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 130C and a reaction time of 60s. Structural analysis indicates the formation of spherical CsEuBr3 nanoparticles with a mean size of 43nm. Using EuI2 instead of EuBr2 leads to the formation of 18nm CsI nanoparticles, while EuCl2 does not show any reaction with cesium oleate forming 80nm EuCl2 nanoparticles. The obtained CsEuBr3 NCs exhibit bright blue emission at 413nm (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 263ns. The long-term stability of the optical properties is observed, making inorganic lead-free CsEuBr3 NCs promising deep blue emitters for optoelectronics.
@article{arxiv.2010.07653,
title = {Eu$^{2+}$: a suitable substituent for Pb$^{2+}$ in CsPbX$_3$ perovskite nanocrystals?},
author = {Firoz Alam and K. David Wegner and Stephanie Pouget and Lucia Amidani and Kristina Kvashnina and Dmitry Aldakov and Peter Reiss},
journal= {arXiv preprint arXiv:2010.07653},
year = {2020}
}