 2026

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The case of the vanishing seeds: How curiosity-driven research is future-proofing “Smart Windows”

Daniel Morton — Tue, 27 Jan 2026 17:02:14 +0000

The case of the vanishing seeds: How curiosity-driven research is future-proofing “Smart Windows” Daniel Morton Tue, 01/27/2026 - 10:02

Daniel Morton

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Have you ever walked into a room on a glorious Colorado summer day and felt the heat radiating through the glass?

We usually solve this by cranking up the air conditioning or closing the blinds, losing our mountain view in the process. But what if the window itself could think? A team led by Mike McGehee, a Fellow at RASEI, describes research that improves the robustness of such a device.

For years researchers have been working on “smart windows”, devices that could “sense” the conditions outside and “react” to them. This investigation centers around a promising technology called Reversible Metal Electrodeposition (RME). The technical details of this process are complex, but you can understand the concept by thinking of it as a reversible coat of paint. At the flip of a switch, a thin layer of metal, in this case silver, spreads across the glass to form a layer that tints it, blocking out the heat and the glare. Flip the switch again and the silver dissolves back into a clear liquid, making the window transparent.

Buildings are responsible for consuming around 40% of all generated energy globally, much of which is expended in regulating the temperature, heating and cooling the building interior. Installing smart windows that can react to the environmental conditions could provide a very effective mechanism to reduce energy use and slash energy bills by automatically managing how much heat enters a room. It has been estimated that just by controlling the amount of sunlight that is let into a building through a window, we could cut energy bills by up to as much as 20%.

However, there have been a number of challenges to overcome in order to take this initial discovery from the lab to a product that can be deployed for use in buildings. One challenge is that early versions of these windows started out fast but grew “lazy” over time. After a few thousand uses the tinting / de-tinting process slowed, taking almost four times longer than it did on day one.

This is where the researchers undertook some detailed investigations to identify what was going on, and what could be done to fix it. A collaboration between the McGehee group (at the 91��Ҹ� 91��Ҹ�) and the Barile Group (at the University of Nevada) set out to find out exactly what was happening. The team decided to look closer, using a combination of high-powered x-rays and electrochemical tests. The windows were using tiny “seeds” of platinum to help the silver grow on the glass. Platinum is recognized for being tough and non-reactive, and so should be perfect as a nucleation point for the silver. Using these advanced techniques the team explored exactly what was happening to the platinum seeds during the clearing phase, when the silver “paint” is stripped away.

To their surprise, the platinum was not as tough as they initially thought. In the special liquid environment needed for the windows, the platinum seeds were actually dissolving and washing away when the window was switched to clear. As the number of seeds dropped, the silver had fewer locations to grow from, which was the cause behind the window tinting slowing.

This led the team to ask the question “What can we do to make the seeds more resilient?”, which led them to use gold in place of platinum. While gold and platinum are both precious metals, in water, which is the solvent used inside the window panels, gold is more stable and less susceptible to decomposition and dissolving. When they swapped the platinum seeds for gold ones, the results were immediate. Even after 7,500 cycles, the equivalent of years of daily use, the windows transitioned just as fast as the first time they were used.

These gold-based windows provide an exciting range of opportunities. Not only because of their improved stability over many thousands of cycles, but also because they can express multiple colors by varying the voltage, a feature of the size of the gold particles. This presents opportunities for their use in displays and communications devices. This technology offers a better, smarter window that could passively save significant amounts of energy if deployed in commercial and residential buildings. This work shows how the impact of making fundamental chemical changes can unlock the potential of new technologies.

January 2026

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Locking in Solar Power: How a Stronger Interlayer Boosts Perovskite Cell Durability

Daniel Morton — Mon, 05 Jan 2026 19:31:00 +0000

Locking in Solar Power: How a Stronger Interlayer Boosts Perovskite Cell Durability Daniel Morton Mon, 01/05/2026 - 12:31

New Molecular Designs Extend the Life and Efficiency of Next-Generation Solar Cells

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Posted on the RASEI website with permission and minor modifications from the piece published by David DeFusco on the UNC Chapel Hill Applied Physical Sciences Site here.

A new study published in Science led by researchers at UNC-Chapel Hill, with collaborators from the Renewable and Sustainable Energy Institute (RASEI), explains why perovskite solar cells—fast-rising rivals to traditional silicon panels—tend to break down under prolonged heat and sunlight, especially ultraviolet light, and reveals a promising strategy to dramatically slow that damage.

The work focuses on a thin “interlayer” that sits between the electrode and the perovskite material inside a solar cell. This layer is only a single molecule thick, but it plays an outsized role in how long the device lasts.

“These interlayers are meant to help charges move efficiently out of the perovskite and into the circuit,” said Chengbin Fei, first author of the study and a postdoctoral researcher in UNC’s Department of Applied Physical Sciences. “But we found that some of the same chemical features that make them useful can also cause long-term damage if they’re not tightly attached to the electrode.”

Many high-performance perovskite solar cells use interlayers based on phosphonic acids. These molecules stick to a transparent electrode made of indium tin oxide, or ITO, and help pull positive charges out of the perovskite. Until now, most researchers assumed these layers were harmless once installed. Fei and his colleagues discovered that this is not always true.

The researchers found that some of these tiny helper molecules aren’t firmly stuck to the solar cell’s surface. When the cell gets hot or sits in sunlight that includes ultraviolet rays, those that are loosely attached molecules can break free. Once that happens, they start interfering with the solar material itself. They trigger harmful changes inside the cell: key ingredients fall apart, iodine-related components react in damaging ways and lead turns into a form that no longer works properly. Over time, all of this damage adds up and causes the solar cell to produce less and less electricity.

“In simple terms, the acid part of these molecules can act like a slow poison,” said Fei. “At high temperatures and under UV light, it accelerates chemical reactions that the perovskite just can’t tolerate.”

To understand what was happening, the researchers used a range of techniques, including spectroscopy and X-ray measurements, to watch how the materials changed over time. They found that stronger acids caused faster damage and that UV light made the reactions much worse. This explained why devices that look stable at first can fail after hundreds or thousands of hours outdoors.

The key advance came when the researchers at UNC and the 91��Ҹ� 91��Ҹ� created a new version of this thin helper layer containing a combination of two molecules that sticks much more tightly to the electrode surface. Seth Marder, the senior author at the 91��Ҹ�-91��Ҹ� and Director of the Renewable and Sustainable Energy Institute (RASEI) says “the molecule our team developed was designed to not only interact with the electrode surface but more strongly with its neighboring molecules. Consequently the molecules stay more securely in place, reducing the reactive parts that can break away and damage the solar material that is deposited on top ”. As a result, the layer still helps charges flow out of the cell, but it no longer triggers the damaging reactions that shorten the cell’s lifetime.

Simply put, “when the molecule is firmly locked onto the surface, it can’t wander into the perovskite and cause trouble,” said Fei. “That simple change makes a huge difference over time.”

Solar cells made with the new interlayer design showed striking improvements and met a key performance milestone. Under harsh test conditions—85 degrees Celsius, continuous bright light that included UV and constant operation—the devices ran for nearly 3,000 hours before losing just 10 percent of their efficiency. That level of durability has not been reported before for this type of perovskite solar cell.

The molecule our team developed was designed to not only interact with the electrode surface but more strongly with its neighboring molecules. Consequently the molecules stay more securely in place, reducing the reactive parts that can break away and damage the solar material that is deposited on top.
- Seth Marder

The researchers also scaled up their approach to small solar modules, closer to what might be used in real products. These “minimodules,” about the size of a postcard, reached power conversion efficiencies above 22 percent and kept working for more than 2,000 hours under the same stressful conditions, which is considered very high performance for this type of solar technology.

Jinsong Huang, senior author of the paper and UNC Louis D. Rubin Distinguished Professor, said the results address one of the most important barriers to commercialization. “Efficiency alone is not enough,” he said. “For perovskite solar technology to succeed outside the lab, it must survive heat, light and time. This work shows a clear chemical pathway to make that happen.”

Beyond improving one specific material, the study sends a broader message to the field. Tiny details at buried interfaces—places that are hard to see and easy to overlook—can control the lifetime of an entire solar module. By understanding and managing these details, researchers can design devices that last far longer.

“This study reminds us that stability is a chemistry problem as much as an engineering one,” said Wei You, a co-author of the study and UNC Cary C. Boshamer Distinguished Professor of Chemistry and Applied Physical Sciences. “Once you understand the chemistry, you can start to fix it.”

January 2026

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The Filament Factory: How two specialized cells team up to build microscopic rock and drive carbon capture

Daniel Morton — Mon, 05 Jan 2026 17:26:55 +0000

The Filament Factory: How two specialized cells team up to build microscopic rock and drive carbon capture Daniel Morton Mon, 01/05/2026 - 10:26

Daniel Morton

In the tiny, beaded chain of the cyanobacterium Anabaena sp. ATCC 33047, two different cells, the photosynthetic factory worker and the nitrogen-fixing specialist, play distinct and powerful roles in creating solid minerals.

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A team led by Renewable And Sustainable Energy Institute (RASEI) Fellow Jeff Cameron and Nature, Environment, Science & Technology (NEST) Studio co-founder Erin Espelie, used advanced high-resolution microscopy to capture the key moments; the factory worker leaks materials when stressed, and the specialist accelerates crystal growth through contact, proving that single-cell behaviors are a vital trigger for biomineralization. Understanding the cellular processes could inform large-scale applications, from oceanic buffering and soil improvement to mineral formation, and living building materials that sequester carbon.

A central enabling technology to lower pollution and reduce carbon emissions is developing clever ways to capture, and handle carbon dioxide. One avenue of investigation is to use processes already developed by Nature. There is significant research focused on using one of the Earth’s oldest and powerful processes: Microbiologically Induced Calcium Carbonate Precipitation, or MICP for short. Bacteria and algae through their normal life functions naturally create rock, specifically calcium carbonate, the main component of limestone. This process is a critical process in oceanic buffering and holds immense potential promise for green technologies. If we can understand, and harness this process, we could use such bacteria for a broad range of applications. We could create “living” cements for self-healing concrete, stabilize fragile soils, even enhance industrial carbon dioxide sequestration. However, to control this process we first need to understand the specific cellular blueprints that guide these microbial construction projects. Until now, those blueprints have been frustratingly fuzzy.

To better understand the puzzle of biomineralization the team explored the cellular structure of the cyanobacteria Anabaena sp. ATCC 33047 (hereafter Anabaena). Think of this organism as a tiny “Filament Factory”, one that grows as a string of cells, essentially a beaded green chain (they show up as red in the images because of the microscopy technique), where labor is divided in specific jobs. The links in the chain are not identical, it contains two specialized cell types that perform distinct, but equally important tasks.

First, let’s consider the Vegetative Cells, which are like tireless “Photosynthetic Factory Workers”. These are the green, abundant cells with the primary job of harvesting solar energy to convert carbon dioxide into sugars (Photosynthesis). This process has long been proposed as the main cause for triggering rock formation through MICP, as it raises the local pH, making the environment more alkaline, which encourages calcium carbonate to precipitate.

The other kind of cells, which can be found scattered along the filament, are called Heterocysts. These are like “Nitrogen-Fixing Specialists”. These cells are slightly larger, more solidly built, and specialize in converting atmospheric nitrogen gas into a usable form for the entire filament. This requires an extremely lo-oxygen environment, distinguishing the heterocysts and giving them a significant influence over the cells surrounding chemical environment.

To understand the process in a stepwise fashion the team were able to treat the bacterial system with a specific nutrient cocktail that essentially “turned off” the generalized photosynthesis-driven precipitation and instead focus solely on the effects of these two specialized cells. By developing approaches to shutdown specific parts of the process the team could use advanced microscopy techniques to better pin-point the single-cell behaviors responsible for triggering the formation and growth of microscopic rock.

Unlocking this level of detail in the cellular workings of a cyanobacteria requires specialized tools. The researchers used a suites of powerful high-resolution techniques to interrogate the bacteria, including Quantitative Fluorescence Microscopy and Raman Microscopy, that enabled them to watch the action unfold. The ability to directly observe the single-cell processes was critical to determining how the “Filament Factory” uses two distinct mechanisms for biomineralization.

The first observation centers around the Vegetative Cells, or the “Photosynthetic Factory Workers”. While the cells are usually busy using solar energy to capture carbon dioxide the high-resolution microscopy captured what happens when these cells are under mechanical stress, such as when they are bent by other cells, or squashed against an existing mineral structure. The team were able to watch in real-time as this physical pressure caused the cells membrane to rupture. This breach of the membrane releases, or leaks, a key chemical, the sequestered inorganic carbon (bicarbonate) that the cell was holding inside. This rapid, localized surge of carbon creates excellent conditions for the formation of a new crystal at the leakage site. This reframes the start of the process. It is not just a passive gradual change in the environment that causes crystal growth, instead it can be caused by an active, stress-induced cell failure that is a trigger for calcite crystal nucleation.

The second observation concerns the actions of the Heterocyst Cells, or the “Nitrogen-Fixing Specialists”. Using the powerful techniques that enabled the researchers to peer into the inner workings of the cells the team were able to confirm that when a heterocyst cell came into direct contact with an existing calcite crystal “seed”, the crystal experienced rapid and dramatic growth. Crucially, this accelerated growth did not happen when a vegetative cell touched the crystal.

The team proposes that this dramatic crystal growth is connected to the function of Heterocyst Cell. Nitrogen fixation is a chemical transformation that consumes protons (H⁺). By pulling these protons out of the surrounding water, the heterocyst locally, and rapidly, increases the pH (alkalinity) of the microenvironment, which is amplified at the point of contact. This sudden shift in pH provides ideal conditions to effectively “glue” dissolved ions onto the existing crystal, resulting in rapid growth.

These findings describe how these two specialized cells have complementary roles. One is the nucleation trigger when stressed, and the other is the growth accelerator when in contact.

This detailed observation and analysis of the processes happening at the single-cell level shifts our understanding around the processes involved in biomineralization. Instead of thinking of microbial rock formation as a slow and uniform chemical reaction driven by large-scale phenomena like photosynthesis, this work illustrates mechanisms that are controlled and function-specific processes that are dictated by the precise cellular roles and localized behavior of individual cells.

The understanding building from these findings has the potential to inform a wide-range of applications. By isolating the “stress leak” trigger in vegetative cells and the growth accelerator from the heterocysts, researchers could design systems that intentionally apply mechanical stress, triggering crystal formation and accelerating the growth of carbon dioxide sequestering materials. This could have application in oceanic buffering and technologies for bio-concrete and soil rectification.

The development and application of advanced microscopic techniques has provided the bio-engineering world a new set of variable that they can use in bacterial engineering. By moving from a vague knowledge of “microbes make rock”, to a precise understanding of how the “Filament Factory” uses specialized cells to build, and grow, calcite crystals, the field is a step closer to harnessing this powerful natural approach for using carbon dioxide in a cleaner, more efficient way.

January 2026

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New window insulation blocks heat, but not your view

Daniel Morton — Thu, 11 Dec 2025 16:24:44 +0000

New window insulation blocks heat, but not your view Daniel Morton Thu, 12/11/2025 - 09:24

Physicists at CU 91��Ҹ�, led by RASEI Fellow Ivan Smalyukh, have designed a new material for insulating windows that could improve the energy efficiency of buildings worldwide—and it works a bit like a high-tech version of Bubble Wrap.

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The team’s material, called Mesoporous Optically Clear Heat Insulator, or MOCHI, comes in large slabs or thin sheets that can be applied to the inside of any window. So far, the team only makes the material in the lab, and it’s not available for consumers. But the researchers say MOCHI is long-lasting and is almost completely transparent.

CU 91��Ҹ� Today have put together a feature article that has been picked up by a number of other news outlets. Check out the feature and the follow ups with the links to the right.

December 2025

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