Current status and trends of carbon-based electrodes for fully solution-processed perovskite solar cells

Perovskite solar cells(PSCs) have revolutionized photovoltaic research. As a result, a certified power conversion efficiency(PCE) of 25.5% was recorded in late 2020. Although this efficiency is comparable with silicon solar cells;some issues remain partially unsolved, such as lead toxicity, instability of perovskite materials under continuous illumination, moisture and oxygen, and degradation of the metallic counter electrodes. As an alternative to tackle this last concern, carbon materials have been recently used, due to their good electrical and thermal conductivity, and chemical stability, which makes them one of the most promising materials to replace metallic counter electrodes in the fabrication of PSCs. This review highlights the recent advances of carbon-based PSCs, where the carbon electrode(CE) is the main actor.CEs have become very promising candidates for PSCs;they are mainly fabricated using a simple combination of graphite and carbon black powders embedded in a binder matrix, giving a paste that is then solution-processable, resulting in devices with improved quality stability, when compared to metallic electrodes. In this review, CE’s composition is emphasized, since it can give both, high and lowtemperature processed electrodes, compatible with different device configurations. Finally, the tendencies and opportunities to use CE in PSCs devices are presented.

Solution‑Processed Transparent Conducting Electrodes for Flexible Organic Solar Cells with 16.61% Efficiency

Nonfullerene organic solar cells(OSCs)have achieved breakthrough with pushing the efficiency exceeding 17%.While this shed light on OSC commercialization,high-performance flexible OSCs should be pursued through solution manufacturing.Herein,we report a solution-processed flexible OSC based on a transparent conducting PEDOT:PSS anode doped with trifluoromethanesulfonic acid(CF3SO3H).Through a low-concentration and low-temperature CF3SO3H doping,the conducting polymer anodes exhibited a main sheet resistance of 35Ωsq−1(minimum value:32Ωsq−1),a raised work function(≈5.0 eV),a superior wettability,and a high electrical stability.The high work function minimized the energy level mismatch among the anodes,hole-transporting layers and electron-donors of the active layers,thereby leading to an enhanced carrier extraction.The solution-processed flexible OSCs yielded a record-high efficiency of 16.41%(maximum value:16.61%).Besides,the flexible OSCs afforded the 1000 cyclic bending tests at the radius of 1.5 mm and the long-time thermal treatments at 85°C,demonstrating a high flexibility and a good thermal stability.

ANALYTICAL SOLUTION OF FILLING AND EXHAUSTING PROCESS IN PNEUMATIC SYSTEM

The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that： Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.

Natural Aging Effects on the Solutionizing Heat Treatment Process of the A6060 Al Alloy As-Cast Billets for Profile Production

Recently results were presented for an R & D program for handling the as-cast billets of an Al-Si-Mg A6060 Al alloy at the solutionizing heat treatment temperature. A reduction in the solutionizing temperature of the as-cast billets from 585℃ to 540℃ was found. This leads to substantial energy savings without lowering the quality of the final commercial Al profiles. The alloy was treated from the microstructural point of view as an Aluminum Metal-Matrix Composite (Al-MMC). Strengthening of the Al matrix grains during the process was quantified and measured by micro-Vickers hardness testing. A possible application of this is to apply the suggested lower temperature solutionizing process to billets stockpiled in the factory for some months. The alloy undergoes natural aging, a physical process at ambient temperature that alters its microstructural features. Does this aging affect the quality of the lower temperature solutionizing treated profiles? The effect of the natural aging by micro-Vickers hardness testing on some of the same samples of our original work stockpiled in our lab for 10 months was investigated. We applied, further, the Image-Pro Plus image processing software on them in an effort to collect microstructural data and compared them to values taken 10 months earlier. Also we tried an interconnection between the two experimental processes treating the alloy as an Al-MMC.

THE SOLUTION OF RANDOM EIGENVALUE PROBLEM WITH SMALL STOCHASTIC PROCESSES

This paper considers an eigenvalue problem containing small stochastic processes. For every fixed is, we can use the Prufer substitution to prove the existence of the random solutions lambda(n) and u(n) in the meaning of large probability. These solutions can be expanded in epsilon regularly, and their correction terms can be obtained by solving some random linear differential equations.

Highly efficient solution-processed organic photovoltaics enabled by improving packing behavior of organic semiconductors

Solution processability is a unique property of organic semiconductors. The compact and regular π-π stacking between molecules is paramount in the performance of organic optoelectronic devices. However, it is still a challenge to improve their stacking quality without sacrificing the solution-processability from the aspect of materials design. Here, delicately engineered additives are presented to promote the formation of ordered aggregation of conjugated molecules by regulating their nucleation and growth dynamics. Intriguingly, the long-chain BTP-eC9-4F molecules can realize ordered aggregation comparable to short-chain ones without sacrificing processability. The domain size of BTP-eC9-4F aggregation is enlarged from 24.2 to 32.2 nm in blend films.Thereby exciton diffusion and charge transport become faster, contributing to the suppression of recombination losses. As a result, a power conversion efficiency of 19.2% is achieved in D18:BTP-eC9-4F based organic photovoltaics. Our findings demonstrate a facile strategy to improve the packing quality of solution-processed organic semiconductors for high-efficiency photovoltaics and beyond photovoltaics.

Annealing-free alcohol-processable MoO_(X) anode interlayer enables efficient light utilization in organic photovoltaics

Molybdenum oxide(MoO_(x))is a commonly used hole extraction material in organic photovoltaics.The MoO_(x) interlayer is deposited typically via thermal evaporation in vacuum.To meet the need for rollto-roll manufacturing,solution processing of MoO_(x) without post-annealing treatment is essential.Herein,we demonstrate an effective approach to produce annealing-free,alcohol-processable MoO_(x) anode interlayers,namely S-MoO_(x),by utilizing the bis(catecholato)diboron(B_(2) Cat_(2))molecule to modify the surface oxygen sites in MoO_(x).The formation of surface diboron-oxygen complex enables the alcohol solubility of S-MoO_(x).An enhanced light utilization is realized in the S-MoO_(x)-based organic photovoltaics.This affords a superior short-circuit current density(Jsc)close to 26 mA cm^(-2) and ultimately a high power-conversion efficiency(PCE)of 15.2%in the representative PM6:Y6 based inverted OPVs,which is one of the highest values in the inverted OPVs using an as-cast S-MoO_(x) anode interlayer.

Solute Redistribution in Directional Melting Process

The solute redistribution in directional melting process is theoretically studied. Based on quantitative evaluations, uniform.solute distribution in liquid and a quasi-steady solute distribution in solid are supposed. The discussion on the solute balance comes to a simple model for the solute redistribution in directional melting process. As an example, the variation of liquid composition during melting process of carbon steel is quantitatively evaluated using the model. Results show that the melting of an alloy starts at solidus temperature, but approaches the liquidus temperature after a very short transient process.

High-performance all-solution-processed inverted quantum dot light-emitting diodes enabled by water treatment

All-solution-processed inverted quantum dot(QD)light-emitting diodes(QLEDs)with transparent bottom cathodes can be directly connected to the n-type thin-film transistors,offering a feasible solution for low-cost active matrix-driven QD displays.However,the subsequent solution-deposition of the hole-transporting layer destroys the underneath QD films,resulting in largely deteriorated device performance.Various strategies have been implemented to prevent QD film from dissolution,but all at a heavy cost of device performance suffering from either reduced efficiency or increased driving voltage.Here,a facile and effective water-treatment approach for QD film to fabricate inverted QLEDs through all solution processing is reported.The water treatment substitutes the long-chain oleate ligands with hydroxyl groups,resulting in significantly improved non-polar solvent resistance of the QD films.Importantly,the QD films reserve their excellent photoluminescence efficiency after water treatment.With the water-treated QD film as the emissive layer,all-solution-processed inverted red QLED with a peak external quantum efficiency of 19.6%,a turn-on voltage of 1.8 V,and a T50 operational lifetime of 150,000 h at 100 cd·m^(-2) was achieved.Furthermore,efficient and low-voltage-driven green and blue QLEDs can also be prepared with this method.This work provides a feasible strategy for the fabrication of high-performance all-solution-processed inverted QLEDs,paving the way toward achieving QLEDs by all ink-jet printing.

Carbazole-based Multiple Resonance Dendrimers with Narrowband Blue Emission for Solution-Processed OLEDs

Three carbazole-based multiple resonance dendrimers namely D1-BNN,D2-BNN and D3-BNN,are developed for solution-processed narrowband blue organic light-emitting diodes(OLEDs)by introducing the first-,second-,and third-generation carbazole dendrons in periphery of boron,nitrogen-doped polycyclic aromatic hydrocarbon skeleton.Different from D1-BNN containing first-generation carbazole dendron showing moderate photoluminescent quantum efficiency(PLQY)of 68%in solid state and broadened emission bands with full-width at half maximum(FWHM)increasing from 26 nm to 34 nm upon doping concentration growing from 10 wt%to 40 wt%,D3-BNN with the third-generation carbazole dendron exhibits high PLQY of 92%and weak dependence of photoluminescent spectra on doping concentration,which can remain narrowband emissions with unchanged FWHM of 24 nm at same doping concentration range.Solution-processed OLEDs employing D3-BNN as emitter reveal blue electroluminescence at 477 nm with FWHM of 24 nm,and maximum external quantum efficiency(EQE)of 17.3%which is kept at 14.4%at doping concentration of 40 wt%,much superior than the D1-BNN devices showing maximum EQE of 13.0%that drops to 3.7%at 40 wt%doping concentration.

Experimental verification of nanonization enhanced solubility for poorly soluble optoelectronic molecules

Solubility enhancement has been a priority to overcome poor solubility with optoelectronic molecules for solution-processable devices. This study aims to obtain experimental data on the effect of particle sizes on the solubility properties of several typical optoelectronic molecules in organic solvents, including the solubility results of 1,3-bis(9-carbazolyl)benzene(m CP), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)ben zene(TPBi) and 2-(4-tert-butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole(PBD) in ethanol and acetonitrile,respectively. Nanoparticles of m CP, TPBi and PBD with sizes from dozens to several hundred nanometers were prepared by solvent antisolvent precipitation method and their solubility were determined by using isothermal saturation method. The saturation solubility of nanoparticles of three kinds of optoelectronic molecules exhibited increase of 12.9%-25.7% in comparison to the same raw materials in the form of microparticles. The experimental evidence indicates that nanonization technology is a feasible way to make optoelectronic molecules dissolve in liquids with enhanced solubility.

A Solution-Processed n-Type Conducting Polymer Without Side Chains Formed via Nonmetal-Participated Polymerization and in Situ n-Doping

Solution-processed conducting polymers(CPs)are emerging as promising multifunctional materials and are motivating the development of several electronic applications.However,there are fewer highperformance electron conduction-dominated n-type CPs than p-types.Thus,the exploration of other material designs and synthesis methods is required.Accordingly,we developed a facile metal catalystfree method by combining polymerization and in situ n-doping to produce an n-type conducting polymer,poly(benzodithiophenedione)(PBTDO).The doping procedure enabled interaction between the charged conjugated backbones and solvent,dimethyl sulfoxide,making the doped conducting polymer soluble without the assistance of side chains or surfactants.PBTDO exhibited an extremely low-lying reduction level,moderate conductivity,and good air stability with potential applications in n-type organic thermoelectric devices.Moreover,it was found that the in situ doping efficiency in the reaction was highly dependent on the energy level and backbone planarity.Doping cannot occur for polymers with a high lowest unoccupied molecular orbital level and distorted conjugated chains prevent a high doping efficiency from being obtained.This study gains deeper insight into the n-doping mechanisms of conjugated polymers,with guidance for the design of highperformance n-type CPs.

基于模糊群决策的绿色供应商选择和订单分配方法

随着市场竞争愈发激烈、全球环境日益恶化以及公众环保意识的提高,绿色采购问题受到了广泛关注。现有研究绝大多数聚焦于考虑绿色准则的供应商选择问题,以实现可持续经营。然而,在综合考虑时间、价格和成本等因素的前提下,从适应性强的供应商处获得适当的产品,对于企业来说更为可行和经济,即供应商选择和订单分配。为了解决上述关键问题,提出了一种模糊环境下的多准则群体决策方法。提出了一种基于理想解相似性偏好排序和层次分析法(technique for order of preference by similarity to ideal solution and analytic hierarchy process,TOPSIS-AHP)的模糊排序方法,该方法可根据企业战略灵活调整传统准则和绿色准则的权重。在双目标优化模型中引入供应商排名进行订货,在实现采购绩效最大化的同时,最大限度地降低采购成本。结果表明:所提方法能够有效评价供应商绩效,并优化候选供应商之间的订单分配。

Technology Development and Production of Certain Chemical Platinum Metals Compounds at JSC ＂Krastsvetmet＂

In recent years JSC "Krastsvetmet" has successfully developed the production of chemically pure compounds of precious metals.Currently methods have been developed and facilities have been provided for industrial production of the following platinum metals compounds:Rhodium(Ⅲ) chloride hydrate,rhodium(Ⅲ) chloride solution,rhodium(Ⅲ) nitrate solution,rhodium(Ⅲ) iodide,rhodium(Ⅲ) sulfate,hydrated rhodium(Ⅲ) oxide,ammonium hexachlororodiate,rhodium(Ⅲ) phosphate solution,rhodium electrolytes;Iridium(Ⅳ) chloride hydrate,iridium(Ⅲ) chloride hydrate,ammonium hexachloroiridate(Ⅳ),hexa chloriridium acid solution,hexachloriridium crystalline acid;Ruthenium(Ⅲ) chloride hydrate,ruthenium(Ⅳ) hydroxide chloride,ruthenium(Ⅳ) hydroxide chloride solution,ammonium hexachlororuthenate,ruthenium(Ⅲ) chloride solution,potassium,diaquaoctachloronitrido diruthenate.The quality of the production meets the requirements of Russian and foreign consumers.

Optimization of both coercivity and knee-point magnetic field of Sm2Co17-type magnets via solid solution process

It is confirmed that phase homogenization is very important for improving the magnetic properties of 2:17-type Sm-Co sintered magnets,In this work,the influence of solid solution process on microstructure and magnetic properties of the Sm(CobalFe0.233Cu0.073Zr0.024)7.6 sintered magnets was systematically studied.With the solid-solution treating duration(tS)increasing from 0 to 4 h,intrinsic coercivity(Hcj)increases from 12.83 to 36.54 kOe,magnetic field at knee-point(Hknee)increases from2.76 to 19.14 kOe,and the maximum energy product increases from 19.79 to 29.48 MGOe.The electron probe microanalyzer results reveal that there mainly exist gray and dark regions besides"white"rare earth-rich phase,and the conte nt of Sm,Fe and Cu elements for the two kinds of regions changes a lot for the specimens,Furthermore,with tS increasing up to 4 h,the elements content deviation between the gray and dark regions becomes small gradually from 3.94 at%to 0.27 at%,7.66 at%to 0.21 at%and 7.27 at%to 0.16 at%for Sm,Fe and Cu elements,respectively.Moreover,transmission electron microscopy results show that the distribution of cell size is much more concentrated for aged specimens when tS is 4 h.It is also found that the Cu concentration at cell boundaries for the 4 h solid-solution treatment case shows relatively higher values and greater concentration gradient(1.94 at%/nm).It is verified that sufficient solution treatment duration is prerequisite to form these homogeneous microstructural features,which are the key points for obtaining both high Hcj and Hknee.

Towards Flexible All-Carbon Electronics:Flexible Organic Field-Effect Transistors and Inverter Circuits Using Solution-Processed All-Graphene Source/Drain/Gate Electrodes

Flexible organic field-effect transistors(OFETs)using solution-processable functionalized graphene for all the electrodes(source,drain,and gate)have been fabricated for the first time.These OFETs show performance comparable to corresponding devices using Au electrodes as the source/drain electrodes on SiO2/Si substrates with Si as the gate electrode.Also,these devices demonstrate excellent flexibility without performance degradation over severe bending cycles.Furthermore,inverter circuits have been designed and fabricated using these all-graphene-electrode OFETs.Our results demonstrate that the long-sought dream for all-carbon and flexible electronics is now much closer to reality.

Confined-solution process for high-quality CH3NH3PbBr3 single crystals with controllable morphologies

Solution processes have shown excellent potential for application to the growth of single-crystal materials. We have developed a confined-solution method for the preparation of single crystals with a controlled morphology. By confining the precursor solution within a micrometer-thick cavity and then controlling the saturation by adjusting the temperature gradient and fluid flow, high-quality CHBNH3PbBr3 single crystals with tunable morphologies could be obtained. The morphologies of the CH3NH3PbBr3 can be adjusted from sub-square centimeter-scale thin sheets that are square or rectangular, to one-dimensional wires with lengths in the order of centimeters, simply by changing the temperature. The thicknesses of the CH3NH3PbBr3 sheets could be adjusted from hundreds of nanometers to tens of microns. The CH3NHBPbBr3 sheets feature very clean surfaces with an atomic-scale roughness. This simple strategy provides a means of growing high-quality single crystals with clean surfaces, which realize high levels of performance when applied to devices.

The fabrication of color-tunable organic light-emitting diode displays via solution processing

Electroluminescent devices based on organic semiconductors have attracted significant attention owing to their promising applications in flat-panel displays.The conventional display pixel consisting of side-by-side arrayed red,green and blue subpixels represents the mature technology but bears an intrinsic deficiency of a low pixel density.Constructing an individual color-tunable pixel that comprises vertically stacked subpixels is considered an advanced technology.Although color-tunable organic light-emitting diodes(OLEDs)have been fabricated using the vacuum deposition of small molecules,the solution processing of conjugated polymers would enable a much simpler and inexpensive manufacturing process.Here we present the all-solution processing of color-tunable OLEDs comprising two vertically stacked polymer emitters.A thin layer of highly conducting and transparent silver nanowires is introduced as the intermediate charge injection contact,which allows the emission spectrum and intensity of the tandem devices to be seamlessly manipulated.To demonstrate a viable application of this technology,a 4-by-4 pixelated matrix color-tunable display was fabricated.

Scalable Deposition Methods for Large-Area Production of Perovskite Thin Films

The recent steady improvements in the performance of the nascent hybrid perovskite photovoltaic(PV)devices have led to power conversion efficiencies that rival the best-performing established PV technologies.However,to scale these laboratory demonstrations to PV module-scale production will require development of scalable deposition methods for perovskite thin films.Every record result for perovskite PVs so far was achieved via spin coating,a technique that is popular in research laboratories for thin-film coating over relatively small device areas,but not considered to be a method that could be used to scale up the manufacturing of perovskite PVs.Significantly larger thin-film areas are needed for future commercial PV products.Hence,some researchers have focused their efforts on perovskite deposition techniques that can be considered as scalable for mass production and have achieved notable results even on large areas.Here,we present an overview of the solution-based and vapor-based deposition processes;we explain their influence on the molecular crystal growth behavior of perovskite thin films and discuss the morphology as well as other material quality characteristics.By presenting a comprehensive comparison of the deposition techniques and the corresponding performance parameters for different device sizes,we intent to guide the growing research community through the methods that might enable mass production of perovskite solar products.

Lanthanide-containing persistent luminescence materials with superbright red afterglow and excellent solution processability

Lanthanide-containing persistent luminescence materials are promising candidates for a wide range of applications by virtue of splendid superiorities in afterglow performance.However,it is a crucial challenge to achieve high-quality afterglow materials at the attractive nanoscale,with uniform size,controllable morphology,and satisfying brightness.Herein,a bottom-up approach was developed to construct the high-quality afterglow nanoparticles,incorporating luminescent lanthanide complex and organic molecular ingredients under mild conditions.These nanoparticles exhibited intrinsic lanthanide luminescence with superbright red afterglow(>10 cd m^(−2))in a homogeneous solution.The afterglow solution with excellent processability can serve as ideal building blocks for the on-demand fabrication of functional nanomaterials.Water-dispersible afterglow nanoparticles with state-of-the-art high brightness were uniformly constructed to perform whole-blood lateral flow assay of procalcitonin with a naked-eye detection limit of 0.5 ng mL^(−1),promoting the point-of-care testing development.