Article on "Eu2+: A suitable substituent for Pb2+ in CsPbX3 perovskite nanocrystals?" by Alam Firoz, Wegner K. David, Pouget Stephanie, Amidani Lucia, Kvashnina Kristina, Aldakov Dmitry, & Reiss Peter (2019)
Eu2+ is used to replace toxic Pb2+ in metal halide perovskite nanocrystals (NCs). The synthesis implies injection of cesium oleate into a solution of europium (ii) bromide at an experimentally determined optimum temperature of 130 °C and a reaction time of 60 sec. Structural analysis indicates the formation of spherical CsEuBr3 nanoparticles with a mean size of 43 ± 7 nm. Using EuI2 instead of EuBr2 leads to the formation of 18-nm CsI nanoparticles, while EuCl2 doesn't show any reaction with cesium oleate forming 80-nm EuCl2 nanoparticles. The obtained CsEuBr3 NCs exhibit bright blue emission at 413 nm (FWHM 30 nm) with a room temperature photoluminescence quantum yield of 39%. The emission originates from the Laporte-allowed 4f7–4f65d1 transition of Eu2+ and shows a PL decay time of 263 ns. The long-term stability of the optical properties is observed, making inorganic lead-free CsEuBr3 NCs promising deep blue emitters for optoelectronics.