Robust Hydrophobic and Hydrophilic Polymer Fibers Sensitized by Inorganic and Hybrid Lead Halide Perovskite Nanocrystal Emitters

Formation of Hydrogels Based on a Copolymer of N-Vinyl-2-pyrrolidone and Glycidyl Methacrylate in the Presence of the Reaction Product of 1,3-Dimethylmidazolium Dimethylphosphate and Elemental Sulfur

The aim of the study is to search for a reaction that provides the possibility of tandem "one-pot" formation of polymer networks during radical copolymerization of N-vinyl-2-pyrrolidone and glycidyl methacrylate. It was shown that the addition of recently synthesized 1,3-dimethylimidazolium (phosphonooxy-)oligosulfanide makes it possible to obtain a cross-linked copolymer in one stage as a result of radical copolymerization of N-vinyl-2-pyrrolidone and glycidyl methacrylate with a molar ratio of monomers less than 1.4. The structure of the copolymerization products of N-vinyl-2-pyrroldione and glycidyl methacrylate formed in the presence of 1,3-dimethylimidazolium (phosphonooxy-)oligosulfanide was characterized by ¹H NMR, FTIR and MALDI spectroscopy. ¹H NMR spectroscopy revealed an interaction under moderate heating between glycidyl methacrylate and 1,3-dimethylimidazolium (phosphonooxy-)oligosulfanide, accompanied by the formation of a mixture of unsaturated products of complex structure, presumably acting as crosslinking agents. It is shown that when the molar ratio of N-vinyl-2-pyrroldione/glycidyl methacrylate comonomers is 0.89, a densely crosslinked copolymer is formed, capable of limited swelling in water with a velocity constant of 5.06 × 10^-2 min^-1 and an equilibrium degree of swelling of about 227%.

Recent Advances in Synthesis, Properties, and Applications of Metal Halide Perovskite Nanocrystals/Polymer Nanocomposites

Metal halide perovskite nanocrystals (PNCs) have recently garnered tremendous research interest due to their unique optoelectronic properties and promising applications in photovoltaics and optoelectronics. Metal halide PNCs can be combined with polymers to create nanocomposites that carry an array of advantageous characteristics. The polymer matrix can bestow stability, stretchability, and solution-processability while the PNCs maintain their size-, shape- and composition-dependent optoelectronic properties. As such, these nanocomposites possess great promise for next-generation displays, lighting, sensing, biomedical technologies, and energy conversion. The recent advances in metal halide PNC/polymer nanocomposites are summarized here. First, a variety of synthetic strategies for crafting PNC/polymer nanocomposites are discussed. Second, their array of intriguing properties is examined. Third, the broad range of applications of PNC/polymer nanocomposites is highlighted, including light-emitting diodes (LEDs), lasers, and scintillators. Finally, an outlook on future research directions and challenges in this rapidly evolving field are presented.

Poly(catecholamine) coated CsPbBr3 perovskite microlasers: lasing in water and biofunctionalization

Lead halide perovskite (LHP) is a promising material for various optoelectronic applications. Surface coating on particles is a common strategy to improve their functionality and environmental stability, but LHP is not amenable to most coating chemistries because of its intrinsic weakness against polar solvents. Here, we describe a novel method of synthesizing LHP microlasers in a super-saturated polar solvent using sonochemistry and applying various functional coatings on individual microlasers in situ. We synthesize cesium lead bromine perovskite (CsPbBr3) microcrystals capped with organic poly-norepinephrine (pNE) layers. The catechol group of pNE coordinates to bromine-deficient lead atoms, forming a defect-passivating and diffusion-blocking shell. The pNE layer enhances the material lifetime of CsPbBr3 in water by 2,000-folds, enabling bright luminescence and lasing from single microcrystals in water. Furthermore, the pNE shell permits biofunctionalization with proteins, small molecules, and lipid bilayers. Luminescence from CsPbBr3 microcrystals is sustained in water over 1 hour and observed in live cells. The functionalization method may enable new applications of LHP laser particles in water-rich environments.

Recent Advances in Ligand Design and Engineering in Lead Halide Perovskite Nanocrystals

Lead halide perovskite (LHP) nanocrystals (NCs) have recently garnered enhanced development efforts from research disciplines owing to their superior optical and optoelectronic properties. These materials, however, are unlike conventional quantum dots, because they possess strong ionic character, labile ligand coverage, and overall stability issues. As a result, the system as a whole is highly dynamic and can be affected by slight changes of particle surface environment. Specifically, the surface ligand shell of LHP NCs has proven to play imperative roles throughout the lifetime of a LHP NC. Recent advances in engineering and understanding the roles of surface ligand shells from initial synthesis, through postsynthetic processing and device integration, finally to application performances of colloidal LHP NCs are covered here.

Recrystallization of CsPbBr3 Nanoparticles in Fluoropolymer Nonwoven Mats for Down- and Up-Conversion of Light

Inorganic halides perovskite CsPbX₃ (X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) nanoparticles are efficient light-conversion objects that have attracted significant attention due to their broadband tunability over the entire visible spectral range of 410–700 nm and high quantum yield of up to 95%. Here, we demonstrate a new method of recrystallization of CsPbBr₃ nanoparticles inside the electrospun fluoropolymer fibers. We have synthesized nonwoven tetrafluoroethylene mats embedding CsPbBr₃ nanoparticles using inexpensive commercial precursors and syringe electrospinning equipment. The fabricated nonwoven mat samples demonstrated both down-conversion of UV light to 506 nm and up-conversion of IR femtosecond laser radiation to 513 nm green photoluminescence characterized by narrow emission line-widths of 35 nm. Nanoparticle formation inside nonwoven fibers was confirmed by TEM imaging and water stability tests controlled by fluorimetry measurements. The combination of enhanced optical properties of CsPbBr₃ nanoparticles and mechanical stability and environmental robustness of highly deformable nonwoven fluoropolymer mats is appealing for flexible optoelectronic applications, while the industry-friendly fabrication method is attractive for commercial implementations.

Nano-Micro Dimensional Structures of Fiber-Shaped Luminous Halide Perovskite Composites for Photonic and Optoelectronic Applications

Perovskite nanomaterials have been revealed as highly luminescent structures regarding their dimensional confinement. In particular, their promising potential lies behind remarkable luminescent properties, including color tunability, high photoluminescence quantum yield, and the narrow emission band of halide perovskite (HP) nanostructures for optoelectronic and photonic applications such as lightning and displaying operations. However, HP nanomaterials possess such drawbacks, including oxygen, moisture, temperature, or UV lights, which limit their practical applications. Recently, HP-containing polymer composite fibers have gained much attention owing to the spatial distribution and alignment of HPs with high mechanical strength and ambient stability in addition to their remarkable optical properties comparable to that of nanocrystals. In this review, the fabrication methods for preparing nano-microdimensional HP composite fiber structures are described. Various advantages of the luminescent composite nanofibers are also described, followed by their applications for photonic and optoelectronic devices including sensors, polarizers, waveguides, lasers, light-down converters, light-emitting diode operations, etc. Finally, future directions and remaining challenges of HP-based nanofibers are presented.

Fluorescent electrospun PMMA microfiber mats with embedded NaYF4: Yb/Er upconverting nanoparticles

Functional upconverting nanoparticles (UCNPs) can offer new possibilities in fluorescent applications as they exhibit desired characteristic properties like large shift between the fluorescent emission signal and the infrared excitation wavelength, multi- and narrow-band absorption and emission in visible and near infrared - Vis/NIR, together with excellent photostability and low toxicity as opposed to semiconducting quantum dots. The upconversion luminescence emission or quenching characteristics of UCNPs can be altered upon exposure to physical or chemical environmental factors providing thus a functionality that can be utilized for sensing or imaging. Furthermore their functionalization with suitable indicator dyes or recognition elements can extend the range of luminescence response and ratiometric sensing to specific analytes. Synergistically, electrospun nano- and microfibers offering large surface area can enhance the functionality of UCNPs by retaining the fluorescence efficiency and improving the overall responsivity due to dramatically increased surface. For the optimization of this hybrid material system the controllable incorporation of UCNPs is required especially at increased concentration conditions needed for high brightness. Herein, we report the fabrication, morphological and optical characterization of electrospun polymer-based nanocomposite fibers, consisting of poly(methyl methacrylate) (PMMA) and upconverting lanthanide doped nanoparticles of the type NaYF₄ : 20% Yb³⁺/2% Er³⁺ @ NaYF₄. Morphological studies regarding the uniformity and aggregation effects of the UCNP inclusion within the fibers have been implemented followed by upconversion emission characterization by pulsed near-infrared excitation. The study and optimization of such nanocomposite fibrous systems could provide useful insights for the development of efficient upconverting electrospun fiber mats for a number of imaging and sensing applications.