[In Depth] Cesium fortifies next-generation solar cells
In a world looking for better, cheaper alternative energy, the solar cell materials called perovskites are a bright hope. Their efficiency at converting sunlight into electricity is climbing faster than that of any solar technology before them. They're cheap and easy to make, can be manufactured roll-to-roll like newsprint, and can even be layered atop conventional silicon solar cells to boost their output. But they are fragile stars: Moisture, air, heat, or even prolonged sunlight makes them fall apart. Now, these materials are toughening up. Over the past few months, three separate teams have reported that adding a dash of cesium to their perovskite recipes produces efficient solar cells that are far more stable when exposed to the elements. Meanwhile, other researchers report that their latest cells are as efficient as standard silicon cells and may soon rival costly gallium arsenide cells. Author: Robert F. Service