Electrons In Layer Research Articles

Buried interface passivation with bis(3-aminopyrid-2-yl) sulfide for carbon-based perovskite solar cells

Electron layer defects are one of the key factors affecting the performances of perovskite solar cells (PSCs). In this work, high efficiency for PSCs was achieved by using bis(3,3-2-aminopyridine) sulfide...

Controlled Surface Polarity and Crystallinity of Gallium Nitride on Si (111) Using Atomic Layer Deposition for Selective Wet-Etch and STEM Analysis

Gallium nitride (GaN) has gained interest as photoelectronic materials and a buffer layer for other III-V deposition with applications in power electronics operated at high voltage and high temperature. The crystallinity and polarity of III-V semiconductors have a key role for the passivation layers on microLED, the formation of 2D electron gasses in high electron mobility transistors, and for templating growth of piezoelectric materials. The atomic layer annealing (ALA) was reported to improve the crystallinity of the III-V compounds (aluminum nitride) at low temperatures as compared to the conventional thermal ALD. In ALA, a pulse of ion bombardment is added to each ALD cycle to ensure polycrystalline film formation at low temperature. Polycrystalline GaN has been deposited by ALA at low temperatures even on amorphous substrates, but the polarity was not reported. The selective wet-etch process has several advantages for the III-V semiconductor device integration since the conventional plasma ion etching process is expensive, complicated, and leads to the surface damage by reactive plasma ion. The GaN surface polarity (N-polar or metal-polar) on sapphire was selectively etched by aqueous KOH solution. However, electrochemical etching study on the polarity of GaN ALD films has not yet been studied as types of ALD process. Figure 1a and 1b show the process parameter switching diagram for the GaN thermal ALD and GaN ALA processes, respectively. The chemical compositions of ALA and ALD GaN on Si were estimated by in-situ AES as shown in Figure 1c. Lower O content (below 3.3 at. %) and higher N/Ga atomic ratio were observed in the ALA GaN on Si (111) as compared to the thermal ALD GaN film (4.6 at. %). Figure 1d shows that the intensity of GaN (002) XRD pattern in thermal ALD GaN on Si was greatly improved in the GaN stacks (GaN thermal ALD/ALA/Si) with an ALA GaN buffer layer. The electrochemical behavior of the GaN ALD films was studied to elucidate the impact of surface polarity on selective KOH wet-etch. The linear sweep voltammograms of GaN thermal ALD and GaN ALA films in 1 M KOH solution were shown in Figure 1e. The applied potential was swept from zero (vs. Normal Hydrogen Electrode) to positive 3.7 V. The peak of current density at ~1.7 V was observed in the voltammogram of the GaN ALA film (N-polar), suggesting the occurrence of etching reaction by the dissolution and formation via the equations in Figure 1f. On the other hand, the absence of current density peak in the GaN thermal ALD film (Ga-polar) could suggest the unfavorable etching reaction as compared to the GaN ALA film. Figure 2a and 2b shows the HAADF-STEM images of ALD GaN on Si demonstrate highly ordered 3 nm x 5 nm ALD GaN layers with bright and dark regions. The circles of bright regions and the center of dark regions represent Ga atoms and tunnel points (empty element), respectively. The GaN polarity could be determined by drawing triangles connecting adjacent three tunnel points without the interruption of Ga. Using this method, upward triangles were obtained in the HAADF-STEM image (Figure 2a), suggesting the formation of N-polar GaN layers during the ALA GaN process on Si. Conversely, downward triangles from the STEM image of thermal ALD GaN /ALA GaN /Si (Figure 2b) suggested Ga-polar GaN during GaN thermal ALD process. The inset figures show the top-view SEM image of selectively wet-etched (30 min, 20 wt.% KOH (aq)) GaN films. The etched surface on the ALA GaN layers (inset of Figure 2a) indicated N-polar GaN surface. The inset SEM image in Figure 2b shows a nearly unchanged GaN surface in thermal ALD GaN /ALA GaN / Si is consistent with the Ga-polar GaN surface. These observations are in good agreement with the HAADF-STEM images.The data is consistent with being able to control the polarity of GaN by switching between thermal ALD and ALA. The ion bombardment in ALA promotes N-polar GaN while thermal ALD promotes metal polar GaN. This allows the facile formation of both electron and hole gas layers between ALA and ALD GaN. Figure 1

Tafel Slope Estimation of Electronic Resistance Laden Catalyst Layer in PEMFC Using Polarization Curve Correction Methodology

The higher cost of PEMFC systems proves to be a major bottleneck in their adoption. Platinum being a costly material (used as a catalyst in PEMFC) contributes significantly (42%) to the overall cost of the PEMFC stack.1 The majority of the Platinum catalyst is loaded on the cathode side due to the slow nature of the oxygen reduction reaction (10-8 A/cm2 for ORR). Hence, alternative options for the cathode catalysts are being persued as a potential alternative for platinum metal group-free (PGM-free) catalyst to improve the economics of such systems.2 The sluggish kinetics of PGM-free catalysts requires much thicker CCL (compared to the Pt catalyst) to have comparable fuel cell performance at low currents.3 Thicker CCLs will lead to poorer protonic and electronic conduction.Voltage breakdown analysis from the polarization curve (Cell voltage vs Current density) is quite common in literature and is used to gather selective insights into the working of PEMFC. Work by Neyerlin et al. mathematically quantified the effect of proton conduction on the polarization curve.4 In their work, they also proposed a systematic correction methodology to retrieve the Tafel Slope by correcting the polarization curve for proton conduction and other ohmic resistances (membrane and external resistances). It is to be noted that the correction approach presented by Neyerlin et al. works well for systems with neglible electronic resistance (since it was designed for Platinum based CCLs which are thin and highly electronically conducting). However, for PGM-free catalysts which are thicker and poorer electronic conductors than Pt-based CCLs, contribution from both electronic and protonic conduction will affect the polarization curve.We propose a method to correct the polarization curve in PEMFC for effective total transport loss (both electronic and protonic) to get back the Tafel slope of the oxygen reduction reaction on the cathode side. Further, we demonstrate the approach for two different CCLs made with commercially available catalysts named PMF and in-house developed catalysts named HM (presented in Li et al)5. Note that this work assumes that the mass transport losses are not present (which is reasonable assumption in H2/O2 system) and assumes that gas cross-over effects (due to the crossing of gases through the membrane to the other side of the PEMFC) are not current dependent during fuel cell operations.Figure 1 shows the correction steps for hypothetical data generated from bvp-5C simulations (for an electronic resistance laden catalyst layer) which is treated as an actual polarization curve (orange curve represented as Ecell). In this work, we develop a semi-analytical expression for effective transport loss (represented by cyan shaded in Figure 1) which can be used to correct the (corrected for membrane proton conduction and other external electronic resistance referred to as Rmem+ext) to obtain a curve which, when fitted with the Tafel kinetics equation gives the value the Tafel slope of that CCL. References S. T. Thompson et al., Solid State Ion., 319, 68–76 (2018).Lefèvre Michel, Proietti Eric, Jaouen Frédéric, and Dodelet Jean-Pol, Science (1979), 324, 67–71 (2009).F. Jaouen et al., Johnson Matthey Technology Review, 62, 231–255 (2018).K. C. Neyerlin, W. Gu, J. Jorne, A. Clark, and H. A. Gasteiger, J. Electrochem. Soc., 154, B279 (2007).Y.-S. Li, D. Menga, H. A. Gasteiger, and B. Suthar, J. Electrochem. Soc., 170, 094503 (2023). Figure 1

Shrink effects on nanoscale MOS capacitor in visible and NIR spectral Ranges

This research explores the influence of visible and near-infrared light on the electrical characteristics of nanoscale MOS capacitors, examining the effects of light intensity and spectral composition. Photon absorption within the device stimulates an enhancement of the inversion electron layer. A spectral analysis encompassing the ultraviolet to near-infrared range (400–1100 nm) is presented. Research on nanoscale devices of this nature can contribute to a profound understanding of fundamental light-matter interactions at the atomic and molecular scale. This knowledge can pave the way for the development of novel optoelectronic coupled devices, which combine light trigger and electronic functionalities. These devices, when integrated in Photonics Integrated Circuits (PICs), could have applications in areas such as solar cells, photodetectors, and future ultrasmall electronic components.

Transport in a Two-Channel Nanotransistor Device with Lateral Resonant Tunneling.

We study field effect nanotransistor devices in the Si/SiO2 material system which are based on lateral resonant tunneling between two parallel conduction channels. After introducing a simple piecewise linear potential model, we calculate the quantum transport properties in the R-matrix approach. In the transfer characteristics, we find a narrow resonant tunneling peak around zero control voltage. Such a narrow resonant tunneling peak allows one to switch the drain current with small control voltages, thus opening the way to low-energy applications. In contrast to similar double electron layer tunneling transistors that have been studied previously in III-V material systems with much larger channel lengths, the resonant tunneling peak in the drain current is found to persist at room temperature. We employ the R-matrix method in an effective approximation for planar systems and compare the analytical results with full numerical calculations. This provides a basic understanding of the inner processes pertaining to lateral tunneling transport.

Ixora Coccinea Extract for Biosynthesis of Titanium Dioxide Nanoparticles: A Precursor for Organic Electronics

This study explores the synthesis, characterization, and evaluation of titanium dioxide nanoparticles (TiO2NPs) as a precursor for the electron transport layer in organic electronics. Traditional physical and chemical synthesis methods are not environmentally friendly or economical, due to the use of toxic chemicals and high energy. However, biosynthesis offers a low-cost, eco-friendly alternative. The synthesized NPs were characterized using various techniques, including X-ray diffraction technique, transmission electron microscopy, scanning electron microscopy, Fourier Transform Infra-red microscopy, electron dispersive X-ray, and UV-visible spectroscopy with a four-point probe equipped with Keithley2400 source meter. Results showed high crystallinity and a band gap energy of 4.02 eV. Electrical properties show sheet resistance, resistivity and conductivity as 67.22 x 106 Ω, 1.71 x 106 Ωm-1 and 0.585 x-6 Sm-1 respectively which were promising, with better photovoltaic characteristics than pure titanium dioxide. These properties suggest potential applications as an electron transport layer for solar cell technology.

ALTERNATIVE EXPLANATION OF FILLING THE ELECTRONIC LAYERS OF ATOMS OF CHEMICAL ELEMENTS

The article provides a new approach to the formation of periods in Mendeleev's periodic system. Reconfiguration of the periods in the Mendeleev table using the newly proposed formula and the newly proposed quantum states for the outer electron shells of atoms of chemical elements is proposed. Purpose of work: Further development of the alternative theory of creation of electronic shells of atoms of chemical elements in D.I.Mendeleev's table. Results and discussions. The following order of formation of electron layers is proposed: principle quantum number (n), then the quantum state of the electrons forming the electronic configuration of the subperiods (first and second), and only then the remaining quantum orbitals (s, d, f and p). First and second new quantum states and a new formula for calculating the number of electrons in the outer electron shell of element periods and subperiods were proposed. The new level of electronic counting (II) and the new quantum number proposed by us allow to change the understanding of the internal structure of chemical elements without changing the general appearance and order of arrangement of chemical elements in D.I.Mendeleev's table itself, and therefore its contents. An important advantage of the proposed alternative model is that it takes into account and relies on already known, classical data for most of its main operational characteristics and is an extension of this important topic for classical chemistry theory. Therefore, the change in the number of periods, the introduction of a new quantum number in the form of D.I.Mendeleev's table, outwardly it does not differ much, but requires the necessary additional explanation. Concept. The proposed alternative approach to the structure and electronic structure of atomic shells of chemical elements in the periods and groups of D.I.Mendeleev's periodic system was recently developed by the authors and has good prospects for development primarily in the following directions: - identification of possible patterns of changes in the characteristics of chemical and physical properties of elements; - development of an accompanying model of the electronic structure of electronic shells of atoms of chemical elements of the proposed alternative model.

Combined experimental and density functional theory approaches to address different mechanisms of nitrogen and sulfur doping on the enhancement of capacitive performance of hierarchical porous biochars

Activated carbon derived from biomass as hierarchical porous biochars (HPB) has been developed as electrode materials for supercapacitors. Nitrogen is known as the doping element that enhances quantum capacitance, but the mechanisms of sulfur doping on the quantum capacitance enhancement remain ambiguous. In this study, conventional approaches to assess the characteristics and capacitive performance of biochars were combined with density functional theory (DFT) calculations to assess different mechanisms of nitrogen and sulfur doping. The Bbiochar samples were prepared from the pyrolyzed fish bone powder at 800 °C without additional doping possessed a specific capacitance of 240 F g−1 at 1 A/g within 1 M H2SO4. Interestingly, additional nitrogen doping through urea mixing and additional sulfur doping through thiosulfate mixing prior to the pyrolysis enhanced the specific capacitance of biochar samples to exceed 400 F g−1 under the same condition. The urea mixed sample possessed low porosity but high charge transfer resistance, while the thiosulfate mixed sample possessed high porosity but low charge transfer resistance. The different underlying mechanisms were discussed through DFT calculations on graphene models designed based on the x-ray photoelectron spectroscopy (XPS) results. Nitrogen-doped configurations with topological defects mainly stored charge at the dangling atoms and possessed a relatively high quantum capacitance. Meanwhile, doped configurations of oxidized sulfur groups required relatively low formation energy and possessed large bond dipoles, corresponding to larger pore size and surface area of the thiosulfate mixed biochars. Understanding the contrary between effects of nitrogen and sulfur doping could resolve the bottleneck on enhancing the performance of electronic double layer supercapacitors.

Cephalopods' Skin-Inspired Design of Nanoscale Electronic Transport Layers for Adaptive Electrochromic Tuning.

Cephalopods can change their skin color by using high-speed electron transduction among receptors, neural networks, and pigmentary effectors. However, it remains challenging to realize a neuroelectrical transmission system like that found in cephalopods, where electrons/ions transmit on nanoscale, which is crucial for fast adaptive electrochromic tuning. Inspired by that, hereby an ideal, rapidly responsive, and multicolor electrochromic biomimetic skin is introduced. Specifically, the biomimetic skin comprises W18O49 nanowires (NWs)that are either colorless or blue, Au nanoparticles@polyaniline (Au NPs@PANI) ranging from green to pink, and a flexible conductive substrate. As the applied voltage changes from 0.4 V to -0.7 V and back to 0V, the color of the biomimetic skin transforms from green to blue and ultimately to pink. This color change is attributed to the electrically induced redox reaction of Au NPs@PANI and W18O49 NWs, triggered by the transfer of electrons and ions. Furthermore, the high versatility and adaptability of electrical stimulus enable the creation of a highly interactive electrochromic biomimetic skin system through the integration of sensitive acoustic sensors, providing a perfect environment-responsive platform. This work provides a biomimetic multicolor electrochromic skin that depends on electron/ion transfer on nanoscale, expands potential uses for camouflage skin.

A fast-switching and ultra low-loss snapback-free reverse-conducting SOI-LIGBT with Adjustable Carrier Technology

A snapback-free Reverse-Conduction Silicon On Insulator Lateral Insulate Gate Bipolar Transistor (RC SOI-LIGBT) with Adjustable Carrier Technology (ACT LIGBT) is proposed in this paper. ACT LIGBT adds Semi-Insulating Polycrystalline Silicon (SIPOS) material on the extended gate dielectric, and introduces the potential of the surface SIPOS into the P-type drift region (P-Drift) through SiO2 trenches. ACT LIGBT generates the inversion layer of electrons in the P-Drift due to the linear potential distribution brought by the high resistance characteristic of SIPOS, resulting in the adjustment of the number of electrons and holes, and forming the technology of ACT. Additionally, ACT LIGBT adds a hole extraction path during it turned off. Meanwhile, compared to SSA LIGBT, ACT LIGBT optimized the BV (700V) by 34 %, while also optimizing the Von (1.69V) by 25 %, turn-off time (toff = 12ns) by 92 %, turn-off loss (Eoff = 0.69 mJ/cm2) by 79 %, and reverse recovery charge (Qrr = 32.98 μC/cm2) by 32.5 %, ultimately achieving a better compromise relationship among BV, Von, toff, Eoff, and Qrr.

Construction of “island-bridge” microstructured conductive coating for enhanced impedance response of organohydrogel strain sensor

Flexible conductive hydrogels (CHs) have received widespread attention in the field of wearable strain sensor, electronic skin, and artificial intelligence owing to their excellent stretchability, biocompatibility, and real-time sensing performance. However, it still remains a critical challenge to design and construct the satisfactory wearable strain sensor integrated with high sensitivity, wide sensing range, and environmental stability, especially at extreme temperatures. Herein, ionic conductive polyacrylamide/sodium alginate nanocomposite organohydrogel anchored with electronic conductive “island-bridge” microstructured carbon nanotubes (CNTs) conformal coating was designed and fabricated for high-performance strain sensor, of which the existence of “island-bridge” microstructured electronic conductive layer and its special structure evolution upon external stretching can significantly enhance the alternating current impedance response behavior of the sensor, featuring with a high sensitivity of 76.54 at 600 % strain, wide sensing range (0–600 % strain), fast responsiveness (110 ms), extremely low detection limit (0.1 %), and favorable stability and reproducibility of over 3200 cycles. Meanwhile, the resultant organohydrogel strain sensor can precisely detect and differentiate complicated human activities even at the environment temperatures of −30 °C and 50 °C, opening a promising avenue for next-generation smart wearable electronics.

High density ferroelectric charges enabled droplet vibration nanogenerator with extraordinary output

Droplet vibration nanogenerator is a promising technology that can transform kinetic energy into electric energy. In this paper, a vibration droplet nanogenerator based on lead zirconate titanate (PZT) (PZT-VDNG) is proposed, which utilizes the change in double electron layer area at the droplet/PZT interface, hence an extraordinary charge variation, induced by mechanical vibrations. Our approach innovatively combines a high fixed surface charge density with ionic solutions to significantly enhance energy conversion efficiency. A theoretical model of the PZT-VDNG is established, showing excellent consistence with the experimental results. The energy conversion efficiency and its correlation with the materials involved, device structure and circuits used, are investigated in detail. Under the optimal conditions of a vibration frequency of 5 Hz, an amplitude of 2 mm, and a droplet size of 40 μL, a short-circuit current output of 31.43 μA and an open-circuit voltage of 1.5 V are obtained by a single vibration of a droplet, respectively, 111 and 37.5 times larger as compared to those from a VDNG with PTFE polymer layer. This marks a significant leap in the efficiency and potential applications of vibration nanogenerators.

A fast-switching low-loss field-stop IGBT with dual control gate of SIPOS material

A fast-switching low-loss field-stop insulated gate bipolar transistor with a dual control gate (DIGBT) of a semi-insulating polycrytalline silicon (SIPOS) material is proposed in this paper. Because the SIPOS has uniform high resistance, it has an approximate linear electric potential distribution. When DIGBT conducts, the higher electric potential on SIPOS causes the P-type drift region (P-drift) to generate an inversion layer of electrons, adjusting the number of carriers and making the generation of non-equilibrium carriers no longer dependent on the doping concentration in P-drift (Nd) but on the electric potential distribution on SIPOS. Therefore, it can solve the contradiction among the breakdown voltage, forward voltage drop [VCE(sat)], turn-off time (toff), and turn-off loss (Eoff) caused by the Nd. Through Technology Computer Aided Design (TCAD) simulation, the VCE(sat) of DIGBT is 30.6% lower than that of SJFS IGBT. Meanwhile, DIGBT reduces the toff by 62.8% while reducing the Eoff by 83.0% compared to SJFS IGBT. In addition, the static latch-up I–V and the forward biased safe operating area of the DIGBT have been significantly improved. This paper adjusts the number of carriers through the characteristics of SIPOS material, enabling the above-mentioned physical phenomena to be applied in insulated gate bipolar transistor power devices and achieving device performance breakthroughs.

Topological Fermi-arc surface state covered by floating electrons on a two-dimensional electride

Two-dimensional electrides can acquire topologically non-trivial phases due to intriguing interplay between the cationic atomic layers and anionic electron layers. However, experimental evidence of topological surface states has yet to be verified. Here, via angle-resolved photoemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM), we probe the magnetic Weyl states of the ferromagnetic electride [Gd2C]2+·2e−. In particular, the presence of Weyl cones and Fermi-arc states is demonstrated through photon energy-dependent ARPES measurements, agreeing with theoretical band structure calculations. Notably, the STM measurements reveal that the Fermi-arc states exist underneath a floating quantum electron liquid on the top Gd layer, forming double-stacked surface states in a heterostructure. Our work thus not only unveils the non-trivial topology of the [Gd2C]2+·2e− electride but also realizes a surface heterostructure that can host phenomena distinct from the bulk.

Understanding the Effects of Anode Catalyst Conductivity and Loading on Catalyst Layer Utilization and Performance for Anion Exchange Membrane Water Electrolysis.

Anion exchange membrane water electrolysis (AEMWE) is a promising technology to produce hydrogen from low-cost, renewable power sources. Recently, the efficiency and durability of AEMWE have improved significantly due to advances in the anion exchange polymers and catalysts. To achieve performances and lifetimes competitive with proton exchange membrane or liquid alkaline electrolyzers, however, improvements in the integration of materials into the membrane electrode assembly (MEA) are needed. In particular, the integration of the oxygen evolution reaction (OER) catalyst, ionomer, and transport layer in the anode catalyst layer has significant impacts on catalyst utilization and voltage losses due to the transport of gases, hydroxide ions, and electrons within the anode. This study investigates the effects of the properties of the OER catalyst and the catalyst layer morphology on performance. Using cross-sectional electron microscopy and in-plane conductivity measurements for four PGM-free catalysts, we determine the catalyst layer thickness, uniformity, and electronic conductivity and further use a transmission line model to relate these properties to the catalyst layer resistance and utilization. We find that increased loading is beneficial for catalysts with high electronic conductivity and uniform catalyst layers, resulting in up to 55% increase in current density at 2 V due to decreased kinetic and catalyst layer resistance losses, while for catalysts with lower conductivity and/or less uniform catalyst layers, there is minimal impact. This work provides important insights into the role of catalyst layer properties beyond intrinsic catalyst activity in AEMWE performance.

Research Progress on Controllable Absorption Properties of Rare Earth Element Doped Electromagnetic Wave Absorbing Materials†

Comprehensive SummaryThe utilization of rare earth (RE) elements is pivotal in wave absorption. In particular cases, RE group elements manifesting unique 4f electron layer structures are doped as impurities into certain materials, which is a practical and reliable method for regulating these materials' magnetic and electrical properties. Moreover, ferrites and metal‐organic frameworks (MOFs), standing out among conventional and emerging wave‐absorbing materials, can achieve significantly enhanced wave absorption through RE doping or substitution. Numerous scholars have dedicated massive research over a substantially long time to explore the utilization of RE elements to reinforce the absorption of these two materials. Therefore, consolidating and summarizing such efforts are crucial and necessary. This review aims to clarify the underlined mechanism of electromagnetic wave (EMW) absorption and elaborate on the impact of RE doping by providing a comprehensive overview of recent progress in ferrites and MOFs dopped with RE elements. Finally, the limitations associated with RE doping in such materials are delineated, and the upcoming prospects for its application are highlighted. Key ScientistsIn 1947, J. A. Marinky et al. obtained promethium from uranium fission products. From the isolates of yttrium soil in 1794 to the discovery of promethium in 1947, it took more than 150 years. In 1975, Guangxian Xu found that the rare earth solvent extraction system has the basic "constant mixed extraction ratio" rule. In 1984, the theory of "one‐cavity multi‐mode" was proposed by Weigan Lin to improve the electromagnetic wave theory further and develop the theory of absorbing materials. In 1995, Omar M. Yaghi synthesized the first MOFs in history, and since then, they have been widely used in gas adsorption and separation and other fields because of their large specific surface area and adjustable pore structure. In recent years, various functional materials based on MOFS‐derived carbon have been studied endlessly. Masato Sagawa, known for inventing NdFeB magnets, won the "28th Japan Prize" in 2012. In recent years, Renchao Che has promoted the development of interface theory and magnetic theory in the field of wave absorption. In addition, Jiurong Liu is committed to developing various wave‐absorbing materials and the respective theoretical research and continues to promote the development of wave‐absorbing materials to "thin, light, wide and strong".

Silicon Nanoribbon Arrays Based Printed Multifunctional Flexible Photovoltaic Microcells

AbstractThe photovoltaic devices offer promising eco‐friendly solution for self‐powered flexible electronics. However, their fabrication on flexible substrate is not easy due to mismatches between the requirements of conventional microfabrication and the thermal, and mechanical features of the substrates. Herein, direct roll printed nanoscale photoactive electronic layers are presented, which are further processed to develop ≈315 µm2 sized miniaturized photovoltaic microcells. Using a set of 32 microcells, connected in parallel configuration, indoor light harvesting is shown at a maximum power density of ≈10 µW cm−2 under white LED illumination. Further, the dual functionality of developed microcells i.e., energy harvesting as well as wideband photodetection is demonstrated. As self‐powered photo sensors the developed photovoltaic microcells exhibit distinctive photo responses under white LED‐UV (365 nm)‐ NIR (850 nm) light illumination, with exceptionally high‐speed response (rise time τRise = 205 µs and fall time τFall = 2000 µs), and a peak responsivity of 2.48 A W−1 to UV light at zero bias voltage. The presented results show the potential usage of printed multifunctional photovoltaic microcells in a wide variety of applications such as self‐powered wearable and flexible electronic systems for health monitoring and indoor robotics.

Composite polymer films with semiconductor nanocrystals for organic electronics and optoelectronics

Organic materials and, in particular, polymer films enhanced with certain nanocrystals have a potential for wide application in electronics and optoelectronics due to their organic flexibility, lightweight, simple integration, affordable manufacturing cost, and low environmental impact of their production. The purpose of this research is to investigate the electrical properties of polymer-based composite films containing Cd1–xCuxS nanocrystals in order to determine their prospects for use as conductive layers in organic electronics and optoelectronics. The paper contains a detailed description of the synthesis method of hybrid nanocomposite films based on peroxide reactive copolymer (PRC) with Cd1–xCuxS nanocrystals. The defect structure of the films is studied by analyzing the photoluminescence spectra. Current-voltage characteristics of the films with different Cd and Cu contents in the Cd1–xCuxS nanocrystals embedded into the polymer matrix, deposited on glass substrates are measured in the dark and under light illumination. The film conductivity is found to increase with the Cu content in the Cd1–xCuxS nanocrystals. The carrier transport corresponds to the Ohm law at low voltages and the space charge limited current (SCLC) or Poole–Frenkel mechanisms at higher ones. The conductivity of the polymer-based hybrid nanocomposite films has a weak dependence on the intensity of light illumination. The explanation of the obtained experimental results is proposed.

Generation of attosecond gigawatt soft x-ray pulses through coherent Thomson backscattering.

Collision between relativistic electron sheets and counterpropagating laser pulses is recognized as a promising way to produce intense attosecond x rays through coherent Thomson backscattering (TBS). In a double-layer scheme, the electrons in an ultrathin solid foil are first pushed out by an intense laser driver and then interact with the laser reflected off a second foil to form a high-density relativistic electron sheet with vanishing transverse momentum. However, the repulsion between these concentrated electrons can increase the thickness of the layer, reducing both its density and subsequently the coherent TBS. Here, we present a systematic study on the evolution of the flying electron layer and find that its resulting thickness is determined by the interplay between the intrinsic space-charge expansion and the velocity compression induced by the drive laser. How the laser driver, the target areal density, the reflector, and the collision laser intensity affect the properties of the produced x rays is explored. Multidimensional particle-in-cell simulations indicate that employing this scheme in the nonlinear regime has the potential to stably produce soft x rays with several gigawatt peak power in hundreds of terawatt ultrafast laser facilities. The pulse duration can be tuned to tens of attoseconds. This compact and intense attosecond x-ray source may have broad applications in attosecond science.

Cetyltrimethylammonium bromide induced generation of highly (200) planes-exposed LiMnPO4 nanosheets coated by nitrogen-doped carbon for high-performance batteries

A simple solvothermal method is designed to synthesize LiMnPO4/N-doped C composites with core-shell structure using cetyltrimethylammonium bromide (CTAB) as surfactant and nitrogen source. The effectively growth of (200) planes and nitrogen-doped carbon layer coated LiMnPO4 nanosheets are obtained. The doped nitrogen induces the generation of active defect sites, which changes the cell electronic layer structure, and improve the electronic conductivity and diffusion rate of lithium ions. Thus, the electrochemical performance is beneficial from the synergistic effect of specific planar exposure and particular interfacial modifications. The optimal sample shows the supreme electrochemical performance at 0.1C, 1C and 5C with capacities of 159.1, 122.6 and 83.1 mAh g−1, respectively. The capacity retention can achieve 98 % even after 200 cycles at 1C. This work provides a simple but effective strategy to design polyanion cathode materials with enhanced electrochemical performance.