The article discusses the high charge carrier mobilities and lifetimes in organolead trihalide perovskites, which have emerged as promising materials for thin-film photovoltaic cells due to their low-cost solution processing and broad absorption across the solar spectrum. The authors investigate the transport properties of methylammonium lead trihalide perovskites, specifically CH3NH3PbI3 and CH3NH3PbI3-xClx, using transient THz spectroscopy. They find that these materials exhibit unexpectedly long charge carrier diffusion lengths due to non-Langevin charge carrier recombination, with bi-molecular recombination rates significantly lower than expected. This results in carrier diffusion lengths exceeding one micron, which is crucial for the performance of planar-heterojunction photovoltaic devices. The study also highlights the importance of spatial separation of electrons and holes within the perovskite structure, which may be tuned through substitutions affecting the electronic structure. The findings suggest that the combination of high charge mobility and low recombination rates makes organolead trihalide perovskites highly suitable for photovoltaic applications.The article discusses the high charge carrier mobilities and lifetimes in organolead trihalide perovskites, which have emerged as promising materials for thin-film photovoltaic cells due to their low-cost solution processing and broad absorption across the solar spectrum. The authors investigate the transport properties of methylammonium lead trihalide perovskites, specifically CH3NH3PbI3 and CH3NH3PbI3-xClx, using transient THz spectroscopy. They find that these materials exhibit unexpectedly long charge carrier diffusion lengths due to non-Langevin charge carrier recombination, with bi-molecular recombination rates significantly lower than expected. This results in carrier diffusion lengths exceeding one micron, which is crucial for the performance of planar-heterojunction photovoltaic devices. The study also highlights the importance of spatial separation of electrons and holes within the perovskite structure, which may be tuned through substitutions affecting the electronic structure. The findings suggest that the combination of high charge mobility and low recombination rates makes organolead trihalide perovskites highly suitable for photovoltaic applications.