Tailoring the Optical, Electronic, and Magnetic Properties of MAPbI3 through Self-Assembled Fe Incorporation

We have produced Fe-doped paramagnetic MAPbI3 microwires by using a novel strategy involving a self-assembly growth process of [PbI6]4– octahedral chains in the presence of liquid water. Structural and morphological studies confirmed that after the dissociation and recrystallization process, the doped samples preserved both the perovskite structure with a tetragonal phase and a microwire shape, while X-ray photoelectron spectroscopy revealed the presence of mixed-valence Fe3+/Fe2+ ions with negligible change in the PbI6 cage environment and the maximum valence band position. From first-principles calculations, we determined that Fe2+ ions are localized in the interstitial site while Fe3+ ones are substitutional on Pb sites. The very high mobility and static dielectric constant, achieved by photogenerated charge carriers in MAPbI3, are suppressed for Fe-doped MAPbI3 samples. These results are discussed based on a nonradiative recombination process assisted by phonons that is activated by the inclusion of the Fe ions. Our ab initio calculations support this model that can be also used to explain the quenching of the photoluminescence emission peaks. The successful insertion of dopants that can tune the perovskite’s physical properties is important to the development of functional devices and is also able to open new potential applications such as in magnetic/semiconducting devices.