Researchers have developed solar cells that function underwater even when submerged to a depth of 10 m and that produce enough power to charge lithium-ion batteries. Such devices could be used to power submerged sensors, cameras, and communication systems. Water dulls the intensity of sunlight even over short distances. To make light-harvesting devices that work underwater, the researchers tuned the electronic properties of perovskite solar cells, endowing them with wider-than-usual band gaps. That customization enables the devices to absorb the spectrum of light that extends beneath the sea surface (Joule 2026, DOI: 10.1016/j.joule.2026.102672).
Perovskite solar cells (PSCs) are a relatively new but well-studied class of low-cost photovoltaic devices. They are made with a variety of light-absorbing materials that share the stoichiometry and crystal structure of the naturally occurring perovskite mineral. The properties of the light-absorbing material in these cells can be modified easily, and it absorbs light strongly. As a result, even very thin layers can absorb sunlight efficiently, which makes perovskite cells promising for lightweight and potentially flexible marine applications.
“With perovskite solar cells the key advantage for underwater usage is we can tune the bandgap by adjusting the material composition,” says Lin Xie, referring to the materials property that quantifies the energy (or wavelengths) of light the material can absorb. Xie is a materials researcher at Yunnan University who works with Wen-Hua Zhang, one of the study’s leaders.
Lie explains that the team designed the light-absorbing material to have a bandgap of around 1.96 eV to be compatible with the underwater solar spectrum, which is strongly altered by water. The researchers found that the new devices achieved a power conversion efficiency—the ratio of light energy in to electrical energy out—of almost 35%. Tests suggest that the cells can operate continuously 10 m underwater for more than 5 years.
In this study, the team used lead halide PSCs modified with polyhexamethylene guanidine hydrochloride. The additive controls the crystallization of perovskite films and reduces defects. It also helps reduce ion migration, which is key to making the devices stable under light.
To test the new cells, the researchers built an underwater solar simulator to accurately reproduce the light spectrum and intensities at various water depths. “We tested our devices under simulated seawater for around 1,000 h and found no significant reduction of device performance,” Xie says. The cells generated 324 mW h of electricity—enough to charge various types of Li-ion batteries—in less than 2 h.
In another test, the team sealed the cells in a nitrogen environment, and found that after 300 days they retained 96% of their power-producing efficiency. On the basis of accelerated aging tests, the researchers predict that the cells will have an operational lifetime of 5.5 years at 25 ºC in submerged conditions. The researchers also successfully tested their submersible PSCs integrated with underwater robots at a 10 m depth in the South China Sea to demonstrate real-world performance.
Nelson Dzade, an energy researcher at Pennsylvania State University who wasn’t part of the study, says the work brings several significant advances to underwater solar harvesting, including demonstration of good efficiency at a depth of 10 m and unprecedented projected lifespan. “The technology translates exceptionally well to real-world applications,” Dzade says, “[bridging] the gap between basic materials science and real-world engineering through several practical validations.”
There are still challenges the researchers are working on. “The biggest one is long-term reliability in real seawater [for which] we need better encapsulation,” Xie says. “Another issue is environmental safety, because perovskite devices contain lead.”
Ivy Asuo, a materials scientist at Penn State who also was not involved in the study, says “halide perovskites are low cost, easily processable, and have a tunable optical bandgap, making them a promising semiconductor for underwater solar harvesting.” She adds that the durability of the device is promising for real-world applications.
