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Trifluoromethyl enable high-performance single-emitter white organic light-emitting devices based on quinazoline acceptor

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Chinese Chemical Letters 2024年第4期35卷 442-446页

作者： Xiangan Song Shaogang Shen Mengyao Lu Ying Wang Yong Zhang School of materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Photochemical Conversion and Optoelectronic materials and TIPC-CityU Joint Laboratory of Functional Materials and DeviceChinese Academy of SciencesTechnical Institute of Physics and ChemistryBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Single-emitter white organic light-emitting diode(WOLED) based on small organic molecule exhibits great potential in simplifying fabrication process of WOLEDs. However, the design and synthesis of molecule for highly efficient single-emitter WOLED still remains a challenge. Herein, two asymmetric donor-acceptor-acceptor'(D-A-A') type molecule(PTZ-PQ-F and PTZ-PQ-CF3) are developed by employing trifluoromethyl(CF_(3)) or fluorine atom as secondary acceptor, which can exhibit white lighting with dual emission bands consisting of blue traditional fluorescence from quasi-axial(ax) conformer and orange thermally activated delayed fluorescence(TADF) from quasi-equatorial(eq) conformer. The introduction of CF_(3) into PTZ-PQ-CF3 greatly enhanced the photoluminescence quantum yield(PLQY) by suppressing the nonradiative deactivation. Owing to electron-inductive-effect of CF3, the “eq” conformer of PTZ-PQCF3 exhibits a much smaller ΔESTof 0.01 e V to realize more efficient reverse intersystem crossing(RISC)process, and then enhance the exciton utilization(nearly 100%) of the whole dual emission system. Consequently, single-emitter WOLEDs based on PTZ-PQ-CF3 show nearly standard white emission with EQE of 13.0% and CIE of(0.35, 0.36) in m CP host and show warm white emission with high EQE of 25.5%and CIE of(0.40, 0.47) in 35 Dcz PPy host, which are the best performance among reported single-emitter WOLEDs.

关键词： Single-emitter white organic light-emitting diode Conformational isomerism Thermally activated delayed fluorescence Trifluoromethyl Exciton utilization

Dead-zone-free atomic magnetometer based on hybrid Poincarébeams

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Photonics Research 2024年第5期12卷 1093-1097页

作者： KE TIAN WEIFENG DING ZHAOYING WANG Zhejiang Province Key Laboratory of Quantum Technology and device School of PhysicsZhejiang UniversityHangzhou 310027China

In this paper,we present the experiment and the theory scheme of light-atom interaction in atomic magnetometers by using a hybrid Poincarébeam(HPB)to solve an annoying problem,named“dead zone.”This kind of magnetometer can be sensitive to arbitrary directions of external magnetic *** HPB has a complex polarization distribution,consisting of a vector radially polarized beam and a scalar circularly polarized beam in our *** two kinds of beams have different directions of dead zones of external magnetic fields;thereby,the atomic magnetometer with an HPB can avoid the non-signal area when the direction of the external magnetic field is in the plane perpendicular to the light polarization ***,the optical magnetic resonance(OMR)signal using an HPB still has no dead zones even when the direction of the external magnetic field is in the plane parallel to the polarization plane in our *** work has the potential to simplify and optimize dead-zone-free atomic magnetometers.

关键词： Poincaré magnetometer atomic

Insight into vertical piezoelectric characteristics regulated thermal transport in van der Waals two-dimensional materials

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Rare Metals 2024年第2期43卷 770-779页

作者： Dong-Hai Wei E Zhou Jin-Yuan Xu Hui-Min Wang Chen Shen Hong-Bin Zhang Zhen-Zhen Qin Guang-Zhao Qin State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha410082China Hunan Key Laboratory for Micro-Nano Energy materials and device and School of physics and Optoelectronics Xiangtan UniversityXiangtan411105China Institute of materials Science Technical University of DarmstadtAlarich-Weiss-Str.264287DarmstadtGermany School of physics and Microelectronics Zhengzhou UniversityZhengzhou450001China

The urgent demand of extreme(ultra-high/low)thermal conductivity materials is triggered by the high-power device,where exploring the theories and mechanisms of regulating thermal transport properties plays a key ***,we elaborately investigate the effect of vertical(out-of-plane)piezoelectric characteristics on thermal transport,which is historically *** different stacking-order(AA and AB)bilayer boron nitride(Bi-BN)in two-dimensional(2D)materials are selected as study *** performing state-of-the-art first-principles calculations,it is found that the polarization charge along the out-of-plane orientation ascends significantly with the increasing piezoelectric response in AB stacked Bi-BN(Bi-BN-AB)followed by the enhanced interlayer B–N atomic ***,the amplitude of phonon anharmonicity in Bi-BN-AB increases larger than that in the AA stacked Bi-BN(Bi-BN-AA),resulting in the dramatic weakening of the thermal conductivity by 20.34%under 18%*** research reveals the significant role of the vertical(out-of-plane)piezoelectric characteristic in regulating thermal transport and provides new insight into accurately exploring the thermal transport performance of 2D van der Waals materials.

关键词： Thermal conductivity Piezoelectric effect 2D materials Bilayer BN Strain engineering

Determination of molecular energies via variational-based quantum imaginary time evolution in a superconducting qubit system

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Science China(physics,Mechanics & Astronomy) 2024年第4期67卷 1-11页

作者： Zhiwen Zong Sainan Huai Tianqi Cai Wenyan Jin Ze Zhan Zhenxing Zhang Kunliang Bu Liyang Sui Ying Fei Yicong Zheng Shengyu Zhang Jianlan Wu Yi Yin Zhejiang Province Key Laboratory of Quantum Technology and device School of PhysicsZhejiang UniversityHangzhou 310027China Tencent Quantum Laboratory Shenzhen 518057China

As a valid tool for solving ground state problems,imaginary time evolution(ITE)is widely used in physical and chemical *** ITE-based algorithms in their quantum counterpart have recently been proposed and applied to some real *** experimentally realize the variational-based quantum imaginary time evolution(QITE)algorithm to simulate the ground state energy of hydrogen(H_2)and lithium hydride(Li H)molecules in a superconducting qubit *** H_2 molecule is directly simulated using the 3-qubit circuit with unitary-coupled clusters(UCC)*** also combine QITE with the cluster mean-field(CMF)method to obtain an effective *** Li H molecule is correspondingly simulated using the 3-qubit circuit with hardware-efficient *** comparison,the Li H molecule is also directly simulated using the 4-qubit circuit with UCC ansatz at the equilibrium *** the experimental results show a convergence within 4 iterations,with high-fidelity ground state energy *** a more complex system in the future,the CMF may allow further grouping of interactions to obtain an effective Hamiltonian,then the hybrid QITE algorithm can possibly simulate a relatively large-scale system with fewer qubits.

关键词： quantum computation quantum algorithm superconducting qubit

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Symmetry transformation of nonlinear optical current of tilted Weyl nodes and application to ferromagnetic MnBi_(2)Te_(4)

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Chinese physics B 2024年第4期33卷 160-171页

作者：卢倬成冯济 International Center for Quantum materials School of PhysicsPeking UniversityBeijing 100871China

A Weyl node is characterized by its chirality and *** develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and *** on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC *** results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.

关键词： nonlinear optical response topological Weyl semimetals chiral anomaly

Spin logic devices based on negative differential resistance -enhanced anomalous Hall effect

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International Journal of Minerals,Metallurgy and materials 2024年第6期31卷 1437-1448页

作者： Hongming Mou Ziyao Lu Yuchen Pu Zhaochu Luo Xiaozhong Zhang Key Laboratory of Advanced materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory of Artificial Microstructure and Mesoscopic physics School of PhysicsPeking UniversityBeijing 100871China

Owing to rapid developments in spintronics,spin-based logic devices have emerged as promising tools for next-generation computing *** paper provides a comprehensive review of recent advancements in spin logic devices,particularly focusing on fundamental device concepts rooted in nanomagnets,magnetoresistive random access memory,spin–orbit torques,electric-field modu-lation,and magnetic domain *** operation principles of these devices are comprehensively analyzed,and recent progress in spin logic devices based on negative differential resistance-enhanced anomalous Hall effect is *** devices exhibit reconfigur-able logic capabilities and integrate nonvolatile data storage and computing *** current-driven spin logic devices,negative differential resistance elements are employed to nonlinearly enhance anomalous Hall effect signals from magnetic bits,enabling reconfig-urable Boolean logic ***,voltage-driven spin logic devices employ another type of negative differential resistance ele-ment to achieve logic functionalities with excellent cascading *** cascading several elementary logic gates,the logic circuit of a full adder can be obtained,and the potential of voltage-driven spin logic devices for implementing complex logic functions can be *** review contributes to the understanding of the evolving landscape of spin logic devices and underscores the promising pro-spects they offer for the future of emerging computing schemes.

关键词： spin logic spin–orbit torque negative differential resistance full-adder

Understanding the Thermal Impedance of Silicone Rubber/Hexagonal Boron Nitride Composites as Thermal Interface materials

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Chinese Journal of Polymer Science 2024年第3期42卷 352-363,I0008页

作者： Yuan Ji Shi-Da Han Hong Wu Shao-Yun Guo Feng-Shun Zhang Jian-Hui Qiu The State Key Laboratory of Polymer materials Engineering Sichuan Provincial Engineering Laboratory of Plastic/Rubber Complex Processing TechnologyPolymer Research InstituteSichuan UniversityChengdu 610065China Institute of Chemical materials China Academy of Engineering PhysicsMianyang 621900China Department of Mechanical Engineering Faculty of Systems Science and TechnologyAkita Prefectural UniversityAkita 015-0055Japan

Silicone rubber(SR) composites are most widely used as thermal interface materials(TIMs) for electronics heat dissipation. Thermal impedance as the main bottleneck limiting the performance of TIMs is usually neglected. Herein, the thermal impedance of SR composites loaded with different levels of hexagonal boron nitride(h-BN) as TIMs was elaborated for the first time by the ASTM D 5470 standard test and finite element analysis. It was found that elastic modulus and surface roughness of SR composites increased with the increase of h-BN content, indicating that the conformity was reduced. When the assembly pressure was 0.69 MPa, there existed an optimal h-BN content at which the contact resistance was minimum(0.39 K·cm^(2)·W^(-1)). Although the decreased bond line thickness(BLT) by increasing the assembly pressure was beneficial to reduce the thermal impedance, the proper assembly pressure should be selected to prevent the warpage of the contact surfaces and the increase in contact resistance, according to the compression properties of the SR composites. This study provides valuable insights into fabrication of high-performance TIMs for modern electronic device applications.

关键词： Thermal interface materials Hexagonal boron nitride Thermal impedance Surfaces

Orbital-Ordering Driven Simultaneous Tunability of Magnetism and Electric Polarization in Strained Monolayer VCl_(3)

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Chinese physics Letters 2024年第4期41卷 126-131页

作者：郭的坪王聪王侣锦陆赟豪吴骅张妍宁季威 Beijing Key Laboratory of Optoelectronic Functional materials&Micro-Nano devices Department of PhysicsRenmin University of ChinaBeijing 100872China Key Laboratory of Quantum State Construction and Manipulation(Ministry of Education) Renmin University of ChinaBeijing 100872China Zhejiang Province Key Laboratory of Quantum Technology and device State Key Laboratory of Silicon MaterialsDepartment of PhysicsZhejiang UniversityHangzhou 310027China Laboratory for Computational Physical Sciences(MOE) State Key Laboratory of Surface Physicsand Department of PhysicsFudan UniversityShanghai 200433China Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China

Two-dimensional(2D)van der Waals magnetic materials have promising and versatile electronic and magnetic properties in the 2D limit,indicating a considerable potential to advance spintronic *** predictions thus far have not ascertained whether monolayer VCl_(3) is a ferromagnetic(FM)or anti-FM monolayer;this also remains to be experimentally *** theoretically investigate the influence of potential factors,including C_(3) symmetry breaking,orbital ordering,epitaxial strain,and charge doping,on the magnetic ground *** first-principles calculations,we predict a collinear type-Ⅲ FM ground state in monolayer VCl_(3) with a broken C_(3) symmetry,wherein only the former two of three t_(2g)orbitals(a_(1g),e_(g2)^(π)and e_(g1)^(π))are *** atomic layer thickness and bond angles of monolayer VCl_(3) undergo abrupt changes driven by an orbital ordering switch,resulting in concomitant structural and magnetic phase *** doping to the underlying Cl atoms of monolayer VCl_(3) without C_(3) symmetry simultaneously induces in-and out-of-plane *** can achieve a multiferroic phase transition if combined with the discovered adjustments of magnetic ground state and polarization magnitude under *** establishment of an orbital-ordering driven regulatory mechanism can facilitate deeper exploration and comprehension of magnetic properties of strongly correlated systems in monolayer VCl_(3).

关键词： monolayer symmetry orbital

Sensitive humidity sensor based on moisture-driven energy generation

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Nano Research 2024年第6期17卷 5578-5586页

作者： Qingchao Ni Qing Lou Chenglong Shen Guangsong Zheng Runwei Song Jingnan Hao Jialu Liu Jinyang Zhu Jinhao Zang Lin Dong Chong-Xin Shan Henan Key Laboratory of Diamond Optoelectronic materials and devices Key Laboratory of Materials PhysicsMinistry of Educationand School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China State Centre for International Cooperation on Designer Low-Carbon&Environmental materials and School of Materials Science and EngineeringZhengzhou UniversityZhengzhou 450001China

The emergence of novel self-powered humidity sensors has attracted considerable attention in the fields of smart electronic devices and personal ***,self-powered humidity sensors have been fabricated using a moisture-driven energy generation(MEG)device based on asymmetric tubular graphitic carbon nitride(g-CN)films prepared on anodized aluminum(AAO)*** a relative humidity(RH)of 96%,the MEG device can provide an open-circuit voltage of 0.47 V and a short-circuit current of 3.51μA,with a maximum output power of 0.08μ*** inherent self-powered ability and humidity response via current variation,an extraordinary response of 1.78×106%(41%-96%RH)can be gained from the MEG *** possible power generation mechanism is that g-CN/AAO heterostructure can form ion gradient and diffusion under the action of moisture to convert chemical potential into electrical potential,evoking a connaturally sensitive response to ***-powered respiration monitoring device based on the sensor is designed to monitor human movement(sitting,warming up,and running)and sleep status(normal,snoring,and apnea),maintaining excellent stability during cumulative 12-h respiration *** self-powered humidity sensing technology has promising potential for extensive integration into smart electronic and round-the-clock health monitoring devices.

关键词： graphitic carbon nitride moisture-driven energy generation humidity sensor respiration monitoring