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<jats:p>The performance of the self-powered photodetectors based on the Cu<jats:sub>2</jats:sub>O/electrolyte heterojunctions is optimized by adjusting morphology and structure of the Cu<jats:sub>2</jats:sub>O film. The Cu<jats:sub>2</jats:sub>O film with a deposition time of 2000 s possesses a largest current density of 559.6 μA/cm<jats:sup>2</jats:sup> under visible light illumination at zero bias, with a rising time of 5.2 ms and a recovering time of 9.0 ms. This optimized Cu<jats:sub>2</jats:sub>O film has a highest responsivity of about 25.8 mA/W for visible light, and a negligible responsivity for UV light. The high crystallinity and excellent charge transfer property are responsible for the improved photodetection performance.</jats:p>

<jats:p>We design and fabricate <jats:italic>λ</jats:italic>/2 coplanar waveguide NbN resonators, the thickness and length of which are only several nanometers and hundred microns, respectively. The quality factor of such compact resonators can reach up to 7.5 × 10<jats:sup>4</jats:sup> at single photon power level at 30 mK with the resonance frequency around 6.835 GHz. In order to tune the resonant frequency, the resonator is terminated to the ground with a dc-SQUID. By tuning the magnetic flux in the dc-SQUID, the effective inductance of the dc-SQUID is varied, which leads to the change in the resonant frequency of the resonator. The tunability range is more than 30 MHz and the quality factor is about 3 × 10<jats:sup>3</jats:sup>. These compact and tunable NbN resonators have potential applications in the quantum information processing, such as in the precision measurement, coupling and/or reading out the quantum states of qubits.</jats:p>

<jats:p>The influence of positive bias temperature instability (PBTI) on 1 / <jats:italic>f</jats:italic> noise performance is systematically investigated on n-channel fin field-effect transistor (FinFET). The FinFET with long and short channel (<jats:italic>L</jats:italic> = 240 nm, 16 nm respectively) is characterized under PBTI stress from 0 s to 10<jats:sup>4</jats:sup> s. The 1 / <jats:italic>f</jats:italic> noise features are analyzed by using the unified physical model taking into account the contributions from the carrier number and channel mobility fluctuations. The <jats:italic>I</jats:italic> <jats:sub>d</jats:sub>–<jats:italic>V</jats:italic> <jats:sub>g</jats:sub>, <jats:italic>I</jats:italic> <jats:sub>d</jats:sub>–<jats:italic>V</jats:italic> <jats:sub>d</jats:sub>, <jats:italic>I</jats:italic> <jats:sub>g</jats:sub>–<jats:italic>V</jats:italic> <jats:sub>g</jats:sub> tests are conducted to support and verify the physical analysis in the PBTI process. It is found that the influence of the channel mobility fluctuations may not be neglected. Due to the mobility degradation in a short-channel device, the noise level of the short channel device also degrades. Trapping and trap generation regimes of PBTI occur in high-<jats:italic>k</jats:italic> layer and are identified based on the results obtained for the gate leakage current and 1 / <jats:italic>f</jats:italic> noise.</jats:p>

<jats:p>A graphene/AlGaN deep-ultraviolet (UV) photodetector is presented with ultrahigh responsivity of 3.4 × 10<jats:sup>5</jats:sup> A/W at 261 nm incident wavelength and 149 pW light power. A gain mechanism based on electron trapping at the potential well is proposed to be responsible for the high responsivity. To optimize the trade-off between responsivity and response speed, a back-gate electrode is designed at the AlGaN/GaN two-dimensional electron gas (2DEG) area which eliminates the persistent photocurrent effect and shortens the recovery time from several hours to milliseconds. The 2DEG gate is proposed as an alternative way to apply the back gate electrode on AlGaN based devices on insulating substrates. This work sheds light on a possible way for weak deep-UV light detection.</jats:p>

<jats:p>Organic light-emitting diode (OLED) is an electroluminescent technology that relies on charge-carrier dynamics and is a potential light source for variable environmental conditions. Here, by exploiting a self-developed low-temperature testing system, we investigated the characteristics of hole/electron transport, electro-optic conversion efficiency, and operation lifetime of OLEDs at low-temperature ranging from –40 °C to 0 °C and room temperature (25 °C). Compared to devices operating at room temperature, the carrier transport capability is significantly decreased with reducing temperature, and especially the mobility of the hole-transporting material (HTM) and electron-transporting material (ETM) at –40 °C decreases from 1.16 × 10<jats:sup>−6</jats:sup> cm<jats:sup>2</jats:sup>/V⋅s and 2.60 × 10<jats:sup>−4</jats:sup> cm<jats:sup>2</jats:sup>/V⋅s to 6.91 × 10<jats:sup>−9</jats:sup> cm<jats:sup>2</jats:sup>/V⋅s and 1.44 × 10<jats:sup>−5</jats:sup> cm<jats:sup>2</jats:sup>/V⋅s, respectively. Indeed, the temperature affects differently on the mobilities of HTM and ETM, which favors unbalanced charge-carrier transport and recombination in OLEDs, thereby leading to the maximum current efficiency decreased from 6.46 cd⋅A<jats:sup>−1</jats:sup> at 25 °C to 2.74 cd⋅A<jats:sup>−1</jats:sup> at –40 °C. In addition, blue fluorescent OLED at –20 °C has an above 56% lifetime improvement (time to 80% of the initial luminance) over the reference device at room temperature, which is attributed to efficiently dissipating heat generated inside the device by the low-temperature environment.</jats:p>

<jats:p>Lateral heterogeneity of a cell membrane, including the formation of lipid raft-like clusters and the inter-leaflet coupling of specific phase domains, is crucial for cellular functions such as membrane trafficking and transmembrane signaling. However, the wide diversity in lipid species and the consequent complexity in lipid–lipid interplays hinder our understanding of the underlying mechanism. In this work, with coarse-grained molecular dynamics simulations, the effect of lipid tail structures on the phase behavior of a model ternary lipid membrane was systematically explored. A serial of 27 lipid membrane systems consisting of saturated, unsaturated lipids, and cholesterol (Chol) molecules, at a fixed molar ratio of 4:4:2 while varying in lipid structures including tail length, unsaturation degree, and/or position of unsaturated atoms, were constructed. These structural factors were found to exert sophisticated influences on packing states of the constituent molecules, especially Chol, in a bilayer, and modulate the complicated entropy–enthalpy competition of the membrane system accordingly. Specifically, an appropriate difference in effective tail length and distinct feature of the tail ends between the saturated and unsaturated lipid compositions promised an enhanced phase separation of the membrane into the Chol-rich Lo and Chol-poor Ld phase domains, with a full inter-leaflet coupling of each domain. Our results provide insights into the lipid organizations and segregations of the cellular plasma membrane.</jats:p>

<jats:p>Many animals can detect the multi-frequency signals from their external surroundings. The understanding for underlying mechanism of signal detection can apply the theory of vibrational resonance, in which the moderate high frequency driving can maximize the nonlinear system’s response to the low frequency subthreshold signal. In this work, we study the roles of chemical autapse on the vibrational resonance in a single neuron for signal detection. We reveal that the vibrational resonance is strengthened significantly by the inhibitory autapse in the neuron, while it is weakened typically by the excitatory autapse. It is generally believed that the inhibitory synapse has a suppressive effect in neuronal dynamics. However, we find that the detection of the neuron to the low frequency subthreshold signal can be improved greatly by the inhibitory autapse. Our finding indicates that the inhibitory synapse may act constructively on the detection of weak signal in the brain and neuronal system.</jats:p>

<jats:p>The dielectric properties of nucleated erythrocytes from bullfrogs were measured in a frequency range of 10 kHz–110 MHz. The complex permittivity (<jats:italic>ε</jats:italic> <jats:sup>*</jats:sup>), complex conductivity (<jats:italic>κ</jats:italic> <jats:sup>*</jats:sup>), and complex resistivity (<jats:italic>ρ</jats:italic> <jats:sup>*</jats:sup>) were analyzed and compared in the 10.63% to 37.58% haematocrit (Hct) range. The relaxation behavior, the passive electrical properties, and the cellular structure parameters, including the cell membrane, the cytoplasm, the nuclear membrane, and the nucleoplasm of the nucleated erythrocyte suspensions were investigated. The method used is based on the binomial Cole–Cole equation and the double spherical-shell physical models. Upon the elimination of the electrode polarization effect, two definite relaxations related to the interfacial polarization are observed on low- and high-frequency dispersions. The permittivity values and the characteristic frequency values differ by one order of magnitude: the low-frequency relaxation increments [Δ <jats:italic>ε</jats:italic> <jats:sub>1</jats:sub> = (5.63 ± 1.43)× 10<jats:sup>3</jats:sup>] and the characteristic frequency [<jats:italic>f</jats:italic> <jats:sub>c1</jats:sub> = (297.06 ± 14.48) kHz] derived from the cell membrane, the high-frequency relaxation increments [Δ <jats:italic>ε</jats:italic> <jats:sub>2</jats:sub> = (5.21 ± 1.20) × 10<jats:sup>2</jats:sup>] and the characteristic frequency [<jats:italic>f</jats:italic> <jats:sub>c2</jats:sub> = (3.73 ± 0.06) MHz] derived from the dielectric response to the external electric field of the nuclear membrane, respectively. Moreover, the other core dielectric parameters, such as the relative permittivity of the cell membrane [<jats:italic>ε</jats:italic> <jats:sub>m</jats:sub> = (7.57 ± 0.38)] and the nuclear envelope [<jats:italic>ε</jats:italic> <jats:sub>ne</jats:sub> = (23.59 ± 4.39)], the conductivity of the cytoplasm (hemoglobin, <jats:italic>κ</jats:italic> <jats:sub>Hb</jats:sub> = (0.50 ± 0.13) S/m] and the nuclear endoplasm [<jats:italic>κ</jats:italic> <jats:sub>np</jats:sub> = (2.56 ± 0.75) S/m], and the capacitance of the bilayer membranes [<jats:italic>C</jats:italic> <jats:sub>m</jats:sub>: (0.84 ± 0.04) μF/cm<jats:sup>2</jats:sup>], and <jats:italic>C</jats:italic> <jats:sub>ne</jats:sub>: (0.52 ± 0.10) μF/cm<jats:sup>2</jats:sup>] were also accurately and reliably measured. This work presents a feasible method to evaluate the dielectric parameters and the cellular structure of the erythrocytes of bullfrogs. Moreover, it paves the way for new studies on the haematology of frogs and the detection of nucleated cells via dielectric impedance spectroscopy.</jats:p>

<jats:p>A filtered ghost imaging (GI) protocol is proposed that enables the Rayleigh diffraction limit to be exceeded in an intensity correlation system; a super-resolution reconstructed image is achieved by low-pass filtering of the measured intensities. In a lensless GI experiment performed with spatial bandpass filtering, the spatial resolution can exceed the Rayleigh diffraction bound by more than a factor of 10. The resolution depends on the bandwidth of the filter, and the relationship between the two is investigated and discussed. In combination with compressed sensing programming, not only high resolution can be maintained but also image quality can be improved, while a much lower sampling number is sufficient.</jats:p>

<jats:p>Flexible Cu<jats:sub>2</jats:sub>ZnSn(S,Se)<jats:sub>4</jats:sub> (CZTSSe) solar cells show great potential applications due to low-cost, nontoxicity, and stability. The device performances under an especial open circuit voltage (<jats:italic>V</jats:italic> <jats:sub>OC</jats:sub>) are limited by the defect recombination of CZTSSe/CdS heterojunction interface. We improve the deposition technique to obtain compact CdS layers without any pinholes for flexible CZTSSe solar cells on Mo foils. The efficiency of the device is improved from 5.7% to 6.86% by highquality junction interface. Furthermore, aiming at the S loss of CdS film, the S source concentration in deposition process is investigated to passivate the defects and improve the CdS film quality. The flexible Mo-foil-based CZTSSe solar cells are obtained to possess a 9.05% efficiency with a <jats:italic>V</jats:italic> <jats:sub>OC</jats:sub> of 0.44 V at an optimized S source concentration of 0.68 mol/L. Systematic physical measurements indicate that the S source control can effectively suppress the interface recombination and reduce the <jats:italic>V</jats:italic> <jats:sub>OC</jats:sub> deficit. For the CZTSSe device bending characteristics, the device efficiency is almost constant after 1000 bends, manifesting that the CZTSSe device has an excellent mechanical flexibility. The effective improvement strategy of CdS deposition is expected to provide a new perspective for promoting the conversion efficiency of CZTSSe solar cells.</jats:p>