In this research, a theoretical investigation of the perovskite-based solar cells (PSCs) was performed to rationalize the marked difference in the incident photon to current conversion efficiency (IPCE). To achieve this goal, we described photovoltaic processes quantitatively/qualitatively. The ground to excited state transition electric dipole moments (rk,kˊ) and the quantum chemistry reactivity indices such as electrophilicity (ω) of the methylammonium make halide perovskites (MAPbCl3/MAPbBr3) attractive for energy conversion. These properties were investigated through natural bond orbital (NBO) and time-dependent density functional theory (TD-DFT) [1, 2]. According to the ground state of the studied perovskites, MAPbCl3 has a less tendency of electron donating, which in turn enhances the electron transfer path to be loaded in external circuit. Also, it shows a greater oscillating strength (f) than MAPbBr3, which means a greater probability of charge transfer between the molecular orbitals in the Cl-based perovskite. In addition to the f values, we extracted rk,kˊ values from the excited states analysis to understand the PSCs performances better. Obtained results show a higher value of rk,kˊ in MAPbCl3 and IPCE in MAPbCl3-based solar cell (Fig. 1). This behavior may be interpreted by an advance in the efficient electron-hole separation in MAPbCl3. Finally, on the basis of different analyses, MAPbCl3 is proposed as a good candidate to be applied in the PSC.

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