Textured Perovskite/Silicon Tandem Solar Cells Achieving Over 30% Efficiency Promoted by 4-Fluorobenzylamine Hydroiodide

Monolithic textured perovskite/silicon tandem solar cells(TSCs)are expected to achieve maximum light capture at the lowest cost,potentially exhibiting the best power conversion efficiency.However,it is challenging to fabricate high-quality perovskite films and preferred crystal orientation on commercially textured silicon substrates with micrometersize pyramids.Here,we introduced a bulky organic molecule(4-fluorobenzylamine hydroiodide(F-PMAI))as a perovskite additive.It is found that F-PMAI can retard the crystallization process of perovskite film through hydrogen bond interaction between F^(−)and FA^(+)and reduce(111)facet surface energy due to enhanced adsorption energy of F-PMAI on the(111)facet.Besides,the bulky molecular is extruded to the bottom and top of perovskite film after crystal growth,which can passivate interface defects through strong interaction between F-PMA+and undercoordinated Pb^(2+)/I^(−).As a result,the additive facilitates the formation of large perovskite grains and(111)preferred orientation with a reduced trap-state density,thereby promoting charge carrier transportation,and enhancing device performance and stability.The perovskite/silicon TSCs achieved a champion efficiency of 30.05%based on a silicon thin film tunneling junction.In addition,the devices exhibit excellent longterm thermal and light stability without encapsulation.This work provides an effective strategy for achieving efficient and stable TSCs.

Optimization study of station track utilization in high-speed railroad based on constraints of control in random origin and process

Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and process factors during interval operations and can accumulate over multiple intervals.The aim is to enhance the robustness of high-speed rail station arrival and departure track utilization schemes.Design/methodologylapproach-To achieve this objective,the paper simulates actual train operations,incorporating the fluctuations in interval operation times into the utilization of arrival and departure tracks at the station.The Monte Carlo simulation method is adopted to solve this problem.This approach transforms a nonlinear model,which includes constraints from probability distribution functions and is difficult to solve directly,into a linear programming model that is easier to handle.The method then linearly weights two objectives to optimize the solution.Findings-Through the application of Monte Carlo simulation,the study successfully converts the complex nonlinear model with probability distribution function constraints into a manageable linear programming model.By continuously adjusting the weighting coefficients of the linear objectives,the method is able to optimize the Pareto solution.Notably,this approach does not require extensive scene data to obtain a satisfactory Pareto solution set.Originality/value-The paper contributes to the field by introducing a novel method for optimizing high-speed rail station arrival and departure track utilization in the presence of fluctuations in interval operation times.The use of Monte Carlo simulation to transform the problem into a tractable linear programming model represents a significant advancement.Furthermore,the method's ability to produce satisfactory Pareto solutions without relying on extensive data sets adds to its practical value and applicability in real-world scenarios.

I/P interface modification for stable and efficient perovskite solar cells

Interface engineering has played an increasingly essential role in the development of perovskite solar cells(PSCs).Herein,we adopted an effective and simple one-step interface passivation method on a FA-based perovskite to fabricate efficient and stable planar PSCs.The surface defects are reduced by the perovskite interface passivation layer incorporated between the hole transport and perovskite absorber layers,and then non-radiative recombination is suppressed while interfacial carrier extraction is enhanced.The passivated planar PSCs demonstrates 20.83%power conversion efficiency(PCE),which is caused by the simultaneous enhancement of the fill factor and open-circuit voltage.In addition,the device also shows great ambient and thermal stability.It retains 94%of its original PCE after 1000 h under ambient air without encapsulation as well as90%of its initial efficiency after 400 h under continuous heating at 65°C with encapsulation.This research provides a strategy for the development of efficient and stable PSCs.

Composite electron transport layer for efficient N-I-P type monolithic perovskite/silicon tandem solar cells with high open-circuit voltage

Perovskite/silicon tandem solar cells(PSTSCs) have exhibited huge technological potential for breaking the Shockley-Queisser limit of single-junction solar cells. The efficiency of P-I-N type PSTSCs has surpassed the single-junction limit, while the performance of N-I-P type PSTSCs is far below the theoretical value. Here, we developed a composite electron transport layer for N-I-P type monolithic PSTSCs with enhanced open-circuit voltage(VOC) and power conversion efficiency(PCE). Lithium chloride(Li Cl) was added into the tin oxide(SnO_(2)) precursor solution, which simultaneously passivated the defects and increased the electron injection driving force at the electron transfer layer(ETL)/perovskite interface.Eventually, we achieved monolithic PSTSCs with an efficiency of 25.42% and V_(OC) of 1.92 V, which is the highest PCE and VOCin N-I-P type perovskite/Si tandem devices. This work on interface engineering for improving the PCE of monolithic PSTSCs may bring a new hot point about perovskite-based tandem devices.

Highly efficient bifacial semitransparent perovskite solar cells based on molecular doping of CuSCN hole transport layer

Coper thiocyanate(CuSCN)is generally considered as a very hopeful inorganic hole transport material(HTM)in semitransparent perovskite solar cells(ST-PSCs)because of its low parasitic absorption,high inherent stability,and low cost.However,the poor electrical conductivity and low work function of CuSCN lead to the insufficient hole extraction and large open-circuit voltage loss.Here,2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane(F4TCNQ)is employed to improve conductivity of CuSCN and band alignment at the CuSCN/perovskite(PVK)interface.As a result,the average power conversion efficiency(PCE)of PSCs is boosted by≈11%.In addition,benefiting from the superior transparency of p-type CuSCN HTMs,the prepared bifacial semitransparent n-i-p planar PSCs demonstrate a maximum efficiency of 14.8%and 12.5%by the illumination from the front side and back side,respectively.We believe that this developed CuSCN-based ST-PSCs will promote practical applications in building integrated photovoltaics and tandem solar cells.

(Parallel) kinetic resolution of 3,3-disubstituted indolines via organocatalyzed reactions with azodicarboxylates

A novel kinetic resolution(KR) method has been developed for 3,3-disubstituted indolines, whose catalytic asymmetric synthesis remains a significant challenge in organic synthesis. The key to the success of this KR protocol lies in the utilization of chiral phosphoric acid-catalyzed triazane formation reaction with azodicarboxylates, which enables the enantioselective synthesis of various substituted indolines bearing C3-quaternary stereocenters with good to high enantioselectivities(with sfactors up to 70). Moreover, an intriguing parallel kinetic resolution(PKR) has been developed by combining triazane formation and dehydrogenation reactions using different azodicarboxylates. Experimental studies have provided insight into the mechanism of this PKR reaction, demonstrating stereoselectivity in both triazane formation and dehydrogenation steps, favoring the opposite enantiomers. The large-scale synthesis and diverse derivatizations of the products, particularly the imine groupcontaining 3H-indoles, demonstrate the value of these(P)KR methods.

Friction reactions induced by selective hydrogenation of textured surface under lubricant conditions

The passivation of hydrogen atoms and the conformation of textured surfaces under oil-lubricated conditions are effective strategies to obtain amorphous carbon(a-C)films with extremely low friction.It is critical to understanding the influence mechanism of selective surface hydrogenation on the tribological behaviors of textured a-C film under oil-lubricated conditions.In particular,the interactions of hydrogen atoms and lubricants are confusing,which is enslaved to the in situ characterization technique.The reactive molecular dynamics(RMD)simulations were conducted to analyze the friction response of textured a-C films with selective hydrogenation surfaces under oil-lubricated conditions.The results indicate that the existence of hydrogen atoms on specific bump sites significantly decreases the friction coefficient(μ)of textured a-C film,which is highly dependent on the surface hydrogen content.The repulsion between hydrogen atoms and lubricant molecules prompts the formation of a dense lubricant film on the surface of the mating material.Interestingly,with the enhancement of the surface hydrogen content,the passivation of the friction interface and the repulsion between hydrogen atoms and lubricants play dominant roles in reducing the friction coefficient instead of hydrodynamic lubrication.

A robust low-friction triple network hydrogel based on multiple synergistic enhancement mechanisms

Hydrogels exhibit promising applications,particularly due to their high water content and excellent biocompatibility.Despite notable progress in hydrogel technology,the concurrent enhancement of water content,mechanical strength,and low friction poses substantial challenges to practical utilization.In this study,employing molecular and network design guided based on multiple synergistic enhancement mechanisms,we have developed a robust polyvinyl alcohol(PVA)-polyacrylic acid(PAA)-polyacrylamide(PAAm)three-network(TN)hydrogel exhibiting high water content,enhanced strength,low friction,and fatigue resistance.The hydrogel manifests a water content of 63.7%,compression strength of 6.3 MPa,compression modulus of 2.68 MPa,tensile strength reaching 7.3 MPa,and a tensile modulus of 10.27 MPa.Remarkably,even after one million cycles of dynamic loading,the hydrogel exhibits no signs of fatigue failure,with a minimal strain difference of only 1.15%.Furthermore,it boasts a low sliding coefficient of friction(COF)of 0.043 and excellent biocompatibility.This advancement extends the applications of hydrogels in emerging fields within biomedicine and soft bio-devices,including load-bearing artificial tissues,artificial blood vessels,tissue scaffolds,robust hydrogel coatings for medical devices,and joint parts of soft robots.

Synthesis and Characterization of PVA-HA-Silk Composite Hydrogel by Orthogonal Experiment

PVA-HA-Silk composite hydrogel was synthesized with polyvinyl alcohol （PVA）, nano-hydroxyapatite （HA） and natural silk by using the method of repeated freezing and thawing. A series of tests were performed to study water content, stress relaxation behavior, elastic modulus, and creep characteristics of PVA-HA-Silk composite hydrogel. Orthogonal experimental design method was used to analyze the influence degree of PVA, HA and silk （three kinds of raw materials） on mechanical properties and water content of the PVA-HA-Silk composite hydrogel to select the best material ratio according to their overall performance. The results demonstrate that the mass percentage of PVA has the greatest impact on the water content, followed by HA and silk. Compression stress-strain variation of PVA-HA-Silk composite hydrogel presents a nonlinear relationship, which proves that it is a typical viscoelastic material. Comparing the mechanical properties of 16 formulas, the formula of PVA-HA-silk composite hydrogel with mass percentage of PVA 15%, HA 2.0% and silk 1.0% is the best.

A Facile Modifier-free Approach to Fabricate Antistatic Superhydrophobic Composite Coatings with Remarkable Thermal Stability and Corrosion Resistance

Research on antistatic superhydrophobic surfaces has attracted widespread attention in some fields.However,in the application of superhydrophobic materials,fabricating stable and practical superhydrophobic surfaces through facile and low-cost approaches still faces considerable challenges.Herein,a polyphenylene sulfide(PPS)-based antistatic superhydrophobic composite coating with a high water contact angle(166°)and a low sliding angle(2°)was fabricated on a Q345 steel surface through a simple spray-coating method without any modifier.Furthermore,the as-prepared superhydrophobic coating also displayed excellent superhydrophobicity for water droplets at different pH values,as well as self-cleaning,anti-fouling and anti-icing properties.Importantly,the superhydrophobic coating still exhibited superhydrophobicity after calcination at 350°C for 1 h,indicating its outstanding thermal stability.Excellent antistatic and anticorrosion properties were obtained on the prepared coating surface,which allows the coating to be applied under harsh conditions.Benefiting from the above characteristics,compared with the commercial coating,the as-obtained antistatic superhydrophobic coating may be applied more widely in related fields.

Research on the Interstitial Fluid Load Support Characteristics and Start-Up Friction Mechanisms of PVA-HA-Silk Composite Hydrogel

Hydrogel has been extensively studied as an articular cartilage repair and replacement material. PVA-HA-Silk composite hydrogel was prepared by freezing-thawing method in this paper. Mechanical properties were determined by experiments and the friction coefficient of PVA-HA-Silk composite hydrogel against steel ball was verified using micro-tribometer. Finite Element Method （FEM） was used to study the lubrication mechanism of PVA-HA-Silk composite hydrogel and the relation between the interstitial fluid load support and the start-up friction resistance. The results show that the elastic modulus and the permeability are 2.07 MPa and 10^-15m^4N^-1s^-1, respectively, and the start-up friction coefficients of PVA-HA-Silk composite hydrogel are in the range of 0.154）.2 at different contact loads, contact time and sliding speeds. The start-up friction resistance of PVA-HA-Silk composite hydrogel increases with the contact load and contact time. With the increase in sliding speed, the start-up friction resistance of PVA-HA-Silk composite hydrogel decreases. There is an inverse relation between the start-up friction resistance and the interstitial fluid load support. The change of fluid flow with the increase in sliding displacement has an important effect on the interstitial fluid load support and friction resistance. The interstitial fluid load support decreases with the increase in contact load and contact time, while the interstitial fluid load support reinforces with the increase in sliding speed. Moreover, PVA-HA-Silk composite hydrogel has mechanical properties of recovery and self-lubricating.

Cartilage-bone inspired the construction of soft-hard composite material with excellent interfacial binding performance and low friction for artificial joints

Inspired by the cartilage-bone structure in natural joints,soft-hard integrated materials have received extensive attention,which are the most promising candidates for artificial joints due to their combination of excellent load-bearing properties and lubricating properties.The latest progress showed that the combination of hydrogel and titanium alloy can realize a bionic natural joint lubrication system on the surface of titanium alloy.However,obtaining a tough interface between the hydrogel(soft and wet)and the titanium substrate(hard and dry)is still a great challenge.Here,we designed a"soft(hydrogel)-hard(Ti6Al4V)"integrated material with outstanding combination,which simulates the structure and function of cartilage-bone in the natural joint.The load-bearing properties,binding performance,and tribological behaviors for different forms of the soft-hard integrated materials were investigated.The results showed that the hydrogel layer and Ti6Al4V substrate possess ultra-high interfacial toughness(3,900 J/m^(2)).In addition,the combination of the hydrogel layer and Ti6Al4V substrate provided a good lubrication system to endow the"soft(hydrogel)-hard(Ti6Al4V)"integrated material with high load-bearing and excellent tribological properties.Therefore,this study provided an effective strategy for prolonging the service life of Ti6Al4V in the biomedical field.

Optical properties of conductive silver-nanowire films with different nanowire lengths

Transparent electrodes made of silver nanowires （Ag NWs） exhibit a higher flexibility than conventional indium tin oxide electrodes.For this reason,Ag NWs may find applications in future flexible electronic and optoelectronic devices.However,different optoelectronic devices have different specific requirements for Ag NWs.For example,the optical transmittance haze is an important but rarely studied aspect of Ag NW films.In this study,the optical transmittance and optical scattering of long （5-50 μm,L-NWs） and short （1-20 μm,S-NWs） Ag NW films were investigated.The L-NWs exhibited better optical transmission than the S-NWs,whereas the S-NWs exhibited better light-scattering properties than the L-NWs.Our results indicate that the L-NWs are suitable for touch-screen displays,whereas the S-NWs are better suited as transparent conductive films for solar cells.We analyzed the scattering ratio of forward-scattered light to backscattered light for both the L-NWs and S-NWs and discovered that the mesh size affected the scattering ratio.For longer wavelengths,a larger mesh yielded a higher backscattering ratio,whereas a smaller mesh yielded a lower backscattering ratio.We formulated an equation for calculating the reflection haze using the total reflection （Ag NWs/glass）,R and the reflection of glass,R0.The reflection haze of the S-NWs and L-NWs exhibited different trends in the visible-near-infrared region.An omnidirectional scattering model for the Ag NWs was used to evaluate the Ag NW scattering properties.The results of this study have great significance for the evaluation of the performance of Ag NWs in optoelectronic devices.

Kinetic Resolution of 1,2-Diamines via Organocatalyzed Asymmetric Electrophilic Aminations of Anilines

An efficient kinetic resolution(KR)protocol for 1,2-diamines has been developed through asymmetric electrophilic aminations of anilines enabled by chiral phosphoric acid catalysis.A wide array of substituted 1,2-diamines were compatible with this method,generating both the recovered staring materials and the amination products with high enantioselectivities(with s-factor up to 218).Notably,this method is amenable to the kinetic resolution of 1,2-diamines bearingα-tertiary amine moieties,which represents the first KR of this type of 1,2-diamines.Facile removal of the introduced hydrazine group and oxidative cleavage of the N-aryl group to release the free primary amine demonstrate the value of this method.

Wear mechanism and debris analysis of PEEK as an alternative to CoCrMo in the femoral component of total knee replacement

The polyetheretherketone(PEEK)-highly cross-linked polyethylene(XLPE),all-polymer knee prosthesis has excellent prospects for replacing the traditional metal/ceramic-polyethylene joint prosthesis,improving the service life of the joint prosthesis and the quality of patients’life.The long-term wear mechanism of PEEK-XLPE knee joint prosthesis is comprehensively evaluated from wear amount,wear morphology,and wear debris compared to that of CoCrMo-XLPE joint prosthesis.After 5 million cycles of in vitro wear,the wear loss of XLPE in PEEK-XLPE(30.9±3.2 mg)is lower than that of XLPE in CoCrMo-XLPE(32.1±3.1 mg).Compared to the XLPE in CoCrMo-XLPE,the plastic deformation of XLPE in PEEK-XLPE is more severe in the early stage,and the adhesive peeling and adhesion are lighter in the later stage.The size distribution of XLPE wear debris in PEEK-XLPE is relatively dispersed,which in CoCrMo-XLPE is relatively concentrated.Wear debris is mainly flake and block debris,and the wear mechanism of XLPE was abrasive wear.The wear volume per unit area of PEEK femoral condyle(10.45×10^(5)μm^(3)/mm^(2))is higher than that of CoCrMo(8.32×10^(5)μm^(3)/mm^(2)).The PEEK surface is mainly furrows and adhesions,while the CoCrMo surface is mainly furrows and corrosion spots.The PEEK wear debris is mainly in flakes and blocks,and the CoCrMo wear debris is mainly in the shape of rods and blocks.The wear mechanism of PEEK is abrasive wear and adhesion,and that of CoCrMo is abrasive wear and corrosion.

Tribo-corrosion interaction of the parallel steel wires in the suspension bridges

The effect of contact load and relative displacement on tribo-corrosion interaction of parallel steel wires of main cable in the suspension bridge was investigated in this study.A self-made tribo-corrosion test bench was employed to conduct tribo-corrosion tests of parallel steel wires in 3.5%(wt%)NaCl solution and deionized water under different contact loads and different relative displacements.The friction coefficient and wear coefficient of wires were presented.Electrochemical corrosion behavior(Tafel polarization curves,Nyquist diagram,and equivalent circuit diagram)was characterized by electrochemical analyzer.Wear morphology was observed by scanning electron microscope.Wear volume loss and corrosion‒wear interaction were quantitatively demonstrated by high-precision weighing balance.The results show that the electrochemical corrosion ability of the steel wires increases with the increase of the contact load or relative displacement.The increased contact load or relative displacement increases the volume loss of corrosion‒wear and pure wear,but decreases the wear coefficient.The wear mechanisms in 3.5%NaCl solution are adhesive wear,abrasive wear,and corrosive wear as compared to adhesive wear and abrasive wear in deionized water under different contact loads.The wear mechanisms of parallel steel wires are slightly different under different relative displacements.But the main wear mechanisms are similar to that under different contact loads.The interaction effects of corrosion and wear produced by the contact load and relative displacement are all the synergistic effects.

Effect of Directional Stretching on Properties of PVA-HA-PAA Composite Hydrogel

Polyvinyl alcohol(PVA)hydrogels with excellent characteristics are considered as promising cartilage replacement materials.However,there are still some main issues to be solved for PVA hydrogel,such as poor mechanical strength and disordered structure.Inspired by the highly ordered structure of biological soft tissues such as articular cartilage,here,we prepared a high-strength but anisotropic polyvinyl alcohol-nanohydroxyapatite-polyacrylic acid(PVA-HA-PAA)composite hydrogel by directional stretching,freezing–thawing,and annealing method.Stretching of an as-prepared isotropic PVA-HA-PAA composite hydrogel leads to the orientation of PVA crystallites and PVA chains,which enables the formation of ordered structure and more hydrogen bonds via freezing under stretching.The microstructure,water content,swelling and creep performance,tensile and bio-tribology properties of the composite hydrogel are studied,the results indicated that the properties of the hydrogel are aff ected by stretching due to the formation of ordered structure in the anisotropic hydrogel.For instance,the elastic modulus and tensile strength of the anisotropic hydrogel reach 5.703 MPa and 18.958 MPa,respectively,which is significantly enhanced by comparing with isotropic hydrogel.Moreover,the friction property is anisotropic,and the Coefficient Of Friction(COF)reduced in the parallel direction.Thus,this work provides a simple and practicable strategy to design strong and anisotropic hydrogels for potential applications in biomedical materials such as cartilage substitute.

Ultrahigh hardness of carbon steel surface realized by novel solid carburizing with rapid diffusion of carbon nanostructures

In this study, a novel rapid solid carburizing process with a large diffusion depth using nano-diamonds（NDs） was conducted for low carbon steel. Changes of annealed NDs were obtained by Raman spectroscopy and transmission electron microscopy（TEM）, and the results suggested that the NDs experience a stripping process before a special solid-reaction with surface iron atoms from steel substrate. Onionlike carbon（OLC） derived from the annealed NDs provided broken graphitic ribbons as carbon sources that accelerated the rate of adsorption and diffusion. Examination of the surface layer at equilibrium using TEM and X-ray photoelectron spectroscopy（XPS） also revealed the special state of carbon, and an ultrafine mixed phase microstructure was obtained by rapid solid-phase transformation. As a result, a surface hardened layer with ultrahigh hardness and a smooth transition region were realized. We believe that these kinds of diamond or graphitic structures with high activity states have an important influence not only on adsorption and diffusion but also on this special solid-phase transformation.

Perovskite/silicon-based heterojunction tandem solar cells with 14.8%conversion efficiency via adopting ultrathin Au contact

A rising candidate for upgrading the performance of an established narrow-bandgap solar technology without adding much cost is to construct the tandem solar cells from a crystalline silicon bottom cell and a high open-circuit voltage top cell.Here,we present a four-terminal tandem solar cell architecture consisting of a selffiltered planar architecture perovskite top cell and a silicon heterojunction bottom cell.A transparent ultrathin gold electrode has been used in perovskite solar cells to achieve a semi-transparent device.The transparent ultrathin gold contact could provide a better electrical conductivity and optical reflectance-scattering to maintain the performance of the top cell compared with the traditional metal oxide contact.The four-terminal tandem solar cell yields an efficiency of 14.8%,with contributions of the top（8.98%）and the bottom cell（5.82%）,respectively.We also point out that in terms of optical losses,the intermediate contact of self-filtered tandem architecture is the uppermost problem,which has been addressed in this communication,and the results show that reducing the parasitic light absorption and improving the long wavelength range transmittance without scarifying the electrical properties of the intermediate hole contact layer are the key issues towards further improving the efficiency of this architecture device.

基于纤维增强和磁场诱导构建坚韧、抗疲劳各向异性水凝胶及其性能研究

生物组织(如肌腱、软骨等)不仅具有优异的强度、模量和韧性,而且具有长期稳定性,可承受数百万次高应力循环而不断裂,其疲劳阈值超过1000 J m^(−2).相比之下,尽管合成水凝胶在强度、模量、韧性和其他性能方面与天然软组织相当,但这些增韧水凝胶仍然会在反复循环载荷下遭受疲劳断裂,其疲劳阈值通常低于100 J m^(−2).在本工作中,我们报道了一种简单的策略,用于开发韧性和抗疲劳的各向异性水凝胶,其疲劳阈值超过常规水凝胶的100倍.各向异性水凝胶通过两步工艺合成,包括磁场定向工艺形成优先排列的PDA-Fe_(3)O_(4)-CF纤维结构,以及冷冻解冻-退火工艺处理.优先排列纤维结构和高结晶度的协同作用使各向异性水凝胶具有超高的强度和韧性、优异的摩擦学性能和非凡的抗疲劳性能.各向异性水凝胶的抗拉强度、抗压强度和疲劳阈值分别高达11.82±0.85 MPa、5.95±0.35 MPa和1845 J m^(−2),显著高于大多数生物凝胶和合成水凝胶.因此,本研究为制造性能优异的软材料提供了一种可行的方法,拓展了软质材料在承重材料(如人工软组织)、软机器人、柔性电子等领域的应用.