A flexible perovskite-silicon tandem solar cell has reached a certified 29.88% power conversion efficiency, placing it among the highest recorded results for this class of device and bringing the technology within striking distance of the 30% threshold. The result, reported in a peer-reviewed paper in Nature Communications, was achieved on a device with an aperture area of 1.04 square centimeters and a steady-state efficiency of 29.2%. For an industry that has spent years trying to push thin, bendable solar cells past the mid-20s in efficiency, the gap between lab promise and practical performance just narrowed considerably.
How the 29.88% Figure Was Reached
The team behind the result built a monolithic tandem cell that stacks a perovskite absorber on top of a silicon base, a design that lets each layer capture a different portion of the solar spectrum. Perovskite materials are prized for their ability to absorb specific wavelengths very effectively, and the U.S. Department of Energy describes these semiconducting compounds as a versatile family that can be tuned for high photovoltaic performance. Pairing a carefully engineered perovskite layer with crystalline silicon allows the combined device to convert more incoming energy than either material could alone, because the top cell harvests higher-energy photons while the bottom cell captures lower-energy light that passes through.
What distinguishes this device from earlier high-efficiency tandems is its flexibility. Rigid tandem cells have posted strong numbers before, but bending a multi-layer stack without cracking the perovskite or degrading the interface between layers has been a persistent engineering problem. The researchers addressed this through two specific technical strategies: achieving phase homogeneity within the perovskite layer and engineering stress release at the interface between the perovskite and silicon. In the Nature Communications report, accessible through the journal’s main article page, the authors describe how a uniform crystal structure reduces mechanical weak points while tailored interlayers help dissipate strain.
Phase homogeneity means the perovskite film maintains a consistent crystal phase across its area, rather than forming mixed domains that respond differently to stress. Inhomogeneous regions can act as crack initiation sites when the device is bent. By contrast, a single dominant phase distributes strain more evenly. At the same time, stress release at the interface prevents the mismatch in stiffness between perovskite and silicon from concentrating force in one narrow region. The team used compositional engineering and interface design to spread mechanical loads, allowing the stack to flex without severe delamination or fracture.
These structural refinements were not limited to the active junction. The researchers also paid attention to transport layers and encapsulation, which must remain intact as the device bends. According to the Nature Communications login and access authentication portal, the work sits within a broader effort to translate high-performing but fragile perovskite stacks into mechanically robust architectures. Together, these innovations allowed the cell to maintain high performance while remaining physically flexible, a combination that rigid-only designs do not need to solve.
What “Certified” Actually Means Here
Solar cell efficiency numbers are only as trustworthy as the testing behind them. The field has a well-known problem with overstated or poorly measured results, which is why independent certification matters. The Best Research-Cell Efficiency Chart, maintained by the National Laboratory of the Rockies and updated periodically, sets strict inclusion criteria: measurements must come from recognized test labs, use standardized test conditions, follow reference spectra standards, and meet defined area requirements.
The 29.88% figure for this flexible tandem was certified under those conditions, meaning it was not simply a self-reported lab measurement taken under unusually favorable lighting or temperature. This distinction is important because manufacturers and research groups sometimes announce headline efficiencies measured on tiny active areas, under concentrated light, or with incomplete accounting of losses. The chart’s criteria exist specifically to guard against such inflation. When a result is documented in or aligned with the National Renewable Energy Laboratory’s broader photovoltaic performance database, it carries more weight than a number pulled only from a press announcement.
The reported steady-state efficiency of 29.2%, measured alongside the peak certified value, offers another layer of credibility. Peak efficiency can sometimes reflect a brief flash measurement, capturing a momentary maximum before the device settles into a lower operating point. Steady-state output, by contrast, better represents how a cell performs under sustained illumination. The relatively small gap between 29.88% and 29.2% suggests the device holds its performance over time rather than spiking and fading, which is encouraging for real-world use where panels operate for hours rather than milliseconds.
Context From Recent Tandem Records
This result did not emerge in isolation. The past two years have seen a rapid escalation in perovskite tandem efficiency records, with multiple research groups pushing the boundaries in different device configurations. Scientists at the National University of Singapore, working through the Solar Energy Research Institute of Singapore (SERIS), reported a tandem design that reached 26.4% efficiency earlier in 2025, surpassing a previous benchmark of 24.4% for similar devices. That work used a different architecture, but it underscored how quickly tandem performance is improving.
Even before that, NUS researchers had announced a significant advance in early 2024 focused on boosting single-junction perovskite cell performance. Their engineering faculty described a new materials discovery that pushed perovskite efficiency to record levels, laying groundwork for later tandem gains. The pattern is clear: groups around the world are closing in on and, in some cases, surpassing the mid-20% range for flexible and rigid perovskite devices, while tandem configurations are now crowding the 30% line.
What sets the 29.88% flexible tandem apart within this broader race is the mechanical requirement. Most of the highest-efficiency tandems reported to date have been rigid devices built on polished silicon wafers, suitable for flat rooftop or utility-scale modules but poorly matched to curved or mobile surfaces. A flexible cell that nearly matches rigid-cell performance opens up applications that flat, brittle panels cannot serve, from building-integrated photovoltaics that conform to architectural features to portable power systems and aerospace uses where weight and conformability matter as much as raw efficiency.
The Gap Between Lab Results and Real Panels
The 1.04 square centimeter aperture area of the tested device is worth examining honestly. Lab-scale cells at this size are the standard proving ground for new materials and interfaces, but commercial solar panels measure in the range of thousands of square centimeters. Scaling a perovskite film from roughly one square centimeter to a full module while maintaining uniform crystal quality, controlled phase behavior, and intact interfaces is a separate engineering challenge that this particular paper does not claim to have solved.
Defects that are rare on a small device can become common across a large area, leading to shunting pathways, local hot spots, or early mechanical failure. For flexible modules, the challenge is even sharper: every additional square centimeter experiences bending, thermal cycling, and environmental exposure that can accumulate into cracks or delamination. Manufacturing processes must therefore be adapted to deposit perovskite and transport layers uniformly on flexible substrates, potentially at high throughput, without sacrificing the carefully tuned phase homogeneity and stress-management strategies that enabled the record efficiency.
Perovskite stability also remains an open question that the available reporting does not fully resolve for this specific device. Perovskite materials have historically degraded when exposed to moisture, heat, and prolonged ultraviolet light, limiting their operational lifetimes compared with conventional silicon modules. While the stress-release and phase-homogeneity strategies reported here improve mechanical durability during bending, they do not automatically solve chemical stability under real-world outdoor conditions. Long-term encapsulation, barrier layers, and compositional tweaks to resist ion migration will still be necessary before flexible tandems can match the decades-long service life expected of today’s commercial panels.
Certification pathways further complicate the transition from lab cells to products. The same independent testing infrastructure that validates record efficiencies will need to confirm durability, power retention, and safety for flexible modules subjected to repeated bending and environmental stress. That means extended testing under damp heat, thermal cycling, and mechanical fatigue, not just one-time measurements under standard test conditions. Until those data are available, the 29.88% figure should be viewed as a strong indicator of technical potential rather than a guarantee of near-term commercial performance.
Why This Record Still Matters
Despite these caveats, the new flexible perovskite-silicon tandem stands as a meaningful milestone. It demonstrates that mechanical flexibility does not have to come at a steep efficiency penalty, and that careful control of perovskite phase behavior and interface stress can deliver nearly 30% conversion in a bendable format. In the broader context of recent tandem advances from institutions such as NUS and others, it signals that the field is maturing beyond fragile, lab-only prototypes toward architectures that could, with further work, be integrated into real products.
If researchers can translate this design from a 1.04-square-centimeter cell to larger-area modules while preserving both performance and flexibility, the payoff could be substantial: lighter, more adaptable solar surfaces that can be wrapped around vehicles, integrated into building skins, or deployed rapidly in the field. For now, the record serves as a benchmark and a challenge, showing how close flexible tandems have come to the 30% barrier and how much opportunity remains in the space between a single high-performing cell and a durable, market-ready panel.
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*This article was researched with the help of AI, with human editors creating the final content.
