Solvatochromic Photoluminescent Effects in All-Inorganic Manganese(II)-Based Perovskites by Highly Selective Solvent-Induced Crystal-to-Crystal Phase Transformations

The development of lead-free perovskite photoelectric materials has been an extensive focus in the recent years. Herein, a novel one-dimensional (1D) lead-free CsMnCl3(H2O)(2) single crystal is reported with solvatochromic photoluminescence properties. Interestingly, after contact with N,N-dimethylacetamide (DMAC) or N,N-dimethylformamide (DMF), the crystal structure can transform from 1D CsMnCl3(H2O)(2) to 0D Cs3MnCl5 and finally transform into 0D Cs2MnCl4(H2O)(2). The solvent-induced crystal-to-crystal phase transformations are accompanied by loss and regaining of water of crystallization, leading to the change of the coordination number of Mn2+. Correspondingly, the luminescence changes from red to bright green and finally back to red emission. By fabricating a test-paper containing CsMnCl3(H2O)(2), DMAC and DMF can be detected quickly with a response time of less than one minute. These results can expand potential applications for low-dimensional lead-free perovskites.