Controlled Growth of Highly Oriented Perovskite Crystals in Polymer Solutions via Selective Solvent Vapor Diffusion.

Organic-inorganic hybrid perovskites have garnered significant attention in optoelectronics owing to their outstanding tunable optical characteristics. Controlled growth of perovskite nanocrystals from solutions is key for controlling the emission intensity and photoluminescence lifetime of perovskites. In particular, most studies have focused on controlling the crystallization of perovskite through chemical treatment using chelating ligands or physical treatment via antisolvent diffusion, and there exists a trade-off between the photoluminescence intensity and lifetime of perovskites. Herein, a selective solvent vapor-assisted crystallization with the aid of a functional polymer, which nanoscale perovskite crystals are grown andante from precursor solution, is presented for tuning the crystallization and optical properties of a common halide perovskite, methylammonium lead bromide (MAPbBr3 ). The proposed method here produces perovskite nanocrystals in the range of 200-300 nm. The spin-coated thin film formed from the perovskite solution exhibits strong green photoluminescence with a long lifetime. The effects of the functional group and polymer dosage on the crystallization of MAPbBr3 are systematically investigated, and the crystallization mechanism is explained based on a modified LaMer model. This study provides an advanced solution process for precisely controlling perovskite crystallization to enhance their optical properties for next-generation optoelectronic devices.

Relationship between exhaled nitric oxide and atopy in Asian young adults.

OBJECTIVES: The relationship between exhaled nitric oxide and atopy is controversial. The aim of this study was to determine the relationship between exhaled nitric oxide (FE(NO)) and atopy in Asian young adults. METHODOLOGY: Subjects were assessed by: (i) the International Study of Asthma and Allergies in Childhood questionnaire to differentiate asthmatic from nonasthmatic and rhinitis from non-rhinitis subjects; (ii) skin prick testing to 10 allergens; and (iii) FE(NO) measurements performed online at a flow rate of 50 mL/s. RESULTS: Complete results were available for 84 subjects. FE(NO) values were highest in atopic asthmatics (n = 34; median FE(NO), 59.8 p.p.b.; interquartile range, 30.4-85.5 p.p.b), followed by atopic nonasthmatics (n = 34; median, 38.4 p.p.b.; range, 16.7-49.3 p.p.b), nonatopic asthmatics (n = 5; median, 19.1 p.p.b.; range, 17.9-33.4 p.p.b), and lowest in nonatopic nonasthmatics (n = 11; median, 15.7 p.p.b.; range, 11.5-21.7 p.p.b). FE(NO) values were significantly higher in atopic (n = 68; median, 44.7 p.p.b.; range, 27.3-75.2 p.p.b) compared to nonatopic subjects (n = 16; median, 17.0 p.p.b.; range, 11.7-23.8 p.p.b.; P < 0.0001), regardless of asthma and rhinitis status. FE(NO) levels correlated with the severity of atopy (wheal size) for both asthmatic (r = 0.44, P = 0.005) and nonasthmatic subjects (r = 0.48, P = 0.001). There was no significant difference in FE(NO) levels between nonatopic asthmatics and nonatopic nonasthmatic subjects (P = 0.25). CONCLUSIONS: Increased FE(NO) levels are more reflective of atopy rather than asthma, and increased nitric oxide production may be predominantly a feature of atopy in asthmatics.