Perovskites

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) 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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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 �鶹��Ѱ��, 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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Nickel-oxide hole-transport layers prevent abrupt reverse-bias breakdown and permanent shorting of perovskite solar cells caused by pinhole defects

Daniel Morton — Tue, 13 Jan 2026 00:25:38 +0000

Nickel-oxide hole-transport layers prevent abrupt reverse-bias breakdown and permanent shorting of perovskite solar cells caused by pinhole defects Daniel Morton Mon, 01/12/2026 - 17:25

EES SOLAR, 2026, ASAP

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Electrochemical quantification of phosphonic acid passivated surface sites of NiOx for perovskite solar cells

Daniel Morton — Mon, 12 Jan 2026 17:26:07 +0000

Electrochemical quantification of phosphonic acid passivated surface sites of NiOx for perovskite solar cells Daniel Morton Mon, 01/12/2026 - 10:26

ENERGY & ENVIRONMENTAL SCIENCE, 2026, 19, 884-895

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Photophysical Properties and Phase Behavior of Ultrawide Photovoltaic Bandgap Cesium–Lead-Based Triple Halide Perovskites

Daniel Morton — Tue, 06 Jan 2026 00:19:00 +0000

Photophysical Properties and Phase Behavior of Ultrawide Photovoltaic Bandgap Cesium–Lead-Based Triple Halide Perovskites Daniel Morton Mon, 01/05/2026 - 17:19

CHEMISTRY OF MATERIALS, 2026, ASAP

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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 �鶹��Ѱ�� 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 University of Colorado-Boulder 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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Limiting phosphonic acid interlayer–perovskite reactivity to stabilize perovskite solar modules

Daniel Morton — Fri, 02 Jan 2026 00:02:56 +0000

Limiting phosphonic acid interlayer–perovskite reactivity to stabilize perovskite solar modules Daniel Morton Thu, 01/01/2026 - 17:02

SCIENCE, 2026, 391, 6780, eadz7969

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P-Type Doping of Mixed Tin–Lead Halide Perovskites Using Electron Transfer to Mo(tfd-COCF3)3 and F4TCNQ

Daniel Morton — Wed, 10 Dec 2025 18:42:59 +0000

P-Type Doping of Mixed Tin–Lead Halide Perovskites Using Electron Transfer to Mo(tfd-COCF3)3 and F4TCNQ Daniel Morton Wed, 12/10/2025 - 11:42

ACS APPLIED MATERIALS & INTERFACES, 2025, 17, 51, 69676-69685

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Deposition-Dependent Coverage and Performance of Phosphonic Acid Interface Modifiers in Halide Perovskite Optoelectronics

Daniel Morton — Wed, 26 Nov 2025 18:35:36 +0000

Deposition-Dependent Coverage and Performance of Phosphonic Acid Interface Modifiers in Halide Perovskite Optoelectronics Daniel Morton Wed, 11/26/2025 - 11:35

ACS APPLIED MATERIALS & INTERFACES, 2025, 17, 49, 67197-67209

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Toward Fullerene-Free PIN Perovskite Solar Cells

Daniel Morton — Wed, 19 Nov 2025 00:28:58 +0000

Toward Fullerene-Free PIN Perovskite Solar Cells Daniel Morton Tue, 11/18/2025 - 17:28

ACS ENERGY LETTERS, 2025, 10, 12, 6307-6317

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Thermally Activated Circularly Polarized Photoluminescence in a 2D Hybrid Perovskite with Giant Spin Splitting

Daniel Morton — Fri, 14 Nov 2025 18:21:24 +0000

Thermally Activated Circularly Polarized Photoluminescence in a 2D Hybrid Perovskite with Giant Spin Splitting Daniel Morton Fri, 11/14/2025 - 11:21

ADVANCED FUNCTIONAL MATERIALS, 2025, e17358

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