Promoted Growth and Multiband Emission in Heterostructured Perovskites Through Cs⁺ -Sublattice Interaction

Precise control of exciton confinement in metal halide perovskites is critical to the development of high-performance, stable optoelectronic devices. A significant hurdle is the swift completion of ionic metathesis reactions, often within seconds, making consistent control challenging. Herein, the introduction of different steric hindrances in a Cs⁺ sublattice within CsYb₂ F₇ is reported, which effectively modulates the reaction rate of Cs⁺ with lead (Pb²⁺ ) and halide ions in solution, extending the synthesis time for perovskite nanostructures to tens of minutes. Importantly, the Cs⁺ sublattice provides a crystal facet-dependent preference for perovskite growth and thus exciton confinement, allowing the simultaneous occurrence of up to six emission bands of CsPbBr₃ . Moreover, the rigid CsYb₂ F₇ nano template offers high activation energy and enhances the stability of the resulting perovskite nanostructures. This methodology provides a versatile approach to synthesizing functional heterostructures. Its robustness is demonstrated by in-situ growth of perovskite nanostructures on Cs⁺ -mediated metal-organic frameworks.