Layered Perovskite Doping with Eu and β-diketonate Eu Complex.

Metal halide perovskites are attracting great interest for the fabrication of light-emitting devices encompassing light-emitting diodes, lasers, and scintillators. As the field develops, perovskite doping emerges as a promising way to enrich the material functionalities and enhance the luminescence yield and tunability. While Mn addition has been well explored, doping with lanthanides has received less attention, even though their intense and line-like luminescence is interesting for a wide range of applications. In this work, we study the doping of NMAPbBr layered perovskites with Eu and Eu tetrakis β-diketonate complex. By exploiting the antenna effect of the naphthalene-based functional cation (NMA = 1-naphtylmethylammonium), direct sensitization of Eu is obtained; nevertheless, it is not very efficient due to the non-optimal energy level alignment with the resonance acceptor level of the lanthanide. Protection of Eu in the form of tetrakis β-diketonate complex grants a more ideal coordination geometry and energetic landscape for the energy transfer to europium in the perovskite matrix, allowing for a nearly 30-fold improvement in luminescence yield. This work sets the basis for new synthetic strategies for the design of functional perovskite/lanthanide host-guest systems with improved luminescence properties.