http://www.sciencemag.org/news/2019/04/amp-solar-cells-scientists-ditch-silicon

Tandem solar cells with two layers of perovskites aim to replace conventional silicon solar cells. 

Silicon dominates the world of solar power. Even the newest solar cell designs, tandem devices that have a silicon solar cell below a cell made of a crystalline material called a perovskite, rely on the material. Now, researchers are doing away with silicon altogether, creating tandems from two of the best yet perovskites, each tailored to absorb a different part of the solar spectrum. Because perovskites are easier to manufacture than silicon cells, the advance could lead to less costly solar power.