Extending Carrier Lifetimes of Metal Halide Perovskites by Defect Passivation with Alkaline Earth Metals: A Time-Domain Study

Abstract

Intrinsic defects that serve as non-radiative recombination centers significantly accelerate charge and energy losses in hybrid organic–inorganic perovskites. The defect I_MA, formed by replacing an MA with an I in MAPbI₃ (MA = CH₃NH₃⁺), creates an I trimer that produces a deep electron trap state. Non-adiabatic (NA) molecular dynamics simulations demonstrate that an excited conduction band electron is rapidly captured by this electron trap within 100 ps, followed by recombination with a valence band hole within 1 ns, which is 3 times faster than that in the pristine system. Doping with interstitial Sr and Ba eliminates the electron trap state by breaking the I trimer, thereby restoring the electron–hole recombination across the bandgap to durations up to 3.20 and 4.36 ns, respectively. The delayed recombination is attributed to decreased NA coupling and a shortened decoherence time. These findings provide critical insights into perovskite defect passivation strategies with alkaline earth metals.