Inkjet-Printing Controlled Phase Evolution Boosts the Efficiency of Hole Transport Material Free and Carbon-Based CsPbBr_(3) Perovskite Solar Cells Exceeding 9%

Hole transport material free carbon-based all-inorganic CsPbBr_(3)perovskite solar cells(PSCs)are promising for commercialization due to its low-cost,high open-circuit voltage(V_(oc))and superior stability.Due to the different solubility of PbBr_(2)and CsBr in conventional solvents,CsPbBr_(3)films are mainly obtained by multi-step spin-coating through the phase evolution from PbBr_(2)to CsPb_(2)Br_(5)and then to CsPbBr_(3).The scalable fabrication of high-quality CsPbBr_(3)films has been rarely studied.Herein,an inkjet-printing method is developed to prepare high-quality CsPbBr_(3)films.The formation of long-range crystalline CsPb_(2)Br_(5)phase can effectively improve phase purity and promote regular crystal stacking of CsPbBr_(3).Consequently,the inkjet-printed CsPbBr_(3)C-PSCs realized PCEs up to 9.09%,8.59%and 7.81%with active areas of 0.09,0.25,and 1 cm^(2),respectively,demonstrating the upscaling potential of our fabrication method and devices.This high performance is mainly ascribed to the high purity,strong crystal orientation,reduced surface roughness and lower trap states density of the as-printed CsPbBr_(3)films.This work provides insights into the relationship between the phase evolution mechanisms and crystal growth dynamics of cesium lead bromide halide films.

Long-Chain Gemini Surfactant-Assisted Blade Coating Enables Large-Area Carbon-Based Perovskite Solar Modules with Record Performance

Carbon-based perovskite solar cells show great potential owing to their low-cost production and superior stability in ambient air.However,scaling up to high-efficiency carbon-based solar modules hinges on reliable deposition of uniform defect-free perovskite films over large areas,which is an unsettled but urgent issue.In this work,a long-chain gemini surfactant is introduced into perovskite precursor ink to enforce self-assembly into a network structure,considerably enhancing the coverage and smoothness of the perovskite films.The long gemini surfactant plays a distinctively synergistic role in perovskite film construction,crystallization kinetics modulation and defect passivation,leading to a certified record power conversion efficiency of 15.46%with Voc of 1.13 V and Jsc of 22.92 mA cm^(-2)for this type of modules.Importantly,all of the functional layers of the module are printed through a simple and high-speed(300 cm min^(-1))blade coating strategy in ambient atmosphere.These results mark a significant step toward the commercialization of all-printable carbon-based perovskite solar modules.

13X微孔沸石和MCM-41介孔材料的合成及用于处理含Cd^(2+)废水

以天津蓟县钾长石矿粉为主要原料,经选矿、煅烧、水热处理等工艺成功合成了13X微孔沸石．以气相氧化硅、氢氧化钠、十六烷基三甲基溴化铵等为主要原料,在水热条件下合成了MCM-41有序介孔材料．采用XRD和N_2吸附-脱附等手段对合成的13X沸石和MCM-41介孔材料的物相、比表面积、孔径、孔体积等进行了分析对比．在此基础上,对13X沸石和MCM-41介孔材料处理含Cd^(2+)废水的效果和机理进行了对比研究,确定了不同分子筛用量、不同初始pH值、不同混合时间下13X沸石和MCM-41介孔分子筛对水中Cd^(2+)的吸附率和吸附量．研究发现,尽管MCM-41的比表面积和孔径远大于13X沸石,但其对水中Cd^(2+)的处理效果却低于13X沸石,这与13X沸石和MCM-41的孔道结构类型、化学组成、表面荷电性质等有关．

Fabrication and mechanical properties of MWCNTs-reinforced aluminum composites by hot extrusion

Over the past decade,the interest in aluminum composites reinforced with carbon nanotubes has grown significantly.Studies have been carried out to overcome problems with uniform dispersion,interfacial bonding,void formation and carbide formation of the composites.In the present work,multi-wall carbon nanotubes(MWCNTs) aluminum composites were produced.High-energy ball milling with the aim at developing well-dispersed MWCNTs Al composites was followed by cold compaction,sintering,and hot extrusion at 500 ℃.Different amounts of stearic acid as processing control agent(PCA) is used in order to minimize cold welding of the Al particles,and to produce finer particles.Differential scanning calorimetry(DSC),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray diffraction(XRD) were employed to analyze the MWCNTs,the aluminum powder,and the composites’ microstructural behavior.The hardness and tensile properties of the composites are also evaluated.The results showed 500% increase in yield stress after the addition of 1 wt% MWCNTs in Al-MWCNTs based composite.The ball-milling time of 4 h is found to be sufficient as excessive milling time destroys a vast number of MWCNTs.

Effect of diode size and series resistance on barrier height and ideality factor in nearly ideal Au/n type-GaAs micro Schottky contact diodes

Small high-quality Au/n type-GaAs Schottky barrier diodes （SBDs） with low reverse leakage current are produced using lithography. Their effective barrier heights （BHs） and ideality factors from current-voltage （I-V） characteristics are measured by a Pico ampere meter and home-built I-V instrument. In spite of the identical preparation of the diodes there is a diode-to-diode variation in ideality factor and barrier height parameters. Measurement of topology of a surface of a thin metal film with atomic force microscope （AFM） shows that Au-n type-GaAS SD consists of a set of parallel-connected micro and nanocontacts diodes with sizes approximately in a range of 100-200 nm. Between barrier height and ideality factor there is an inversely proportional dependency. With the diameter of contact increasing from 5 μm up to 200 μm, the barrier height increases from 0.833 up to 0.933 eV and its ideality factor decreases from 1.11 down to 1.006. These dependencies show the reduction of the contribution of the peripheral current with the diameter of contact increasing. We find the effect of series resistance on barrier height and ideality factor.

Perfection of Perovskite Grain Boundary Passivation by Rhodium Incorporation for Efficient and Stable Solar Cells

Organic cation and halide anion defects are omnipresent in the perovskite films,which will destroy perovskite electronic structure and downgrade the properties of devices.Defect passivation in halide perovskites is crucial to the application of solar cells.Herein,tiny amounts of trivalent rhodium ion incorporation can help the nucleation of perovskite grain and passivate the defects in the grain boundaries,which can improve efficiency and stability of perovskite solar cells.Through first-principle calculations,rhodium ion incorporation into the perovskite structure can induce ordered arrangement and tune bandgap.In experiment,rhodium ion incorporation with perovskite can contribute to preparing larger crystalline and uniform film,reducing trap-state density and enlarging charge carrier lifetime.After optimizing the content of 1% rhodium,the devices achieved an efficiency up to 20.71% without obvious hysteresis,from 19.09% of that pristine perovskite.In addition,the unencapsulated solar cells maintain 92% of its initial efficiency after 500 h in dry air.This work highlights the advantages of trivalent rhodium ion incorporation in the characteristics of perovskite solar cells,which will promote the future industrial application.

Antioxidative solution processing yields exceptional Sn(Ⅱ) stability for sub-1.4 eV bandgap inorganic perovskite solar cells

Owing to the combined features of sub-1.4 eV bandgap and all-inorganic composition,cesium tin–lead(Sn-Pb)triiodide perovskite is promising for approaching the Shockley-Queisser limit of solar cells while avoiding the use of volatile organic cations.But the low Sn(Ⅱ)stability in this perovskite remains a hurdle for delivering its theoretically attainable device performance.Herein we present a synthesis method of this perovskite based on an acetylhydrazine-incorporated antioxidative solution system.Mechanistic investigation shows that acetylhydrazine effectively reduces the oxidation of solution-phase Sn(Ⅱ)and meanwhile creates an electron-rich,protective nano-environment for solid-state Sn(Ⅱ)ions.These lead to high oxidation resistance of the final film as well as effective defect inhibition.The resultant solar cells demonstrate power conversion efficiencies up to 15.04%,the highest reported so far for inorganic perovskite devices with sub-1.4 eV bandgaps.Furthermore,the T_(90) lifetime of these devices can exceed 1000 hours upon light soaking in a nitrogen atmosphere,demonstrating the potential advantage when lower-bandgap perovskite solar cells go all-inorganic.

Structural and electrical properties of carbon-ion-implanted ultrananocrystalline diamond films

We investigate the structural and electrical properties of carbon-ion-implanted ultrananocrystalline diamond（UNCD）films. Impedance spectroscopy measurements show that the impedance of diamond grains is relatively stable, while that of grain boundaries（GBs）（Rb） significantly increases after the C~＋ implantation, and decreases with the increase in the annealing temperature（Ta） from 650℃ to 1000℃. This implies that the C~＋ implantation has a more significant impact on the conductivity of GBs. Conductive atomic force microscopy demonstrates that the number of conductive sites increases in GB regions at Ta above 900℃, owing to the formation of a nanographitic phase confirmed by high-resolution transmission electronic microscopy. Visible-light Raman spectra show that resistive trans-polyacetylene oligomers desorb from GBs at Ta above 900℃, which leads to lower Rb of samples annealed at 900 and 1000℃. With the increase in Ta to 1000℃, diamond grains become smaller with longer GBs modified by a more ordered nanographitic phase, supplying more conductive sites and leading to a lower Rb.

MOF-Transformed In_(2)O_(3-x)@C Nanocorn Electrocatalyst for Efficient CO_(2)Reduction to HCOOH

For electrochemical CO_(2) reduction to HCOOH,an ongoing challenge is to design energy efficient electrocatalysts that can deliver a high HCOOH current density(JHCOOH)at a low overpotential.Indium oxide is good HCOOH production catalyst but with low con-ductivity.In this work,we report a unique corn design of In_(2)O_(3-x)@C nanocatalyst,wherein In_(2)O_(3-x)nanocube as the fine grains dispersed uniformly on the carbon nanorod cob,resulting in the enhanced conductivity.Excellent performance is achieved with 84%Faradaic efficiency(FE)and 11 mA cm^(−2)JHCOOH at a low potential of−0.4 V versus RHE.At the current density of 100 mA cm^(−2),the applied potential remained stable for more than 120 h with the FE above 90%.Density functional theory calculations reveal that the abundant oxygen vacancy in In_(2)O_(3-x) has exposed more In^(3+) sites with activated electroactivity,which facilitates the formation of HCOO*intermediate.Operando X-ray absorp-tion spectroscopy also confirms In^(3+) as the active site and the key intermediate of HCOO*during the process of CO_(2) reduction to HCOOH.

Performance enhancement of ZnO nanowires/PbS quantum dot depleted bulk heterojunction solar cells with an ultrathin Al_2O_3 interlayer

Depleted bulk heterojunction （DBH） PbS quantum dot solar cells （QDSCs）, appearing with boosted short-circuit current density （Jsc）, represent the great potential of solar radiation utilization, but suffer from the problem of increased interfacial charge recombination and reduced open-circuit voltage （Voc）. Herein, we report that an insertion of ultrathin A1203 layer （ca. 1.2 A thickness） at the interface of ZnO nanowires （NWs） and PbS quantum dots （QDs） could remarkably improve the performance of DBH-QDSCs fabricated from them, i.e., an increase of Voc from 449 mV to 572 mV, J^c from 21.90 mA/cm2 to 23.98 mA/cm2, and power conversion efficiency （PCE） from 4.29% to 6.11%. Such an improvement of device performance is ascribed to the significant reduction of the interfacial charge recombination rate, as evidenced by the light intensity dependence on Jsc and Voc, the prolonged electron lifetime, the lowered trap density, and the enlarged recombination activation energy. The present research therefore provides an effective interfacial engineering means to improving the overall performance of DBH-QDSCs, which might also be effective to other types of optoelectronic devices with large interface area.

Understanding the impact of coal blending decisions on the prediction of coke quality: a data mining approach

The accurate prediction of coke quality is important for the selection and valuation of metallurgical coals. Whilst many prediction models exist, they tend to perform poorly for coals beyond which the model was developed. Further, these models general fail to directly account for physical interactions occurring between the blend components, through the assumption that the aggregate properties of the blend are suitably representative of the overall behavior of the blend. To study this assumption, a parameter termed the vitrinite distribution category was introduced to directly account for the distribution of one of these commonly aggregated parameters, the vitrinite reflectance. The introduction of this parameter in a regression model for coke quality prediction improved the model fit. The vitrinite distribution category was demonstrated to provide new information about coal blending decisions, and was found to be capable of providing insight into the behavior of different blending structures. Residual analysis was applied to explore the behavior of the coke quality prediction model, with the vitrinite distribution category found to explain more than just the presence or absence of coals within a blend. This work provides the foundation of future studies in examining coal blending decisions, with the proposed parameter having the potential to be applied as part of a coke quality prediction model to optimize coal blending decisions.

D-π-D molecular layer electronically bridges the NiO_(x) hole transport layer and the perovskite layer towards high performance photovoltaics

Nickel oxide (NiO_(x)) has significant cost and stability advantages over poly[bis (4-phenyl)(2,4,6-trimethyl phenyl)amine](PTAA) for inverted p-i-n perovskite solar cells (PSCs),but the poor NiO_(x)/perovskite contact stemming from some reactive species at the interface led to suboptimal device performance.To solve this problem,we take a multiple donor molecule approach,using 3,3’-(4,8-bis(hexylthio)benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl)bis(10-(6-bromohexyl)-10H-phenoxazine)(BDT-POZ) as an example,to modify the NiO_(x)/perovskite interface.The primary goal was to reduce the under-coordinated Ni^(≥3+) cations via electron transfer from the donor molecules to NiO_(x),thus mitigating the detrimental reactions between perovskite and NiO_(x).Equally importantly,the hole extraction at the interface was greatly enhanced after the organic donor modification,since the hydrophobic species atop NiO_(x) not only enabled pinhole-free crystallization of the perovskite but also properly tuned the interfacial energy level alignment.Consequently,the PSCs with NiO_(x)/BDT-POZ HTL achieved a high power conversion efficiency (PCE) up to 20.16%,which compared excellently with that of the non-modified devices (17.83%).This work provides a new strategy to tackle the exacting issues that have so far impeded the development of NiO_(x) based PSCs.

Biomedical applications of Jones-matrix tomography to polycrystalline films of biological fuids

Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biological fuids of various human organs has been developed and experimentally tested.The coordinate distributions of phase and amplitude anisotropy of bile films and synovial fuid taken from the knee joint are determined and statistically analyzed.Criteria(statistical moments of 3rd and 4th orders)of differential diagnostics of early stages of cholelithiasis and septic arthritis of the knee joint with excellent balanced accuracy were determined.Data on the diagnostic fficiency of the Jones matrix tomography method for polyerystalline plasma(liver disease),urine(albuminuria)and cytological smears(cervical cancer)are presented.

Development of a database for the prediction of phases in Pt-based Superalloys:Cr-Pt-Ru

Work has been ongoing in building a thermodynamic database for the prediction of phase equilibria in Pt-based superalloys. The alloys are being developed for high texture applications in aggressive environments. The database will aid the design of alloys by enabling the calculation of the composition and proportions of phases present in alloys of different compositions. In order to extend this database, a preliminary assessment of the Cr-Pt-Ru system has been undertaken, using a combination of Pandat and MTDATA software. As a first step, it was necessary to provide thermodynamic models for the three associated binary systems. Owing to a lack of thermodynamic information for these systems, the binary assessments were based on phase diagrams available in the literature. Using recent experimental phase equilibria data for the ternary system, a preliminary assessment of the Cr-Pt-Ru system has been produced. In this preliminary assessment, simplified models were employed for the L12 and sigma phases with a view to extending the descriptions as new experimental information becomes available.

Directing the photogenerated charge flow in a photocathodic metal protection system with single-domain ferroelectric PbTiO_(3)nanoplates

Photocathodic protection(PCP)is arguably an ideal alternative technology to the conventional electrochemical cathodic protection methods for corrosion mitigation of metallic infrastructure due to its eco-friendliness and low-energy-consumption,but the construction of highlyefficient PCP systems still remains challenging,caused primarily by the lack of driving force to guide the charge flow through the whole PCP photoanodes.Here,we tackle this key issue by equipping the PCP photoanode with ferroelectric single-domain PbTiO_(3)nanoplates,which can form a directional“macroscopic electric field”throughout the entire photoanode controllable by external polarization.The properly poled PCP photoanode allows the photogenerated electrons and holes to migrate in opposite directions,that is,electrons to the protected metal and holes to the photoanode/electrolyte interface,leading to largely suppressed charge annihilation and consequently a considerable boost in the overall solar energy conversion efficiency of the PCP system.The as-fabricated photoanode can not only supply sufficient photocurrent to 304 stainless steel to initiate cathodic protection,but also shift the metal potential to the corrosion-free range.Our findings provide a viable design strategy for future high-performance PCP systems based on ferroelectric nanomaterials with enhanced charge flow manipulation.

空间选择性缺陷管理制备高性能碳基CsPbI_(3)钙钛矿太阳能电池

Defects formed at the surface,buried interface and grain boundaries(GB)of CsPbI_(3)perovskite films considerably limit photovoltaic performance.Such defects could be passivated effectively by the most prevalent post modification strategy without compromising the photoelectric properties of perovskite films,but it is still a great challenge to make this strategy comprehensive to different defects spatially distributed throughout the films.Herein,a spatially selective defect management(SSDM)strategy is developed to roundly passivate various defects at different locations within the perovskite film by a facile one-step treatment procedure using a piperazine-1,4-diium tetrafluoroborate(PZD(BF_(4))_(2))solution.The small-size PZD^(2+)cations could penetrate into the film interior and even make it all the way to the buried interface of CsPbI_(3)perovskite films,while the BF_(4)^(-)anions,with largely different properties from I^(-)anions,mainly anchor on the film surface.Consequently,virtually all the defects at the surface,buried interface and grain boundaries of CsPbI_(3)perovskite films are effectively healed,leading to significantly improved film quality,enhanced phase stability,optimized energy level alignment and promoted carrier transport.With these films,the fabricated CsPbI_(3)PSCs based on carbon electrode(C-PSCs)achieve an efficiency of18.27%,which is among the highest-reported values for inorganic C-PSCs,and stability of 500 h at 85℃with 65%efficiency maintenance.

Filterless narrowband photodetectors enabled by controllable band modulation through ion migration: The case of halide perovskites

Narrowband photodetectors conventionally rely on optical structure design orbandpass filters to achieve the narrowband regime. Recently, a strategy forfilterless narrowband photoresponse based on the charge collection narrowing(CCN) mechanism was reported. However, the CCN strategy requires an electrically and optically “thick” photoactive layer, which poses challenges in controlling the narrowband photoresponse. Here we propose a novel strategy forconstructing narrowband photodetectors by leveraging the inherent ion migration in perovskites, which we term “band modulation narrowing” (BMN). Bymanipulating the ion migration with external stimuli such as illumination,temperature, and bias voltage, we can regulate in situ the energy-band structure of perovskite photodetectors (PPDs) and hence their spectral response.Combining the Fermi energy levels obtained by the Kelvin probe force microscopy, the internal potential profiles from solar cell capacitance simulator simulation, and the anion accumulation revealed by the transient ion-drifttechnique, we discover two critical mechanisms behind our BMN strategy: theextension of an optically active but electronically dead region proximal to the top electrode and the down-bending energy bands near the electron transportlayer. Our findings offer a case for harnessing the often-annoying ionmigration for developing advanced narrowband PPDs.

Materials and structures for the electron transport layer of efficient and stable perovskite solar cells

The electron transport layer plays a vital function in extracting and transporting photogenerated electrons, modifying the interface, aligning the interfacial energy level and minimizing the charge recombination in perovskite solar cells. This review summarizes the recent research progress on electron transport materials of metal oxides, organic molecules and multilayers. The doped metal oxides as electron transport materials in regular perovskite solar cells show improved device performance relative to their non-doped counterpart due to enhanced electron mobility and energy level alignment. The non-fullerene organic electron transport materials with better electron mobility and tunable energy level alignment need to be further designed and developed despite their advantages of mechanical flexibility and wide range tunability. The multilayer electron transport materials are suggested to be an important direction of research for efficient and stable perovskite solar cells because of their favorable synergistic interaction.

Evaluation on Properties of CaO-BaO-B_2O_3-Al_2O_3-SiO_2 Glass-Ceramic Sealants for Intermediate Temperature Solid Oxide Fuel Cells

To develop suitable sealants for intermediate temperature solid oxide fuel cells （IT-SOFC）, glass-ceramics based on the CaO-BaO-B203-AI203-Si02 system were studied. Coefficient of thermal expansion （CTE）, glass transition temperature （Tg） and dilatometric softening point temperature （Td） of specimens were determined by means of dilatometer analysis and crystallization temperature was measured by differential thermal analysis （DTA）. Also, crystallization behavior during prolonged heat-treatment and microstructure properties were studied by means of X-ray diffraction （XRD） and scanning electron microscopy （SEM）, respectively. Electrical properties were measured at different temperatures, and the results showed a high resistance （〉104 Ω） at the SOFC operation temperature （600-800 ℃）. Moreover, mechanical properties of heat-treated specimens （1, 10, 30, 50 h） were measured, Microstructure investigation revealed a well-adhered bonding between the sealant glass-ceramic electrolyte and glass.

Tempering Behavior of 4.5Cr-2W-0.25V Steel

The tempering behavior of a Cr-W-V steel was investigated in this research. This new alloy with the com- position of Fe-4.5Cr-2W-0. 25V-0. 1C was austenitized at 1 000 ℃ for 30 rain and tempered at 600 and 700 ℃ for dif- ferent time up to 100 h. An OM analysis of the microstructure of air cooled and water quenched specimens before tempering showed that although under both conditions fully martensitic matrix formed, finer structure had formed in the water quenched specimens. The XRD and TEM results showed that the most stable carbides formed during tempering of the steel were M23C6 and M7C3, respectively. Other carbides such as M3C and M2C, formed in the first stages of tempering, and stable MC were also observed. The results showed that when the tempering time, tempera- ture and cooling rate were increased, mass percent of extracted precipitates was increased. In addition, the formation rate of the stable carbides such as M23 Cs and dissolution rate of the metastable carbides such as M3C and M2C were increased.