Perovskite. Per-ov-skite. In some corners of the materials science world, these new types of solar voltaic cells, with their tongue-twisting name, are all the rage.
This week a group of Italian researchers published a paper in Nature showing they could fire a laser at perovskites and answer some critical questions about their properties with regards to excitability, behavior, and the role of defects in the material. But for now it's more helpful to step back and just get a sense of the idea behind perovskites and why publications like IEEE are saying they're "the new black in the solar world."
New sources of power are at a premium, but few seem more logical than the sun. Researchers have examined putting a photovoltaic cell right into the screen of the phone, but due to weak power production, the idea of a solar-powered mobile device is still a long way off. PV cells are becoming more efficient, albeit slowly. So researchers continue to look at new ways of harvesting solar energy.
Perovskite actually refers to an arrangement of different atoms and their relation to one another in a three-dimensional structure. Different molecules can make up different perovskites but in the end they form a fairly organized-looking set up molecular cubes and support beams -- which generate a voltage in sunlight.
The first perovskite material was first tested as an energy source in 2009, and after important work by Henry Snaith's team at Oxford University, the materials have skyrocketed up the energy efficiency charts. The National Renewable Energy Laboratory shows the best demonstration converting sunlight to power at a 17.9 percent efficiency, well ahead of any other type of emerging photovoltaic cell technology, but still with work to catch silicon-based models.
Still, that's not bad for five years. One of the bits that's got the community so excited, and caused Science to call perovskites a top breakthrough of 2013, is that they capture wavelengths in the visible spectrum not previously captured by PV cells.
Not only that -- and remember these are early days -- but researchers are also starting to show they can produce a type of perovskite at a scale that would be cheaper than silicon-based cells, which as the MIT Tech Review reports, typically require high temperatures to make. Silicon cells are relatively efficient but their production cost is a huge drag on their economics.
Another big concern so far has been that perovskites require lead, so people worry about local toxic effects. Humidity has been shown to break down types of perovskites and release methyl ammonium.
But the research keeps moving along. In May Dr Snaith's group showed perovskites based on tin, albeit at far less efficiencies than lead. Later in August his team showed how perovskites could be used to build LEDs. And they're examining how to combine perovskites with traditional silicon cells.
No doubt Dr Snaith and his company Oxford Photovoltaics are doing their best to show the world all that perovskites can do. Yet there's usually a long way from the lab to market. Let's hope some of the promise comes to pass.
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