Fully inorganic perovskite materials of the Cs–Pb–Br system have been developing rapidly because of their overwhelming stabilities and splendid optoelectronic performance. However, there are few investigations on the parallel system of Cs–Pb–Cl, let alone the two-dimensional (2D) CsPb2Cl5. To fill in the gaps about CsPb2Cl5, we successfully grew large-scale CsPb2Cl5 single crystals (SCs) and partially substituted by Br. The quintessential 2D crystal structure determines the morphology character of slices, with a tetragonal system (I4/mcm). The ledge-connected [Cs–Cl]10 polyhedrons and face-connected [Pb–Cl]8 polyhedrons endow them with asymmetry and further bring crystal lattice distortions, which is beneficial for self-trapped exciton (STE) emission. Additionally, the band gap of the transparent CsPb2Cl5 SC is confirmed to be ∼4.01 eV. The photoluminescence (PL) of CsPb2Cl5 SC is dependent on the excitation energies. Exciton emission centered at 2.32 eV is predominant under higher energy excitation (>3.85 eV), whereas STE emission centered at 1.8 eV with a broad band (FWHM > 120 nm) is the unique emission when the excitation energy is lower than 3.85 eV. In addition, appropriate replacement of Cl with Br can bring larger lattice distortion and facilitate STE emission.
Longfei Ruan,Xueting Jiao,Xinyu Ge,Dapeng Cui,Zhengyi Sun,Xiao-chun Hang,Wei Shen,Zhengtao Deng
Metal ion doped semiconductor nanocrystals have attracted broad interest due to the doping ions could tailor their optical, electronic, transport, structure stability and spintronic properties. Herein, we report a novel ligand-mediated solvent-induced reprecipitation approach to synthesize stable and highly fluorescent thiol-passivated Mn-doped perovskite-related tetragonal CsPb 2 Cl 5 nanosheets (NSs). The rational tuning the chemical composition ( i.e. , Pb/Mn ratio) and controlling the crystal phase of the CsPb 2−x Mn x Cl 5 perovskite NSs have been achieved. Significantly, their crystal structure and photoluminescence properties are found to be well-reserved for over two months under ambient conditions. With the addition of Mn 2+ , the PL lifetime of CsPb 2 Cl 5 decreases, which further confirms the energy transfer of CsPb 2 Cl 5 to Mn 2+ , and energy transfer efficiency (η ET ) from CsPb 2 Cl 5 to Mn 2+ in CsPb 2−x Mn x Cl 5 NSs is as high as 54.9 %. Furthermore, benefited from the Mn 2+ doping, the antiferromagnetic fitting temperature of the NSs is −5 K, which indicates a strong antiferromagnetic coupling. This work suggests an expansive research prospect for application of metal ion doped perovskite-related materials in the field of optical, magnetic, and optoelectronics devices.
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