We don’t recommend licking solar cells, but soon if you can get a familiar tingle, researchers have improved the functionality and durability of solar cells using capsaicin, the molecule that makes chili peppers. After discovering growing production from caffeinated dosed solar cells, researchers seem to be stepping into their favorite chemical pick-me-ups in search of clean energy. Theoretically, perovskite solar cells could be slightly more efficient and much cheaper than existing silicon versions. A successful transition from lab benches to rooftops will make electricity unparalleled during the day and move the world towards a safer future. Despite the remarkably rapid progress, challenges remain.
One of the largest is known as nonradiative recombination, where defects in cell material allow electrons and holes to combine and reduce current flow. Many scientists around the world want to bring it under control, said Dr. Qinye Bao of East China Normal University. In the Bao report on Joule capsaicin, the P-type (having a surplus of holes for electrons) overturned the active layer 100 nanometers below the surface from N-type (having extra electrons).
Adding caffeine to perovskites to increase efficiency was a joke he tried, just to be surprised at his success. Bao’s pepper powder has a different story. He said in a statement, “Considering the electrical, chemical, optical, and stable properties of capsaicin, we initially discovered that it would be a promising candidate.” As a result, the team was not surprised that it worked. Still, they had to experiment a lot to find the ideal recipe for spicy solar cells. Bao and co-authors report that 0.1% capsaicin by weight added to the MAPBL3 perovskite predecessor provided their observation opportunities.
Bao was able to add the maximum efficiency with capsaicin 21.88 percent, which is below the record for any type of perovskite cell, which is now in the mid-20s. However, this is the highest achievement so far for polycrystalline MAPBL3 cells and is close to the record of 21.93 percent, making monocrystaline stronger in making MAPBL3. This cell type is considered a strong candidate for commercialization without being the current skills leader.
Meanwhile, cells that were identical except for the absence of capsaicin achieved only 19.1 percent. More importantly, capsaicin-infected cells maintain better production levels for a more stable, promising period. Capsaicin reduces the number of defects as well as increasing the concentration of surplus electrons in the surface film of cells.
However, you prefer your solar energy to red hot, Bao’s cells as fuel, not food. MAPBI3 means methylammonium lead triiodide, so these cells must be toxic. However, as Bao and others seek to replace lead, its amounts are already very low in both metallic and organic alternative perovskites. If it can be done using molecules that you can grow in your garden, it is even better. At the very least, the world needs to be better than getting out of the core element of sharpness.