Enhancing surface stabilization of CH3NH3PbI3 perovskite by Cl and Br doping: First-principles study.

In this study, the effects of Cl and Br surface doping on the surfaces' structural stability of CH₃NH₃PbI₃ (MAPbI₃) perovskite have been investigated using the density functional theory. Its aim is to pursue how to stabilize a flat surfaces structure (no vacancy) of the MAPbI₃ perovskite in overcoming its chemical instability. In this calculation, the (001) texture of the MAPbI₃ perovskite surface was modeled as a prototype. The 216-atom and 264-atom supercells were employed to imitate the Lead Iodide (PbI₂)- and Methylammonium Iodine (MAI)-terminated surfaces, respectively. It was found that doping of either Cl or Br atoms on perovskite surfaces enhances the energies required for releasing PbI₂ and MAI molecules from the surfaces, causing vacancies on the surfaces. This is owed to the binding energies between the Cl and Br dopants and their surrounding atoms on the surfaces being stronger than those created by the Iodine atom. This implies that the formation of surface vacancies—which causes perovskite's degradation—can be prevented by Cl and Br surface doping. The obtained results elucidate the capability of Cl and Br dopants on surface stabilization, describing why one should incorporate Cl/Br into MAPbI₃ to overcome instability issues and enhance the efficiency of the MAPbI₃-based perovskite solar cell. [ABSTRACT FROM AUTHOR]