Vacancy Defects' Effects on the Optoelectronic Properties of MAPbI.

This work derived the relationship between the concentrations of Pb and I vacancies, along with MA vacancies, in MAPbI crystals and their effect on the short-circuit current of MAPbI-based solar photovoltaic devices. First principles calculations revealed that Pb and I vacancies introduce shallow defect levels near the Fermi level, acting as non-radiative recombination centers, which significantly influence the short-circuit current and open-circuit voltage. In contrast, MA vacancies have a negligible effect on the optoelectronic properties of MAPbI. Based on this correlation, we successfully elucidated the declining trend of the short-circuit current (J) in MAPbI-based devices with increasing Pb/I vacancy concentrations, while uncovering the microscopic mechanism responsible for the minor performance impact of MA vacancies.