Solar Cells That Work Underwater
A Yunnan University team has built perovskite panels that charge batteries on the seafloor. The ocean's power grid just got a blueprint.
By The space-quantum Desk
The cell worked. [1]
The team behind the experiment is led by Simin Ma at Yunnan University, and their findings—published in Joule under DOI 10.1016/j.joule.2026.102672—describe a perovskite solar cell engineered specifically for submarine conditions. [1] Perovskites have long attracted attention as an alternative to silicon: they are cheap to manufacture, can be made into thin, flexible, transparent films, and can convert substantially more incoming solar energy into electricity. [1] The persistent problem is longevity. They degrade quickly, and moisture is among the most destructive forces they face. [1]
That tension—a material that thrives on light but crumbles in water, now asked to do both at once—is exactly the kind of constraint that drives materials science forward. The ocean is not a forgiving laboratory.
The Yunnan team's first insight was spectral. Water blocks the wavelengths that silicon panels rely on, but perovskites can be chemically tuned during production to absorb whatever wavelengths are actually present at depth. [1] Reaching that spectral match a few meters down turned out to be the straightforward part. Making the cells survive long enough to matter was harder. [1]
The solution arrived in the form of an additive: polyhexamethylene guanidine hydrochloride. [1] It does several things simultaneously. It wraps the perovskite in a water-repelling layer, reducing direct moisture contact. It also interacts with the perovskite crystal lattice itself, encouraging larger crystals to form and preventing ions from migrating through the structure—ion migration being one of the primary mechanisms by which perovskites fail. [1] The same compound that keeps water out also tidies the material's internal architecture, and as a bonus, it improves electricity output. [1]
Efficiency numbers tell a striking story. Under light filtered to simulate 10 meters of ocean depth, the cells converted about 35 percent of available light energy into electricity. [1] The comparison is not perfectly apples-to-apples—the filtered underwater spectrum contains far less total energy than direct sunlight—but the figure demonstrates that the perovskite is making the most of what the ocean leaves it.
Durability testing followed. The team submerged a sandwiched, encapsulated panel in seawater for about 40 days; at the end of that period it was still at 99.6 percent of its original efficiency. [1] Extrapolating from that degradation curve, they estimate the panel should last 5.5 years in seawater before dropping to 80 percent output—the threshold conventionally considered the end of a solar cell's useful life. [1] That figure is poor compared to silicon, which can operate reliably for decades, but it is well beyond what most perovskites have achieved in any environment, let alone a marine one. [1]
Five and a half years is not forever. But it is long enough to matter for the specific devices that need power where no cable runs and no surface float survives for long. The calculus of useful lifetime shifts when the alternative is no power at all.
The South China Sea field trial added texture to the lab data. The panel charged coin cell batteries at 2, 6, and 10 meter depths. [1] At 2 meters, power fluctuated pretty strongly thanks to sunlight interacting with the surface waves. [1] At greater depth, scattering smoothed those fluctuations out, producing more consistent if dimmer illumination. [1] At 10 meters, the panel produced a little less than a quarter as much energy as it did at 2 meters. [1] The gradient is steep, but for low-power electronics, the numbers are workable.
The researchers frame their target applications as "autonomous marine power systems and submerged Internet of Things infrastructure"—uncrewed underwater vehicles, environmental sensors, seafloor monitoring arrays. [1] Japan, separately, has been investing heavily in a new kind of ultra-thin, flexible solar panel that it hopes will help it meet renewable energy goals while challenging China's dominance of the sector. [2] Perovskite solar panel roofing was installed at the bus terminal during a press tour of the 2025 Osaka Expo site on Yumeshima island. [2] The underwater application is a different frontier, but the underlying material science is converging from multiple directions.
The depth ceiling is real and worth stating plainly. Light sufficient for photovoltaic generation runs out well before the abyssal zones where much of the ocean's scientific and commercial interest lies. [1] The technology described here is not a solution for deep-sea mining robots or hadal pressure sensors. It is a solution for the coastal and epipelagic band—the first few tens of meters where underwater infrastructure is already being deployed and where reliable, cableless power has been the persistent missing piece.
The ocean floor is not waiting for a single breakthrough. It is waiting for an accumulation of small, durable answers to specific problems. A solar cell that survives seawater for five years is not the whole answer. It is, unmistakably, one of them.
The next design challenge is not efficiency—the perovskite already beats silicon on that metric in filtered light. [1] It is the encapsulation stack: the protective sandwich that keeps seawater from reaching the active layer over thousands of days of continuous submersion. Solve that, and the depth limit becomes the only remaining boundary. The ocean's interior power grid does not need a cable from shore. It needs a cell that refuses to dissolve.
autonomous marine power systems and submerged Internet of Things infrastructureSimin Ma et al.