Roof tiles are becoming a thing of the past: Today, more and more Swiss roofs boast large black and blue rectangles that convert sunlight into electricity. The blueish color comes from silicon crystals, as the majority of solar cells available today are based on this semiconductor material. But silicon is not the only way to make a solar cell—and possibly not even the best.
Light, flexible, efficient: Perovskite-based tandem solar cells
