Crystal structure and luminescence of Cs-Pb-Sn-Br nanocrystals
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RESEARCH PAPER
Crystal structure and luminescence of Cs-Pb-Sn-Br nanocrystals Yubin Zhao & Meng Li & Katarzyna Matras-Postolek & Ping Yang
Received: 23 June 2020 / Accepted: 10 September 2020 # Springer Nature B.V. 2020
Abstract Sn2+ ions were introduced in Cs-Pb-Br nanocrystals (NCs) to test the change of crystal structure and photoluminescence (PL) property. In the cases of Sn/Pb ratios less than 20%, the CsPb1-xSnxBr3 NCs revealed CsPbBr3 crystal structure. With increasing the Sn/Pb ratio, Cs-Pb-Sn-Br NCs exhibited a mixture phase of CsPbBr3 and Cs4PbBr6. The NCs show bright PLQYs (87%) for Sn/Pb molar ratio of 30%. This is ascribed to little amount Cs4PbBr6 decreased the electrons and holes non-radiation recombination of CsPbBr3. With increasing the Sn/Pb ratio to 80%, the Cs4Pb1-xSnxBr6 NCs exhibited pure Cs4PbBr6 phase structure. Furthermore, a weak blue-emitting peak around 450 nm was observed for the Cs4Pb1-xSnxBr6 NCs. This confirms that Sn2+ ions were successfully introduced into Cs4PbBr6 structure. The morphologies of samples changed from initial cubic to hexagonal with increasing Sn/Pb ratios from 20 to 80%. The excitons and free carrier dynamics of the NCs were discussed.
Keywords Semiconductors . Nanostructures . Luminescence . Chemical synthesis Y. Zhao : M. Li : P. Yang (*) School of Material Science & Engineering, University of Jinan, Jinan 250022, People’s Republic of China e-mail: [email protected] K. Matras-Postolek Faculty of Chemical Engineering and Technology, Cracow University of Technology, Krakow, Poland
Introduction In recent years, fully inorganic cesium halide perovskite (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) have received extensive attention due to their excellent photoelectric properties such as tunable band gap in the whole visible spectral region (Su et al. 2019a, b; Li et al. 2018a, b; Shen et al. 2019). Inorganic halide cesium lead perovskite NCs have a narrow emission band with full width at half maxima (FWHM) of 10– 40 nm, high photoluminescence quantum yield (PLQYs) of 50–90%, and radiative advantages of short fluorescence lifetime. By changing the proportion of solvents, synthetic temperature, and reaction time, the NCs with different shapes including cube, nanofilm, nanowire, and nanorod were obtained (Guo et al. 2019; Chen et al. 2018a, b; Li et al. 2018a, b). This makes important applications in photovoltaic and photoelectric fields including solar cell (Saliba et al. 2018), light-emitting diode (LED) (Zhang et al. 2016), photodetector (Wei et al. 2016), and laser (Li et al. 2017; Giorgi and Anni 2019). Among all inorganic cesium lead halide perovskites, the Cs-Pb-Br compound is the most prominent due to the diversity of their chemical composition and geometric structure. It therefore exhibits well stability with temperature and non-moisture absorption (Kang and Biswas 2018; Chen et al. 2016; Xuan et al. 2018). The interesting geometric structures of the NCs are threedimensional (3D) CsPbBr3, two-dimensional (2D) CsPb2Br5, and zero-dimensional (0D) Cs4PbBr6,
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