Epitaxial Growth of MgGa₂O₄/CsPbBr₃ Heterostructure with Controlled Defect Tolerance for Dynamic Photoluminescence

Abstract Epitaxial growth of halide perovskite heterostructures endows unique electronic structures for diversified luminescent properties. Herein, an epitaxial growth strategy is proposed to assemble MgGa₂O₄/CsPbBr₃ heterostructure with dynamic photoluminescence. Interface defect passivation during integration transforms interstitial and antisite interface defects of CsPbBr₃ nanocrystals to shallow states, enhancing photoluminescence stability of the heterostructure against irradiation, solvents, and heat as well. Finally, the as‐constructed heterostructure shows a reversible dynamic photoluminescence from green to blue under 254 nm ultraviolet (UV) irradiation, which is attributed to the electron injection from shallow defects to the emission centers in MgGa₂O₄ and CsPbBr₃ with different radiative recombination rates. Encryption applying binary encoding method based on MgGa₂O₄/CsPbBr₃ and dynamic anti‐counterfeiting feature of its polymer hybrid film are further investigated.