Modulating perovskite crystallization and band alignment using coplanar molecules for high-performance indoor photovoltaics

The proper bandgap and exceptional photostability enable CsPbI_(3) as a potential candidate for indoor photovoltaics(IPVs),but indoor power conversion efficiency(PCE) is impeded by serious nonradiative recombination stemming from challenges in incomplete DMAPbI_(3) conversion and lattice structure distortion.Here,the coplanar symmetric structu re of hexyl sulfide(HS) is employed to functionalize the CsPbI_(3) layer for fabricating highly efficient IPVs.The hydrogen bond between HS and DMAI promotes the conversion of DMAPbI_(3) to CsPbI_(3),while the copianar symmetric structure enhances crystalline order.Simultaneously,surface sulfidation during HS-induced growth results in the in situ formation of PbS,spontaneously creating a CsPbI_(3) N-P homojunction to enhance band alignment and carrier mobility.As a result,the CsPbI_(3)&HS devices achieve an impressive indoor PCE of 39.90%(P_(in):334.6 μW cm^(-2),P_(out):133.5 μW cm^(-2)) under LED@2968 K,1062 lux,and maintain over 90% initial PCE for 800 h at ^(3)0% air ambient humidity.

Efficient and Stable Inverted Perovskite Solar Modules Enabled by Solid-Liquid Two-Step Film Formation

A considerable efficiency gap exists between large-area perovskite solar modules and small-area perovskite solar cells.The control of forming uniform and large-area film and perovskite crystallization is still the main obstacle restricting the efficiency of PSMs.In this work,we adopted a solid-liquid two-step film formation technique,which involved the evaporation of a lead iodide film and blade coating of an organic ammonium halide solution to prepare perovskite films.This method possesses the advantages of integrating vapor deposition and solution methods,which could apply to substrates with different roughness and avoid using toxic solvents to achieve a more uniform,large-area perovskite film.Furthermore,modification of the NiO_(x)/perovskite buried interface and introduction of Urea additives were utilized to reduce interface recombination and regulate perovskite crystallization.As a result,a large-area perovskite film possessing larger grains,fewer pinholes,and reduced defects could be achieved.The inverted PSM with an active area of 61.56 cm^(2)(10×10 cm^(2)substrate)achieved a champion power conversion efficiency of 20.56%and significantly improved stability.This method suggests an innovative approach to resolving the uniformity issue associated with large-area film fabrication.

Highly Efficient and Stable FAPbI_(3) Perovskite Solar Cells and Modules Based on Exposure of the(011)Facet

Perovskite crystal facets greatly impact the performance and stability of their corresponding photovoltaic devices.Compared to the(001)facet,the(011)facet yields better photoelectric properties,including higher conductivity and enhanced charge carrier mobility.Thus,achieving(011)facet-exposed films is a promising way to improve device performance.However,the growth of(011)facets is energetically unfavorable in FAPbI_(3) perovskites due to the influence of methylammonium chloride additive.Here,1-butyl-4-methylpyridinium chloride([4MBP]Cl)was used to expose(011)facets.The[4MBP]^(+)cation selectively decreases the surface energy of the(011)facet enabling the growth of the(011)plane.The[4MBP]^(+)cation causes the perovskite nuclei to rotate by 45°such that(011)crystal facets stack along the out-of-plane direction.The(011)facet has excellent charge transport properties and can achieve better-matched energy level alignment.In addition,[4MBP]Cl increases the activation energy barrier for ion migration,suppressing decomposition of the perovskite.As a result,a small-size device(0.06 cm2)and a module(29.0 cm2)based on exposure of the(011)facet achieved power conversion efficiencies of 25.24%and 21.12%,respectively.

Coexisting lattice contractions and expansions with decreasing thicknesses of Cu(100)nano-films

Lattice parameters are a basic quantity in material characterization,and a slight alteration in lattice parameters directly affects the properties of materials.However,there are still considerable controversies as to whether lattice expansion or contraction occurs in metallic nanomaterials with size reduction.Here,the size dependences of the lattice parameter and surface free energy of clean Cu(100)films are investigated via simulations.Lattice parameters of the exposed surfaces contract,whereas lattice expansion occurs along the direction perpendicular to the surfaces with decreasing film thicknesses.This is striking since the metallic bonds usually lack strong directionality,and it is always regarded that the lattice variations in all directions are consistent.The contraction parallel to the surface is more severe than the expansion perpendicular to the surface in films.The lattices change from cubic to tetragonal with decreasing film thickness.Consequently,common contractions and occasional expansions of the lattice parameters of Cu nanoparticles have been observed in previous experiments.Increasing free energy and surface free energy with decreasing thicknesses is the thermodynamic origin of the lattice variations.Our study therefore provides a comprehensive physical basis for the surface effects on the lattice variations.

Smart Design and Manufacturing the Welded Q350 Steel Frames via Lifecycle Management Strategy of Digital Twin

Artificial intelligent aided design and manufacturing have been recognized as one kind of robust data-driven and data-intensive technologies in the integrated computational material engi-neering(ICME)era.Motivated by the dramatical developments of the services of China Railway High-speed series for more than a decade,it is essential to reveal the foundations of lifecycle man-agement of those trains under environmental conditions.Here,the smart design and manufacturing of welded Q350 steel frames of CR200J series are introduced,presenting the capability and opportu-nity of ICME in weight reduction and lifecycle management at a cost-effective approach.In order to address the required fatigue life time enduring more than 9×10^(6)km,the response of optimized frames to the static and the dynamic loads are comprehensively investigated.It is highlighted that the maximum residual stress of the optimized welded frame is reduced to 69 MPa from 477 MPa of previous existing one.Based on the measured stress and acceleration from the railways,the fatigue life of modified frame under various loading modes could fulfil the requirements of the lifecycle man-agement.Moreover,our recent developed intelligent quality control strategy of welding process mediated by machine learning is also introduced,envisioning its application in the intelligent weld-ing.

Brominated PEAI as Multi-Functional Passivator for High-Efficiency Perovskite Solar Cell

The interfaces of perovskite solar cells(PSCs)are well known to be rich in deep-level carrier traps,which serve as non-radiative recombination centers and limit the open-circuit voltage(Voc)and power conversion efficiency(PCE)of PSCs.Defect chemistry and surface passivators have been researched extensively and mainly focused on the neutralization of uncoordinated lead or anion defects.Herein,a novel brominated passivator 2-bromophenethylammonium iodide(2-Br-PEAI)is introduced for a multi-functional passivation effect at the perovskite interface.The brominated species readily form 2D perovskite on top of the 3D perovskite and multi-interact with the 3D perovskite surface.Apart from the halide vacancy filling and anion bonding ability,the Br atoms on the benzene ring can interact with the FA cations via strong hydrogen bonding N-H…Br and interact with the[PbI_(6)]^(4−)inorganic framework.The interface defects in the PSCs are well passivated,minimizing non-radiative recombination and enhancing device performance.As a result,a champion PCE of 24.22%was achieved with high V_(oc)and fill factor.In addition,modified devices also showed enhanced operational stability(retention of>95%initial PCE after 400 h)and humidity resistance(>90%initial PCE maintained after 1500 h under~50%RH).

Effect of the projector augmented wave potentials on the simulation of thermodynamic properties of vanadium

We report significant differences in high-pressure properties of vanadium at zero temperature and finite temperature when different projector augmented wave(PAW)potentials are used in simulations based on density functional theory.When a PAW potential with only five electrons taken as valence electrons is used,the cold pressures in the high-pressure region are seriously underestimated,and an abnormality occurs in the melting curve of vanadium at about 400 GPa.We show that the reason for these discrepancies lies in the differences in the descriptions of the interatomic force,electron dispersion,and anisotropy of electron bonding obtained from differentPAWpotentials at high pressure,which lead to striking differences in the mechanical stability of the system.We propose a procedure for selecting PAW potentials suitable for simulations at high temperature and high pressure.Our results provide valuable guidance for future simulations of thermodynamic properties under extreme conditions.

First-principles study on the electronic structure transition ofβ-UH3 under high pressure

We investigate the electronic properties of stableβ-UH3 under high pressure up to 75 GPa within the first-principles DFT+U formalism with pressure-dependent U in a self-consistent calculation,and we find an electronic structure transition at about 20 GPa due to the quantum process of localization and itinerancy for partially filled uranium 5f electrons.The electronic structure transition is examined from four perspectives:magnetization,band structure,density of states,and 5f electron energy.On the basis of the density of states of 5f electrons,we propose an order parameter,namely,the 5f electron energy,to quantify the electronic structure transition under pressure.Analogously to the isostructural transition in 3d systems,β-UH3 retains its magnetic order after the electronic structure transition;however,this is not accompanied by volume collapse at the transition point.Our calculation is helpful for understanding the electronic properties ofβ-UH3 under high pressure.

Chiral cation promoted interfacial charge extraction for efficient tin-based perovskite solar cells

Pb-free Sn-based perovskite solar cells(PSCs) have recently made inspiring progress, and power conversion efficiency(PCE) of 14.8% has been achieved. However, due to the energy-level mismatch and poor interfacial contact between commonly used hole transport layer(i.e., poly(3,4-ethylenedioxythio phene):poly(styrene sulfonate), PEDOT:PSS) and FASnI_(3) film, it is still challenging to effectively extract holes at the interface. Owing to the p-type nature of Sn-based perovskites, the efficient hole extraction is of particular significance to improve the PCE of their solar cells. In this work, for the first time, the role of chiral cations, a-methylbenzylamine(S-/R-/rac-MBA), in promoting hole transportation of FASnI_(3)-based PSCs is demonstrated. The introduction of MBAs is found to form 2D/3D film with lowdimensional structures locating at PEDOT:PSS/FASnI_(3) interface, which facilitates the energy level alignment and efficient charge transfer at the interface. Importantly, chiral-induced spin selectivity(CISS)effect of R-MBA_(2)SnI_(4)induced by chiral R-MBA cation is found to further assist the specific interfacial transport of accumulated holes. As a result, R-MBA-based PSCs achieve decent PCE of 10.73% with much suppressed hysteresis and enhanced device stability. This work opens up a new strategy to efficiently promote the interfacial extraction of accumulated charges in working PSCs.

Tartaric acid additive to enhance perovskite multiple preferential orientations for high-performance solar cells

Perovskite film quality is a decisive factor governing the performance and long-term stability of perovskite solar cells(PSCs). To passivate defects for high-quality perovskite films, various additives have been explored in perovskite precursor with notable achievements in the development of highperformance PSCs. Herein, tartaric acid(TA) was applied as additive in perovskite precursor solution to modulate the crystal growth leading to high quality thin films with enhanced multiple preferential orientations favoring efficient charge transport along multiple directions. It is also noticed that TA can improve the energy level alignment in PSCs, which effectively accelerates both carrier extraction and transportation with non-radiative recombination suppressed at the perovskite interfaces. Based on the present perovskite films, the fabricated PSCs achieved an excellent champion power conversion efficiency(PCE) of 21.82% from that of 19.70% for the control device without TA additive. In addition, a PSC with TA additive was shown to exhibit impressive operational stability by retaining 92% of its initial PCE after~1200 h of aging at room temperature in ambient air with a relative humidity of about 10%–25%. In summary, the present work demonstrates a facile and versatile approach by using TA as additive in perovskite precursor to fabricate high quality perovskite films with enhanced multiple preferential orientations for high-efficiency stable PSCs.

Influence of helium on the evolution of irradiation-induced defects in tungsten:An object kinetic Monte Carlo simulation

Understanding the evolution of irradiation-induced defects is of critical importance for the performance estimation of nuclear materials under irradiation.Hereby,we systematically investigate the influence of He on the evolution of Frenkel pairs and collision cascades in tungsten(W)via using the object kinetic Monte Carlo(OKMC)method.Our findings suggest that the presence of He has significant effect on the evolution of irradiation-induced defects.On the one hand,the presence of He can facilitate the recombination of vacancies and self-interstitial atoms(SIAs)in W.This can be attributed to the formation of immobile He-SIA complexes,which increases the annihilation probability of vacancies and SIAs.On the other hand,due to the high stability and low mobility of He-vacancy complexes,the growth of large vacancy clusters in W is kinetically suppressed by He addition.Specially,in comparison with the injection of collision cascades and He in sequential way at 1223 K,the average sizes of surviving vacancy clusters in W via simultaneous way are smaller,which is in good agreement with previous experimental observations.These results advocate that the impurity with low concentration has significant effect on the evolution of irradiation-induced defects in materials,and contributes to our understanding of W performance under irradiation.

Discovering the ultralow thermal conductive A_(2)B_(2)O_(7)-type high-entropy oxides through the hybrid knowle dge-assiste d data-driven machine learning

Lattice engineering and distortion have been considered one kind of effective strategies for discovering advanced materials.The instinct chemical flexibility of high-entropy oxides(HEOs)motivates/accelerates to tailor the target properties through phase transformations and lattice distortion.Here,a hybrid knowledge-assisted data-driven machine learning(ML)strategy is utilized to discover the A_(2)B_(2)O_(7)-type HEOs with low thermal conductivity(κ)through 17 rare-earth(RE=Sc,Y,La-Lu)solutes optimized A-site.A designing routine integrating the ML and high throughput first principles has been proposed to predict the key physical parameter(KPPs)correlated to the targetedκof advanced HEOs.Among the smart-designed 6188(5RE_(0.2))_(2)Zr_(2)O_(7)HEOs,the best candidates are addressed and validated by the princi-ples of severe lattice distortion and local phase transformation,which effectively reduceκby the strong multi-phonon scattering and weak interatomic interactions.Particularly,(Sc_(0.2)Y_(0.2)La_(0.2)Ce_(0.2)Pr_(0.2))_(2)Zr_(2)O_(7)with predictedκbelow 1.59 Wm^(−1)K^(−1)is selected to be verified,which matches well with the ex-perimentalκ=1.69 Wm^(−1)K^(−1)at 300 K and could be further decreased to 0.14 Wm^(−1)K^(−1)at 1473 K.Moreover,the coupling effects of lattice vibrations and charges on heat transfer are revealed by the cross-validations of various models,indicating that the weak bonds with low electronegativity and few bond-ing charge density and the lattice distortion(r∗)identified by cation radius ratio(r A/r B)should be the KPPs to decreaseκefficiently.This work supports an intelligent designing strategy with limited atomic and electronic KPPs to accelerate the development of advanced multi-component HEOs with proper-ties/performance at multi-scales.

Highly ordered inkjet-printed quantum-dot thin films enable efficient and stable QLEDs with EQE exceeding 23%

Inkjet-printed quantum dot light-emitting diodes(QLEDs)are emerging as a promising technology for next-generation displays.However,the progress in fabricating QLEDs using inkjet printing technique has been slower compared to spin-coated devices,particularly in terms of efficiency and stability.The key to achieving high performance QLEDs lies in creating a highly ordered and uniform inkjet-printed quantum dot(QD)thin film.In this study,we present a highly effective strategy to significantly improve the quality of inkjet-printed CdZnSe/CdZnS/ZnS QD thin films through a pressure-assisted thermal annealing(PTA)approach.Benefiting from this PTA process,a high quality QD thin film with ordered packing,low surface roughness,high photoluminescence and excellent electrical property is obtained.The mechanism behind the PTA process and its profound impact on device performance have been thoroughly investigated and understood.Consequently,a record high external quantum efficiency(EQE)of 23.08%with an impressive operational lifetime(T50)of up to 343,342h@100cdm−2,and a record EQE of 22.43%with T50 exceeding to 1,500,463h@100cdm−2 are achieved in inkjet-printed red and green CdZnSe-based QLEDs,respectively.This work highlights the PTA process as an important approach to realize highly efficient and stable inkjet-printed QLEDs,thus advancing QLED technology to practical applications.

Predicting the utilization factor of blasthole in rock roadways by random forest

The utilization factor of blasthole is a crucial indicator of the effectiveness of blasting in rock roadways.A significant value means that the explosive energy is fully utilized,the single-cycle advance is high,and the excavation rate is fast.A good blasting programme is a prerequisite for improving the utilization rate and predicting the utilization rate before blasting operations can verify the feasibility of the blasting programme.Firstly,a database of rock roadway blasting covering different geological and production conditions is estab-lished.Secondly,error analysis and the Gini coefficient method are used to weight the characteristic variables,quantify the importance of the variables and identify eight key indicators affecting the blasting hole utilization rate.Then,a random forest algorithm-based model for predicting utilization factor of blasthole is proposed,and the results of the model on the test set are:root mean square error(RMSE)is 0.0137,mean absolute error(MAE)is 0.0087,and coefficient of determination(R^(2))is 0.905.The performance of this method is com-pared with that of the neural network and support vector machine models on the test sets to verify the superiority of the random forest algorithm.Finally,to verify the generalization ability and practicality of the random forest prediction model,the model is applied to the rock roadway blasting construction of Gu Bei coal mine in Anhui Province.The results show that R2 is 0.913,so the model is reliable and accurate,which can meet the actual engineering requirements and lay the foundation for the promotion and application of this technology.

Stress compensation based on interfacial nanostructures for stable perovskite solar cells

The long-term stability issue of halide perovskite solar cells hinders their commercialization.The residual stress-strain affects device stability,which is derived from the mismatched thermophysical and mechanical properties between adjacent layers.In this work,we introduced the Rb_(2)CO_(3)layer at the interface of SnO_(2)/perovskite with the hierarchy morphology of snowflake-like microislands and dendritic nanostructures.With a suitable thermal expansion coefficient,the Rb_(2)CO_(3)layer benefits the interfacial stress relaxation and results in a compressive stress-strain in the perovskite layer.Moreover,reduced nonradiative recombination losses and optimized band alignment were achieved.An enhancement of open-circuit voltage from 1.087 to 1.153 V in the resultant device was witnessed,which led to power conversion efficiency(PCE)of 22.7%(active area of 0.08313 cm^(2))and 20.6%(1 cm2).Moreover,these devices retained 95%of its initial PCE under the maximum power point tracking(MPPT)after 2700 h.It suggests inorganic materials with high thermal expansion coefficients and specific nanostructures are promising candidates to optimize interfacial mechanics,which improves the operational stability of perovskite cells.

The investigation of an amidine-based additive in the perovskite films and solar cells

Here,we introduced acetamidine（C2H3N2H3,Aa）-based salt as an additive in the fabrication of perovskite（CH3NH3PW3）layer for perovskite solar cells.It was found that as an amidine-based salt,this additive successfully enhanced the crystallinity of CH3NH3PW3 and helped to form smooth and uniform films with comparable grain size and full coverage.Besides,perovskite film with additive showed a much longer carrier lifetime and an obviously enhanced open-circuit voltage in the corresponding devices,indicating that the acetamidine-based salt can reduce the carrier recombination in both the film and device.We further demonstrate a promising perovskite device based on acetamidine salt by using a configuration of ITOATiO2/Perovskite/Spiro-OMeTAD/Au under 〈 150 ℃ fabrication condition.A power conversion efficiency（PCE）of 16.54%was achieved,which is much higher than the control device without acetamidine salt.These results present a simple method for film quality optimization of perovskite to further improve photovoltaic performances of perovskite solar cells,which may also benefit the exploration of A cation in perovskite materials.

Origin of High Efficiency and Long-Term Stability in Ionic Liquid Perovskite Photovoltaic

Environment-friendly protic amine carboxylic acid ionic liquids(ILs)as solvents is a significant breakthrough with respect to traditional highly coordinating and toxic solvents in achieving efficient and stable perovskite solar cells(PSCs)with a simple one-step air processing and without an antisolvent treatment approach.However,it remains mysterious for the improved efficiency and stability of PSCs without any passivation strategy.Here,we unambiguously demonstrate that the three functions of solvents,additive,and passivation are present for protic amine carboxylic acid ILs.We found that the ILs have the capability to dissolve a series of perovskite precursors,induce oriented crystallization,and chemically passivate the grain boundaries.This is attributed to the unique molecular structure of ILs with carbonyl and amine groups,allowing for strong interaction with perovskite precursors by forming C=O…Pb chelate bonds and N-H…I hydrogen bonds in both solution and film.This finding is generic in nature with extension to a wide range of IL-based perovskite optoelectronics.

Efficient and stable Ruddlesden-Popper layered tin-based perovskite solar cells enabled by ionic liquid-bulky spacers

The crucial component,bulky spacers,in two-dimensional Ruddlesden-Popper(2 DRP)layered tin(Sn)perovskites are highly limited by halide ammonium salts,leading to the insufficient control of complex crystallization process due to the limited interaction between bulky spacers and 2 DRP perovskite frameworks.Here,we report an ionic liquid-bulky spacer,butylammounium acetate(BAAc O),for constructing efficient and stable 2 DRP Sn-based perovskite solar cells(PSCs).In contrast to the traditional halide ammonium bulky spacer,butylammounium iodide(BAI),the Ac O^(-)-functional group in BAAc O has a strong interaction with formamidine ions(FA^(+))and Sn2+.The inter-component interaction allows the formation of controllable intermediates for the favorable growth of smooth,dense,and highly oriented perovskite films.A PSC with power conversion efficiency of 10.36%(7.16%for BAI)is achieved,which is the highest report,along with improved stability with~90%retained after~600 h storage in N_(2) atmosphere without any encapsulation.

High-throughput investigations of configurational-transformation-dominated serrations in CuZr/Cu nanolaminates

Metallic amorphous/crystalline(A/C)nanolaminates exhibit excellent ductility while retaining their high strength.However,the underlying physical mechanisms and the resultant structural changes during plastic deformation still remain unclear.In the present work,the structure-property relationship of CuZr/Cu A/C nanolaminates is established through integrated high-throughput micro-compression tests and molecular dynamics simulations together with high-resolution transmission electron microcopy.The serrated flow of nanolaminates results from the formation of hexagonal-close-packed(HCP)-type stacking faults and twins inside the face-centered-cubic(FCC)Cu nano-grains,the body-centered-cubic(BCC)-type ordering at their grain boundaries,and the crystallization of the amorphous CuZr layers.The serration behavior of CuZr/Cu A/C nanolaminates is determined by several factors,including the formation of dense dislocation networks from the multiplication of initial dislocations that formed after yielding,weak-spots-related configurational-transitions and shear-transition-zone activities,and deformation-induced devitrification.The present work provides an insight into the heterogeneous deformation mechanism of A/C nanolaminates at the atomic scale,and mechanistic base for the microstructural design of self-toughening metallic-glass(MG)-based composites and A/C nanolaminates.

Injecting spectral indices to transferable convolutional neural network under imbalanced and noisy labels for Landsat image classification

Stable and continuous remote sensing land-cover mapping is important for agriculture,ecosystems,and land management.Convolutional neural networks(CNNs)are promising methods for achieving this goal.However,the large number of high-quality training samples required to train a CNN is difficult to acquire.In practice,imbalanced and noisy labels originating from existing land-cover maps can be used as alternatives.Experiments have shown that the inconsistency in the training samples has a significant impact on the performance of the CNN.To overcome this drawback,a method is proposed to inject highly consistent information into the network,to learn general and transferable features to alleviate the impact of imperfect training samples.Spectral indices are important features that can provide consistent information.These indices can be fused with CNN feature maps which utilize information entropy to choose the most appropriate CNN layer,to compensate for the inconsistency caused by the imbalanced,noisy labels.The proposed transferable CNN,tested with imbalanced and noisy labels for inter-regional Landsat time-series,not only is superior in terms of accuracy for land-cover mapping but also demonstrates excellent transferability between regions in both time series and cross-regional Landsat image classification.