Cesium lead mixed-halide perovskite thin films were fabricated by using a chemical vapor anion exchange procedure. Optical and structural properties of the materials obtained were studied comprehensively.

Inorganic cesium lead halide perovskite nanowires, generating laser emission in the broad spectral range at room temperature and low threshold, have become powerful tools for the cutting-edge applications in the optoelectronics and nanophotonics. However, to achieve high-quality nanowires with the outstanding optical properties, it was necessary to employ long-lasting and costly methods of their synthesis, as well as postsynthetic separation and transfer procedures that are not convenient for large-scale production. Here we report a novel approach to fabricate high-quality CsPbBr3 nanolasers obtained by rapid precipitation from dimethyl sulfoxide solution sprayed onto hydrophobic substrates at ambient conditions. The synthesis technique allows producing the well-separated nanowires with a broad size distribution of 2–50 μm in 5–7 min, being the fastest method to the best of our knowledge. The formation of nanowires occurs via ligand-assisted reprecipitation triggered by intermolecular proton transfer from (CH3)2­CHOH to H2O in the presence of a minor amount of water. The XRD patterns confirm an orthorhombic crystal structure of the as-grown CsPbBr3 single nanowires. Scanning electron microscopy images reveal their regular shape and truncated pyramidal end facets, while high-resolution transmission electron microscopy ones demonstrate their single-crystal structure. The lifetime of excitonic emission of the nanowires is found to be 7 ns, when the samples are excited with energy below the lasing threshold, manifesting the low concentration of defect states. The measured nanolasers of different lengths exhibit pronounced stimulated emission above 13 μJ cm–2 excitation threshold with quality factor Q = 1017–6166. Their high performance is assumed to be related to their monocrystalline structure, low concentration of defect states, and improved end facet reflectivity.

Halide perovskite nanomaterials are widely used in optoelectronics and photonics due to their outstanding luminescent properties, whereas their strong multiphoton absorption makes them prospective for bioimaging. Nonetheless, instability of perovskites in aqueous solutions is an important limitation that prevents their application in biology and medicine. Here, we demonstrate fluorescence and upconversion imaging in living cells by employing CsPbBr 3 nanocrystals (NCs) that show an improved waterresistance (at least for 24 h) after their coating as individual particles with various silicabased shells. The obtained phTEOS-TMOS@CsPbBr 3 NCs possess high quality, which we confirm with high-resolution transmission and scanning transmission electron microscopy, X-ray diffraction analysis, Fourier-transform infrared and energy-dispersive X-ray spectroscopies, as well as with fluorescence optical microscopy. The developed platform can make the halide perovskite NCs suitable for various bioimaging applications.

Chemically synthesized inorganic lead halide perovskite lasers based on nanostructures, generating coherent light at room temperature, and having a low threshold, have become powerful tools for various photonic applications. However, to fabricate high-quality nanostructures on a substrate, it is crucial to provide certain surface parameters and precisely keep synthesis conditions. Here, we report a novel approach for the one-step fabrication of high-quality CsPbBr3 nanolasers in the form of suspension obtained by rapid precipitation in a microfluidic chip. The synthesis technique allows us to control the nanostructure morphology (size and shape) depending on the chip configuration and reagents’ flow rates in microchannels. One of the main advantages of the proposed approach is the ability to deposit the obtained perovskite nanolasers on an arbitrary surface. This paves the way for creating various nanophotonic designs with high throughput and excellent control of geometrical parameters.