Two-Step Crystallization for Low-Oxidation Tin-Based Perovskite Light-Emitting Diodes.

Metal halide perovskites attract significant attention because of their excellent optoelectronic and semiconducting properties. However, there are environmental concerns related to the toxicity of the lead metal that is mainly used in these perovskites. PEA2SnI4 perovskite is a potential candidate for lead-free perovskites because of its pure red emission. Although, undesired Sn4+ oxidation results in the deterioration of PEA2SnI4 perovskite. We demonstrate the two-step crystallization of PEA2SnI4 through the (i) reprecipitation and (ii) recrystallization processes. A film prepared using this method exhibits narrowed emission, with a full width at half-maximum from 30.0 to 26.1 nm, because of its homogeneous emission. Moreover, the Sn4+ content of two-step-crystallized PEA2SnI4 films is five times lower than that of a control film. Diffusion-ordered spectroscopy analysis indicates that the two-step precursor exhibits a smaller hydrodynamic radius crystal seed, which enhances crystallization during spin coating. The resulting two-step crystallized PEA2SnI4-based light-emitting diode (LED) exhibits a maximum external quantum efficiency (EQE) of 0.4% with an average of 0.2%, which is two times greater than that of the control device. This two-step approach may be generalized to synthesize other lead-free materials.

Optical property control of π-electronic systems bearing Lewis pairs by ion coordination.

π-Electronic systems bearing Lewis pairs were synthesized and their optical responses to added ions were investigated. The tuning of the optical properties was demonstrated by the addition of various ion pairs, and these behaviours were elucidated by theoretical calculations.

Fluorescence color change of aggregation-induced emission of 4-[bis(4-methylphenyl)amino]benzaldehyde.

Together we shine: Fluorescence color change of 4-[bis(4-methylphenyl)amino]benzaldehyde (BMABA) could be induced by vigorous stirring and heating of the suspension. This is attributed to a morphological change of the particles from an amorphous state to a crystalline state; therefore, BMABA is identified as a new aggregation-induced emission material.

Short-term effects of external and internal biliary drainage on liver and cellular immunity in experimental obstructive jaundice.

BACKGROUND/PURPOSE: The effects of preoperative biliary drainage for obstructive jaundiced patients are controversial. Although experimental studies have proven the benefit of internal biliary drainage (ID) over external biliary drainage (ED), ID has several clinical problems, such as clogging or tube replacement. The aim of this study was to determine whether there were any differences in T-cell function, liver function, and histology, between rats in ID and ED groups in short-term experiments. METHODS: Following bile duct ligation (BDL) for 14 days, rats in the ED and ID groups had 7 days of ED and 7 days of ID, respectively. Normal rats were used as negative controls (control group). For positive controls, we used a group with BDL and no drainage (BDL group). Serum bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) were measured, splenic T-cell proliferation was assayed to check cellular immunity, and liver histology was examined. RESULTS: Recovery of bilirubin and ALT was similar in the ED and ID groups. Recovery of AST was worse in the ID group than in the ED group, but the difference was not statistically significant. Levels of ALP in the BDL and ID groups were significantly higher than those in the control and ED groups. Rats in the BDL group showed a significant decrease in T-cell function compared to the control group. The ED group showed better recovery of T-cell function than the ID group in the 7 days after relief of obstructive jaundice. The livers in the ID group demonstrated histologically moderate interface hepatitis with periportal inflammation and lymphocyte infiltration, which strongly suggested incomplete tube obstruction, but those in the ED group showed minimal change. CONCLUSIONS: ED is superior to ID concerning the recovery of cellular immunity and liver inflammation in the short-term after relief from biliary obstruction in this model. As the patency of the tube is well maintained in ED compared to ID, patency of the tube is essential to obtain good recovery of cellular immunity, irrespective of the drainage method.