ABSTRACT
Perovskite nanocrystals (PNCs) have attracted substantial attention due to their inspiring intrinsic merits such as low cost, high performance, and solution processability, but when it comes to the usage of blends of different colored PNCs with the purpose of covering the broadband spectrum field, the high degree of instability remains a major bottleneck. Herein, we report a family of dendritic ammonium ligands that act as stiff shell-encapsulating PNCs for improving their stability and suppressing ion permeability in mixed colloidal PNC solutions. The as-synthesized ligand-encapsulated PNCs notably achieve near-unity photoluminescence quantum yields (PLQYs) and strongly resist the unwanted ion exchange reaction under aggressive anion source attack. To fabricate self-powered white-emitting glass, the stabilized mixed colored PNCs were embedded into the laminated glass, which simultaneously acted as absorbers-emitters for luminescent solar concentrators (LSCs) and emitters for white light-emitting glass.
ABSTRACT
Optical image encryption technology, in which the emission on/off can be controlled by using specially appointed wavelengths, is useful in information storage and protection. Herein, we report a family of sandwiched heterostructural nanosheets, consisting of three-layered (n = 3) perovskite (PSK) frameworks in center with two different polycyclic aromatic hydrocarbons [triphenylene (Tp) and pyrene (Py)] in periphery. Both heterostructural nanosheets (Tp-PSK and Py-PSK) exhibit blue emissions under UVA-I irradiation; however, different photoluminescent properties are observed under UVA-II. A bright emission of Tp-PSK is attributed to the fluorescence resonance energy transfer (FRET) from Tp-shield to PSK-core, whereas the observed photoquenching phenomenon in Py-PSK is due to the competitive absorption between Py-shield and PSK-core. We exploited the unique photophysical features (on/off emission) of the two nanosheets in a narrow UV window (320-340 nm) for optical image encrypting.
ABSTRACT
Lead-free all-inorganic halide materials with different Mn2+-based crystal structures (Cs3MnBr5 and CsMnBr3) were obtained using a convenient synthetic method. Cs3MnBr5 had a bright green emission (522 nm), with a unique single-exponential lifetime (τavg = 236 µs) and a high photoluminescence quantum yield (82 ± 5%). A red emission was observed in the case of the CsMnBr3 structure with a two-exponential fluorescence decay curve, and the lifetime was 1.418 µs (93%) and 18.328 µs (7%), respectively. By a judicious tuning of the synthetic conditions, a mixed phase of Cs3MnBr5/CsMnBr3 was also produced that emitted white light, covering almost the entire visible spectrum. White-light-emitting diodes (WLEDs) with color coordinates (0.4269, 0.4955), a color temperature of (3773 K), and a color rendering index (68) were then fabricated using the as-prepared powder of mixed phases of Cs3MnBr5/CsMnBr3 with a commercial UV LED chip (365 nm).
Subject(s)
Inorganic Chemicals , Manganese , Bromides , Calcium Compounds , OxidesABSTRACT
Chinese cooking fume is one of the sources of volatile organic compounds (VOCs) in the air. An innovative control technology combining photocatalytic degradation and ozone oxidation (UV/TiO2+O3) was developed to decompose VOCs in the cooking fume. Fiberglass filter (FGF) coated with TiO2 was prepared by an impregnation procedure. A continuous-flow reaction system was self-designed by combining photocatalysis with advanced ozone oxidation technique. By passing the simulated cooking fume through the FGF, the VOC decomposition efficiency in the cooking fume could be increased by about 10%. The decomposition efficiency of VOCs in the cooking fume increased and then decreased with the inlet VOC concentration. A maximum VOC decomposition efficiency of 64% was obtained at 100â¯ppm. Similar trend was observed for reaction temperature with the VOC decomposition efficiencies ranging from 64 to 68%. Moreover, inlet ozone concentration had a positive effect on the decomposition of VOCs in the cooking fume for inlet ozone≤1000â¯ppm and leveled off for inlet ozone>1000â¯ppm. 34% of VOC decomposition efficiency was achieved solely by ozone oxidation with or without near-UV irradiation. A maximum of 75% and 94% VOC decomposition efficiency could be achieved by O3+UV/TiO2 and UV/TiO2+O3 techniques, respectively. The maximum decomposition efficiencies of VOCs decreased to 79% for using UV/TiO2+O3 technique with adding water in the oil fume. Comparing the chromatographical species of VOCs in the oil fume before and after the decomposition of VOCs by using UV/TiO2+O3technique, we found that both TVOC and VOC species in the oil fume were effectively decomposed.
