Solar cells are great for harvesting that precious sunlight energy and converting it to useful electricity, but their high cost is undeniably one of the key factors that are keeping their applications limited. Solar cells need high-quality pure crystalline silicon for the rays capturing and energy conversion to take place, and this silicon is expensive to source and mold. Whether you’re talking about monocrystalline, polycrystalline, or amorphous solar cells, all of them contain silicon, and 90% of the world’s solar cells are of this type. So, finding a feasible and well-performing replacement for silicon would be a great way to address the cost problem, and it looks like scientists from the St Andrew University have managed to achieve precisely that.
As Dr. Jonathon Harwell of the university’s physics and astronomy department explains, his team has successfully incorporated lead-halite perovskite into their test solar cells, which is an excellent replacement to the good-old silicon. First of all, perovskite, which is a calcium titanium oxide mineral has very similar electrical properties to silicon. Secondly, and contrary to silicon which requires melting at 1000OC and a gradual forming of the crystals, perovskite is very inexpensive to produce. It is crystallized out of a solution that contains two cheap raw materials, and can be printed through conventional additive manufacturing tools and methods.
Moreover, the perovskite solar cells aren’t as fragile as their silicon counterparts, and thus they can be made to be thinner and more flexible. Combine the much lower cost with the above, and we have a game-changer here. The team is currently occupied with finding the optimal way to sandwich the layers and creating a working geometry. Moreover, they would like to take indium tin oxide out of the equation entirely. Right now, it is used for the top layer, and it limits the cells to being rigid and expensive. The team is also looking for a cost-effective way to manufacture perovskite wafers, which are rather thick right now (300 nm), so this is another engineering obstacle they have to overcome.