Perovskite Solar Cells Harvest Power Beneath the South China Sea
Blue-green light powers submerged electronics at 10 meters
Offsea field trials in the South China Sea have demonstrated that customized perovskite solar cells can harvest energy directly beneath the ocean’s surface. Mounted to a specialized robotic submersible, the next-generation photovoltaic cells generated stable electrical currents to charge onboard coin-cell batteries at depths reaching 10 meters.
The module was tested in open water at two meters, six meters, and 10 meters below sea level using a small submarine platform designed to reach and maintain pre-set sub-surface depths. At two meters, power production fluctuated significantly because of surface wave motion, light refraction, and water turbulence. At six and 10 meters, total light levels decreased, but the electrical output became substantially more stable.
Ocean penetration rapidly removes red, infrared, and other long-wavelength light through absorption by water molecules. The remaining illumination is concentrated in a narrow optical spectrum dominated by blue and green light between roughly 400 and 550 nanometers. At the 10-meter mark, the submerged panel produced less than one-quarter of the electricity generated by the same module when measured eight meters above the water’s surface.
Conventional crystalline silicon solar cells, which dominate terrestrial energy production, have a fixed bandgap near 1.1 electron-volts optimized for broad-spectrum sunlight. Their efficiency diminishes under the filtered, short-wavelength illumination found underwater. Synthetic metal-halide perovskites can instead be chemically adjusted during synthesis to alter their bandgap and match the blue-green spectrum that reaches lower aquatic depths.
Before the ocean deployment, controlled laboratory testing evaluated the treated perovskite panels under simulated light conditions matching a depth of 10 meters. Under those low-light conditions, the material converted approximately 35% of the available light into electricity, while standard commercial silicon solar panels convert roughly 20% of direct surface sunlight under standard terrestrial testing conditions.
Perovskites are a class of compounds sharing a specific crystal structure first discovered in the Ural Mountains of Russia in 1839 and named after mineralogist L. A. Perovski. They are historically prone to rapid breakdown when exposed to moisture: water molecules typically penetrate crystal boundaries, triggering chemical hydrolysis that decomposes the material into component metal halides.
To endure submerged operations, the research team modified the chemical formulation of the perovskite material to form larger crystal structures. This reduced the density of vulnerable grain boundaries where degradation begins. The team also applied a water-repelling hydrophobic coating over the active cell layers to isolate the compound from seawater corrosion and ion exchange.
Accelerated degradation tests conducted in the laboratory indicated that the sealed perovskite cells could retain most of their initial operational efficiency for more than five years. The field experiment involved a growing effort to adapt high-efficiency semiconductor materials to aquatic environments where natural sunlight is severely attenuated.
The ability to capture energy directly at depth targets operational challenges facing the expanding marine Internet of Things (IoT) and oceanographic sensing networks. Autonomous underwater vehicles (AUVs), environmental monitoring sensors, hydro-acoustic arrays, and submerged research gear traditionally rely on heavy primary lithium batteries or power cables linked to surface platforms.
Surface buoys carrying conventional solar panels are vulnerable to open-ocean storms, marine biofouling, navigation risks, and salt-spray corrosion, creating demand for low-profile, long-duration submerged power sources.
