Synthesis and characterization of cesium europium chloride bromide lead-free Perovskite nanocrystals

Abstract

Due to the high toxicity of lead, research on new lead-free perovskite semiconductor materials with suitable optical and electronic properties has been of great interest. For this reason, rare earth halide perovskites are a promising class of materials for this purpose. Here, cesium europium bromide chloride (CsEu(ClxBr1−x)3 ) perovskite nanocrystals (NCs) with Eu2+ in the B site were successfully synthesized by a hot colloidal injection method. Different proportions of the molar ratio Cs:Eu were proposed in order to enhance the optical properties to promote a deep blue emission. High resolution TEM (HRTEM) revealed that the resulting nanoparticles were spherical shaped with an average diameter of ~ 10 nm. The electronic absorption spectra show bands peaked around 380 nm. The photoluminescence (PL) spectra of NCs excited at 393 nm exhibit bands peaked at 453 nm, 590 nm, 615 nm, and 697 nm. These PL peaks coincide with the emission of Eu3+ and Eu2+, covering the entire emission spectrum. PL spectra shows that Eu2+ induces a slight broadening in the full width at half maximum (FWHM) when higher concentration ratio is used. Moreover, the PL results shows a change in the intensity of the 615 nm peak which implies that with further introduction of Eu2+ into the lattice, changes in radiative and non-radiative recombination are obtained. This work shows that the Europium based Lead-free perovskite nanocrystals are a promising candidate for optoelectronic devices.