Effect of dimensional expansion on carrier transport behaviors of the hexagonal Bi-based perovskite crystals

All-inorganic Cs_(3)Bi_(2)I_(9)(CBI)halide perovskites are sought to be candidate for photoelectrical materials because of their low toxicity and satisfactory stability.Unfortunately,the discrete molecular[Bi2I9]3−clusters limit the charge-transport behaviors.Herein,the defect halide perovskite based on trivalent Bi^(3+)is expanded to Cs_(3)Bi_(2)I_(6)Br_(3)(CBIB).Centimeter-size CBIB single crystal(Φ15×70 mm^(3))was grown by the vertical Bridgeman method.The powder X-ray diffraction analysis shows that CBIB has structure with lattice parameters of a=b=8.223Å,c=10.024Å,α=β=90°andγ=120°.The density functional theory(DFT)calculations demonstrate that the charge density distribution was enhanced after the dimensional expansion.The enhancement of carrier transport ability of(00l)in-plane is characterized before and after dimensional improvement.The obtained CBIB(001)exhibited an electron mobility up to 40.03 cm^(2)V^(−1)s^(−1)by time-of-flight(TOF)technique,higher than 26.46 cm^(2)V^(−1)s^(−1)of CBI(001).Furthermore,the X-ray sensitivity increases from 707.81μC Gy^(−1)cm^(−2)for CBI(001)to 3194.59μC Gy−1 cm^(−2)for CBIB(001).This research will deepen our understanding of Bi-based perovskite materials and afford more promising strategies for lead-free perovskite optoelectronic devices modification.

Video Conference System in Mixed Reality Using a Hololens

The mixed reality conference system proposed in this paper is a robust,real-time video conference application software that makes up for the simple interaction and lack of immersion and realism of traditional video conference,which realizes the entire process of holographic video conference from client to cloud to the client.This paper mainly focuses on designing and implementing a video conference system based on AI segmentation technology and mixed reality.Several mixed reality conference system components are discussed,including data collection,data transmission,processing,and mixed reality presentation.The data layer is mainly used for data collection,integration,and video and audio codecs.The network layer uses Web-RTC to realize peer-to-peer data communication.The data processing layer is the core part of the system,mainly for human video matting and human-computer interaction,which is the key to realizing mixed reality conferences and improving the interactive experience.The presentation layer explicitly includes the login interface of the mixed reality conference system,the presentation of real-time matting of human subjects,and the presentation objects.With the mixed reality conference system,conference participants in different places can see each other in real-time in their mixed reality scene and share presentation content and 3D models based on mixed reality technology to have a more interactive and immersive experience.

Biomass Straw Based Activated Porous Carbon Materials for High-Performance Supercapacitors

Biomass straws are often regarding as agricultural waste, usually burned off in rural areas, which results in severe resource waste andair pollution. In this work, biomass-based porous carbon material with a lamellar microstructure is obtained via simple hydrothermaland subsequent KOH activation, the optimum activate process is determined by the proportion of activator. Scanning electronmicroscopy (SEM) and nitrogen adsorption techniques are conducted to investigate the physical properties of the materials. Cyclicvoltammetry and constant current discharge/charge in the three-electrode system and symmetrical double-layer capacitors resultsindicate the best electrochemical performance of SCA-1.5 electrode material, with a capacity of 250.0 F g-1 at 1.0 A g-1. And notably,high recycling stability at a high cycling rate of 1.0 A g-1 after 18,000 cycles.