In 2007, a student at the University of Tokyo brought a lump of a grey, sparkly mineral to his professor Tsutomu Miyasaka, with the hope that this material might have potential to make cheap and efficient solar cells. But it only converted 4 percent of the sun energy to electricity. Not that remarkable.
Now, however, things have changed. Seven years later the unremarkable lump of rock called perovskite is beating out most solar cells on the market, getting 20 percent efficiency. The progress has sped up because researchers around the world saw the potential in this mineral.
While the sun is pretty much a limitless source of energy for all of us, the cost to capture it remains the challenge. The typical residential solar roof might get about 15 percent efficiency in sunlight and provides electricity at 50 cents/watt. This is twice the cost of coal.
So it’s got to get cheaper in order to pull ahead as our number one energy source. Right now the top-performing cells, made of gallium arsenide get a maximum efficiency of about 30 percent but are prohibitively expensive.
The cheaper options like copper indium gallium selenide (a flexible material) or cadmium telluride (as cheap as silicon) get only about 20 percent efficiency.