Stable and Low-Threshold Amplified Spontaneous Emission in Quasi-2D Perovskite Films with Mixed Ruddlesden-Popper and Dion-Jacobson Phase

Dion-Jacobson (DJ) phase halide perovskites have garnered significant attention in photoluminescence applications due to their excellent stability compared to three-dimensional (3D) perovskites. However, in solution-processed DJ-phase perovskite films, the complex crystallization process and the formation of multi-dispersed quantum well structures significantly impact the optoelectronic properties of the DJ-phase perovskite. This work presents a quasi-two-dimensional (quasi-2D) mixed-phase perovskite (MPP) film by introducing Ruddlesden-Popper (RP)-type aromatic ammonium cations into the DJ-phase precursor. The resulting MPP0.2 film, with the chemical formula (PEA2)0.2HDA0.8FA7Pb8Br25 (where HDA = hexamethylenediammonium and PEA = phenylethylammonium), exhibits improved morphology, a more uniform distribution of n phase components, higher crystallinity, and enhanced hydrophobicity compared to the neat DJ-phase films. Notably, the amplified spontaneous emission (ASE) threshold of the quasi-2D MPP0.2 film decreased from 120 to 60 mu J/cm2. This research shows that quasi-2D MPP films have great potential as waveguide materials for stable, low-threshold ASE.