Charge Carrier Lifetimes Exceeding 15 μs in Methylammonium Lead Iodide Single Crystals

The charge carrier lifetime in organic-inorganic perovskites is one of the most important parameters for modeling and design of solar cells and other types of devices. In this work, we use CH₃NH₃PbI₃ single crystal as a model system to study optical absorption, charge carrier generation, and recombination lifetimes. We show that commonly applied photoluminescence lifetime measurements may dramatically underestimate the intrinsic carrier lifetime in CH₃NH₃PbI₃, which could be due to severe charge recombination at the crystal surface and/or fast electron-hole recombination close to the surface. By using the time-resolved microwave conductivity technique, we investigated the lifetime of free mobile charges inside the crystals. Most importantly, we find that for homogeneous excitation throughout the crystal, the charge carrier lifetime exceeds 15 μs. This means that the diffusion length in CH₃NH₃PbI₃ can be as large as 50 μm if it is no longer limited by the dimensions of the crystallites.