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Lead-free halide double perovskites (DPs) with superior photoelectric performance are of great importance in perovskites materials family. In this paper, a series of rare-earth (RE) based Cs 2 NaRECl 6 (RE = Y, Ce–Nd, Sm–Gd, Dy–Lu) DPs microcrystals (MCs) were prepared by convenient hydrothermal method. Cs 2 NaCeCl 6 and Cs 2 NaEuCl 6 MCs exhibit typical UV emission from the 5d→4f transition of Ce3+ and orange-red emission from characteristic 5D 1 → 7F 0 , 5D 0 → 7F 1 , 5D 0 → 7F 2 , 5D 0 → 7F 3 , 5D 0 → 7F 4 transitions of Eu3+, respectively. The blue light emissions of Cs 2 NaYCl 6 (300–650 nm) and Cs 2 NaLuCl 6 (300–550 nm) are from the respective self-trapped exciton states (STEs). In addition, the bandgap and partial density of state (PDOS) of Cs 2 NaRECl 6 (RE = Ce, Eu, Y, Lu) were calculated based on density functional theory (DFT) to have a further insight into the optical properties of the RE-DPs. The as-prepared RE based DPs have potential applications in advanced lighting, displaying and anti-counterfeiting, etc. [ABSTRACT FROM AUTHOR]

Lead-free halide double perovskites (DPs) with superior photoelectric performance are of great importance in perovskites materials family. In this paper, a series of rare-earth (RE) based Cs 2 NaRECl 6 (RE = Y, Ce–Nd, Sm–Gd, Dy–Lu) DPs microcrystals (MCs) were prepared by convenient hydrothermal method. Cs 2 NaCeCl 6 and Cs 2 NaEuCl 6 MCs exhibit typical UV emission from the 5d→4f transition of Ce3+ and orange-red emission from characteristic 5D 1 → 7F 0 , 5D 0 → 7F 1 , 5D 0 → 7F 2 , 5D 0 → 7F 3 , 5D 0 → 7F 4 transitions of Eu3+, respectively. The blue light emissions of Cs 2 NaYCl 6 (300–650 nm) and Cs 2 NaLuCl 6 (300–550 nm) are from the respective self-trapped exciton states (STEs). In addition, the bandgap and partial density of state (PDOS) of Cs 2 NaRECl 6 (RE = Ce, Eu, Y, Lu) were calculated based on density functional theory (DFT) to have a further insight into the optical properties of the RE-DPs. The as-prepared RE based DPs have potential applications in advanced lighting, displaying and anti-counterfeiting, etc. [ABSTRACT FROM AUTHOR]

All-inorganic lead-free zero-dimensional (0D) metal halides perovskites with intriguing photoluminescent (PL) properties have aroused much interest due to their application in lighting and artificial illumination. Herein, 0D Cs 2 ZnBr 4 perovskite single crystals were synthesized through simple solvothermal method. The phase purity, the electronic band structure and electronic density of states of Cs 2 ZnBr 4 are investigated by X-ray diffraction (XRD) measurement and density functional theory (DFT) calculation. Under 430 nm blue light excitation, Cs 2 ZnBr 4 single crystals exhibit broadband emission covering the visible region from 450 to 750 nm and large Stokes shift about 120 nm, originating from self-trapped excitons (STEs) radiative recombination. And Cs 2 ZnBr 4 shows excellent thermal and air stability. These results indicate the potential application of Cs 2 ZnBr 4 as environmental-friendly light emitters for solid state lighting and displaying. [ABSTRACT FROM AUTHOR]