A perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer. Perovskite materials, such as methylammonium lead halides and all-inorganic cesium lead halide, are cheap to produce and simple to manufacture. Solar cell efficiencies of devices using these materials have increased from 3.8% in 2009 to 25.2% in 2020 in single-junction architectures, and, in silicon-based tandem cells, to 29.1%, exceeding the maximum efficiency achieved in single-junction silicon solar cells. Perovskite solar cells are therefore currently the fastest-advancing solar technology. With the potential of achieving even higher efficiencies and very low production costs, perovskite solar cells have become commercially attractive.