Yong Liu

Superlattice films are promising candidates for obtaining excellent thermoelectric performance because the hetero-interface can effectively regulate both carrier and phonon transport. However, the atomic and electronic structures at the hetero-interface remain largely unexplored, limiting the deep understanding of interfacial effects. Here, 1T′-MoTe2/Bi2Te3 quantum-dot films were fabricated for investigating the 1T′-MoTe2/Bi2Te3 hetero-interface and its effect on electrical transport. Atomic-scale characterizations indicate apparent Mo doping at the hetero-interface, while band structure calculations and transport measurements reveal that Mo doping can reconstruct the conduction band and enhance band degeneracy, leading to a large carrier effective mass of ∼1.6 m0. Meanwhile, spectroscopy measurements verify donor-like states and local band bending at the hetero-interface, which introduce modulation doping and thereby enable synergistically optimized electron density and carrier mobility. As a result, the best (1T′-MoTe2)0.8(Bi2Te3)12 film achieves a peak power factor of ∼3.74 mW m–1 K–2 at 325 K. These findings provide new insights of interfacial effects on synergistically optimizing carrier transport and electrical properties of thermoelectric superlattice or quantum-dot films.

The magnetic field responsiveness of spin-polarized electrons renders their modulation a novel strategy for achieving active tunability and multi-dimensional enhancement of battery performance. However, the independent effects and mechanisms of spin-polarized electrons have not been systematically elucidated. Herein, using first-principles calculations, we propose a novel strategy for inducing spin-polarized delocalized electrons through the synergistic effect of vacancy doping and ion adsorption, which can significantly modulate and enhance battery performance. The introduction of S or Se vacancies into the non-magnetic MoSSe system (MoSSe-VS and MoSSe-VSe) can break the crystal symmetry and simultaneously introduce defect energy levels near the Fermi level. When different cations are adsorbed on the defective surface, the system will generate intrinsic magnetism. We systematically compare the calculated intrinsic ion storage properties of pristine and vacancy modified MoSSe, including ion migration barriers, charge transfer, theoretical specific capacities, and open circuit voltages. More importantly, Se vacancies can induce the generation of more spin-polarized electrons in the adsorbed systems, thus leading to a more prominent performance enhancement effect. The results of this study provide important theoretical guidance for the design of high-performance ion batteries with active tunability.

Precise control of electronic structure remains a central challenge in thermoelectric thin films. Here, we demonstrate that ion implantation provides a controllable route to engineer electronic states in Sb2Te3 thin films. By introducing Ni ions with tunable dose, localized states are formed near the Fermi level, leading to a significant modification of the electronic structure. Notably, the Seebeck coefficient is enhanced despite an increase in carrier concentration, deviating from the conventional trade-off behavior in degenerate semiconductors. The optimal sample achieves a Seebeck coefficient of 160.42 μV K−1 and a power factor of 2.95 mW m−1 K−2 at 575 K. Combined transport analysis and first-principles calculations reveal that this behavior originates from implantation-induced resonant states, which increase the density of states near the Fermi level and enhance the carrier effective mass. These results demonstrate that ion implantation enables non-equilibrium band structure engineering in thermoelectric thin films.

Flexible films enable high-performance X-ray imaging and ionization detection.

Tansparent uniform scintillators fabricated via in-situ crystallization of Bmpip ₂ Cu ₂ Br ₄ and Bmpip ₂ Cu ₂ Br ₂ I ₂ in PMMA showed high X-ray spatial resolution of > 20 lp mm ⁻¹ and excellent α/β/γ detectability, ideal for imaging and radiation monitoring.

Stable One-Selector-One-Resistors (1S1R) have potential applications in fabricating high-density cross-point storage arrays. In this work, Pt/NbOx/Nb/NbOx/Pt devices were fabricated by intercalating Nb thin layer in Nb2O5 thin film, and influences of annealing at various temperatures on their microstructures and resistive switching performance were extensively investigated. The devices fabricated from the as deposited NbOx/Nb/NbOx and the tri-layer annealed at 300 °C exhibit volatile (TS) resistive switching performance under low compliance current. When the compliance current is increased, the devices display stable 1S1R resistive switching performance due to the synergistic effect of Nb2O5 and NbO2, which was formed via the redox reaction between Nb and Nb2O5. However, when the annealing temperature reaches the crystallization temperature of Nb2O5, the oxygen vacancies conductive filaments without NbO2 are formed along the grain boundaries, leading to the failure of the volatile resistive switching performance of the device. Correspondingly, the resistive switching performance is dominated by the rupture and reformation of oxygen vacancy conductive filaments, exhibiting more stable non-volatile resistive switching performance. This work demonstrates that stable 1S1Rs can be achieved for Pt/NbOx/Pt devices by inserting Nb thin layer and annealing, which provides a new approach for regulating resistive switching performance of oxide memristors.

Reconfigurable neural networks represent a paradigm shift towards more efficient, adaptive, and hardware-utilized intelligent systems. The achievement of controllable switching between volatile and non-volatile resistive characteristics in devices serves as a crucial enabler for this architecture. The resistive switching characteristics of NbO _x memristors are modulated by variations in the chemical stoichiometry of the two constituent elements within the NbO _x film. In this study, the resistive switching performance of the devices was modulated by depositing Ti buffer layers with varying thicknesses onto Nb ₂ O ₅ thin films. X-ray photoelectron spectroscopy results confirmed the oxidation of the deposited Ti buffer layers and revealed a concomitant increase in oxygen vacancy concentration within the resistive switching layer. As the thickness of the Ti buffer layer increased, the concentration of oxygen vacancies progressively rose, ultimately leading to a transition in the device’s resistive switching behavior from non-volatile to volatile. Furthermore, a thinner Ti buffer layer promotes the formation of oxygen vacancy conductive filaments, thereby improving the device’s non-volatile resistive switching performance. Our work provides a feasible strategy for modulating the performance of NbO _x memristors, thereby providing the physical foundation for implementing reconfigurable neural networks at the hardware level.