Solar cells, which convert sunlight to electricity, have long been part of the global vision for renewable energy. Although individual cells are very small, when upscaled to modules, they can be used to charge batteries and power lights. If laid side-by-side, they could, one day, be the primary energy source for buildings. But the solar cells currently on the market utilize silicon, which makes them expensive to fabricate when compared to more traditional power sources.

That's where another, relatively new-to-science, material comes in -- metal halide perovskite. When nestled at the center of a solar cell, this crystalline structure also converts light to electricity, but at a much lower cost than silicon. Furthermore, perovskite-based solar cells can be fabricated using both rigid and limber substrates so, alongside being cheaper, they could be more light-weight and flexible. But, to have real-world potential, these prototypes need to increase in size, efficiency, and lifespan.

Now, in a new study, published in Nano Energy, researchers within the Energy Materials and Surface Sciences Unit, led by Professor Yabing Qi, at the Okinawa Institute of Science and Technology Graduate University (OIST) have demonstrated that creating one of the raw materials necessary for perovskites in a different way could be key to the success of these cells.

"There's a necessary crystalline powder in perovskites called FAPbI3, which forms the perovskite's absorber layer," explained one of the lead authors, Dr. Guoqing Tong, Postdoctoral Scholar in the Unit. "Previously, this layer was fabricated by combining two materials -- PbI2 and FAI. The reaction that takes place produces FAPbI3. But this method is far from perfect. There are often leftovers of one or both of the original materials, which can impede the efficiency of the solar cell."

To get around this, the researchers synthesized the crystalline powder using a more precise powder engineering method. They still used one of the raw materials-PbI2 -- but also included extra steps, which involved, amongst other things, heating the mixture to 90 degrees Celsius and carefully dissolving and filtering out any leftovers. This ensured that the resulting powder was high quality and structurally perfect.