Large-Area Transparent Antimony-Based Perovskite Glass for High-Resolution X-ray Imaging.

Nonlead low-dimensional halide perovskites attract considerable attention as X-ray scintillators. However, most scintillation screens exhibit pronounced light scattering, which detrimentally reduces the quality of X-ray imaging. Herein, we employed a simple and straightforward solvent-free melt-quenching method to fabricate a large-area zero-dimension (0D) antimony-based perovskite transparent medium, namely (C20H20P)2SbCl5 (C20H20P+ = ethyltriphenylphosphine). The transparency is due to the large steric hindrance of C20H20P+, which hinders the formation of crystals during the quenching process, thus forming a glass with low refractive index and uniform structure. This medium exhibits a high transmittance exceeding 80% in the range of 450-800 nm and shows a large Stokes shift of 245 nm, thereby minimizing light scattering, mitigating self-absorption, and enhancing the clarity of X-ray imaging. Moreover, it exhibits a high radioluminescence light yield of ∼12,535 photons MeV-1 and displays a high X-ray spatial resolution of 30 lp mm-1 owing to its high transparency. This study presents an alternative candidate for achieving high-quality X-ray detection and extends the applicability of transparent perovskite scintillators.

Response of sediment microbial communities to different levels of PAC contamination and exposure time.

Coagulants such as polyaluminium chloride (PAC) are widely used for removing phosphorus from eutrophic water, but its application for water treatment can potentially harm the environment. In this study, a four-timepoint exposure experiment was performed at week 1, 3, 7 and 10 to investigate how microbial communities in lake sediments respond to different concentrations of PAC (RS (raw lake water with nothing added), Low, Medium and High). The results showed that, while PAC can efficiently decrease the amount of C, N and P in lake water, the presence of residual aluminum and aluminum precipitates can greatly affect the microbial communities in lake sediments. In particular, different concentrations of PAC and exposure time affected the microbial diversity and structure of lake sediments, with changes being especially obvious at high concentration of PAC after 10 weeks of exposure. Moreover, the use of PAC significantly increased the relative abundances of Gammaproteobacteria and Competibacter, while reducing those of Thermodesulfovibrionia, Vicinamibacterales, and BSV26 in time- and concentration-dependent manners. Network analysis further showed strong correlations between differential bacterial species of PAC in high concentration at 10 weeks, which further suggested that PAC treatment changed the complex structure of microbiota in lake sediment. Finally, correlation analysis indicated a close connection between water parameters and differential species induced by PAC treatment. Overall, PAC contamination changed the microbial communities at different taxonomy levels and influenced the functional pathways to potentiate the P removal, and the results offered interesting insights into the use of PAC in water treatment and its impact on biogeochemical cycling. These results indicated that more attention need to be paid to the potential impact of chemical phosphorus removing reagents on the environment, including eutrophic water.

Facile synthesis of N-aryl phenothiazines and phenoxazines via Brønsted acid catalyzed C-H amination of arenes.

N-Aryl phenothiazines and phenoxazines are of significant importance in various disciplines throughout academia and industry. The conventional synthetic strategy for the construction of these structures centers on the transition-metal-catalyzed cross-coupling of aryl halides with phenothiazines or phenoxazines. Here we present an organocatalytic approach to access N-naphthyl phenothiazine and phenoxazine scaffolds through a straightforward C-H amination of arenes as enabled by an azo group. This reaction features operational simplicity, adequate substrate generality and excellent functional group compatibility. Notably, the efficiency of the catalyst could be perfectly preserved after 5 catalytic cycles.

Tetraphenylethylene-Arylamine Derivatives as Hole Transporting Materials for Perovskite Solar Cells.

A series of hole transporting materials (HTMs) with fused tetraphenylethylene cores (9,9'-bifluorenylidene and dibenzo[g,p]chrysene) as well as different substitution positions of arylamine side arms has been designed and synthesized. A reference HTM with a non-fused tetraphenylethylene core is also prepared for a comparative study. It is noted that fused tetraphenylethylene molecules show a bathochromic spectral shift, electronegative character, and lower reorganization energies than the non-fused ones. Furthermore, the molecules with side arms located on the meta-position on the tetraphenylethylene core in terms of a double bond exhibit a deeper highest occupied molecular orbital level than those of the para-position-based ones whether tetraphenylethylene is fused or not. Moreover, the reorganization energies of fused meta-position-based HTMs are lower than those of para-position-based HTMs. Fused tetraphenylethylene HTMs own a better hole-extraction capability than the non-fused ones. When used in perovskite solar cells, all devices with fused tetraphenylethylene HTMs display better performance than those of the non-fused ones. The HTMs based on dibenzo[g,p]chrysene exhibit better performance than those of bifluorenylidene. Moreover, the devices with HTMs with side arms located on the meta-position on the tetraphenylethylene core display higher power conversion efficiency than those of the para-position-based ones. The results give some new insight and reference to develop ideal HTMs for perovskite solar cells.

Fused tetraphenylethylene-triphenylamine as an efficient hole transporting material in perovskite solar cells.

A fused tetraphenylethylene-based hole transporting material shows higher power conversion efficiency and better stability compared with its non-fused counterpart, and the former molecule even outperforms the conventional spiro-OMeTAD.