Designing a Multifunctional Magnetic Microtube with Enhanced Conductivity through Local Heterojunction Decoration of CsPbBr3 Nanocrystals

The integration of magnetic and semiconducting materials into one single nano-/micro-heterostructure can combine the advantages of different physical properties. Here, photoluminescent CsPbBr3 perovskite nanocrystals (NCs) were placed on the surface of magnetic microtubes comprised high magnetic moment ferrimagnetic Fe3O4 magnetite and very low magnetic moment antiferromagnetic Fe2O3 hematite. The Fe2O3/Fe3O4 magnetic microtubes were synthesized through a diffusive thermal oxidation process, while the colloidal CsPbBr3 quantum dot solution was obtained by the hot injection method. Structural, morphological, magnetic, and optical characterizations indicate the successful fabrication of magnetic heterostructures comprised by hematite/magnetite microtubes decorated with green-emitting (2.56 eV band gap energy) CsPbBr3 NCs forming local nanojunctions. The high band gap magnetic microtubes decorated with CsPbBr3 NCs present a significant increase in electrical conductivity. The time-resolved photoluminescence and X-ray photoelectron spectroscopy measurements shed light on the dynamics of defect state formation, excitons, and charge carrier recombination pointing to an electrical charge transfer scenario from perovskite NCs into the magnetic semiconducting microtube. These results corroborate the formation of chemically interacting local nano-heterostructures which can be used to fine tune its electronic properties, which gives extra functionality to the photoluminescent and magnetic microtubes. Our magnetic and semiconducting multifunctional device integrates two hierarchical morphologies into one single heterostructure that could rationally combine the advantages of different magnetic-optic-electronic applications. (AU)