Jiatian Guo

Bio: Jiatian Guo is an academic researcher from Shandong Normal University. The author has contributed to research in topics: Medicine & Biology. The author has an hindex of 2, co-authored 6 publications receiving 14 citations.

Tuning electronic and optical properties of monolayer PdSe2 by introducing defects: first-principles calculations.

Abstract: Based on the density functional theory, the electronic and optical properties of pristine monolayer PdSe2 with Pd or Se vacancy-defect are investigated. Our results show that the Se defect is energetically more favorable than that of Pd defect. The band gap reduces, and some new midgap states appear after the Pd or Se defects are introduced. In terms of the optical properties, the prominent anisotropic characters are remained. The obvious new peaks of the dielectric constant appear after introducing defects. The light absorption in the visible energy range expands based on the appearance of the midgap states induced by the Pd or Se defects. The changes of the refractive index and reflectivity are similar with those of the dielectric constants and the light absorption. The energy loss spectrum of the PdSe2 with Pd or Se defects is obviously different, which can be used to identify different defects in PdSe2. These findings provide effective strategies to tune electronic and optical properties of monolayer PdSe2 by introducing defects.

Self-powered topological insulator Bi2Te3/Ge heterojunction photodetector driven by long-lived excitons transfer

Abstract: Due to the wide spectral absorption and ultrafast electron dynamical response under optical excitation, topological insulator (TI) was proposed to have appealing application in next-generation photonic and optoelectronic devices. Whereas, the bandgap-free speciality of Dirac surface states usually leads to a quick relaxation of photoexcited carriers, making the transient excitons difficult to manipulate in isolated TIs. Growth of TI Bi2Te3/Ge heterostructures can promote the specific lifetime and quantity of long-lived excitons, offering the possibility of designing original near-infrared optoelectronic devices, however, the construction of TI Bi2Te3/Ge heterostructures has yet to be investigated. Herein, the high-quality Bi2Te3/Ge heterojunction with clear interface was prepared by physical vapor deposition strategy. A significant photoluminescence quenching behaviour was observed by experiments, which was attributed to the spontaneous excitation transfer of electrons at heterointerface via theoretical analysis. Then, a self-powered heterostructure photodetector was fabricated, which demonstrated a maximal detectivity of 1.3 × 1011 Jones, an optical responsivity of 0.97 A W−1, and ultrafast photoresponse speed (12.1 μs) under 1064 nm light illumination. This study offers a fundamental understanding of the spontaneous interfacial exciton transfer of TI-based heterostructures, and the as-fabricated photodetectors with excellent performance provided an important step to meet the increasing demand for novel optoelectronic applications in the future.

Current Status of Mosquito Handling, Transporting and Releasing in Frame of the Sterile Insect Technique

Abstract: Simple Summary With the increasing burden of mosquito-borne diseases around the world and the traditional control methods showing drawbacks, the sterile insect technique (SIT) is now a potential new tool in the field of controlling mosquitoes. During the implementation of SIT, several steps, such as handling, transportation and release, are of great importance and stand a chance to be optimized. Here, we provide an overview of the key steps in the whole SIT process, listing the main handling, transporting and releasing methods described in the present studies in order to maximize the success of the SIT. With the relevant technical summary, the cognition of this technology can be more accurate; the explorations and results may evoke more follow-up research, making them more directional. Abstract The sterile insect technique (SIT) and its related technologies are considered to be a powerful weapon for fighting against mosquitoes. As an important part of the area-wide integrated pest management (AW-IPM) programs, SIT can help reduce the use of chemical pesticides for mosquito control, and consequently, the occurrence of insecticide resistance. The mosquito SIT involves several important steps, including mass rearing, sex separation, irradiation, packing, transportation, release and monitoring. To enable the application of SIT against mosquitoes to reduce vector populations, the Joint Food and Agriculture Organization of the United Nations (FAO) and the International Atomic Energy Agency (IAEA) Centre (previously called Division) of Nuclear Techniques in Food and Agriculture (hereinafter called Joint FAO/IAEA Centre) and its Insects Pest Control sub-program promoted a coordinated research project (CRP) entitled “Mosquito handling, transport, release and male trapping methods” to enhance the success of SIT. This article summarizes the existing explorations that are critical to the handling and transporting of male mosquitoes, offers an overview of detailed steps in SIT and discusses new emerging methods for mosquito releases, covering most processes of SIT.

Wolbachia wPip Blocks Zika Virus Transovarial Transmission in Aedes albopictus

Abstract: Area-wide application of Wolbachia to suppress mosquito populations and their transmitted viruses has achieved success in multiple countries. However, the mass release of Wolbachia-infected male mosquitoes involves a potential risk of accidentally releasing fertile females. In this study, we employed ovarian cells of the Ae. albopictus GUA, HC, and GT lines, which exhibit key traits, and compared them to better understand how Wolbachia inhibits ZIKV transovarial transmission. ABSTRACT Wolbachia is being developed as a biological tool to suppress mosquito populations and/or interfere with their transmitted viruses. Adult males with an artificial Wolbachia infection have been released, successfully yielding population suppression in multiple field trials. The main characteristic of the artificial Wolbachia-infected mosquitoes used in the suppression program is the lower vector competence than that in native infected/uninfected mosquitoes in horizontal and vertical transmission. Our previous studies have demonstrated that the Aedes albopictus HC line infected with a trio of Wolbachia strains exhibited almost complete blockade of dengue virus (DENV) and Zika virus (ZIKV) in horizontal and vertical transmission. However, the extent to which Wolbachia inhibits virus transovarial transmission is unknown since no studies have been performed to determine whether Wolbachia protects ovarian cells against viral infection. Here, we employed ovarian cells of the Ae. albopictus GUA (a wild-type mosquito line superinfected with two native Wolbachia strains, wAlbA and wAlbB), HC, and GT lines (tetracycline-cured, Wolbachia-uninfected mosquitoes), which exhibit key traits, and compared them to better understand how Wolbachia inhibits ZIKV transovarial transmission. Our results showed that the infection rate of adult GT progeny was significantly higher than that of GUA progeny during the first and second gonotrophic cycles. In contrast, the infection rates of adult GT and GUA progeny were not significantly different during the third gonotrophic cycle. All examined adult HC progeny from three gonotrophic cycles were negative for ZIKV infection. A strong negative linear correlation existed between Wolbachia density and ZIKV load in the ovaries of mosquitoes. Although there is no obvious coexistence area in the ovaries for Wolbachia and ZIKV, host immune responses may play a role in Wolbachia blocking ZIKV expansion and maintenance in the ovaries of Ae. albopictus. These results will aid in understanding Wolbachia-ZIKV interactions in mosquitoes. IMPORTANCE Area-wide application of Wolbachia to suppress mosquito populations and their transmitted viruses has achieved success in multiple countries. However, the mass release of Wolbachia-infected male mosquitoes involves a potential risk of accidentally releasing fertile females. In this study, we employed ovarian cells of the Ae. albopictus GUA, HC, and GT lines, which exhibit key traits, and compared them to better understand how Wolbachia inhibits ZIKV transovarial transmission. Our results showed an almost complete blockade of ZIKV transmission in HC female mosquitoes. Wolbachia in natively infected GUA mosquitoes negative affected ZIKV, and this interference was shown by slightly lower loads than those in HC mosquitoes. Overall, our work helps show how Wolbachia blocks ZIKV expansion and maintenance in the ovaries of Ae. albopictus and aids in understanding Wolbachia-ZIKV interactions in mosquitoes.

Valley selective optical Stark effect in monolayer WS2

Abstract: Breaking space-time symmetries in two-dimensional crystals (2D) can dramatically influence their macroscopic electronic properties. Monolayer transition metal dichalcogenides (TMDs) are prime examples where the intrinsically broken crystal inversion symmetry permits the generation of valley-selective electron populations [1–4], even though the two valleys are energetically degenerate, locked by time-reversal symmetry. Lifting the valley degeneracy in these materials is of great interest because it would allow for valley-specific band engineering and offer additional control in valleytronic applications. While applying a magnetic field should in principle accomplish this task, experiments to date have observed no valley-selective energy level shifts in fields accessible in the laboratory. Here we show the first direct evidence of lifted valley degeneracy in the monolayer TMD WS2 [5]. By applying intense circularly polarized light, which breaks time-reversal symmetry, we demonstrate that the exciton level in each valley can be selectively tuned by as much as 18 meV via the optical Stark effect. These results offer a novel way to control valley degree of freedom and may provide a means to realize new valley-selective Floquet topological phases [6–8] in 2D TMDs.

Black Phosphorus Field-effect Transistors

Abstract: Two-dimensional crystals have emerged as a class of materials that may impact future electronic technologies. Experimentally identifying and characterizing new functional two-dimensional materials is challenging, but also potentially rewarding. Here, we fabricate field-effect transistors based on few-layer black phosphorus crystals with thickness down to a few nanometres. Reliable transistor performance is achieved at room temperature in samples thinner than 7.5 nm, with drain current modulation on the order of 10(5) and well-developed current saturation in the I-V characteristics. The charge-carrier mobility is found to be thickness-dependent, with the highest values up to ∼ 1,000 cm(2) V(-1) s(-1) obtained for a thickness of ∼ 10 nm. Our results demonstrate the potential of black phosphorus thin crystals as a new two-dimensional material for applications in nanoelectronic devices.

Giant and tunable valley degeneracy splitting in MoTe$_2$

Abstract: Valleys in monolayer transition-metal dichalcogenides seamlessly connect two basic carriers of quantum information, namely, the electron spin and photon helicity. Lifting the valley degeneracy is an attractive route to achieve further optoelectronic manipulations. However, the magnetic field only creates a very small valley splitting. We propose a strategy to create giant valley splitting by the proximity-induced Zeeman effect. Our first principles calculations of monolayer ${\\mathrm{MoTe}}_{2}$ on a EuO substrate show that valley splitting over 300 meV can be generated. Interband transition energies become valley dependent, leading to selective spin-photon coupling by optical frequency tuning. The valley splitting is also continuously tunable by rotating the substrate magnetization. The giant and tunable valley splitting adds a different dimension to the exploration of unique optoelectronic devices based on magneto-optical coupling and magnetoelectric coupling.

Self-powered broadband photodetector based on MoS2/Sb2Te3 heterojunctions: a promising approach for highly sensitive detection

Abstract: Abstract Topological insulators have shown great potential for future optoelectronic technology due to their extraordinary optical and electrical properties. Photodetectors, as one of the most widely used optoelectronic devices, are crucial for sensing, imaging, communication, and optical computing systems to convert optical signals to electrical signals. Here we experimentally show a novel combination of topological insulators (TIs) and transition metal chalcogenides (TMDs) based self-powered photodetectors with ultra-low dark current and high sensitivity. The photodetector formed by a MoS2/Sb2Te3 heterogeneous junction exhibits a low dark current of 2.4 pA at zero bias and 1.2 nA at 1V. It shows a high photoresponsivity of >150 mA W−1 at zero bias and rectification of 3 times at an externally applied bias voltage of 1V. The excellent performance of the proposed photodetector with its innovative material combination of TMDs and TIs paves the way for the development of novel high-performance optoelectronic devices. The TIs/TMDs transfer used to form the heterojunction is simple to incorporate into on-chip waveguide systems, enabling future applications on highly integrated photonic circuits.

Reversible switching of anomalous valley Hall effect in ferrovalley Janus <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mi>T</mml:mi><mml:mo>−</mml:mo><mml:mi>CrO</mml:mi><mml:mi>X</mml:mi></mml:mrow><mml:mo> </mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mi>X

Abstract: The central issue for practical applications of the anomalous valley Hall effect (AVHE) is the tunable and nonvolatile nature of the valley splitting. We predict a type of ferrovalley material, Janus $1T\ensuremath{-}\mathrm{CrO}X (X=\mathrm{F},\mathrm{Cl},\mathrm{Br},\mathrm{I})$, in which the switching effect of the AVHE can be achieved by adjusting the biaxial strain or building a multiferroic heterostructure $\mathrm{CrO}X/{\mathrm{In}}_{2}{\mathrm{Se}}_{3}$. Stable out of plane magnetization in $\mathrm{CrO}X$ induces the valley splitting which can reach to 112 meV in the CrOBr monolayer. Interestingly, we find that the valley splitting of CrOCl is robust against the biaxial strain both in the conduction band and the valence band. In contrast, the valley splitting of the CrOBr at the conduction band can be linearly modulated, while it has a switching response at the valence band due to the strong orbital hybridization induced by compressive strain, so a reversible switch of the AVHE can be achieved. Furthermore, the electric reversible valley splitting switch is also obtained in multiferroic van der Waals heterostructure $\mathrm{CrOCl}/{\mathrm{In}}_{2}{\mathrm{Se}}_{3}$, and the reversible switch of the AVHE can also be manipulated by controlling the polarization states of the ferroelectric layer. The AVHE in $\mathrm{CrO}X$ can be readily switched on or off by either applying biaxial strain or reversing the ferroelectric polarization of the substrate ${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$, which may be a promising application in the field of valleytronics.