Ultra-stable CsPbBr3 Perovskite Nanosheets for X-Ray Imaging Screen

Wet chemistry methods,including hot-injection and precipitation methods,have emerged as major synthetic routes for high-quality perovskite nanocrystals in backlit display and scintillation applications.However,low chemical yield hinders their upscale production for practical use.Meanwhile,the labile nature of halide-based perovskite poses a major challenge for long-term storage of perovskite nanocrystals.Herein,we report a green synthesis at room temperature for gram-scale production of CsPbBr3 nanosheets with minimum use of solvent,saving over 95% of the solvent for the unity mass nanocrystal production.The perovskite colloid exhibits record stability upon long-term storage for up to 8 months,preserving a photoluminescence quantum yield of 63% in solid state.Importantly,the colloidal nanosheets show self-assembly behavior upon slow solidification,generating a crack-free thin film in a large area.The uniform film was then demonstrated as an efficient scintillation screen for X-ray imaging.Our findings bring a scalable tool for synthesis of high-quality perovskite nanocrystals,which may inspire the industrial optoelectronic application of large-area perovskite film.

SHRIMP zircon dating and LA-ICPMS Hf analysis of early Precambrian rocks from drill holes into the basement beneath the Central Hebei Basin,North China Craton

The Central Hebei Basin （CHB） is one of the largest sedimentary basins in the North China Craton, extending in a northeast-southwest direction with an area of 〉350 km2. We carried out SHRIMP zircon dating, Hf-in-zircon isotopic analysis and a whole-rock geochemical study on igneous and metasedi- mentary rocks recovered from drill holes that penetrated into the basement of the CHB, Two samples of gneissic granodiorite （XG1-1） and gneissic quartz diorite 048-1） have magmatic ages of 2500 and 2496 Ma, respectively. Their zircons also record metamorphic ages of 2.41-2.51 and ～2.5 Ga, respec- tively. Compared with the gneissic granodiorite, the gneissic quartz diorite has higher REE contents and lower Eu/Eu＊ and （La/Yb）n values. Two metasedimentary samples （MG1, H5） mainly contain ～2,5 Ga detrital zircons as well as late Paleoproterozoic metamorphic grains. The zircons of different origins have eHf （2.5 Ga） values and Hf crustal model ages ranging from 0 to 5 and 2.7 to 2,9 Ga, respectively, Therefore, ～2.5 Ga magmatic and Paleoproterozoic metasedimentary rocks and late Neoarchean to early Paleoproterozoic and late Paleoproterozoic tectono-thermal events have been identified in the basement beneath the CHB. Based on regional comparisons, we conclude that the early Precambrian basement beneath the CHB is part of the North China Craton.

A universal hydrochloric acid-assistant powder-to-powder strategy for quick and mass preparation of lead-free perovskite microcrystals

Lead-free halide perovskite materials possess low toxicity,broadband luminescence and robust stability compared with conventional lead-based perovskites,thus holding great promise for eyes-friendly white light LEDs.However,the traditionally used preparation methods with a long period and limited product yield have curtailed the commercialization of these materials.Here we introduce a universal hydrochloric acid-assistant powder-to-powder strategy which can accomplish the goals of thermal-,pressure-free,eco-friendliness,short time,low cost and high product yield,simultaneously.The obtained Cs_(2)Na_(0.9)Ag_(0.1)In_(0.95)Bi_(0.05)Cl_(6)microcrystals exhibit bright self-trapped excitons emission with quantum yield of(98.3±3.8)%,which could retain(90.5±1.3)%and(96.8±0.8)%after continuous heating or ultraviolet-irradiation for 1000 h,respectively.The phosphor converted-LED exhibited near-unity conversion efficiency from ultraviolet chip to self-trapped excitons emission at~200 mA.Various ions doping(such as Cs_(2)Na_(0.9)Ag_(0.1)InCl_(6):Ln^(3+))and other derived lead-free perovskite materials(such as Cs_(2)ZrCl_(6)and Cs_(4)MnBi_(2)Cl_(12))with high luminous performance are all realized by our proposed strategy,which has shown excellent availability towards commercialization.

Ultralong afterglow and unity quantum yield from a transparent CsCdCl_(3):Mn crystal

Transparent afterglow crystals are keenly desired for three-dimensional information storage.Herein,CsCdCl3 perovskite crystals were grown by a programmable cool-ing procedure in a hydrothermal reactor.The pristine crystal showed an abnormal optical behavior where the absorption increased by 2.3 folds at high temperature,leading to a fourfold boost of photoluminescence(PL)intensity.After Mn2+dop-ing,the PL quantum yield was improved to nearly unity.Importantly,the doped crystals exhibited an ultralong afterglow up to 12 h after ceasing UV excitation and a high transmittance up to 75%in the visible region.This work brought a new mem-ber to the library of transparent afterglow crystal,opening up many possibilities to advanced applications such as volumetric display and three-dimensional information encryption.

Personality Openness Predicts Driver Trust in Automated Driving

Maintaining an appropriate level of trust in automated driving(AD)is critical to safe driving.However,few studies have explored factors affecting trust in AD in general,and no study,as far as is known,has directly investigated whether driver personality influences driver trust in an AD system.The current study investigates the relation between driver personality and driver trust in AD,focusing on Level 2 AD.Participants were required to perform a period of AD in a driving simulator,during which their gaze and driving behavior were recorded,as well as their subjective trust scores after driving.In three distinct measures,a significant correlation between Openness and driver trust in the AD system is found:participants with higher Openness traits tend to have less trust in the AD system.No significant correlations between driver trust in AD and other personality traits are found.The findings suggest that driver personality has an impact on driver trust in AD.Theoretical and practical implications of this finding are discussed.

X-ray imager of 26-μm resolution achieved by perovskite assembly

Spatial resolution is an important criterion to evaluate the performance of a scintillation screen for X-ray imaging.Perovskite-based X-ray screen,usually made of powders or polycrystalline films,suffers from low spatial resolution(~200μm)due to the large thickness of scintillation layer despite of their compelling sensitivity to X-ray dose.In this work,a concentrated colloid of CsPbBr_(3)nanosheets was synthesized via a co-precipitation method at ambient condition.By drop casting,smooth scintillation screens of varied thickness were formed through self-assembly,which exhibited both high internal and external photoluminescence quantum yield(PL QY)(84.5%and 75.1%,respectively).The screen-based X-ray detector showed a high sensitivity down to 27 nGy/s,two orders of magnitude lower than the regular dose for medical diagnostics.Importantly,the screen of optimal thickness of 15μm showcased an unprecedented spatial resolution(26μm)when used for X-ray radiography,representing one order of magnitude improvement in perovskite community.