This is a theoretical study on the electronic and photovoltaic properties of three inorganic perovskite compounds (CsPbX3; X=Br, Cl, I) in the perovskite solar cells (PSCs). The ground/excited states of these perovskites were investigated at the DFT-B3LYPLANL2DZ/TD-DFT-B3LYP-LANL2DZ level of the theory. The alignment of the energy levels of the perovskites, TiO2, as a semiconductor, and Au, as a counter electrode, is proper to have an efficient electron/hole transfer in the PSCs. We found the reasonable correlations between the photovoltaic parameters such as the rate of the charge transfer, kinj. and the quantum reactivity index such as the chemical hardness, η of the perovskites. The results show that the kinj. is decreased with an increase in the η. Moreover, the trend of the incident photon to current conversion efficiency, IPCE, is according to: CsPbBr3 ˃ CsPbCl3 ˃ CsPbI3. The IPCE decrement from the CsPbBr3 to CsPbI3, is due to the decrease of the light harvesting efficiency, LHE. Also, the electron injection dynamics and regeneration process of the CsPbCl3 more efficiently occurs than that of the other systems. The IPCE behavior as a function of kinj. can be described by an exponential function in the peroveskites. Finally, CsPbCl3 system shows that the IPCE of this perovskite compound is more affected by the kinj..

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