Precise Modulation of Stable 2D/3D Multidimensional (PEA)2PbBr4 Nanosheets via Post Cation Exchange

2D/3D multidimensional perovskite heterostructures have attracted considerable attention due to their inherent stability and efficient charge transport. However, many challenges remain in fabricating stable 2D/3D multidimensional perovskite heterostructures, such as a precise and convenient pathway to control the perovskite phase with stable interfacial interactions between the 2D and 3D perovskite layers. Therefore, developing a convenient method for the construction of 2D/3D perovskite heterostructures is highly necessary. In this study, we have successfully synthesized stable 2D/3D multidimensional (PEA)2PbBr4 perovskite heterostructures by precisely modulating post cation exchange with cesium oleate (CsOA). As CsOA increased, 2D (PEA)2PbBr4 nanosheets gradually transformed into 3D CsPbBr3, resulting in a multidimensional 2D/3D heterostructure with vivid multi-emission changes. Taking advantage of this precise control process, we explored their potential application in the fluorescent colorimetric detection of Cs+ in soybean oil based on multidimension transformation of 2D (PEA)2PbBr4 nanosheets. This novel strategy not only provides a new approach to constructing 2D/3D perovskite heterostructures but also expands the visual detection strategies for Cs+ sensing.