Expanding the Emission of CsPbBr₃ Nanocrystals in the Blue Region

Abstract

We report blue emission, along with the characteristic green emission, in CsPbBr3 nanocrystals (NCs) due to the doping of Eu2+ ions. The doping of Eu2+ was confirmed using TEM-EDAX, FTIR, and XPS techniques. The undoped CsPbBr3 NCs show sharp green emission peaking at 515 nm (fwhm ∼24 nm). Whereas Eu2+:CsPbBr3 NCs show two emission peaks at 498 and 442 nm with fwhm ∼20 and ∼13 nm, respectively. A shift in the green emission of doped NCs is because of reduced average particle size from 19 to 7 nm. The additional emission peak at 442 nm is assigned due to the 4f6(7FJ)5d1 → 4f7 transition of Eu2+ ions. The intensities of blue and green emissions are both significantly influenced by changing the excitation wavelengths. The decay dynamics study suggests an energy transfer from CsPbBr3 to the Eu2+ ions. It is also inferred that Eu2+ doping improves the radiative channels. Further, the CIE coordinate analysis depicts virtuous luminous efficacy of the optical radiation and significant color purity (>85%) of the emission spectra under different excitations. These optical studies show that the Eu2+:CsPbBr3 NCs can be a potential candidate for multicolor LEDs, displays, and anticounterfeiting applications.