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<jats:p>Amorphous–microcrystalline MoS<jats:sub>2</jats:sub> thin films are fabricated using the sol-gel method to produce MoS<jats:sub>2</jats:sub>/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage (<jats:italic>J</jats:italic>–<jats:italic>V</jats:italic>) curves of the solar cells are analyzed. To improve the performance of the solar cells and address the problem of the S-shaped <jats:italic>J</jats:italic>–<jats:italic>V</jats:italic> curve, a MoS<jats:sub>2</jats:sub> film and a p<jats:sup>+</jats:sup> layer are introduced into the front and back interfaces of the solar cell, respectively, which leads to the formation of a p–n junction between the p-Si and the MoS<jats:sub>2</jats:sub> film as well as ohmic contacts between the MoS<jats:sub>2</jats:sub> film and the ITO, improving the S-shaped <jats:italic>J</jats:italic>–<jats:italic>V</jats:italic> curve. As a result of the high doping characteristics and the high work function of the p<jats:sup>+</jats:sup> layer, a high–low junction is formed between the p<jats:sup>+</jats:sup> and p layers along with ohmic contacts between the p<jats:sup>+</jats:sup> layer and the Ag electrode. Consequently, the S-shaped <jats:italic>J</jats:italic>–<jats:italic>V</jats:italic> curve is eliminated, and a significantly higher current density is achieved at a high voltage. The device exhibits ideal p–n junction rectification characteristics and achieves a high power-conversion efficiency (CE) of 7.55%. The findings of this study may improve the application of MoS<jats:sub>2</jats:sub> thin films in silicon-based solar cells, which are expected to be widely used in various silicon-based electronic and optical devices.</jats:p>

<jats:p>High quality PbSe film was first fabricated by a thermal evaporation method, and then the effect of plasma sensitization on the PbSe film was systemically investigated. Typical detectivity and significant photosensitivity are achieved in the PbSe-based photodetector, reaching maximum values of 7.6 × 10<jats:sup>9</jats:sup> cm⋅Hz<jats:sup>1/2</jats:sup>/W and 1.723 A/W, respectively. Compared with thermal annealing, plasma sensitization makes the sensitization easier and significantly improves the performance.</jats:p>

<jats:p>The nature of saltatory conduction in myelinated axon described by equivalent circuit and circuit theory is still contentious. Recent experimental observations of action potentials transmitting through disjointed nerve fibers strongly suggest an electromagnetic wave propagation mechanism of the nerve signals. In this paper, we employ the electromagnetic wave model of the myelinated axon to describe action potential signal propagation. We use the experimental frequency-dependent conductivity and permittivity values of the nerve tissues in order to reliably calculate the electromagnetic modes by using electromagnetic mode solvers. We find that the electromagnetic waves above 10 kHz can be well confined in extracellular fluid–myelin sheath–intracellular fluid waveguide and propagate a distance of 7 mm without much attenuation. Our study may serve as one of the fundamental researches for the better understanding of the nervous system.</jats:p>

<jats:p>Carrier separation in a solar cell usually relies on the p–n junction. Here we show that an n–n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications. The n–n type heterojunction was formed by hydrothermal deposition of Sb<jats:sub>2</jats:sub>(S,Se)<jats:sub>3</jats:sub> and thermal evaporation of Sb<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub>. We found that the n–n junction is able to enhance the carrier separation by the formation of an electric field, reduce the interfacial recombination and generate optimized band alignment. The device based on this n–n junction shows 2.89% net efficiency improvement to 7.75% when compared with the device consisted of semiconductor absorber–metal contact. The study in the n–n type solar cell is expected to bring about more versatile materials utility, new interfacial engineering strategy and fundamental findings in the photovoltaic energy conversion process.</jats:p>

<jats:p>Due to excellent thermal stability and optoelectronic properties, all-inorganic perovskite is one of the promising candidates to solve the thermal decomposition problem of conventional organic-inorganic hybrid perovskite solar cells (PSCs), but the larger voltage loss (<jats:italic>V</jats:italic> <jats:sub>loss</jats:sub>) cannot be ignored, especially CsPbIBr<jats:sub>2</jats:sub>, which limits the improvement of efficiency. To reduce <jats:italic>V</jats:italic> <jats:sub>loss</jats:sub>, one promising solution is the modification of the energy level alignment between the perovskite layer and adjacent charge transport layer (CTL), which can facilitate charge extraction and reduce carrier recombination rate at the perovskite/CTL interface. Therefore, the key issues of minimum <jats:italic>V</jats:italic> <jats:sub>loss</jats:sub> and high efficiency of CsPbIBr<jats:sub>2</jats:sub>-based PSCs were studied in terms of the perovskite layer thickness, the effects of band offset of the CTL/perovskite layer, the doping concentration of the CTL, and the electrode work function in this study based on device simulations. The open-circuit voltage (<jats:italic>V</jats:italic> <jats:sub>oc</jats:sub>) is increased from 1.37 V to 1.52 V by replacing SnO<jats:sub>2</jats:sub> with ZnO as the electron transport layer (ETL) due to more matching conduction band with the CsPbIBr<jats:sub>2</jats:sub> layer.</jats:p>

<jats:p>Chern number is usually characterized by Berry curvature. Here, by investigating the Dirac model of even-dimensional Chern insulator, we give the general relation between Berry curvature and quantum metric, which indicates that the Chern number can be encoded in quantum metric as well as the surface area of the Brillouin zone on the hypersphere embedded in Euclidean parameter space. We find that there is a corresponding relationship between the quantum metric and the metric on such a hypersphere. We give the geometrical property of quantum metric. Besides, we give a protocol to measure the quantum metric in the degenerate system.</jats:p>

<jats:p>An ultra-broadband perfect absorber consisting of cascaded nanodisk arrays is demonstrated by placing insulator–metal–insulator–metal nanodisks on insulator–metal film stacks. The absorber shows over 90% absorption in a wavelength range between 600 nm and 4000 nm under transverse magnetic (TM) polarization, with an average absorptivity of 91.5% and a relative absorption bandwidth of 147.8%. The analysis of the electric field and magnetic field show that the synergy of localized surface plasmons, propagating surface plasmons, and plasmonic resonant cavity modes leads to the ultra-broadband perfect absorption, which accords well with the results of impedance-matched analysis. The influences of structural parameters and different metal materials on absorption performance are discussed. Furthermore, the absorber is polarization-independent, and the absorption remains more than 90% at a wide incident angle up to 40° under TE polarization and TM polarization. The designed ultra-broadband absorber has promising prospects in photoelectric detection and imaging.</jats:p>

<jats:p>We design a nunchakus-like tracer and investigate its self-adaptive behavior in an active Brownian particle (ABP) bath via systematically tuning the self-propelled capability and density of ABPs. Specifically, the nunchakus-like tracer will have a stable wedge-like shape in the ABP bath when the self-propelled force is high enough. We analyze the angle between the two arms of the tracer and the velocity of the joint point of the tracer. The angle exhibits a non-monotonic phenomenon as a function of active force. However, it increases with density of ABPs increasing monotonically. A simple linear relationship between the velocity and the self-propelled force is found under the highly active force. In other words, the joint points of the tracer diffuse and the super-diffusive behavior can make the relation between the self-propelled force and the density of ABPs persist longer. In addition, we find that the tracer can flip at high density of ABPs. Our results also suggest the new self-adaptive model research of the transport properties in a non-equilibrium medium.</jats:p>

<jats:p>We propose a novel rumor propagation model with guidance mechanism in heterogeneous complex networks. Firstly, the sharp threshold of rumor propagation, global stability of the information-equilibrium and information-prevailing-equilibrium under <jats:italic>R</jats:italic> <jats:sub>0</jats:sub> &lt; 1 and <jats:italic>R</jats:italic> <jats:sub>0</jats:sub> &gt; 1 is carried out by Lyapunov method and LaSalle’s invariant principle. Next, we design an aperiodically intermittent stochastic stabilization method to suppress the rumor propagation. By using the Itô formula and exponential martingale inequality, the expression of the minimum control intensity is calculated. This method can effectively stabilize the rumor propagation by choosing a suitable perturb intensity and a perturb time ratio, while minimizing the control cost. Finally, numerical examples are given to illustrate the analysis and method of the paper.</jats:p>

<jats:p>We propose a new scheme to study the exact solutions of a class of hyperbolic potential well. We first apply different forms of function transformation and variable substitution to transform the Schrödinger equation into a confluent Heun differential equation and then construct a Wronskian determinant by finding two linearly dependent solutions for the same eigenstate. And then in terms of the energy spectrum equation which is obtained from the Wronskian determinant, we are able to graphically decide the quantum number with respect to each eigenstate and the total number of bound states for a given potential well. Such a procedure allows us to calculate the eigenvalues for different quantum states via Maple and then substitute them into the wave function to obtain the expected analytical eigenfunction expressed by the confluent Heun function. The linearly dependent relation between two eigenfunctions is also studied.</jats:p>