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...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.展开更多
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 ar...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.展开更多
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 soluti...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.展开更多
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...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.展开更多
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 achie...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.展开更多
In this paper, co-doping method is used to improve the current efficiency of solution-processed organic light-emitting diodes(OLEDs). By changing the ratio of two thermally activated delayed fluorescent(TADF) emitters...In this paper, co-doping method is used to improve the current efficiency of solution-processed organic light-emitting diodes(OLEDs). By changing the ratio of two thermally activated delayed fluorescent(TADF) emitters, we studied the performance of device and its mechanism. A solution processed OLED with a structure of indium tin oxide(ITO, 150 nm)/PEDOT:PSS(30 nm)/CBP:4 Cz IPN-x%:4 Cz PN-y%(30 nm)/TPBi(40 nm)/Li F(1 nm)/Al(100 nm) was fabricated. The current efficiencies of 26.6 cd/A and 26.4 cd/A were achieved by the devices with dopant ratio of 6% 4 Cz IPN:2% 4 Cz PN and 2% 4 Cz IPN:6% 4 Cz PN in emitting material layer(EML), respectively. By investigating the tendency of current density change in devices with different doping ratio, we suggested that the enhancement of the current efficiency should be due to the charge transport balance improvement induced by assist dopant in EML.展开更多
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 ...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.展开更多
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 ...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.展开更多
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 manufactur...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.展开更多
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 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.展开更多
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 activ...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.展开更多
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-...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.展开更多
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 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.展开更多
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...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。展开更多
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 comp...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.展开更多
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,t...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.展开更多
Two soluble tetraalkyl-substituted zinc phthalocyanines(ZnPcs)for use as anode buffer layer materials in tris(8-hydroxyquinoline)aluminum(Alq3)-based organic light-emitting diodes(OLEDs)are presented in this work.The ...Two soluble tetraalkyl-substituted zinc phthalocyanines(ZnPcs)for use as anode buffer layer materials in tris(8-hydroxyquinoline)aluminum(Alq3)-based organic light-emitting diodes(OLEDs)are presented in this work.The holeblocking properties of these Zn Pc layers slowed the hole injection process into the Alq3 emissive layer greatly and thus reduced the production of unstable cationic Alq3(Alq3^+)species.This led to the enhanced brightness and efficiency when compared with the corresponding properties of OLEDs based on the popular poly-(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)buffer layer.Furthermore,because of the high thermal and chemical stabilities of these Zn Pcs,a nonaqueous film fabrication process was realized together with improved charge balance in the OLEDs and enhanced OLED lifetimes.展开更多
Solution processible photovoltaics(PV)are poised to play an important role in scalable manufacturing of low-cost solar cells.Electrospray is uniquely suited for fabricating PVs due to its several desirable characteris...Solution processible photovoltaics(PV)are poised to play an important role in scalable manufacturing of low-cost solar cells.Electrospray is uniquely suited for fabricating PVs due to its several desirable characteristics of an ideal manufacturing process such as compatibility with roll-to-roll production processes,tunability and uniformity of droplet size,capability of operating at atmospheric pressure,and negligible material waste and nano structures.This review begins with an introduction of the fundamentals and unique properties of electrospray.We put emphasis on the evaporation time and residence time that jointly affect the deposition outcome.Then we review the efforts of electrospray printing polymer solar cells,perovskite solar cells,and dye sensitized solar cells.Collectively,these results demonstrate the advantages of electrospray for solution processed PV.Electrospray has also exhibited the capability of producing uniform films as well as nanostructured and even multiscale films.So far,the electrospray has been found to improve active layer morphology,and create devices with efficiencies comparable with that of spin-coating.Finally,we discuss challenges and research opportunities that enable electrospray to become a mainstream technique for industrial scale production.展开更多
Narrow-band emission is crucial for high color purity in panel display.Nevertheless,attaining narrow-band emission is highly challenging because either thermally activated delayed fluorescence or phosphorescence in or...Narrow-band emission is crucial for high color purity in panel display.Nevertheless,attaining narrow-band emission is highly challenging because either thermally activated delayed fluorescence or phosphorescence in organic and metal-organic compounds originates primarily from multiple charge transfer transitions featured with broad bandwidths.In this work,a general tactic for achieving highly efficient narrow-band emission is proposed by the sensitization of ligand-centered phosphorescence through substantial intermetallic interaction.Relative to weak phosphorescence in mononuclear Pt(Ⅱ)precursors,highly efficient ligand-centered phosphorescence is dramatically activated in Pt(Ⅱ)-Au(Ⅰ)heteronuclear complexes with quantum yield as high as 81%in solutions and 97%in doping films.High-efficiency solution-processed organic light-emitting diodes(OLEDs)with narrow-band emission are successfully attained with external quantum efficiency(EQE)of 21.6%and a full width at half maxima(FWHM)of 36 nm for yellow electroluminescence and EQE of 20.8%and FWHM of 32 nm for green electroluminescence.展开更多
Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLED...Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLEDs. In this work, a new electron-donating segment, 2,7-di(9 H-carbazol-9-yl)-9,9-dimethyl-9,10-dihydroacridine(2 Cz-DMAC), was designed to develop solution-processable non-doped TADF emitters. 2 Cz-DMAC can not only simultaneously increase the solubility of compounds and suppress harmful aggregation-caused quenching, but also efficiently broaden the delocalization of the highest occupied molecular orbital and promote the reverse intersystem crossing process. Three new TADF emitters, 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)dibenzo[b,d]thiophene 5,5-dioxide(2 Cz-DMAC-BTB), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)-9 H-thioxanthen-9-one(2 Cz-DMAC-TXO), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)thianthrene 5,5,10,10-tetraoxide(2 Cz-DMAC-TTR), were developed by using 2 Cz-DMAC segment as the electron-donor. As anticipated, the solution-processed non-doped OLEDs employing 2 Cz-DMAC-BTB, 2 Cz-DMAC-TXO and 2 CzDMAC-TTR as the emitters respectively exhibited green, orange and red emissions with maximum external quantum efficiencies of 14.0%, 6.6% and 2.9%. These results successfully demonstrate the feasibility and convenience of developing efficient solution-processable non-doped TADF emitters based on 2 CzDMAC segment.展开更多
基金Project supported by the National Key Research and Development Program of China(2016YFB0700903)the National Natural Science Foundation of China(5159088251401054)。
文摘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.
基金supported by the Cluster of Excellence‘Engineering of Advanced Materials’(EAM)at the University of Erlangen-Nurembergthe support of the EU-project SOLPROCEL(‘Solution processed high performance transparent organic photovoltaic cells’,Grant No.604506)+2 种基金the financial support from the China Scholarship Council(CSC)the financial support from the South China University of Technology and Deutscher Akademischer Austausch Dienst(DAAD)the financial support through the‘Aufbruch Bayern’initiative of the state of Bavaria.
文摘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.
基金The authors acknowledge funding from the National Natural Science Foundation of China(61974150 and 51773213)Key Research Program of Frontier Sciences,CAS(QYZDB-SSW-JSC047)+1 种基金the Fundamental Research Funds for the Central Universities,the CAS-EU S&T cooperation partner program(174433KYSB20150013)the Natural Science Foundation of Ningbo(2018A610135).
文摘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.
基金financial support of the Colombia Scientific Program within the framework of the call Ecosistema Cientifíco (Contract FP44842-218-2018)。
文摘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.
基金supported by the National Key R&D Program of China(2017YFA0205100)the National Natural Science Foundation of China(21937003)。
文摘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.
基金supported by the National High Technology Research and Development Program of China (No.2012AA011901)the National Program on Key Basic Research Project of China (No.2012CB723406)+2 种基金the National Natural Science Foundation of China (No.51573036)the Fundamental Research Funds for the Central Universities of China (No.JD2016JGPY0007)the Industry-University-Research Cooperation Project of Aviation Industry Corporation of China (No.CXY2013HFGD20)。
文摘In this paper, co-doping method is used to improve the current efficiency of solution-processed organic light-emitting diodes(OLEDs). By changing the ratio of two thermally activated delayed fluorescent(TADF) emitters, we studied the performance of device and its mechanism. A solution processed OLED with a structure of indium tin oxide(ITO, 150 nm)/PEDOT:PSS(30 nm)/CBP:4 Cz IPN-x%:4 Cz PN-y%(30 nm)/TPBi(40 nm)/Li F(1 nm)/Al(100 nm) was fabricated. The current efficiencies of 26.6 cd/A and 26.4 cd/A were achieved by the devices with dopant ratio of 6% 4 Cz IPN:2% 4 Cz PN and 2% 4 Cz IPN:6% 4 Cz PN in emitting material layer(EML), respectively. By investigating the tendency of current density change in devices with different doping ratio, we suggested that the enhancement of the current efficiency should be due to the charge transport balance improvement induced by assist dopant in EML.
文摘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.
基金supported by the National Natural Science Foundation of China(52303239)the Natural Science Foundation of Shandong Province(ZR2022QB141,2023HWYQ-087)+1 种基金Jiangsu Key Laboratory for Carbon-Based Functional Materials&Devices,Soochow University(KJS2209)Sichuan Science and Technology Program(2023NSFSC0990)。
文摘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.
基金supported by the National Natural Science Foundation of China(62074022,62074149)the Natural Science Foundation of Chongqing(cstc2018jszx-cyzdX0137)+3 种基金the Chongqing Science Foundation for Distinguished Young Scholars(cstc2020jcyj-jq0112)the“Artificial Intelligence”Key Project of Chongqing(cstc2017rgzn-zdyf0120)the Venture&Innovation Support Program for Chongqing Overseas Returnees(cx2019107)the Fundamental Research Funds for the Central Universities(2020CDJQY-A055,2019CDXYDL0007)。
文摘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.
基金The research is funded by the National Natural Science FOundation of China! (No.59931030)
文摘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.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.61905230,52072355,11904345,52103241,and 61904160)Natural Science Foundation of Zhejiang Province(No.LQ19F040004)the Liu Zugang Expert Workstation of Yunnan Province。
文摘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.
基金financially supported by the National Natural Science Foundation of China(Nos.52073282,52122309,51833009 and 21975247)the CAS-Croucher Funding Scheme for Joint Laboratories:Poly U-CIAC Joint Laboratory(No.121522KYSB20200040)the Open Project of State Key Laboratory of Supramolecular Structure and Materials(No.sklssm2023019)。
文摘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.
基金financial support from National Natural Science Foundation of China (22288102)the Fundamental Research Funds for the Central Universities of China (buctrc202016)。
文摘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.
基金National Key Research and Development Program of China Under Grant(2020YFB1712203)。
文摘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。
基金The authors acknowledge financial support from the National Natural Science Foundation of china(NSFC)(Nos.50933003,20774047)the Ministry of Science and Technology of the People’s Repulic of China(MOST)(No.2009AA032304)Natural Science Foundation(NSF)of Tianjin City(No.08JCZDJC25300).
文摘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.
基金funded by the MIT-Tata Grid Edge Solar research program
文摘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.
基金Project supported by the Shenzhen Personal Maker Project,China(Grant No.GRCK2017082316173208)the Shenzhen Overseas High-level Talents Innovation Plan of Technical Innovation,China(Grant No.KQJSCX20180323140712012)the Special Funds for the Development of Strategic Emerging Industries in Shenzhen,China(Grant No.JCJY20170818154457845)
文摘Two soluble tetraalkyl-substituted zinc phthalocyanines(ZnPcs)for use as anode buffer layer materials in tris(8-hydroxyquinoline)aluminum(Alq3)-based organic light-emitting diodes(OLEDs)are presented in this work.The holeblocking properties of these Zn Pc layers slowed the hole injection process into the Alq3 emissive layer greatly and thus reduced the production of unstable cationic Alq3(Alq3^+)species.This led to the enhanced brightness and efficiency when compared with the corresponding properties of OLEDs based on the popular poly-(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)buffer layer.Furthermore,because of the high thermal and chemical stabilities of these Zn Pcs,a nonaqueous film fabrication process was realized together with improved charge balance in the OLEDs and enhanced OLED lifetimes.
基金X.Z.acknowledges the funding support from National Science Foundation of China(NSFC)(No.61975073 and No.61605076)W.D.thanks the financial support from NSFC(No.11872199 and No.11932009).
文摘Solution processible photovoltaics(PV)are poised to play an important role in scalable manufacturing of low-cost solar cells.Electrospray is uniquely suited for fabricating PVs due to its several desirable characteristics of an ideal manufacturing process such as compatibility with roll-to-roll production processes,tunability and uniformity of droplet size,capability of operating at atmospheric pressure,and negligible material waste and nano structures.This review begins with an introduction of the fundamentals and unique properties of electrospray.We put emphasis on the evaporation time and residence time that jointly affect the deposition outcome.Then we review the efforts of electrospray printing polymer solar cells,perovskite solar cells,and dye sensitized solar cells.Collectively,these results demonstrate the advantages of electrospray for solution processed PV.Electrospray has also exhibited the capability of producing uniform films as well as nanostructured and even multiscale films.So far,the electrospray has been found to improve active layer morphology,and create devices with efficiencies comparable with that of spin-coating.Finally,we discuss challenges and research opportunities that enable electrospray to become a mainstream technique for industrial scale production.
基金supported by the National Natural Science Foundation of China(92061202 and 21801242)the Fujian Science and Technology Project(2020L3022)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB20000000)。
文摘Narrow-band emission is crucial for high color purity in panel display.Nevertheless,attaining narrow-band emission is highly challenging because either thermally activated delayed fluorescence or phosphorescence in organic and metal-organic compounds originates primarily from multiple charge transfer transitions featured with broad bandwidths.In this work,a general tactic for achieving highly efficient narrow-band emission is proposed by the sensitization of ligand-centered phosphorescence through substantial intermetallic interaction.Relative to weak phosphorescence in mononuclear Pt(Ⅱ)precursors,highly efficient ligand-centered phosphorescence is dramatically activated in Pt(Ⅱ)-Au(Ⅰ)heteronuclear complexes with quantum yield as high as 81%in solutions and 97%in doping films.High-efficiency solution-processed organic light-emitting diodes(OLEDs)with narrow-band emission are successfully attained with external quantum efficiency(EQE)of 21.6%and a full width at half maxima(FWHM)of 36 nm for yellow electroluminescence and EQE of 20.8%and FWHM of 32 nm for green electroluminescence.
基金supported by the National Natural Science Foundation of China (Nos.51773029,52073040 and 51821002)the Fundamental Research Funds for the Central Universities (No.ZYGX2016Z010)the International Cooperation and Exchange Project of Science and Technology Department of Sichuan Province (No.2019YFH0057)。
文摘Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLEDs. In this work, a new electron-donating segment, 2,7-di(9 H-carbazol-9-yl)-9,9-dimethyl-9,10-dihydroacridine(2 Cz-DMAC), was designed to develop solution-processable non-doped TADF emitters. 2 Cz-DMAC can not only simultaneously increase the solubility of compounds and suppress harmful aggregation-caused quenching, but also efficiently broaden the delocalization of the highest occupied molecular orbital and promote the reverse intersystem crossing process. Three new TADF emitters, 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)dibenzo[b,d]thiophene 5,5-dioxide(2 Cz-DMAC-BTB), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)-9 H-thioxanthen-9-one(2 Cz-DMAC-TXO), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)thianthrene 5,5,10,10-tetraoxide(2 Cz-DMAC-TTR), were developed by using 2 Cz-DMAC segment as the electron-donor. As anticipated, the solution-processed non-doped OLEDs employing 2 Cz-DMAC-BTB, 2 Cz-DMAC-TXO and 2 CzDMAC-TTR as the emitters respectively exhibited green, orange and red emissions with maximum external quantum efficiencies of 14.0%, 6.6% and 2.9%. These results successfully demonstrate the feasibility and convenience of developing efficient solution-processable non-doped TADF emitters based on 2 CzDMAC segment.
