Lasing in Two-Dimensional Tin Perovskites.

Two-dimensional (2D) perovskites have been proposed as materials capable of improving the stability and surpassing the radiative recombination efficiency of three-dimensional perovskites. However, their luminescent properties have often fallen short of what has been expected. In fact, despite attracting considerable attention for photonic applications during the last two decades, lasing in 2D perovskites remains unclear and under debate. Here, we were able to improve the optical gain properties of 2D perovskite and achieve optically pumped lasing. We show that the choice of the spacer cation affects the defectivity and photostability of the perovskite, which in turn influences its optical gain. Based on our synthetic strategy, we obtain PEA2SnI4 films with high crystallinity and favorable optical properties, resulting in amplified spontaneous emission (ASE) with a low threshold (30 µJ/cm2), a high optical gain above 4000 cm-1 at 77 K, and ASE operation up to room temperature.

Layered Perovskite Doping with Eu3+ and ß-diketonate Eu3+ 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+2 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 NMA2PbBr4 layered perovskites with Eu3+ and Eu3+ tetrakis ß-diketonate complex. By exploiting the antenna effect of the naphthalene-based functional cation (NMA = 1-naphtylmethylammonium), direct sensitization of Eu3+ 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 Eu3+ in the form of tetrakis ß-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.