Crystal Chemistry Could Make Perovskite Solar Efficient Enough to Compete With Silicon

Think about what happens inside a solar cell the moment light hits it. Photons jostle electrons loose from their atoms, and those electrons have to travel, quickly, through a crystalline lattice before they recombine and the energy is wasted as heat. In a tandem cell built from two stacked layers of perovskite, a man-made mineral compound that can be tuned to absorb different wavelengths, this journey is complicated by a fundamental mismatch: the two layers crystallize at different speeds and...