This study reports on the long-range balanced electron- and hole-transport lengths in solution-processed organic-inorganic perovskite CH3NH3PbI3. The research team, led by Guichuan Xing and Nripan Mathews, used femtosecond transient optical spectroscopy to investigate the photophysical properties of CH3NH3PbI3. They found that the material exhibits balanced long-range electron and hole transport lengths of at least 100 nm, which is significantly longer than the typical 10 nm diffusion lengths in solution-processed semiconductors. This finding is crucial for understanding the high efficiency of CH3NH3PbI3-based solar cells, as it indicates that the material can efficiently transport both electrons and holes over long distances, overcoming the traditional limitations of solution-processed photovoltaics. The study involved measuring the photoluminescence (PL) quantum yield and lifetimes of CH3NH3PbI3 films with and without electron or hole extraction layers. The results showed that the PL quantum yield was significantly reduced when the perovskite was interfaced with these layers, indicating efficient charge carrier extraction. The PL lifetimes were also shortened, suggesting that the charge carrier diffusion lengths within the CH3NH3PbI3 layer are comparable to or longer than the layer thickness. These findings were supported by transient absorption spectroscopy (TAS) measurements, which further confirmed the long-range transport of charge carriers. The research team also used a diffusion model to estimate the charge carrier diffusion lengths, finding them to be approximately 130 nm for electrons and 110 nm for holes. These values are significantly longer than those reported for other solution-processed materials, indicating that CH3NH3PbI3 has superior charge transport properties. The study highlights the potential of CH3NH3PbI3 as a promising material for high-efficiency solar cells due to its balanced electron and hole transport lengths, which enable efficient charge separation and transport. The findings contribute to a deeper understanding of the fundamental photophysical mechanisms in perovskite materials and their application in photovoltaic devices.This study reports on the long-range balanced electron- and hole-transport lengths in solution-processed organic-inorganic perovskite CH3NH3PbI3. The research team, led by Guichuan Xing and Nripan Mathews, used femtosecond transient optical spectroscopy to investigate the photophysical properties of CH3NH3PbI3. They found that the material exhibits balanced long-range electron and hole transport lengths of at least 100 nm, which is significantly longer than the typical 10 nm diffusion lengths in solution-processed semiconductors. This finding is crucial for understanding the high efficiency of CH3NH3PbI3-based solar cells, as it indicates that the material can efficiently transport both electrons and holes over long distances, overcoming the traditional limitations of solution-processed photovoltaics. The study involved measuring the photoluminescence (PL) quantum yield and lifetimes of CH3NH3PbI3 films with and without electron or hole extraction layers. The results showed that the PL quantum yield was significantly reduced when the perovskite was interfaced with these layers, indicating efficient charge carrier extraction. The PL lifetimes were also shortened, suggesting that the charge carrier diffusion lengths within the CH3NH3PbI3 layer are comparable to or longer than the layer thickness. These findings were supported by transient absorption spectroscopy (TAS) measurements, which further confirmed the long-range transport of charge carriers. The research team also used a diffusion model to estimate the charge carrier diffusion lengths, finding them to be approximately 130 nm for electrons and 110 nm for holes. These values are significantly longer than those reported for other solution-processed materials, indicating that CH3NH3PbI3 has superior charge transport properties. The study highlights the potential of CH3NH3PbI3 as a promising material for high-efficiency solar cells due to its balanced electron and hole transport lengths, which enable efficient charge separation and transport. The findings contribute to a deeper understanding of the fundamental photophysical mechanisms in perovskite materials and their application in photovoltaic devices.