Quantum dot–induced phase stabilization of α-CsPbI 3 perovskite for high-efficiency photovoltaics

Maintaining a stable phase For solar cell applications, all-inorganic perovskite phases could be more stable than those containing organic cations. But the band gaps of the former, which determine the electrical conductivity of these materials, are not well matched to the solar spectrum. The cubic structure of CsPbI 3 is an exception, but it is stable in bulk only at high temperatures. Swarnkar et al. show that surfactant-coated α-CsPbI 3 quantum dots are stable at ambient conditions and have tunable band gaps in the visible range. Thin films of these materials can be made by spin coating with an antisolvent technique to minimize surfactant loss. When used in solar cells, these films have efficiencies exceeding 10%, making them promising for light harvesting or for LEDs. Science , this issue p. 92