Perovskite solar cells have considerable potential. These are constructed from a combination of organic molecules and inorganic elements. When optimally combined the semi-conductor material captures sunlight and convert this into electricity. This is done in a way that is more efficient than the more typical silicon-based solar cells.
A limitation with perovskite photovoltaic devices has been with manufacturing them in a cost-effective way. New techniques are now making the process easier, through the use of a flexible substrate.
The process involves a different way of combining two perovskite solar cell materials, each of which is tuned to absorb a different wavelength or color of sunlight, into one structure termed a “graded bandgap solar cell.” This construct is more efficient because it absorbs close to the complete spectrum of visible light.
The reference to bandgap relates to the semi-conductor properties of perovskite. The material can only conduct electricity when the electrons absorb sufficient energy. Here crossing this energy threshold involves exceeding an energy gap or bandgap. Crossing the bandgap is made easier through the material absorbing more light from across the visible spectrum.
As an additional advantage, the solar cells can be made flexible through the production process (where the crystals are grown). Here a perovskite and boron nitride sandwich is positioned onto a lightweight aerogel of graphene, and this leads to a lighter and more flexible structure.
The process has been developed jointly between researchers from University of California, Berkeley, and Lawrence Berkeley National Laboratory.
In a research note, one of the lead scientists Dr. Alex Zettl said: “We have set the record now for different parameters of perovskite solar cells, including the efficiency”, adding “This has a great potential to be the cheapest photovoltaic on the market, plugging into any home solar system.”
Once commercialized (which is expected during 2017), perovskite solar cells could capture 20 percent of the sun’s energy, which is a considerable advance over silicone-based solar cells.
The research has been published in the journal Nature Materials, in a paper called “Graded bandgap perovskite solar cells.”
