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In this study we fabricated highly oxidized graphene oxides (GO) to reduce the optical bulk absorption, and to achieve a low-loss GO/silicon hybrid optical waveguide. The highly oxidized GO was fabricated using triple amount of oxidants and elongated oxidizing time via a modified Hummers’ method, together with post ozone treatment to effectively break down the C = C pi-conjugation network. The high oxidation degrees of GO were confirmed by a wide interlayer spacing (1.26 nm) in XRD patterns and a high fraction of oxygenated carbon (61.57%) observed in XPS spectra. Integrating a GO thin film on top of a silicon ring resonator revealed an extra optical loss of 1.2 dB/cm, while this value reduced to 0.8 dB/cm in a GO grating covered silicon strip waveguide. The resulting GO/silicon hybrid waveguide grating provided an extinction ratio of up to 35 dB at Bragg wavelength. We further demonstrated GO/silicon hybrid waveguide moire gratings to provide dual stopbands with a controllable stopband interval from 2.5 to 20 nm. All results validate the promising optical properties of such GO material for low-loss heterogeneous integration on silicon-on-insulator.

The development of quasi-two-dimensional (2D) Ruddlesden-Popper phase perovskite solar cells (PSCs) has greatly improved the stability of devices. However, the presence of quantum confinement effects and insulating spacer cations in 2D perovskite films will widen the bandgap and hinder carrier transportation, thereby discounting the efficiency of 2D PSCs. Here, a quantum well reversely graded structure is introduced into FA-MA mixed 2D perovskite films via isopropanol washing. 2D perovskites, mainly the n=2 phase, are concentrated at the top of the film. We find that half of the spacer cations are washed away by isopropanol, and the average n-value evolves from 5 in the precursor to about 18 in the final annealed film. As a result, the quantum confinement effect inside the film is weakened, and the external quantum efficiency response wavelength is extended to 812 nm. More importantly, the film shows out-of-plane orientation, enlarged apparent grain size (688 nm), and a long carrier lifetime (936 ns). A record-high power conversion efficiency (PCE) of 20.12% is achieved. The unencapsulated device retains 98% of its initial PCE after aging at 30±5% relative humidity for 2000 h, and 96% after continuous working at maximum power point for 360 h. The fine regulation of quantum wells can be the answer to highly efficient and highly stable PSCs.

A new polymorph of β-cyclodextrin (β-CD) was produced by optical trapping with a 1064 nm continuous wave laser beam in D2O solution. Upon optical trapping of β-CD in unsaturated solutions, a single...

In this study, NbTaMoW medium-entropy alloy films were prepared using a cosputtering apparatus with four sputter guns. Pure-element targets were used for sputtering. The rotational speeds of the substrate holder (RS) were 1–30 rpm. Lower RS values resulted in the formed films exhibiting a multilayer stacked structure with a cyclical gradient concentration. The crystalline phases, mechanical properties, and oxidation behavior of the prepared NbTaMoW films were investigated. The uniformity of the prepared multilayered alloy films increased with the RS value. The monolithic NbTaMoW alloy films prepared at 30 rpm exhibited a single body-centered cubic (BCC) phase, hardness of 12.9 GPa, and Young's modulus of 278 GPa. The BCC phase evolved into a combination of multiple BCC phases when RS was

Zn4Sb3 has received interest for thermoelectric (TE) applications due to its low cost and low environmental impact. In this study, the Zn4Sb3 TE material was diffusion-bonded with multiple electrode materials of Ni, Ag, Cu, Pd and Ti for evaluation of the manufacturing of TE modules. Intermetallic compounds formed at the interfaces of the Zn4Sb3 diffusion couples, with Ni, Ag, Cu, and Pd exhibiting the selective reaction effect with zinc due to its high chemical affinity and low formation energies. Optimized bonding strengths of 6.6 to 8.2 MPa were achieved in Zn4Sb3 bonded with Ni, Ag and Cu materials at 350 °C. The Pd material could only bond at a temperature above 300 °C, and cracks presented after longer bonding times. As for the titanium, Zn4Sb3/Ti was successfully joined only at temperatures between 400 °C and 500 °C. It was observed that a rather thin TiSb2 intermetallic compound formed during the interfacial reactions between Zn4Sb3 and Ti, which grew significantly more slowly than those formed at the interfaces of Zn4Sb3 diffusion-coupled with Ni, Ag, Cu, and Pd metallic materials. Our results provide a reference for evaluating these common materials as suitable electrode and barrier layer candidates for utilizing the Zn4Sb3 TE material.

The spatial structure of the constrained space determines the polishing efficiency and polishing quality of the soft abrasive flow (SAF) polishing method. A basic SAF polishing mode with universal guiding significance was built in this paper, and the effect of the spatial structure of constrained space on SAF polishing was studied. Based on the coupling of the Euler’s multiphase flow model and the standard turbulence model, a SAF hydrodynamic model was constructed to obtain the dynamic characteristics of the abrasive flow in the constrained flow passage and to reveal how the key parameters determining the spatial structure of constrained space affect the SAF polishing. The results showed that the inlet angle of the constrained space determines the injection posture of the abrasive flow. When the inlet angle reduces, the impact between the abrasive flow and the constrained wall is weakened, and the distributions of fluid turbulent kinetic energy, dynamic pressure, and granular pressure tend to be uniform. The height of the constrained space is a key factor affecting the polishing efficiency of the SAF. As the height of the space decreases, the material removal rate is enhanced significantly, but the turbulent impact ability of the abrasive particles is weakened. The height of the constrained space should be set to near the critical value of turbulent flow variation. Based upon the simulation, an experimental platform for SAF polishing was built, and the accuracy of the simulation results and the effectiveness of the polishing method were verified by the comparative polishing experiments.

The remarkable electrical, thermal, mechanical, and optical properties of graphene and its derivative grapheme oxide have recently gained great importance, along with the large surface area and single-atoms thickness. In this respect, several techniques of synthesis such as chemical exfoliation, mechanical exfoliation, or chemical synthesis have been discovered. However, the development of graphene with fewer defects and on a large scale poses major challenges; therefore, it is increasingly necessary to produce it in large proportions with high quality. This paper reviews the top-down synthesis approach of graphene and its well-known derivative graphene oxide. Furthermore, characterization of graphene oxide nanomaterial is a critical component of the analysis. The characterization techniques employed to determine the quality, defects intensity, number of layers, and structures for graphene oxide nanomaterial at the atomic scale. This article focuses on the different involved characterization methodology for graphene oxide with their percentage utilization for the past 11 years. Additionally, reviewing all of the characterization literature for the last 11 years would be a difficult task. Therefore, the aim is to outline the existing state of graphene oxide by different characterization techniques and provide a comparative analysis based on their percentage utilization.

Hierarchically porous MOFs (HP-MOFs) present advantageous synergism of micro- and mesopore but challenging in synthetic control at molecular scale. Herein, we present the first example of reversible and controllable mesopore generation and renovation in a microporous MOF of HKUST-1 via synthetic manipulation at molecular scale. An ammonia-gas etching strategy is proposed to create mesopores in carboxylate-based microporous MOFs and thus produce HP-MOFs. Gas-phase etching ensures uniform mesopore formation inside the MOF crystals via plane-oriented cutting the carboxylate-metal bonds off without affecting the crystal size and morphology. The mesopore size is controlled by the etching temperature, while the mesopore volume could be tuned by adjusting etchant pressure. The generated mesopores could be renovated using MOF precursors solutions so that to achieve controllable mesopore generation/closure, and encapsulation of the adsorbed molecules. This work demonstrates a powerful protocol for precisely tailoring and tuning the properties of MOF materials at molecular scale.

Considering that SF $_6$ is a potent greenhouse gas, SF $_{6}$ /N $_2$ gas mixtures are preferred to serve as the insulating gas for its environmental friendliness and good insulation. Since heat transfer analysis is very useful for ascertaining the appropriate temperature rise range, which can ensure the safe operation and extension of remaining useful life of GIL, it is essential to study the thermal properties of SF $_{6}$ /N $_2$ gas mixtures. Nevertheless, very few studies investigate on the temperature field of SF $_{6}$ /N $_2$ gas mixtures under ideal conditions. To reflect the heat transfer characteristics accurately, in this paper, by using the finite-element method and multi-physics coupling, the heat transfer properties in the GIL is analyzed by using a three-dimensional (3-D) axisymmetric GIL model. By varying the SF $_{6}$ /N $_2$ mixing ratio and observing the corresponding heat transfer characteristics, the mapping between SF $_{6}$ /N $_2$ mixing ratio and the temperature rise is obtained by using the model. Furthermore, the mappings are studied under different gas pressures, line currents and ambient temperatures, which correspond to different real-life operating conditions. The proposed strategies can effectively give guidance of choosing proper SF $_{6}$ /N $_2$ mixing ratio for desired temperature rise, and thus having great values of practical applications.

The interchangeable operation of alkaline oxygen evolution and reduction using bifunctional electrocatalysts in devices consolidates the commercialization milestone of energy storage in hydrogen, a...

Free-standing two-dimensional (2D) organic nanomaterials are highly attractive for biological applications because of their unique structural properties and high biocompatibility. Herein, we design...

Platinum diselenide (PtSe2) is a group-10 two-dimensional (2D) transition metal dichalcogenide that exhibits the most prominent atomic-layer-dependent electronic behavior of "semiconductor-to-semimetal" transition when going from monolayer to bulk form. This work demonstrates an efficient photoelectrochemical (PEC) conversion for direct solar-to-hydrogen (H2) production based on 2D layered PtSe2/Si heterojunction photocathodes. By systematically controlling the number of atomic layers of wafer-scale 2D PtSe2 films through chemical vapor deposition (CVD), the interfacial band alignments at the 2D layered PtSe2/Si heterojunctions can be appropriately engineered. The 2D PtSe2/p-Si heterojunction photocathode consisting of a PtSe2 thin film with a thickness of 2.2 nm (or 3 atomic layers) exhibits the optimized band alignment and delivers the best PEC performance for hydrogen production with a photocurrent density of -32.4 mA cm-2 at 0 V and an onset potential of 1 mA cm-2 at 0.29 V versus a reversible hydrogen electrode (RHE) after post-treatment. The wafer-scale atomic-layer controlled band engineering of 2D PtSe2 thin-film catalysts integrated with the Si light absorber provides an effective way in the renewable energy application for direct solar-to-hydrogen production.

A 28-GHz high linearity active up-conversion mixer using 28-nm CMOS is presented in this letter. To enhance the modulated output power level under high-order modulation with IM3 improvement in the high IF input power region, the second-order intermodulation (IM2) signal injection technique is adopted. The positive third-order intermodulation (IM3) signal is generated by mixing the IM2 signal and IF input signal with transistors in the transconductance stage biasing in triode region. Therefore, by combining these opposite IM3 signal at the output of transconductance stage, the IM3 distortion can be alleviated. Besides, the proposed mixer achieves an IM3 distortion improvement in a wide IF power range. The measurement results demonstrate conversion gain (CG) of −6.4 dB and output 1-dB compression point (OP1 dB) of −2.2 dBm with 19 mW. The two-tone measurement results exhibit 10.2 dBm output third-order intercept point (OIP3). Furthermore, with the modulation measured results using single-carrier 256-QAM signal, the proposed mixer also exhibits a distinguished output power enhancement when the linearizer turns on. To the best of the author’s knowledge, this design is the first demonstration and implemented of an IM2 signal injection technique in millimeter-wave frequency, which also improves the output power level of the high-order modulation measurement.

Biobased polymers have received extensive research attention in flexible and renewable electronics to meet the concept of environmental sustainability. In this study, we develop a series of new polyimides (PIs) from biosources to serve as the substrate and dielectrics for a flexible organic field-effect transistor (OFET). The bioderived diamine, (3R,6S)-hexahydrofuro[3,2-b]furan-3,6-diyl bis(4-aminobenzoate) (ISBA), synthesized from isosorbide (ISB), was reacted with three dianhydrides of pyromellitic dianhydride (PMDA), 3,3′,4,4′-biphenyl-tetracarboxylic dianhydride (BPDA), and cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) to obtain PIs and copolyimides (Co-PIs) with a high biomass content up to 53%. These bioderived PIs possessed high Td’s over 400 °C and Tg’s over 250 °C. Furthermore, the CBDA-based and PMDA-based PIs exhibited CTE values below 50 ppm K–¹ due to the rigid heterocyclic ISB unit and the structural linearity of the CBDA and PMDA moieties in the polymer backbone. High transparency and low coloration were also observed in the biobased PIs. Finally, highly thermal-resistant PI(ISBA-C95B5) consisting of the CBDA/BPDA mole ratio of 95/5 was applied as the substrate and dielectrics in flexible OFET, demonstrating the compatible and stable performance even after being baked at 200 °C for 2 h or 1000 bending cycles. The present study reveals the potential application of biobased PIs in electronic devices for a sustainable economy.

The fabrication of ordered architectures that intimately integrate polymer, protein, and inorganic components remains difficult. Two promising building blocks to tackle this challenge are peptoids, peptide mimics capable of self-assembly into well-defined structures, and solid-binding peptides, which offer a biological path to controlled inorganic assembly. Here, we report on the synthesis of 3.3-nm-thick thiol-reactive peptoid nanosheets from equimolar mixtures of unmodified and maleimide-derivatized versions of the Nbpe6Nce6 oligomer, optimize the location of engineered cysteine residues in silica-binding derivatives of superfolder green fluorescent protein for maleimide conjugation, and react the two components to form protein-peptoid hybrids exhibiting partial or uniform protein coverage on both of their sides. Using 10 nm silica nanoparticles, we trigger the stacking of these 2D structures into a multilayered material composed of alternating peptoid, protein, and organic layers. This simple and modular approach to hierarchical hybrid synthesis should prove useful in bioimaging and photocatalysis applications.

This letter reports the fabrication of polycrystalline silicon (poly-Si) tunneling field effect transistors (Tunneling FETs) using green nanosecond laser crystallization (GLC). During the GLC process, the Si is full-melted by laser scanning, hence the recrystallized poly-Si thin films with grain size as large as $1.2~\mu \text{m}$ are attained. This makes it possible to fabricate tunneling FET with high-quali ty poly-Si thin films. Compare with the tunneling FETs fabricated by solid phase crystallization (SPC), the ones via GLC show better subthreshold swing (S.S) of 418 mV/dec. and larger on/off ratio of $6.02 \times 10^{5}$ . Moreover, the activation energy curve is also presented to further demonstrate the con nection between device performance and crystallinity of poly-Si thin films.

The two-dimensional (2D)/three-dimensional (3D) heterojunction perovskite solar cell (PSC) has recently been recognized as a promising photovoltaic structure for achieving high efficiency and long-...

Black phosphorus (BP), a promising 2D material, has sparked a research boom in various areas, while its fatal atmospheric instability seriously obstructs the progress of most practical applications. To realize the novel scalable concept of can-sealing protection, the selective deposition of a series of hydrophobically- or hydrophilically-functionalized Al2O3 nanostructured capping layers has been successfully achieved to seal the top surface of the exfoliated BP flake assemblies on Ag-patterned substrates. The hydrophobic Al2O3 columnar capping is evidenced as the most promising candidate to provide comprehensive protection against the severe rapid degradation of pristine BP even under a very high-humidity environment (RH = 85%) for a long period of time. The present work provides valuable insight into the distinct anisotropic degradation of the sealed BP flake assemblies evidently induced by the deposited hydrophobically- or hydrophilically-functionalized Al2O3 capping.

The development of conjugated polymers through the statistical terpolymerization of conjugation break spacers (CBSs) has received great attention because of their synergistic potential in enhancing fracture strain and tensile strength. In this study, a series of bulky and branched CBSs with ester functional groups and dimethyl (P1), methyl/propyl (P2), ethyl/butyl (P3), and dibutyl (P4) alkyl groups were incorporated into naphthalenediimide–bithiophene-based conjugated polymers through statistical terpolymerization. Morphological studies, including atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXD) studies, were applied to pristine and stretched polymer films to decipher the structure–stretchability relationship; further, their mobility–stretchability relationship was investigated by studying their field-effect transistor (FET) characteristics. We found that polymers with bulky and branched CBSs exhibit reduced backbone rigidity, allowing polymer chains to entangle more easily than those of stiffer polymers with similar molecular weights. Therefore, the polymer film exhibits a more uniform load distribution throughout the channel layer, and the branched CBSs serve as lubricants that deter crack propagation during deformation. Consequently, P4 with symmetrically extended alkyl groups shows good ductility and mobility–stretchability properties, with orthogonal μe,‖/μe,⊥ retention of approximately 20–30% with 60% strain and 30–40% after 400 stretching–releasing cycles with 60% strain. Our results indicated that statistical terpolymerization with branched CBSs is a versatile and effective methodology for controlling orientational and stacking patterns to achieve good mobility–stretchability properties in conjugated polymers.

Cesium lead halide perovskite nanocrystals (NCs) have attracted extensive attention for photoelectric device application due to their excellent optoelectronic properties. However, the toxicity of lead has hindered their commercialization. Consequently, lead free cesium metal halide NCs have been developed, but these materials suffer from low photoluminescence quantum yield (PLQY) and poor stability. Here, a new class of lead-free non-perovskite blue-emitting cesium bromine (CsBr) and cesium iodine (CsI) halide NCs are realized by zinc doping. High PLQYs of 79.05% and 78.95% are achieved by CsBr:Zn and CsI:Zn NCs, respectively, attributed to the improved local structural order and reduced strain between the lattices of the NCs after storing under ambient conditions for 20 to 30 days. Moreover, zinc doped cesium halide NCs show excellent air stability for at least 50 days. Our results for zinc doped cesium halide NCs have shown a new avenue to fabricate lead-free halide NCs for blue lighting and display applications.

In the journey to obtain well-crystallized mixed tin (Sn)–lead (Pb) iodide perovskite films for solar cell application, great difficulties have been presented due to very different crystallization rates between Sn- and Pb-based perovskite components. Herein, we report a new strategy to grow highly crystallized Sn–Pb perovskite (FA0.7MA0.3Sn0.5Pb0.5I3) for perovskite solar cells (PSCs). An iso-pentylammonium tetrafluoroborate ([PNA]BF4) ionic salt layer is introduced on top of poly(3,4-ethylenedioxythiophene)-poly-(styrenesulfonate) (PEDOT:PSS) to function as anchoring agent to bond Pb2+ to the surface of PEDOT:PSS, which can facilitate a quick crystallization of Pb-containing perovskite components and homogeneously distribute Sn/Pb elements inside the perovskite film in a vertical direction, uncovered by focused ion beam time-of-flight secondary ion mass spectrometry. Additionally, greatly reduced surface residual stress was also confirmed by X-ray diffraction. Lastly, these ionic salt molecules are able to encapsulate the acidic and hygroscopic surface of PEDOT:PSS to further ensure device stability. As a result, our strategies enabled a champion PCE of 20.11% for mixed Sn–Pb PSCs with improved thermal stability at 85 °C over 240 hours and shelf storage stability over 1200 hours. This work provides a new strategy to regulate the crystallization process of mixed Sn–Pb perovskites for both high performance and stability.

In this study, the adsorption material is fabricated from the aluminum residues using inductively coupled plasma (ICP) technique and applied as a raw material to manufacture porous solid desiccant wheel. An ICP system is developed to refine aluminum hydroxide extracted from aluminum residues into activated alumina by utilizing its high energy densities. A six-turn induction coil is suitable for our match box to produce alternating electromagnetic field, to sustain space discharge, and to have well reaction zone. The ICP generator power is set at 800 W, and the batch of aluminum residues is purified to generate activated alumina with a BET surface area of 122 m2/g. The porous desiccant wheel is manufactured using activated alumina with a 3-D random porous structure and applied to adsorb moisture from the air. The equilibrium time for the solid desiccant wheel and humidity are determined by observed kinetics in the adsorption experiment. The adsorption equilibrium time of the desiccant wheel (60 pores per inch) with 15-cm diameter and 5-cm thickness is 12 minutes. The maximum adsorption capacity is 51.4 g (at 12 min) and per gram of the desiccant wheel can adsorb 0.184-g water.

In this study, different carbon quantum dots (CQDs)/NaBiO3 hybrid materials were synthesized as photocatalysts to effectively utilize visible light for the photocatalytic degradation of contaminants effectively. These hybrid materials exhibit an enhanced photocatalytic reduction of hexavalent chromium (Cr(VI)) in the aqueous medium. Zero-dimensional nanoparticles of CQDs were embedded within the two-dimensional NaBiO3 nanosheets by the hydrothermal process. Compared with that of the pure NaBiO3 nanosheets, the photocatalytic performance of the hybrid catalysts was significantly high and 6 wt.% CQDs/NaBiO3 catalyst exhibited better photocatalytic performance. We performed the first-principles density functional theory calculations to study the interfacial properties of pure NaBiO3 nanosheets and hybrid photocatalysts, and confirmed the CQDs played an important role in the CQDs/NaBiO3 composites. The experimental results indicated that the enhanced reduction of Cr(VI) was probably due to the high loading of CQDs (electron acceptor) on NaBiO3, which made NaBiO3 nanomaterials to respond in visible light and significantly improved their electron-hole separation efficiency.

Extensive studies on lead halide perovskites have shown that these materials are excellent candidates as gain mediums. Recently, many efforts have been made to incorporate perovskite lasers in integrated optical circuits. Possible solutions would be to utilize standard lithography with an etching/lift-off process or a direct laser etching technique. However, due to the fragile nature of the lead halide perovskites which gives rise to significant material deterioration during the lithography and etching processes, realizing a small-size, low-roughness, and single-mode laser remains a challenge. Here, a lithographic in-mold patterning method realized by nanocrystal concentration control and a multi-step filling-drying process is proposed to demonstrate CsPbBr3 nanocrystals distributed-Bragg-reflector (DBR) waveguide lasers. This method realizes the patterning of the CsPbBr3 nanocrystal laser cavity and DBR grating without lift-off and etching processes, and the smallest fabricated structures are obtained in a few hundred nanometers. The single-mode lasing is demonstrated at room temperature with a threshold of 23.5 μJ cm-2. The smallest full width at half maximum FWHM of the laser output is 0.4 nm. Due to the fabrication process and the DBR laser geometry, the lasers can be fabricated in a compact array, which is important for incorporating perovskite-based lasers in complex optoelectronic circuits.

Solar distillation is emerging as an environmentally friendly and energy-effective technology for clean water generation. However, bulk water heating and the possibly complex composition of water matrices of source water could undermine the system efficacy. In this study, an interfacial evaporation device consisting of activated carbon combined with P25 TiO2 as the top layer and polyethylene foam as the bottom layer (AC-P25/foam device) was established. With the excellent optical absorbance of AC and the heat localization effect contributed by the PE foam, the evaporation rate (revp) of the device (revp = 2.1 kg m−2 h−1) was improved by 209% and 71% compared with that of the water-only (revp = 0.68 kg m−2 h−1) and conventional evaporation (i.e., submerged AC-P25) systems (revp = 1.23 kg m−2 h−1), respectively. The reusability test showed the stable evaporation performance of AC-P25/foam within 7 cycles; this interfacial evaporation was also found to be less affected by suspended solids in water due to a reduction in the influence of light scattering. The AC-P25/foam device not only possessed photothermal ability for water distillation but was also able to prevent enrichment of volatile organic compounds (i.e., phenol) with ∼95% removal efficiency through adsorption and photocatalytic reactions under illumination. Additionally, an outdoor solar distillation test performed with synthetic saline water demonstrated the desalination ability of the AC-P25/foam device, with the concentrations of all ions in the distilled water ≤3.5 mg L−1, far below the drinking water guideline value provided by the World Health Organization. The materials of the AC-P25/foam photothermal device are readily available and easily fabricated, showing the practical feasibility of this device for clean water generation.

The present study is concerned with the experimental impingement of two consecutive droplets on an inclined solid surface. Attention is mainly paid to the effects of impingement timing with various oblique angles (Φ) of the surface on the impact phenomena, which mainly affect the maximum droplet spreading diameter. The investigation considers four impingement scenarios differentiated by impingement timing, namely Case 1: single-droplet impingement; Case 2 of Δt1: the moment when the leading droplet starts spreading along the oblique surface; Case 3 of Δt2: the moment when the leading droplet reaches its maximum spreading; and Case 4 of Δt3: the moment when the leading droplet starts retracting. It is observed that deformation behavior of two successive droplets impacting on the inclined surface experiences a complex asymmetric morphology evolution due to the enhancement of gravity effect and various conditions of the impingement timing. The merged droplet becomes slender with increasing oblique surface angle in the final steady shape, causing the decrease in the value of front and back contact angles. The impingement timing has a significant influence on the change of the maximum height of the merged droplet. The coalesced droplet spreads to the maximum dimensionless width diameter at Δt = Δt2 and the oblique angle of Φ = 45°, but reaches the maximum dimensionless height for Δt = Δt2 at Φ = 30°. The front contact angles converge to a fixed value eventually for all conditions of impingement timing, and the values become lower with the increasing surface inclination.

The market's increasing demand for portable electronic products has made the research in flexible devices very attractive. Flexible solar cells are one of the most eye-catching devices in the field of flexible photovoltaic devices. And the perovskite material has become a powerful candidate material for manufacturing flexible solar cells due to its excellent optical properties, low price and the ability to tolerate more stress accumulation. However, as an active layer, the perovskite film still faces the issue that cracks are easily generated when bending and encountering temperature changes for the limited flexibility. There are many factors that affect the mechanical stability of the perovskite layer: the characteristics of the material itself, the influence of the other layers in the device and the presence or absence of a protective layer. This work reviews some reported strategies of improving the perovskite bending durability, classifies them according to the influencing factors mentioned above, and describes them in detail respectively.

Quasi two-dimensional (2D) Ruddlesden–Popper perovskites films fabricated by a solution process are composed of multiple 2D perovskite phases, and carrier transportation is limited by low-n-value 2D perovskite phases (n = 1 and n = 2). Systematic characterization shows that BA based 2D perovskites do not form low-n-value phases, while PEA and FPEA based 2D perovskites have strong n = 1, 2 signals when excited from the bottom of the perovskite films. To solve this problem, a lamellar nickel oxide substrate (lamellar-NiOx) fabricated by the hydrothermal method is employed as a hole transporting layer, forming a vertical charge transport pathway at the bottom of perovskite films, thus bypassing the charge trapping and recombination centers of the low-n-value regions of PEA and FPEA based 2D perovskites. As a result, both fill factor and open-circuit voltage are greatly enhanced for PEA and FPEA based 2D perovskite solar cells and a champion power conversion efficiency of 15.2% is achieved with a composition of FPEA2MA3Pb4I13. Furthermore, 2D perovskite films on lamellar-NiOx show enlarged grain size, improved out-of-plane orientation, and enhanced carrier transport efficiency between different n-value 2D perovskite phases. These findings suggest that lamellar-NiOx is an ideal substrate candidate to help overcome the carrier transport limitation of low-n-value 2D perovskite phases near the bottom of perovskite films.

Hole transporting materials (HTMs) play a crucial role in achieving highly efficient and stable perovskite solar cells (PSCs). Spiro-typed materials being the most widely used HTMs are commonly uti...

The purpose of this study is to examine the dilution effect on combustion characteristics of methane/nitrous oxide inverse tri-coflow diffusion flame through the addition of various dilution gases....

Background/purpose The fixation stability is the key factor for orthodontic micro-implant to succeed. This study evaluated the mechanical properties of three types of micro-implants by analyzing their structural configurations. Materials and methods Thirty micro-implants of three types (diameter 1.5 mm, Types A, B, C) were assessed. All micro-implants were manually driven into artificial bones at an 8-mm depth. The insertion torque (IT), pullout strength (PS), and gripping volume (GV) of each type were measured. The indexes of mechanical properties denoted as the PS/IT, GV/IT and PS/GV ratios. Intergroup comparisons and intragroup correlation were examined using statistical analysis. Results Type B had the greatest inner–outer diameter ratio (0.67), and Type A had the smallest (0.53). The IT of Type A (5.26 Ncm) was significantly (p = 0.038) lower than that of Type C (8.8 Ncm). There was no significant difference in the pullout strength. The GV of Type A (9.7 mm3) was significantly greater than Type C (8.4 mm3). Type C was significantly greater than Type B (7.2 mm3). The ratios of mechanical properties (PS/IT, PS/GV, and GV/IT) were found significant in intergroup comparison. The PS/GV ratio was in order: Type B (26.5) > Type A (23.0) > Type C (20.2). Spearman's rho rank correlation test showed that PS of Type B was correlated significantly with GV. Conclusion The design of thread and gripping volume were the important factors that contributes to the mechanical strengths of micro-implant.

After explosive growth of efficiency in organic solar cells (OSCs), achieving ideal morphology of bulk heterojunction remains crucial and challenging for advancing OSCs into consumer market. Herein, by utilizing the amphiphobic nature and temperature-dependent miscibility of fluorous solvent, hot fluorous solvent soaking method is developed to optimize the morphology with various donor/acceptor combinations including polymer/small-molecule, all-polymer and all-small-molecule systems. By immersing blend film into hot fluorous solvent which is utilized as liquid medium with better thermal conductivity, the molecular reorganization is accelerated. Furthermore, fluorous solvent can be miscible with the residue of chloroform and chloronaphthalene above upper critical solution temperature. This mixed solvent diffuses around inside the active layer and selectively promotes molecular reorganization, leading to optimized morphology. Compared to widely-used thermal annealing, this approach processed under mild conditions achieves superior photovoltaic performance, indicating the practicality and universality for morphological optimization in OSCs as well as other optoelectronic devices., Morphology control of bulk heterojunction organic solar cells has been a challenge for realising optimal photovoltaic performance. Here, the authors utilise amphiphobic nature and temperature-dependent miscibility of fluorous solvent to promote molecular reorganisation and morphological optimisation.

The wettability and growth of intermetallic compounds (IMCs) of stud bump materials Ag, Ag-4Pd, Cu, and Au with Sn-3Ag-0.5Cu (SAC305) solder have been investigated. Stud bumps produced using wire bonding techniques are widely employed in flip chip assembly, especially in 3D integrated circuit packaging. The material of stud bumps is a key factor in the reliability of the bonds. The wettability of IMCs as studied in this study decreased in the order Au > Ag ≈ Ag-4Pd > Cu, indicating that Ag and Ag-alloy bumps were only slightly inferior to those of Au but superior to those of Cu. Moreover, the morphologies and growth behaviors of the IMCs were evaluated by aging at 100°C to 200°C for 100 h to 1000 h. Without the gold embrittlement effect found in Au or the Kirkendall void issue of Cu, IMCs contained mainly Ag3Sn at the interface after long-term aging tests, and thickened IMCs with Ag3Sn and PdSn4 were observed in the case of Ag-4Pd after prolonged aging for 1000 h at 200°C. The growth kinetics of the IMCs in Ag and Ag-4Pd stud bumps with SAC305 solder followed the Arrhenius equation, with activation energies of 56.45 kJ/mol and 57.37 kJ/mol, respectively. The formation mechanisms of the IMCs in Ag and Ag-4Pd stud bumps were found to be diffusion controlled. The results indicated that Ag and Ag-4Pd are better than Au and Cu for application as stud bump materials.

Stud bumping using a traditional wire bonding process followed by the severing of the wire material from the ball bond has been widely applied in flip chip packages. Traditionally, Au stud bumps were employed because of the physical properties of gold, but the mediocre reliability of Au with Al pads and the cost of gold make this material unfavorable for industrial needs. Copper stud bumps were also considered, but the intrinsic features of Cu, such as its high hardness and ease of oxidation, present no advantages over gold stud bumps. However, Ag-alloy stud bumps exhibit satisfactory bondability and have been proposed as the optimal substitute for Au stud bumps to ensure better reliability in soldering and better intermetallic growth kinetics with Al bond pads. In this article, the intermetallic growth of Ag stud bumps alloyed with 2%, 10%, and 12% Pd after high-temperature storage tests (HTSTs) is investigated. The results indicated that the Pd atoms remained immobile in the bump-side matrix without diffusing into the aluminum pad side. Alloying with higher Pd content enhanced the formation of the favorable Ag2Al intermetallic compound (IMC), whereas lower Pd content resulted in severe cracking due to the formation of Ag3Al IMC. Compositional analysis showed that continuous layers of Ag–Al IMCs doped with large amounts of Pd formed at the interfaces close to the Ag stud bumps, but no Pd was detected on the Al pad side. The bonding strength increased after aging at 150 °C and 200 °C for 200 h, but it decayed drastically after aging at 250 °C for 200 h. The relationship between intermetallic growth and failure mode was established.

This paper studies the parametric instability of hybrid nanocomposite plates under an arbitrary periodic load in thermal environments. The hybrid nanocomposite plate is a three-layer board. It has metal layers on both surfaces and one core reinforced with functionally graded (FG) carbon nanotubes (CNTs). The Galerkin method with a reduced eigenfunction transformation is applied to establish the governing equations of motion. According to the Bolotin method, a set of Mathieu-type differential equations is formed to determine dynamic instability regions and dynamic instability index (DII). The in-plane periodic stress is taken to be a combination of pulsating axial and bending stresses in the example problems. The effects of the layer thickness ratio, CNTs volume fraction, CNTs distribution type, temperature, bending stress, static and dynamic load on the dynamic instability of hybrid nanocomposite plates are investigated and discussed.

This brief presents an all-digital CMOS pulse-shrinking time-to-digital converter (TDC) with temperature-measuring capability for higher circuit value and cost saving. A pulse generator is proposed to generate either a time-added pulse or a temperature-sensing pulse. A cyclic delay line (DL) composed of a temperature-sensing DL and a pulse-shrinking DL becomes area efficient and achieves sufficiently wide dynamic range. A time subtractor that eliminates the effect of the offset error enhances accuracy. The proposed TDC is fabricated with TSMC 0.35- $\mu \text{m}$ CMOS process and has a small area of approximately 0.019 mm2. The effective time resolution is approximately 45 ps, with an integral nonlinearity of −0.5 to 0.85 least significant bit (LSB). The achieved temperature resolution is nearly 0.1 °C/LSB, with an inaccuracy of −1.35 °C to 0.7 °C for a range of 0 °C–90 °C. Experimental results prove that we have proposed the first TDC that successfully measures time and temperature.

Polymers with abundant amorphous domain should facilitate energy dissipation upon stretching, making near amorphous π-conjugated polymers have immense potential in realizing intrinsically stretchab...

Peptoids (poly-N-substituted glycines) are a class of synthetic polymers that are regioisomers of peptides (poly-C-substituted glycines), in which the point of side-chain connectivity is shifted from the backbone C to the N atom. Peptoids have found diverse applications as peptidomimetic drugs, protein mimetic polymers, surfactants, and catalysts. Computational modeling is valuable in the understanding and design of peptoid-based nanomaterials. In this work, we report the bottom-up parameterization of coarse-grained peptoid force fields based on the MARTINI peptide force field against all-atom peptoid simulation data. Our parameterization pipeline iteratively refits coarse-grained bonded interactions using iterative Boltzmann inversion and nonbonded interactions by matching the potential of mean force for chain extension. We assure good sampling of the amide bond cis/trans isomerizations in the all-atom simulation data using parallel bias metadynamics. We develop coarse-grained models for two representative peptoids-polysarcosine (poly(N-methyl glycine)) and poly(N-((4-bromophenyl)ethyl)glycine)-and show their structural and thermodynamic properties to be in excellent accord with all-atom calculations but up to 25-fold more efficient and compatible with MARTINI force fields. This work establishes a new rigorously parameterized coarse-grained peptoid force field for the understanding and design of peptoid nanomaterials at length and time scales inaccessible to all-atom calculations.

During past decades, a variety of two-dimensional (2D) nanomaterials have been developed through molecular self-assembly. Among them, those assembled from sequence-defined polymers have received pa...

Smart glass offers dynamic control over the transmission of light to address various needs in energy conservation, privacy, and information display; yet, most of the existing technologies still req...

Most chemical vapor deposition methods for transition metal dichalcogenides use an extremely small amount of precursor to render large single-crystal flakes, which usually causes low coverage of the materials on the substrate. In this study, a self-capping vapor-liquid-solid reaction is proposed to fabricate large-grain, continuous MoS2 films. An intermediate liquid phase-Na2Mo2O7 is formed through a eutectic reaction of MoO3 and NaF, followed by being sulfurized into MoS2. The as-formed MoS2 seeds function as a capping layer that reduces the nucleation density and promotes lateral growth. By tuning the driving force of the reaction, large mono/bilayer (1.1 mm/200 μm) flakes or full-coverage films (with a record-high average grain size of 450 μm) can be grown on centimeter-scale substrates. The field-effect transistors fabricated from the full-coverage films show high mobility (33 and 49 cm2 V−1 s−1 for the mono and bilayer regions) and on/off ratio (1 ~ 5 × 108) across a 1.5 cm × 1.5 cm region., Here, the authors develop a self-capping vapour-liquid-solid reaction to fabricate large-grain continuous MoS2 films, whereby an intermediate liquid phase-Na2Mo2O7 is formed through a eutectic reaction of MoO3 and NaF, followed by sulphurisation into MoS2.