Ⅲ–Ⅴ compounds as single photon emitters

Single-photon emitters (SPEs) are one of the key components in quantum information applications. The ideal SPEs emit a single photon or a photon-pair on demand, with high purity and distinguishability. SPEs can also be integrated in photonic circuits for scalable quantum communication and quantum computer systems. Quantum dots made from Ⅲ-Ⅴ compounds such as InGaAs or GaN have been found to be particularly attractive SPE sources due to their well studied optical performance and state of the art industrial flexibility in fabrication and integration. Here, we review the optical and optoelectronic properties and growth methods of general SPEs. Subsequently, a brief summary of the latest advantages in Ⅲ-Ⅴ compound SPEs and the research progress achieved in the past few years will be discussed. We finally describe frontier challenges and conclude with the latest SPE fabrication science and technology that can open new possibilities for quantum information applications.

Luminescence properties and optical sensing behaviors of Sr_(2)GdSbO_(6):Eu^(3+) phosphors

Novel orange-red Sr_(2)GdSbO_(6):xEu^(3+)(x=0,0.05,0.1,0.2,0.3,0.4,0.5 and 0.6) phospho rs were successfully prepared by the traditional high-temperature solid-state method.The results of Rietveld refinement,energy dispersive spectroscopy(EDS) spectrum and elemental mapping demonstrate that Eu^(3+) successfully replaces the Gd^(3+) sites and distributes uniformly in the particles of phosphors.The luminescence properties of Sr_(2)GdSbO_(6):Eu_(3+)phosphors were investigated in detail.The emission spectra of the strongest emission peak is the ^(5)D_(0)→^(7)F_(1)(593 nm) transition,which can emit orange-red light under393 nm excitation.When the doping concentration of Eu3+ions is x=0.2,the luminescence intensity of the phosphors reaches the highest.The detailed mechanism of concentration quenching is attributed to dipole-dipole interaction.The thermal stability values of Sr_(2)GdSbO_(6):0.2Eu^(3+) phosphors are 87%,82% and114% under 393,467 and 527 nm excitations,respectively.The causes of the abnormal thermal quenching under 527 nm excitation were analyzed.Based on the abnormal thermal quenching under527 nm excitation,the optical thermometry properties of Sr_(2)GdSbO_(6):0.2Eu^(3+)phosphors were investigated by fluorescence intensity ratio(FIR) technique,and appreciable relative sensitivity was obtained.The results suggest that Sr_(2)GdSbO_(6):0.2Eu^(3+)phosphors can be potentially applied to w-LEDs and optical thermometers.

Oligolayered Ti3C2Tx MXene towards high performance lithium/sodium storage

Nano Research volume 13,pages1659–1667(2020)Cite this article 232 Accesses 3 Citations Metrics details Abstract 2D MXenes are highly attractive for achieving ultrafast and stable lithium/sodium storage due to their good electric conductivity and abundant redox active sites.While,effective strategies for scalable preparation of oligolayered MXenes are still under exploration.Herein,oligolayered Ti3C2Tx MXene is successfully obtained after conventional synthesis of multilayered Ti3C2 and subsequent delamination process via an organic solvent of tetramethyl-ammonium hydroxide(TMAOH).Comprehensive electrochemical study reveals that surface-controlled redox reaction dominated the charge storage behavior of oligolayered Ti3C2Tx with fast reaction kinetics.Impressively,the obtained oligolayered Ti3C2Tx exhibits excellent lithium/sodium storage performance,featured for a high specific capacity of 330 mAhg^−1 at 1.0 Ag^−1 after 800 cycles for lithium storage and 280 mAhg^−1 at 0.5 Ag^−1 after 500 cycles for sodium storage.Such impressive performance will advance the development of oligolayered Ti3C2Tx based materials for lithium/sodium storage and even broaden their application into energy storage.

Preparation and characterization of a new orange-red phosphor Ba_(2)LaTaO_(6):Eu^(3+)with abnormal thermal quenching

Herein,double-perovskite Ba_(2)LaTaO_(6) Eu-doped orange-red phosphors were successfully synthesized using a high-temperature solid-phase method.The phosphor phase purity was investigated using X-ray diffraction and microscopic morphology analyses.Their luminescence properties were investigated using absorption,emission,excitation,and temperature-dependent spectra.The transition mechanism mainly involves a magnetic-dipole transition with an energy transfer mode featuring multipole-multipole interactions,and concentration quenching is achieved via dipole-dipole interactions.In addition,the intensity of the temperature-dependent spectrum increases abnormally between 298 and 373 K,with the luminous intensity at 373 K increasing to 110%of that observed at room temperature.This phenomenon can be attributed to lattice defects in Ba_(2)LaTaO_(6):Eu^(3+),and the phosphor luminous intensity at473 K remains at 80.62%of that at room temperature.In addition,white-light-emitting diode devices based on this novel Ba_(2)LaTaO_(6):0.35Eu^(3+)phosphor were fabricated to evaluate the potential applications of the as-prepared phosphor.

Multiferroic oxide BFCNT/BFCO heterojunction black silicon photovoltaic devices

Multiferroics are being studied increasingly in applications of photovoltaic devices for the carrier separation driven by polarization and magnetization.In this work,textured black silicon photovoltaic devices are fabricated with Bi_(6)Fe_(1.6)Co_(0.2)Ni_(0.2)Ti_(3)O_(18)/Bi_(2)FeCrO_(6)(BFCNT/BFCO)multiferroic heterojunction as an absorber and graphene as an anode.The structural and optical analyses showed that the bandgap of Aurivillius-typed BFCNT and double perovskite BFCO are 1.62±0.04 eV and 1.74±0.04 eV respectively,meeting the requirements for the active layer in solar cells.Under the simulated AM 1.5 G illumination,the black silicon photovoltaic devices delivered a photoconversion efficiency(η)of 3.9%with open-circuit voltage(Voc),short-circuit current density(Jsc),and fill factor(FF)of 0.75 V,10.8 mA cm^(-2),and 48.3%,respectively.Analyses of modulation of an applied electric and magnetic field on the photovoltaic properties revealed that both polarization and magnetization of multiferroics play an important role in tuning the built-in electric field and the transport mechanisms of charge carriers,thus providing a new idea for the design of future high-performance multiferroic oxide photovoltaic devices.