A promising new way of making high-efficiency solar cells, using perovskites instead of silicon, could solve all three silicon limitions at once and supercharge the production of electricity from sunlight.
To extract silicon, typically, manufacturers melt silicon dioxide (beach sand) at 1500–2000 degrees Celsius in an electrode arc furnace. The energy needed to run such furnaces makes the silicon PV cells expensive and also adds to the emissions of greenhouse gases. Besides silicon PV cells work best when they are flat and housed in large, heavy panels.
Perovskites—a wide-ranging class of materials in which organic molecules, made mostly of carbon and hydrogen, bind with a metal such as lead and a halogen such as chlorine in a three-dimensional crystal lattice—can be made much more cheaply and with fewer emissions. Manufacturers can mix up batches of liquid solutions and then deposit the perovskites as thin films on surfaces of virtually any shape, no furnace needed. The film itself weighs very little.
The power conversion efficiency of silicon cells has been stuck at 25 percent for the 15 years. In the last seven years, perovskite solar-cell efficiencies increased five-fold and it achieved a stunning doubling in efficiency within just the past two years. While it is now close to silicon PV cells, it is still moving upwards rapidly.