Stable Organic Solar Cells Enabled by Simultaneous Hole and Electron Interlayer Engineering

The development of high-performance organic solar cells(OSCs)with high operational stability is essential to accelerate their commercialization.Unfortunately,our understanding of the origin of instabilities in state-of-the-art OSCs based on bulk heterojunction(BHJ)featuring non-fullerene acceptors(NFAs)remains limited.Herein,we developed NFA-based OSCs using different charge extraction interlayer materials and studied their storage,thermal,and operational stabilities.Despite the high power conversion efficiency(PCE)of the OSCs(17.54%),we found that cells featuring self-assembled monolayers(SAMs)as hole-extraction interlayers exhibited poor stability.The time required for these OSCs to reach 80%of their initial performance(T_(80))was only 6h under continuous thermal stress at 85℃in a nitrogen atmosphere and 1 h under maximum power point tracking(MPPT)in a vacuum.Inserting MoO_(x)between ITO and SAM enhanced the T_(80)to 50 and~15 h after the thermal and operational stability tests,respectively,while maintaining a PCE of 16.9%.Replacing the organic PDINN electron transport layer with ZnO NPs further enhances the cells'thermal and operational stability,boosting the T_(80)to 1000 and 170 h,respectively.Our work reveals the synergistic roles of charge-selective interlayers and device architecture in developing efficient and stable OSCs.

Photophysics and electrochemistry relevant to photocatalytic water splitting involved at solid–electrolyte interfaces

Direct photon to chemical energy conversion using semiconductor–electrocatalyst–electrolyte interfaces has been extensively investigated for more than a half century. Many studies have focused on screening materials for efficient photocatalysis. Photocatalytic efficiency has been improved during this period but is not sufficient for industrial commercialization. Detailed elucidation on the photocatalytic water splitting process leads to consecutive six reaction steps with the fundamental parameters involved: The photocatalysis is initiated involving photophysics derived from various semiconductor properties(1: photon absorption, 2: exciton separation). The generated charge carriers need to be transferred to surfaces effectively utilizing the interfaces(3: carrier diffusion, 4: carrier transport). Consequently, electrocatalysis finishes the process by producing products on the surface(5: catalytic efficiency, 6: mass transfer of reactants and products). Successful photocatalytic water splitting requires the enhancement of efficiency at each stage. Most critically, a fundamental understanding of the interfacial phenomena is highly desired for establishing 'photocatalysis by design' concepts, where the kinetic bottleneck within a process is identified by further improving the specific properties of photocatalytic materials as opposed to blind material screening. Theoretical modeling using the identified quantitative parameters can effectively predict the theoretically attainable photon-conversion yields. This article provides an overview of the state-of-the-art theoretical understanding of interfacial problems mainly developed in our laboratory.Photocatalytic water splitting(especially hydrogen evolution on metal surfaces) was selected as a topic,and the photophysical and electrochemical processes that occur at semiconductor–metal, semiconductor–electrolyte and metal–electrolyte interfaces are discussed.

Growth behavior and electronic properties of Ge_(n+1) and AsGe_n(n = 1–20) clusters: a DFT study

We present a systematic computational study based on the density functional theory(DFT) aiming to high light the possible effects of one As doping atom on the structural, energetic, and electronic properties of different isomers of Ge_(n+1) clusters with n = 1–20 atoms. By considering a large number of structures for each cluster size, the lowest-energy isomers are determined. The lowest-energy isomers reveal three-dimensional structures starting from n = 5. Their relative stability versus atomic size is examined based on the calculated binding energy, fragmentation energy, and second-order difference of energy. Doping Ge_(n+1) clusters with one As atom does not improve their stability. The electronic properties as a function of the atomic size are also discussed from the calculated HOMO–LUMO energy gap, vertical ionization potential, vertical electron affinity, and chemical hardness. The obtained results are significantly affected by the inclusion of one As atom into a Gen cluster.

Strategic comparison of membrane-assisted and membrane-less water electrolyzers and their potential application in direct seawater splitting(DSS)

Electrocatalytic splitting of water by means of renewable energy as the electricity supply is one of the most promising methods for storing green renewable energy as hydrogen. Although two-thirds of the earth’s surface is covered with water, there is inadequacy of freshwater in most parts of the world. Hence, splitting seawater instead of freshwater could be a truly sustainable alternative. However, direct seawater splitting faces challenges because of the complex composition of seawater. The composition, and hence, the local chemistry of seawater may vary depending on its origin, and in most cases, tracking of the side reactions and standardizing and customizing the catalytic process will be an extra challenge. The corrosion of catalysts and competitive side reactions due to the presence of various inorganic and organic pollutants create challenges for developing stable electro-catalysts. Hence, seawater splitting generally involves a two-step process, i.e., purification of seawater using reverse osmosis and then subsequent fresh water splitting. However, this demands two separate chambers and larger space, and increases complexity of the reactor design. Recently, there have been efforts to directly split seawater without the reverse osmosis step. Herein, we represent the most recent innovative approaches to avoid the two-step process, and compare the potential application of membrane-assisted and membrane-less electrolyzers in direct seawater splitting(DSS). We particularly discuss the device engineering, and propose a novel electrolyzer design strategies for concentration gradient based membrane-less microfluidic electrolyzer.

Passivation agent with dipole moment for surface modification towards efficient and stable perovskite solar cells

Recently,there has been renewed interest in interface engineering as a means to further push the performance of perovskite solar cells closer to the Schockly-Queisser limit.Herein,for the first time we employ a multi-functional 4-chlorobenzoic acid to produce a self-assembled monolayer on a perovskite surface.With this interlayer we observe passivation of perovskite surface defects and a significant suppression of non-radiative charge recombination.Furthermore,at the surface of the interlayer we observe,charge dipoles which tune the energy level alignment,enabling a larger energetic driving force for hole extraction.The perovskite surface becomes more hydrophilic due to the presence of the interlayer.Consequently,we observe an improvement in open-circuit voltage from 1.08 to 1.16 V,a power conversion efficiency improvement from 18%to 21%and an improved stability under ambient conditions.Our work highlights the potential of SAMs to engineer the photo-electronic properties and stability of perovskite interfaces to achieve high-performance light harvesting devices.

Experimental observation of interlayer perpendicular standing spin wave mode with low damping in skyrmion-hosting[Pt/Co/Ta]_(10)multilayer

An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.

Review of deep learning algorithms in molecular simulations and perspective applications on petroleum engineering

In the last few decades,deep learning(DL)has afforded solutions to macroscopic problems in petroleum engineering,but mechanistic problems at the microscale have not benefited from it.Mechanism studies have been the strong demands for the emerging projects,such as the gas storage and hydrate production,and for some problems encountered in the storage process,which are common found as the chemical interaction between injected gas and mineral,and the formation of hydrate.Emerging advances in DL technology enable solving molecular dynamics(MD)with quantum accuracy.The conventional quantum chemical method is computational expensive,whereas the classical MD method cannot guarantee high accuracy because of its empirical force field parameters.With the help of the DL force field,precision at the quantum chemistry level can be achieved in MD.Moreover,the DL force field promotes the computational speed compared with first-principles calculations.In this review,the basic knowledge of the molecular force field and deep neural network(DNN)is first introduced.Then,three representative opensource packages relevant to the DL force field are introduced.As the most common components in the development of oil and gas reservoirs,water and methane are studied from the aspects of computational efficiency and chemical reaction respectively,providing the foundation of oil and gas researches.However,in the oil and gas problems,the complex molecular topo structures and various element types set a high challenge for the DL techniques in MD.Regarding the computational efficiency,it needs improvement via GPU and parallel accelerations to compete with classical MD.Even with such difficulties,the booming of this technique in the area of petroleum engineering can be predictable.

Tuning the electronic structure of the earth-abundant electrocatalysts for oxygen evolution reaction(OER)to achieve efficient alkaline water splitting-A review

Tuning the electronic structure of the electrocatalysts for oxygen evolution reaction(OER)is a promising way to achieve efficient alkaline water splitting for clean energy production(H2).At first,this paper introduces the significance of the tuning of electronic structure,where modifying the electronic structure of the electrocatalysts could generate active sites having optimal adsorption energy with OER intermediates,and that could diminish the energy barrier for OER,and that could improve the activity for OER.Later,this paper reviews the tuning of electronic structure along with catalytic performances,synthetic methodologies,chemical properties,and DFT calculations on various nanostructured earth-abundant electrocatalysts for OER in alkaline environment.Further,this review discusses the tuning of the electronic structure of the several nanostructured earth-abundant electrocatalysts including oxide,(oxy)hydroxide,layered double hydroxide,alloy,metal phosphide/phosphate,nitride,sulfide,selenide,carbon containing materials,MOF,core-shell/hetero/hollow structured materials,and materials with vacancies/defects for OER in alkaline environment(including activity:overpotential(η)of ≤200 mV at10 m A cm^(-2);stability:≥100 h;durability:≥5000 cycles).Then,this review discusses the robust stability of the electrocatalysts for OER towards practical application.Moreover,this review discusses the in situ formation of thin layer on the catalyst surface during OER.In addition,this review discusses the influence of the adsorption energy of the OER intermediates on OER performance of the catalysts.Finally,this review summarizes the various promising strategies for tuning the electronic structure of the electrocatalysts to achieve enhanced performance for OER in alkaline environment.

Time-Domain Full Waveform Inversion Using the Gradient Preconditioning Based on Transmitted Wave Energy

The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge memory consumption of the gradient preconditioning algorithms based on the Hessian matrix. However, the accuracy of this approach is prone to be influ- enced by the energy of reflected waves. To tackle this problem, the paper proposes a new gradient preconditioning method based on the energy of transmitted waves. The approach scales the gradient through a precondition factor, which is calculated by the ‘ap- proximate transmission wavefield’ simulation based on the nonreflecting acoustic wave equation. The method requires no computing nor storing of the Hessian matrix and its inverse matrix. Furthermore, the proposed method can effectively eliminate the effects of geometric spreading and disproportionality in the gradient illumination. The results of model experiments show that the time-domain full waveform inversion (FWI) using the gradient preconditioning based on transmitted wave energy can achieve higher inversion accuracy for deep high-velocity bodies and their underlying strata in comparison with the one using the gradient preconditioning based on seismic wave energy. The field marine seismic data test shows that our proposed method is also highly applicable to the FWI of field marine seismic data.

Optical solitons supported by finite waveguide lattices with diffusive nonlocal nonlinearity

We investigate the properties of fundamental,multi-peak,and multi-peaked twisted solitons in three types of finite waveguide lattices imprinted in photorefractive media with asymmetrical diffusion nonlinearity.Two opposite soliton selfbending signals are considered for different families of solitons.Power thresholdless fundamental and multi-peaked solitons are stable in the low power region.The existence domain of two-peaked twisted solitons can be changed by the soliton self-bending signals.When solitons tend to self-bend toward the waveguide lattice,stable two-peaked twisted solitons can be found in a larger region in the middle of their existence region.Three-peaked twisted solitons are stable in the lower(upper)cutoff region for a shallow(deep)lattice depth.Our results provide an effective guidance for revealing the soliton characteristics supported by a finite waveguide lattice with diffusive nonlocal nonlinearity.

Large Barocaloric Effect with High Pressure-Driving Efficiency in a Hexagonal MnNi0.77Fe0.23Ge Alloy

The hydrostatic pressure is expected to be an effective knob to tune the magnetostructural phase transitions of hexagonal MM’X alloys(M and M’denote transition metals and X represents main group elements).We perform magnetization measurements under hydrostatic pressure on an MM’X martensitic MnNi0.77Fe0.23Ge alloy.The magnetostructural transition temperature can be efficiently tuned to lower temperatures by applying moderate pressures,with a giant shift rate of-151 K/GPa.A temperature span of 30 K is obtained under the pressure,within which a large magnetic entropy change of-23 J·kg-1K-1 in a field change of 5 T is induced by the mechanical energy gain due to the large volume change.Meanwhile,a decoupling of structural and magnetic transitions is observed at low temperatures when the martensitic transition temperature is lower than the Curie temperature.These results show a multi-parameter tunable caloric effect that benefits the solid-state cooling.

Phase separation and domain crystallinity control enable open-air-printable highly efficient and sustainable organic photovoltaics

Organic solar cells(OSCs)have emerged as a promising solution for sustainable energy production,offering advantages such as a low carbon footprint,short energy payback period,and compatibility with eco-solvents.However,the use of hazardous solvents continues to dominate the best-performing OSCs,mainly because of the challenges of controlling phase separation and domain crystallinity in eco-solvents.In this study,we combined the solvent vapor treatment of CS2 and thermal annealing to precisely control the phase separation and domain crystallinity in PM6:M-Cl and PM6:O-Cl systems processed with the eco-solvent o-xylene.This method resulted in a maximum power conversion efficiency(PCE)of 18.4%,which is among the highest values reported for sustainable binary OSCs.Furthermore,the fabrication techniques were transferred from spin coating in a nitrogen environment to blade printing in ambient air,retaining a PCE of 16.0%,showing its potential for high-throughput and scalable production.In addition,a comparative analysis of OSCs processed with hazardous and green solvents was conducted to reveal the differences in phase aggregation.This work not only underscores the significance of sustainability in OSCs but also lays the groundwork for unlocking the full potential of open-air-printable sustainable OSCs for commercialization.

Ferromagnetism and ferroelectricity in a superlattice of antiferromagnetic perovskite oxides without ferroelectric polarization

We study the structural,electronic,and magnetic properties of the SrCrO_(3)/YCrO_(3) superlattice and their dependence on epitaxial strain.We discover that the superlattice adopts A-type antiferromagnetic(A-AFM)ordering in contrast to its constituents(SrCrO_(3):C-AFM;YCrO_(3):G-AFM)and retains it under compressive strain while becoming ferromagnetic(5μB per formula unit)at+1%strain.The obtained ferroelectric polarization is significantly higher than that of the R2NiMnO6/La2NiMnO6(R=Ce to Er)series of superlattices[Nat.Commun.5,4021(2014)]due to a large difference between the antipolar displacements of the Sr and Y cations.The superlattice is a hybrid-improper multiferroic material with a spontaneous ferroelectric polarization(13.5μC/cm^(2))approaching that of bulk BaTiO_(3)(19μC/cm^(2)).The combination of ferromagnetism with ferroelectricity enables multistate memory applications.In addition,the charge-order-driven p-type semiconducting state of the ferromagnetic phase(despite the metallic nature of SrCrO_(3))is a rare property and interesting for spintronics.Monte Carlo simulations demonstrate a magnetic critical temperature of 90 K for the A-AFM phase without strain and of 115 K for the ferromagnetic phase at+5%strain,for example.

Magnetic soliton confinement and discretization effects in Cr_(1/3)TaS_(2)nanoflakes

Topological spin textures have been considered very promising for emerging magnetic memory applications.Recently,Cr_(1/3)TaS_(2)(CTS),a layered magnetic material,has been demonstrated to be a chiral helimagnet,and onedimensional magnetic solitons have been observed via Lorentz transmission electron microscopy.In this paper,we demonstrated the magnetic soliton confinement and discretization effects of CTS through the magneto transport measurements on the samples of different thicknesses.

A synergetic layered inorganic–organic hybrid film for conductive, flexible, and transparent electrodes

Conductive electrodes are major components of flexible optoelectronic devices.However,existing materials are either very conductive but brittle(e.g.,ITO[indium tin-oxide]),or non-brittle but less conductive,with an environment-dependent conductivity(e.g.,PEDOT:PSS[poly-(3,4 ethylenedioxythiophene):poly(styrene sulfonic acid)]).Here,we propose a new design that simultaneously takes advantage of both the high conductivity of ITO and the high flexibility of PEDOT:PSS.In our design,a PEDOT:PSS interface is inserted between the film substrate and the ITO layer,creating a hybrid layered structure that retains both its high conductivity and high stability,when the film is deformed.The rational behind the creation of this structure,is that PEDOT:PSS,used as an interface between the locally delaminated ITO layer and the substrate,substantially reduces the detrimental effects of cracks on the electrode’s conductivity.These results open the path for a new generation of transparent electrodes in advanced flexible devices.

Room-temperature multiple ligands-tailored SnO_(2) quantum dots endow in situ dual-interface binding for upscaling efficient perovskite photovoltaics with high V_(OC)

The benchmark tin oxide(SnO_(2))electron transporting layers(ETLs)have enabled remarkable progress in planar perovskite solar cell(PSCs).However,the energy loss is still a challenge due to the lack of“hidden interface”control.We report a novel ligand-tailored ultrafine SnO_(2) quantum dots(QDs)via a facile rapid room temperature synthesis.Importantly,the ligand-tailored SnO_(2) QDs ETL with multi-functional terminal groups in situ refines the buried interfaces with both the perovskite and transparent electrode via enhanced interface binding and perovskite passivation.These novel ETLs induce synergistic effects of physical and chemical interfacial modulation and preferred perovskite crystallization-directing,delivering reduced interface defects,suppressed non-radiative recombination and elongated charge carrier lifetime.Power conversion efficiency(PCE)of 23.02%(0.04 cm^(2))and 21.6%(0.98 cm^(2),V_(OC) loss:0.336 V)have been achieved for the blade-coated PSCs(1.54 eV E_(g))with our new ETLs,representing a record for SnO_(2) based blade-coated PSCs.Moreover,a substantially enhanced PCE(V_(OC))from 20.4%(1.15 V)to 22.8%(1.24 V,90 mV higher V_(OC),0.04 cm^(2) device)in the blade-coated 1.61 eV PSCs system,via replacing the benchmark commercial colloidal SnO_(2) with our new ETLs.

Alkyl-thiophene-alkyl linkers to construct double-cable conjugated polymers for single-component organic solar cells

In this work,semirigid linkers of the alkyl-thiophene-alkyl structure are developed to construct double-cable polymers.Three alkyl units,propyl(C3H6),hexyl(C6H12),and dodecyl(C12H24),are applied as semirigid linkers,yielding three double-cable polymers:PBC6-T,PBC12-T,and PBC24-T,respectively.PBC12-T which uses C6H12-thiophene-C6H12 linkers is found to exhibit the best device efficiency of 5.56%,while PBC6-T and PBC24-T with shorter or longer linkers yield device efficiencies of only 2.65%and 1.09%in single-component organic solar cells(SCOSCs).Further studies reveal that PBC12-T exhibits higher crystallinity and improved charge transport,resulting in better efficiencies.Our work provides an approach to construct double-cable conjugated polymers with long alkyl linkers,and it shows the importance of the linker length for the photovoltaic performance of SCOSCs.

高硬度六亚甲基四胺基无金属钙钛矿单晶及其高性能X射线探测

无金属卤化物钙钛矿(MFHaP)因其出色的光电性质、化学兼容性、轻量级特征和环保性能,受到了广泛关注.传统的MFHaPs材料主要是在A位采用DABCO^(2)+(1,4-二氮杂二环[2.2.2]辛烷)及其衍生物和B位采用铵根离子组成的,这种结构一般都有较低的硬度和高的离子迁移.为了克服这些难题,我们通过在A位引入了笼状有机阳离子六亚甲基四胺(hmta^(2+)),成功合成了具有较高机械硬度(1.5 GPa)的hmtaNH_(4)Br_(3)单晶.这主要得益于hmta-NH_(4)Br_(3)单晶中较短的氢键和更接近1的容忍因子.此外,hmta-NH_(4)Br_(3)单晶还表现出优异的结构稳定性和环境稳定性.采用低缺陷hmta-NH_(4)Br_(3)单晶构建的X射线探测器不仅大幅减少了离子迁移,还实现了150μC Gyair^(-1)cm^(-2)的高灵敏度,展现了其在高能辐射检测领域的巨大潜力.

Application of phase-field method in rechargeable batteries

Rechargeable batteries have a profound impact on our daily life so that it is urgent to capture the physical and chemical fundamentals affecting the operation and lifetime.The phase-field method is a powerful computational approach to describe and predict the evolution of mesoscale microstructures,which can help to understand the dynamic behavior of the material systems.In this review,we briefly introduce the theoretical framework of the phase-field model and its application in electrochemical systems,summarize the existing phase-field simulations in rechargeable batteries,and provide improvement,development,and problems to be considered of the future phase-field simulation in rechargeable batteries.

Develop a 3D neurological disease model of human cortical glutamatergic neurons using micropillar-based scaffolds

Establishing an effective three-dimensional(3D) in vitro culture system to better model human neurological diseases is desirable, since the human brain is a 3D structure. Here, we demonstrated the development of a polydimethylsiloxane(PDMS) pillar-based 3D scaffold that mimicked the 3D microenvironment of the brain. We utilized this scaffold for the growth of human cortical glutamatergic neurons that were differentiated from human pluripotent stem cells. In comparison with the 2D culture, we demonstrated that the developed 3D culture promoted the maturation of human cortical glutamatergic neurons by showing significantly more MAP2 and less Ki67 expression. Based on this 3D culture system,we further developed an in vitro disease-like model of traumatic brain injury(TBI), which showed a robust increase of glutamate-release from the neurons, in response to mechanical impacts, recapitulating the critical pathology of TBI. The increased glutamate-release from our 3D culture model was attenuated by the treatment of neural protective drugs, memantine or nimodipine. The established 3D in vitro human neural culture system and TBI-like model may be used to facilitate mechanistic studies and drug screening for neurotrauma or other neurological diseases.