A simple and versatile in situ fabrication of MAPbX3 nanocrystal‐embedded polymer composite films is developed by controlling the crystallization process from precursor solutions. The composite films ...exhibit enhanced photoluminescence properties, improved stability, and excellent piezoelectric and mechanical properties. Applications of these composite films as color converters in liquid‐crystal‐display backlights are demonstrated, showing bright potential in display technology.
Waveplates are widely used in photonics to control the polarization of light1,2. Often, they are fabricated from birefringent crystals that have different refractive indices along and normal to the ...crystal axis. Similar optical components are found in the natural world, including the eyes of mantis shrimp3,4 and the iridescence of giant clams5, fish6 and plants7. Optical retardation in biology relies on sophisticated self-assembly, whereas man-made systems comprise multiple-layered materials8–11. Here we report a discovery that bridges these two design principles. We observe wideband achromatic retardation in the visible and near-infrared (532–800 nm) regions for Cs4PbBr6 perovskite crystals embedded with CsPbBr3 nanocrystals. We explain our observations as matched dispersions of the refractive indices of the ordinary and extraordinary rays caused by the ordered embedding of the nanocrystals in the host. The wideband performance and ease of fabrication of these perovskite materials are attractive for future applications.Perovskite crystals of Cs4PbBr6 embedded with CsPbBr3 nanocrystals are shown to act as wideband, achromatic waveplates in the visible and near-infrared regions.
Since the emergence of the concept of chemical topology, interlocked molecular assemblies have graduated from academic curiosities and poorly defined species to become synthetic realities. ...Coordination-directed synthesis provides powerful, diverse, and increasingly sophisticated protocols for accessing interlocked molecules. Originally, metal ions were employed solely as templates to gather and position building blocks in entwined or threaded arrangements. Recently, metal centers have increasingly featured within the backbones of the integral structural elements, which in turn use noncovalent interactions to self-assemble into intricate topologies. By outlining ingenious recent examples as well as seminal classic cases, this Review focuses on the role of metal–ligand paradigms in assembling molecular links. In addition, the ever-evolving approaches to efficient assembly, the structural features of the resulting architectures, and their prospects for the future are also presented.
Abstract
K‐metal batteries have become one of the promising candidates for the large‐scale energy storage owing to the virtually inexhaustible and widely potassium resources. The uneven K
+
...deposition and dendrite growth on the anode causes the batteries prematurely failure to limit the further application. An integrated K‐metal anode is constructed by cold‐rolling K metal with a potassiphilic porous interconnected mediator. Based on the experimental results and theoretical calculations, it demonstrates that the potassiphilic porous interconnected mediator boosts the mass transportation of K‐metal anode by the K affinity enhancement, which decreases the concentration polarization and makes a dendrite‐free K‐metal anode interface. The interconnected porous structure mitigates the internal stress generated during repetitive deposition/stripping, enabling minimized the generation of electrode collapse. As a result, a durable K‐metal anode with excellent cycling ability of exceed 1, 000 h at 1 mA cm
−2
/1 mAh cm
−2
and lower polarization voltage in carbonate electrolyte is obtained. This proposed integrated anode with fast K
+
kinetics fabricated by a repeated cold rolling and folding process provides a new avenue for constructing a high‐performance dendrites‐free anode for K‐metal batteries.
As the cost-effective and nontoxic alternative for hydrogen evolution reaction (HER), Co9S8 has attracted much attention. This paper explores the regulation of Zn doping impacted the unique ...nanostructure and electrocatalytic performance on Co9S8. Herein, utilizing copper foam (CF) as substrate, a series of different nanostructure of (Zn-)Co9S8@CF has been synthesized by accurately varying the ratio of Zn2+ to Co2+. Compared with aggregated pure Co9S8 and other different ratios contrast samples, Zn–Co9S8@CF-(1-1) with a zinc to cobalt ratio of 1 possesses highly dispersity which can be attributed to the novel nano-neuron network structure. The electrochemical measurements for HER demonstrate that Zn–Co9S8@CF-(1-1) not only reveals superior activity with small overpotentials to achieve a current density of 10 mA cm−2 in acidic (278 mV) and alkaline (273 mV) media, but also exhibits long-time durability in the solution with a wide range of pH. The excellent performance of Zn–Co9S8@CF-(1-1) can be attributed to the unique reticular structure which can facilitate exposure of numerous active sites and favorable long-term stability. The substrate of three-dimensional CF can provide the remarkable conductivity. This work provides a precise and effective approach to regulate three-dimensional nanostructure of Zn-doped electrocatalysts for HER.
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•Zn–Co9S8 on copper foam (CF) with a nano-neuron network structure is synthesized.•The ratios of Zn2+ to Co2+ can affect the structure of Zn–Co9S8@CF.•Zn–Co9S8@CF exhibits excellent activity and long-time durability with a wide range of pH.•Zn doping is a promising method for construct the novel structure of electrocatalysts.
The comparison between organic–inorganic CH3NH3PbBr3 quantum dots and all inorganic halide perovskite CsPbBr3 quantum dots allows to understand the structural difference and corresponding optical ...properties. Using Z‐scan measurements, it is revealed that colloidal CH3NH3PbBr3 exhibits enhanced two‐photon absorption properties compared to those of CsPbBr3 quantum dots due to their structural difference.
The synthesis of open‐shell polycyclic hydrocarbons with large diradical characters is challenging because of their high reactivities. Herein, two diindeno‐fused corannulene regioisomers DIC‐1 and ...DIC‐2, curved fragments of fullerene C104, were synthesized that exhibit open‐shell singlet ground states. The incorporation of the curved and non‐alternant corannulene moiety within diradical systems leads to significant diradical characters as high as 0.98 for DIC‐1 and 0.89 for DIC‐2. Such high diradical characters can presumably be ascribed to the re‐aromatization of the corannulene π system. Although the DIC compounds have large diradical characters, they display excellent stability under ambient conditions. The half‐lives are 37 days for DIC‐1 and 6.6 days for DIC‐2 in solution. This work offers a new design strategy towards diradicaloids with large diradical characters yet maintain high stability.
Above the curve: Two curved diindeno‐fused corannulene regioisomers were synthesized that exhibit open‐shell singlet ground states. These corannulene‐based diradicaloids have significant diradical characters yet maintain high stability.
Background The mortality of humans due to rabies in China has been declining in recent years, but it is still a significant public health problem. According to the global framework, China strives to ...achieve the goal of eliminating human rabies before 2030. Methods We reviewed the epidemiology of human deaths from rabies in mainland China from 2004 to 2018. We identified high risk regions, age and occupational groups, and used a continuous deterministic susceptibility-exposure-infection-recovery (SEIR) model with periodic transmission rate to explore seasonal rabies prevalence in different human populations. The SEIR model was used to simulate the data of human deaths from rabies reported by the Chinese Center for Disease Control and Prevention (China CDC). We calculated the relative transmission intensity of rabies from canines to different human groups, and they provided a reliable epidemiological basis for further control and prevention of human rabies. Results Results showed that human deaths from rabies exhibited regional differences and seasonal characteristics in mainland China. The annual human death from rabies in different regions, age groups and occupational groups decreased steadily across time. Nevertheless, the decreasing rates and the calculated R.sub.0 s of canines of various human groups were different. The transmission intensity of rabies from canines to human populations was the highest in the central regions of China, in people over 45 years old, and in farmers. Conclusions Although the annual cases of human deaths from rabies have decreased steadily since 2007, the proportion of human deaths from rabies varies with region, age, gender, and occupation. Further enhancement of public awareness and immunization status in high-risk population groups and blocking the transmission routes of rabies from canines to humans are necessary. The concept of One Health should be abided and human, animal, and environmental health should be considered simultaneously to achieve the goal of eradicating human rabies before 2030.
We propose and demonstrate an improved quantum illumination protocol based on the time correlation of twin photons, for the high signal-to-noise ratio (SNR) of target detection and signal ...reconstruction in the strong noise environment. The Hong-Ou-Mandel (HOM) interferometer is applied after the spontaneous parametric down-conversion (SPDC) process to construct a probing twin-beam in which the photon times are precisely aligned between the beams. At the radar receiver, we put forward a single real-time coincidence counting (SRCC) method on a series of time slices to reconstruct the probe signals of pulse radar and calculate the SNR advantages against the conventional pulse radar, as well as the quantum illumination (QI) protocol. Our main achievements in this research are the realization of real-time detection of quantum information while acquiring a higher SNR than QI and classical illumination (CI) protocols, as well as its demonstration of strong robustness to noise and losses, which also proposes what we believe to be a novel way for quantum target detection.
Polarized light is very necessary to achieve functional optical systems for display, imaging, and information storage. Luminescent materials with polarized emission are of great interest to achieve ...polarized light. Here, strong polarized photoluminescence from stretched perovskite‐nanocrystal‐embedded polymer composite films is reported by combining an in situ fabrication process with controllable mechanical stretching. The material characterizations show that perovskite quantum dots (QDs) in stretched composite films are oriented aligned into wires along the stretching direction. The optical measurements illustrate that the stretched composite films exhibit not only isotropic absorption but also polarized photoluminescence emission. This feature can be explained with their unique structure of “QD‐aligned wires”. The achieved polarization ratio is consistent with the calculated results by considering the dielectric confinement of optical electric field and exciton–exciton interactions. In addition, the optimized stretched composite films show strong photoluminescence emission with a polarization ratio of up to 0.33 and a quantum yield of 80%. The use of these composite films in liquid crystal display backlights has potential to increase the light transmittance of polarizers from 50% (without considering the optical loss) to 65%, which is of great significance to improve the energy efficiency.
Perovskite nanocrystal‐embedded polymer composite films, which exhibit not only isotropic absorption but also strong polarized photoluminescence (PL) are fabricated by combining an in situ method and controllable mechanical stretching. The stretched composite films contain “quantum‐dot‐aligned wires” along the stretching direction in the polymeric matrix. The polarized PL can be explained by the dielectric confinement effect and exciton–exciton interactions.
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