A class of compounds first uncovered in the Ural Mountains more than a century ago is now a rock star in the world of solar-energy research.

Meet perovskite, the building block for materials that, as a group, have posted unprecedented gains in their solar-energy efficiency—the percentage of sunlight converted into electricity. In the lab, scientists experimenting with perovskite-based materials of different compositions have recently achieved a jump in efficiency to 20%, from around 10% just two years ago.

That is still lower than the most efficient silicon-based cells on the market— SunPower Corp. makes cells that are 24% efficient.

But because of perovskite's rapid increases in efficiency, researchers think it could be used to make cells that are at least as efficient as those fashioned from silicon, but at a much lower cost.

Game Changer?

If it pans out that way, researchers say, perovskite could play a crucial role in the future of solar power.