Amazing stuff!
"... A new study suggests photovoltaics can also work below the ocean’s surface, generating useful amounts of electricity underwater even at depths of 10 meters. ...
To overcome this challenge, ... colleagues designed solar cells that could make full use of shorter wavelength sunlight. They fabricated perovskite solar cells that cover the spectrum of light that does filter through 5 to 10 meters of water, which consists mostly of blue-green 400- to 600-nm wavelengths.
The scientists found that while their photovoltaic cells attained a light-to-electricity conversion efficiency of 17.08 percent under the conditions usually found on land, they achieved 34.71 percent efficiency when given the spectrum of light one would expect submerged 10 meters underwater. Most standard land-based solar panels achieve an average efficiency between 20 and 25 percent. ..."
From the highlights & abstract:
"Context & scale
Underwater solar energy harvesting remains an unresolved challenge due to the strong spectral attenuation of sunlight in water. Herein, to address this challenge, wide-bandgap (∼1.96 eV) lead halide perovskite solar cells (PSCs) are employed, whose absorption is spectrally matched to the underwater solar spectrum at a depth of 10 m.
To achieve highly efficient and durable submerged PSCs (S-PSCs), polyhexamethylene guanidine hydrochloride (PHMG) is introduced for energy-level modulation, which enables the perovskites to convert from p- to n-type, facilitating electron extraction, suppressing halide ion migration, reducing defect density, and improving lattice stability.
Meanwhile, to rationally evaluate the device performance under the submerged spectra, an underwater solar simulator with customized optical filters is designed. Consequently, the S-PSC devices deliver a power conversion efficiency of 34.71% under the simulated spectrum at 10 m water depth, along with long-term stability.
Furthermore, large-area perovskite solar modules are fabricated, which exhibit outstanding performance in practical outdoor operation, successfully demonstrating power generation by charging lithium-ion batteries (LIBs) and lighting up LEDs.
This work paves the way for the practical deployment of perovskite photovoltaics in underwater environments, offering a promising route toward self-sustained marine energy systems and autonomous underwater devices.
Highlights
• The ∼1.96-eV PSCs operate under real-world submerged conditions
• Highest PCEs of 17.08% (AM 1.5G) and 34.71% (simulated 10 m-deep light) were achieved
• Aging tests predict a T80 of ∼5.49 years under simulated 10 m underwater illumination
Summary
Underwater solar harvesting remains challenging due to the strong spectral attenuation of sunlight in water. Here, we demonstrate high-efficiency, durable submerged perovskite solar cells (S-PSCs) using wide-band-gap (∼1.96 eV) perovskites and engineered with polyhexamethylene guanidine hydrochloride (PHMG) as a crystallization additive. The PHMG-modified S-PSCs achieve power conversion efficiencies (PCEs) of 16.79% (certified) under AM 1.5G and 34.71% under simulated 10 m-deep illumination, matching the optimal spectrum at this depth. The additive enhances crystallinity, optimizes energy-level alignment, and suppresses interfacial non-radiative recombination. Accelerated tests predict a T80 lifetime of 48,094 h (∼5.49 years) at 25°C under simulated submerged conditions at a depth of 10 m. The large-area modules demonstrated real-world functionality by generating 324 mWh of electricity upon underwater illumination for 2 h at 10 m depth, sufficient to charge lithium-ion batteries and power LEDs. This work introduces a robust materials-and-device strategy for underwater solar harvesting, enabling autonomous marine power systems and submerged Internet-of-Things infrastructure."
Underwater Solar Cells Capture Energy 10 Meters Deep - IEEE Spectrum "Submerged photovoltaics could recharge subs, underwater robots"
Graphical abstract
