In the search for novel photonic materials, the recent focus on metal halide perovskites (MHPs) has revealed their promise to become groundbreaking low‐threshold, tunable coherent light sources. An accurate determination of the optical gain coefficient (g) would help to screen for materials and design highly efficient perovskite lasers. Nevertheless, contradictory numbers are continuously reported, making this figure of merit unreliable. To address this issue, the present work outlines a meticulous analysis to retrieve g of MAPbI3, based on the variable stripe‐length (VSL) method. This method is often preferred due to its apparent simplicity; however, one can arrive at incorrect conclusions without the adequate considerations. Therefore, here the experimental implementation and numerical treatment of the data are thoroughly discussed to establish a robust VSL methodology. The obtained power dependence and spectral gain evolution point to the role of electron–hole bimolecular recombination dictating the stimulated emission properties of MAPbI3, with a behavior resembling that of bulk GaAs. Beyond providing further knowledge on the procedure to carry out pertinent VSL measurements, this work also outlines a meticulous methodology to study the underlying photophysical gain properties of MHPs and consequently, to obtain a deeper understanding of the lasing properties of these complex materials.
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 NMA 2 PbBr 4 layered perovskites with Eu 3+ and Eu 3+ tetrakis β-diketonate complex. By exploiting the antenna effect of the naphthalene-based functional cation (NMA = 1-naphtylmethylammonium), direct sensitization of Eu 3+ 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 3+ 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.
perovskites have been proposed as materials capable of improving the stability and surpassing the radiative recombination efficiency of threedimensional 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 PEA 2 SnI 4 films with high crystallinity and favorable optical properties, resulting in amplified spontaneous emission (ASE) with a low threshold (30 μJ/cm 2 ), a high optical gain above 4000 cm −1 at 77 K, and ASE operation up to room temperature.
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