Long-time Slashdot reader fahrbot-bot shared this report from ZME ScienceResearchers from the University of Turku, in collaboration with Aalto University and Wageningen University, have developed a bio-based UV protection film for solar cells that not only blocks nearly all harmful ultraviolet light but also outperforms commercial plastic films. The key ingredient is a water extract made from red onion skins... [T]he same sunlight that powers [solar cells] can also degrade their delicate components — particularly the electrolyte inside dye-sensitized solar cells (DSSCs), a type known for their flexibility and low-light performance. To mitigate this, manufacturers typically wrap cells in UV-protective films made from petroleum-based plastics like polyethylene terephthalate (PET). But these plastics degrade over time and are difficult to recycle... Nanocellulose can be processed into thin, transparent films that serve as the perfect substrate for UV-blocking compounds. Their breakthrough came when they dyed these films using an extract from red onion skins, a common kitchen waste. The result was a filter that blocked 99.9% of UV radiation up to 400 nanometers, a feat that outstripped even the PET-based commercial filters chosen for comparison... [T]he onion-treated filter excelled: it let through over 80% of light in the 650-1,100 nm range — an ideal sweet spot for energy absorption... Even predictive modeling based on early degradation trends suggested the CNF-ROE filter could extend a solar cell's lifetime to roughly 8,500 hours. The PET-based filter? Just 1,500 hours... [T]he red onion extract offered a rare combination of longevity, transparency, and sustainability... The team envisions biodegradable solar cells for smart packaging, remote sensors, or wearable devices — especially in applications where recovery and recycling are not feasible. Their work is part of the BioEST project, funded by the Research Council of Finland, which supports sustainable innovation across electronics and materials science. This achievement taps into a broader movement to decarbonize every step of solar energy production. Plastic packaging is one of the overlooked sources of emissions in clean technology. Swapping out fossil-based plastics for biodegradable alternatives helps close that loop... The findings appeared in the journal Applied Optical Materials.Read more of this story at Slashdot.