Halide perovskites are a promising optical gain medium with high tunability and simple solution synthesis. In this study, two gain regimes, namely, amplified spontaneous emission and random lasing, are demonstrated in the same MAPbBr3 halide perovskite single crystal. For this, photoluminescence is measured at a temperature of 4 K with pulsed femtosecond pumping by UV light with an 80 MHz repetition rate. Random lasing is observed in areas of the sample where a random resonator is formed due to cracks and crystal imperfections. In more homogeneous regions of the sample, the dominant regime is amplified spontaneous emission. These two regimes are reliably distinguished by the line width, the mode structure, the growth of the intensity after the threshold, and the degree of polarization of the radiation. The spectral localization of the stimulated emission well below the bound exciton resonance raises a question concerning the origin of the emission in halide perovskite lasers.

2D halide perovskite‐like semiconductors are attractive materials for various optoelectronic applications, from photovoltaics to lasing. To date, the most studied families of such low‐dimensional halide perovskite‐like compounds are Ruddlesden–Popper, Dion–Jacobson, and other phases that can be derived from 3D halide perovskites by slicing along different crystallographic directions, which leads to the spatially isotropic corner‐sharing connectivity type of metal‐halide octahedra in the 2D layer plane. In this work, a new family of hybrid organic–inorganic 2D lead halides is introduced, by reporting the first example of the hybrid organic–inorganic post‐perovskite 3‐cyanopyridinium lead tribromide (3cp)PbBr3. The post‐perovskite structure has unique octahedra connectivity type in the layer plane: a typical “perovskite‐like” corner‐sharing connectivity pattern in one direction, and the rare edge‐sharing connectivity pattern in the other. Such connectivity leads to significant anisotropy in the material properties within the inorganic layer plane. Moreover, the dense organic cation packing results in the formation of 1D fully organic bands in the electronic structure, offering the prospects of the involvement of the organic subsystem into material's optoelectronic properties. The (3cp)PbBr3 clearly shows the 2D quantum size effect with a bandgap around 3.2 eV and typical broadband self‐trapped excitonic photoluminescence at temperatures below 200 K.

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Halide perovskites are a family of materials with a high potential for realization of microlasers, due to their high luminescence quantum yield and broad spectral tunability. We demonstrate a single-step process for lasing microdisk fabrication from a thin film of methylammonium lead iodide (MAPbI3) perovskite through its patterning with tightly focused femtosecond (fs) laser pulses. By using kHz-scale pulse bursts destructive overheating of the material was suppressed. Perovskite microdisks fabricated under such optimized conditions showed stable lasing upon pumping with fs-laser both at lower (50 kHz) and higher (80 MHz) repetition rates and operation temperatures of 300 K and 6 K, respectively.