Solar Panels are the leading source of renewable, clean energy, providing power to homes and businesses with greatly reduced emissions.

One of the biggest downfalls to the production of solar panels is that they can be incredibly hard to dispose of. Scientists are currently looking into producing solar cells using bismuth as a more environmentally friendly, and overall safer alternative to the current leading-edge solar panel technology, without having to sacrifice efficiency.

Most solar panels that we see today have solar cells that are made with silicon. The problem with silicon is that it has a very low “defect tolerance”, meaning it needs to have very high purity levels for the solar cells to function properly. This means that silicon-based solar panels can be very expensive and take a lot of energy to produce. The current leading alternative to these silicon based cells use compounds called lead-halide perovskites, which have a much higher defect tolerance, making them much cheaper to produce. The problem with these cells though, is the lead that the perovskites are alloyed with, which can be dangerous to both humans and the environment.

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Silica (left) verses Perovskites(center) verses Bismuth Oxyiodide(left)

This is where bismuth comes in. A compound called bismuth oxyiodide could be a safer and more environmentally friendly alternative to these lead- based perovskite cells. Bismuth oxyiodide is as tolerant to defects as lead- halide perovskites, making it cheap to produce, and it can be easily mass produced using existing industrial techniques. These bismuth-based cells have also been proven to be just as efficient as perovskite cells at converting light into energy. Another advantage to using Bismuth oxyiodide is that it is stable in air for at least 197 days, showing much less degradation than perovskite compounds, which can degrade within 5 days in the same conditions.

The strongest argument for using bismuth in solar panels remains that it is much safer for humans, animals, and plant life than most other types of solar panels. Solar panels are able to be recycled, but often have to be broken apart to retrieve any valuable compounds. Additionally, the latest technological breakthroughs have made it so they can use the smallest amount of these rare elements as possible, which means the cost of recycling solar panels can be more than the value of the materials that can be recovered. This makes it much cheaper to dispose of solar panels in common landfills. However, when lead-based solar panels are disposed of in a landfill, they have the potential to break and leach heavy metals into the soil, which can stunt plant life and contaminate drinking water. The same goes for other heavy metals used in solar panels such as cadmium and tellurium.

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Bismuth is an eco-friendly, non-toxic solution for solar panels, that has been used in products such as Pepto-Bismol.

The advantage of using bismuth solar cells is that even if they break, bismuth doesn’t leak into the soil or cause problems for the environment. Known as the “green element”, bismuth is right beside lead in the periodic table and shares many of its electronic properties, but even though it is still considered a heavy metal, it is incredibly non-toxic. In fact, bismuth is often used in cosmetics, and common medicines such as Pepto Bismol.

With all this in mind, it is easy to see why bismuth oxyiodide solar panels hold so much potential for scientific breakthroughs, and could greatly reduce the impact that solar panels are currently having on the environment. With decreases in cost and increases in efficiency, bismuth oxide solar panels could very well become the new standard in the solar power industry.

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Bismuth Coins

Flip heads, or tails with The Bismuth Smith Coins. Made of pure Bismuth.

References

Brandt, R. E., Stevanović, V., Ginley, D. S., & Buonassisi, T. (2015). Identifying defect-tolerant semiconductors with high minority-carrier lifetimes: beyond hybrid lead halide perovskites. MRS Communications, 5(2), 265–275. https://doi.org/10.1557/mrc.2015.26 Hoye, R. L. Z., Lee, L. C., Kurchin, R. C., Huq, T. N., Zhang, K. H. L., Sponseller, M., Nienhaus, L., Brandt, R. E., Jean, J., Polizzotti, J. A., Kursumović, A., Bawendi, M. G., Bulović, V., Stevanović, V., Buonassisi, T.; MacManus‐Driscoll, J. L. (2017). Strongly Enhanced Photovoltaic Performance and Defect Physics of Air‐Stable Bismuth Oxyiodide (BiOI). Advanced Materials, 29(36), 1702176. https://doi.org/10.1002/adma.201702176

Huq, T. N., Lee, L. C., Eyre, L., Li, W., Jagt, R. A., Kim, C., Fearn, S., Pecunia, V., Deschler, F., MacManus‐Driscoll, J. L., & Hoye, R. L. Z. (2020). Electronic Structure and Optoelectronic Properties of Bismuth Oxyiodide Robust against Percent‐Level Iodine‐, Oxygen‐, and Bismuth‐Related Surface Defects. Advanced Functional Materials, 30(13), 1909983. https://doi.org/10.1002/adfm.201909983