Layered hybrid lead perovskite single crystals: phase transformations and tunable optical properties

Based on the disadvantages of crystal processing and device fabrications of 3D halide perovskites, there is a need to introduce aromatic ammonium into CH(3)NH(3)Pbl(3) to address these concerns. Herein, we report the controllable growth of layered perovskite (C6H5CH2CH2NH3)(2)(CH3NH3)(n-)(1)Pb(n)I3(n)(+1) (n = 1-3) single crystals realised by controlling the proper molar ratio of reactants in the ambient atmosphere. Interestingly, two polymorphs of (C6H5CH2CH2NH3)(2)PbI4 single crystals coexisted, and their phase transformation were achieved by different strategies. Moreover, the crystal structure determinations, band gap, optical properties, and thermal stability of the (C6H5CH2CH2NH3)(2)(CH3NH3)(n-1)PbnI3n+1 (n = 1-3) single crystals were studied in detail. The (C6H5CH2CH2NH3)(7)(CH3NH3)(n)(-1)Pb(n)I3(n+1) (n < 3) single crystals with quantum well structures exhibited strong photoluminescent properties. These intriguing features may lay the foundation for optoelectronic applications of the layered perovskite materials.