Taurine from octopus and squid neutralizes oxygen radicals that destroy perovskite solar cells, then regenerates to provide continuous protection, dramatically extending operational lifetime.
(Nanowerk Spotlight) Perovskite solar cells can match silicon’s best laboratory efficiencies while promising far cheaper manufacturing. Built from semiconductors deposited from liquid solution at modest temperatures, these devices have reached power-conversion efficiencies above 26% in certified tests. Yet a stubborn problem blocks commercialization: perovskites degrade rapidly under the operating conditions they must endure.
Light, heat, humidity, and electrical stress all attack the perovskite absorber layer. Oxygen poses a particularly insidious threat. When perovskite absorbs photons, it generates energetic electrons capable of converting molecular oxygen into superoxide radicals, reactive species that rip hydrogen atoms from the organic molecules holding the crystal together. This chain reaction carves voids at the buried interface between the perovskite and the metal-oxide layers responsible for extracting charge.
Encapsulation can limit oxygen ingress from the surrounding environment, but cost-effective perovskites are typically fabricated in ambient air, trapping residual oxygen within the finished device. Worse, tin-dioxide electron-transport layers, standard components in high-efficiency designs, harbor non-lattice oxygen species on their surfaces. Under illumination and heat, these species migrate into the perovskite and trigger degradation from within. No seal, however tight, can prevent this internal sabotage.
A study published in Advanced Energy Materials (“Natural Antioxidant‐Inspired Interfacial Engineering for Stable and High‐Performance Perovskite Solar Cells”) now demonstrates that a compound borrowed from marine biology can intercept destructive radicals before they reach the perovskite. Researchers at South Korea’s Daegu Gyeongbuk Institute of Science and Technology and Korea Institute of Science and Technology deposited a thin layer of taurine at the critical interface between the tin-dioxide electron-transport layer and the perovskite absorber.
(a) Schematic illustration of O₂·⁻ radical formation from non-lattice oxygen and FAPbI₃ decomposition by O₂·⁻ radicals. (b) Suppression of O₂·⁻ diffusion by interfacial taurine and the corresponding radical-quenching mechanism. (c) Elementary steps of the O₂·⁻ quenching mechanism by taurine based on DFT calculations. (d) Calculated dissociation mechanism of H₂O₂. (e) Reduction of I₂ to I⁻ ions by the resulting O₂²⁻ species. (Image: Reproduced with permission from Wiley-VCH Verlag) (click on image to enlarge)
Taurine is a sulfur-containing amino acid abundant in octopus, squid, and other cephalopods, where it shields tissues from oxidative damage. Devices incorporating this antioxidant interlayer retained 97% of their initial efficiency after 450 hours of continuous illumination at 65 °C, far outperforming untreated controls.
Density-functional-theory calculations, paired with spectroscopic experiments, revealed how taurine provides protection through a two-stage mechanism that regenerates continuously during operation.
In the first stage, taurine intercepts superoxide radicals forming at oxygen vacancies on the tin-dioxide surface. The molecule carries both a positive charge on its amino group and a negative charge on its sulfonate group, a configuration chemists call zwitterionic, meaning it bears opposite charges at different sites simultaneously. This internal charge separation electrostatically confines superoxide ions. The sulfonate hydrogen then participates in a proton-coupled electron transfer that converts superoxide into hydrogen peroxide, a far less damaging species.
The second stage addresses a downstream threat. Hydrogen peroxide reacts with additional taurine molecules, releasing peroxide ions that reduce iodine gas back into iodide ions. This matters because iodine, a primary byproduct of perovskite breakdown, readily forms triiodide under illumination. Triiodide accelerates further decomposition in a vicious cycle. By converting iodine back to iodide, taurine breaks this feedback loop.
Crucially, the peroxide ions then oxidize to neutral molecular oxygen, regenerating taurine to its original zwitterionic state. This closed cycle enables continuous radical scavenging rather than one-time protection.
Multiple analytical techniques confirmed the protective effect. Transmission-electron microscopy of films exposed to simulated sunlight under nitrogen revealed macroscopic voids at the interface of untreated samples. Films incorporating taurine displayed clean, intact boundaries. X-ray photoelectron spectroscopy depth profiles detected hydroxyl species migrating deep into untreated perovskite, a chemical fingerprint of superoxide attack. Treated films showed no such infiltration. Under accelerated-aging conditions involving ultraviolet light in an ozone-rich atmosphere, taurine-treated samples retained roughly seven times more of the original perovskite phase than controls after 90 minutes.
Beyond radical scavenging, taurine acts as a molecular bridge linking the two materials it separates. Its amino group forms hydrogen bonds with iodide ions in the perovskite lattice. Its sulfonate group coordinates with uncoordinated tin atoms and fills oxygen vacancies on the tin-dioxide surface. This dual anchoring reduces the density of electronic trap states, defect sites that capture charge carriers and cause them to dissipate energy as heat rather than contribute to electrical current.
Electrical measurements quantified these benefits. The trap-filled limit voltage, an indicator of defect density, dropped from 0.85 V in control devices to 0.50 V in treated devices. Electron mobility in the tin-dioxide layer nearly doubled, climbing from 8.6 × 10⁻⁸ to 1.4 × 10⁻⁷ cm² V⁻¹ s⁻¹.
Photoluminescence studies showed that taurine treatment nearly doubled the average carrier lifetime in perovskite films, confirming suppressed energy losses. Ultraviolet photoelectron spectroscopy revealed that taurine shifted the conduction-band minimum of tin dioxide upward, improving energy-level alignment with the perovskite and easing charge extraction.
The best-performing device achieved a power-conversion efficiency of 24.8%, slightly below current laboratory records but with markedly improved stability, along with an open-circuit voltage of 1.18 V and a fill factor of 83.7%, a metric indicating how closely a cell approaches its theoretical maximum power.
Long-term stability tests proved equally compelling. Under maximum-power-point tracking with encapsulated devices operating in ambient air under one-sun illumination, treated devices retained 80% of initial efficiency after 130 hours. Control devices crossed the same threshold after just 23.6 hours, a more than fivefold difference in operational lifetime.
The findings suggest that encapsulation alone cannot deliver the durability commercial deployment demands. Oxygen species embedded in metal-oxide transport layers, or trapped during fabrication in air, initiate degradation that sealing cannot prevent. Engineering the buried interface with compounds that neutralize reactive oxygen offers a complementary defense. That a naturally occurring antioxidant abundant in common seafood can fulfill this role opens a path toward biologically inspired strategies in photovoltaic materials design.
Perovskite commercialization still faces multiple hurdles, but this work demonstrates a clear mechanism and practical method for neutralizing one of the technology’s most damaging failure pathways.
For authors and communications departmentsclick to open
Lay summary
Prefilled posts
ORCID information
Jongmin Choi (Daegu Gyeongbuk Institute of Science and Technology (DGIST))
, 0000-0001-8904-0946 corresponding author
Nanowerk Newsletter
Get our Nanotechnology Spotlight updates to your inbox!
Thank you!
You have successfully joined our subscriber list.
Become a Spotlight guest author! Join our large and growing group of guest contributors. Have you just published a scientific paper or have other exciting developments to share with the nanotechnology community? Here is how to publish on nanowerk.com.
