Bright Blue Light-Emitting Doped Cesium Bromide Nanocrystals: Alternatives of Lead-Free Perovskite Nanocrystals for White LEDs

Lead-based perovskite nanocrystals (NCs) are promising candidates for use in lighting and display applications; however, the toxicity of lead is one critical issue that needs to be solved for its commercialization. Consequently, less toxic tin and bismuth-based perovskite NCs have been developed, but these materials exhibit low photoluminescence quantum yields (PLQYs) and large full width at half maximum (FWHM) values. Due to their similarity in size for Eu2+ and Pb2+, the more environmental-friendly europium shows the potential to replace lead. Herein, the synthesis of Eu2+ doped CsBr NCs with an average size of 51.5 nm via a facile hot-injection method is reported. The prepared CsBr:Eu2+ NCs exhibit an emission peak at 440 nm with an FWHM of 31 nm and PLQY up to 32.8%, which is persistent for at least 60 d. Moreover, the size and FWHM of CsBr:Eu2+ NCs can be tuned to 18.9 and 29 nm, respectively, by co-doping of Ca2+ ions into the NCs. It is also demonstrated that the prepared CsBr:Eu2+ NCs can be employed as efficient color conversion materials for fabricating white light-emitting diodes.