Abstract
All-inorganic CsPbBr3 perovskites exhibit great potential in optoelectronic application due to their outstanding physical properties for optoelectronics. However, the relatively low luminescence efficiency of the bulk CsPbBr3 crystal hampers its further application. Here, we report a facile method to enhance the optical efficiency of halide perovskite powder via doping the transition metal Ni ions. It is demonstrated that Ni doping results in the formation of the Cs(NiPb)Br3 alloy and also triggers the phase transition of CsPbBr3 from orthorhombic to cubic. Both the Cs(NiPb)Br3 alloy and cubic CsPbBr3 are found to contribute to the asymmetric photoluminescence (PL) spectra in the green-yellow light band. The splitting-peak fitting experiments for the overlapped PL spectrum based on the bi-Gaussian line model reveal that the Cs(NiPb)Br3 alloy dominates the contribution of the observed PL enhancement. The Ni2+ doping is also beneficial for optimizing the crystallinity of the CsPbBr3 perovskite, suppressing the nonradiative recombination and significantly enhancing the photoluminescence consequently. Our investigation provides a novel insight into the effect of environmentally friendly metal doping in perovskites.
Highlights
In recent years, all-inorganic halide CsPbX3 (X = Cl, Br and I) perovskite nanocrystals (NCs) have attracted tremendous attention owing to their outstanding optical properties, such as high light-absorption coefficients, narrow spectral width, wide tunable wavelength, and high charge carrier mobility, which make them greatly prospective for designing optoelectronic devices such as LEDs,1–4 solar cells,5,6 photodetectors,7,8 lasers,9–11 and other optoelectronic devices.12,13 The superb properties and performance primarily attribute to the [PbX6]4− octahedral structure in CsPbX3, where Pb2+ plays a vital role in both the valence and the conduction band as well as luminescence performance and structure stability.14 the poor photoluminescence quantum yield (PLQY) of CsPbBr3 seriously affects the performance of the optoelectronic devices and hinders its practical application
The composition of samples was characterized by Inductively couple plasma mass-spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD)
It can be seen that the XRD pattern of undoped CsPbBr3 presents its characteristic diffraction peaks at 15.08○, 15.21○, 21.65○, 30.69○, 37.6○, and 43.6○ corresponding to crystal planes (001), (100), (−110), (200), (211), and (202), respectively, which belongs to orthorhombic phase CsPbBr3 (PDF No 18-0364)
Summary
Divalent metal ion doping, generally a useful strategy to partially replace lead ions, which enhances the stability and optical properties without changing the characteristics of the host CsPbX3, has gained extensive interest. Various metal ions have been successfully doped into the [PbBr6]4− octahedron, and many significant exotic properties have been imparted to halide perovskites. Doping with innoxious metal ions, such as Sn2+, Cd2+, Ca2+, and Sr2+ can result in the broadening of the optical bandgap and the shift of the band edge from the interaction of Pb-X orbitals and lattice contraction of Pb-X bands with a smaller radius of doped ions.. Mn2+ ion doping intrigues the occurrence of new emission bands due to the formation of dopantrelated emitters.. The doping of Bi3+, Al3+, and rare earth ions as Ce3+ and Sm3+18–21 offered means to modify electronic states in CsPbX3 via controlling the bandgap levels.
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