Embedded Two-Dimensional Perovskite Nanoplatelets with Air-Stable Luminescence

Two-dimensional (2D) perovskites represent a class of promising nanostructures for optoelectronic applications owing to their giant oscillator strength transition of excitons and high luminescence. However, major challenges lie in the surface ligand engineering and ambient stability. Here, we show that air-stable quasi-2D CsPbBr3 nanoplatelets can be formed in the matrix of Cs4PbBr6 nanosheets by reducing the thickness of Cs4PbBr6 to ∼7.6 nm, the scale comparable to the exciton Bohr radius of CsPbBr3. The 2D behavior of excitons is evidenced by the linear increase of the radiative lifetime with increasing temperature. Moreover, the wide-bandgap Cs4PbBr6 plays roles of surface passivation and protection, which leads to good photoluminescence properties without the photobleaching effect and with ambient stability for over 1 month. Our work demonstrates a unique quasi-2D heterostructure of perovskite nanomaterials, which may either serve as a workbench for studying the exciton recombination dynamics or find application in high-performance optoelectronic devices.