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Catalytic conversion of a biomass derivative (levulinic acid, LA) to a high value-added product (γ-valerolactone, GVL) has attracted much attention, in which the control of catalytic selectivity plays an important role. Herein, a stepwise method was developed to prepare Co-MoOx catalysts via topological transformation (calcination reduction) from layered double hydroxide (Mo/CoAl-LDH) precursors. X-ray diffraction, high-resolution transmission electron microscopy, and hydrogen temperature-programmed reduction demonstrate the formation of MoOx-decorated Co structures of Co-MoOx samples. Remarkably, the sample that is reduced at 500 °C is featured with the most abundant interfacial Coδ+ (denoted as Co-MoOx-500), which exhibits an excellent catalytic performance toward the hydrodeoxygenation (HDO) reaction of several biomass-derived platform molecules (furfural, FAL; succinic acid, SA; 5-hydroxymethyl-furfural, HMF; and levulinic acid, LA). Especially, this optimal catalyst displays a high yield (99%) toward the HDO reaction of LA to GVL, which stands at the highest level among non-noble metal catalysts. The combination of in situ FT-IR characterization and theoretical calculation further confirms that interfacial Coδ+ sites in Co-MoOx-500 act as adsorption active sites for the polarization of a C═O bond in an LA molecule, which simultaneously promotes C═O hydrogenation and C-O cleavage. Moreover, the MoOx overlayer suppresses the formation of byproducts by covering the Co0 sites. This work offers a cost-effective and efficient catalyst, which can be potentially applied in catalytic conversion of biomass-derived platform molecules.

Hydrodeoxygenation (HDO), one of the effective approaches of C–O bond scission, plays a crucial role in biomass-derived oxygenate conversion to high value-added chemicals and biofuels. Herein, we systematically investigated the HDO reaction of furfural (FAL) to 2-methylfuran (2-MF) over 17 kinds of Ni-based bimetallic catalysts based on periodic density functional theory (DFT) calculations. The Ni-based partner (3d and 4d metals) has an important influence on the catalytic performance toward the FAL HDO reaction, which modifies the Ni electronic environment and induces the bimetal d orbital overlap, giving rise to changes in adsorption configuration and reaction activity. A specific correlation between the oxygen binding energy (OBE) value and energy barrier of C–OH scission/*OH species hydrogenation suggests that OBE serves as the most appropriate descriptor to characterize the activity of bimetallic catalysts. Due to the competitive relationship between C–O scission and *OH species hydrogenation, a trade-off of OBE has been built to promote C–O scission and hydrogenation activity simultaneously, in which Ni–M (M = Fe, Co, Mo, or Ru) bimetallic catalysts show prominent catalytic performance. Besides, we revealed that this descriptor can be extended to other bimetallic catalysts (CoV, CoFe, CuCo). Based on the calculation prediction, we prepared several alloys (NiCu, NiCo and NiZr). A series of characterization techniques (HRTEM, EDS, XPS, H2-TPR) indicated the formation of the alloys, whose catalytic evaluations verify that Ni-based catalysts (e.g., NiCo) with a compromise OBE value (from −4.00 to −2.00 eV) exhibit enhanced catalytic behavior towards FAL HDO to 2-MF, superior to other ones (e.g., NiCu: OBE value > −2.00 eV; NiZr: OBE value < −4.00 eV). This work offers a feasible strategy to design bimetallic catalysts for the HDO reaction based on the electronic environment and chemical nature of doped metals.

Balancing photovoltaic parameters is very challenging to optimize the device performance of nonfullerene small-molecule acceptor (SMA)-based polymer solar cells (PSCs). We herein employed electron-withdrawing fluorinated or chlorinated 1,1-dicyanomethylene-3-indanone (ICF or ICCl) as the terminal acceptor (A) group to develop two acceptor–donor–acceptor (A–D–A) SMAs, DTCFO-ICF and DTCFO-ICCl, with an electron-rich fluorene-fused dithienocyclopentafluorene as the identical central donor (D) core. Compared with the nonhalogenated counterpart (DTCFO-IC), the two halogenated SMAs possessed a red-shifted absorption spectrum, reduced optical bandgap, and increased charge carrier mobility, but these were accompanied by down-shifted HOMO and LUMO levels, especially for the chlorinated molecule (DTCFO-ICCl). Accordingly, with respect to DTCFO-IC, PSCs based on the two halogenated SMAs with polymer PBDB-T as a donor exhibited an improved Jsc, but a dropped Voc, thus leading to a commensurate power conversion efficiency (PCE) of 6.80% for DTCFO-ICF and an increased PCE of 8.55% for DTCFO-ICCl. To further improve the device performance by means of balancing photovoltaic parameters, polymer PBDB-TF with a lower-lying HOMO level relative to PBDB-T was used to replace PBDB-T as the donor. The PCEs of PBDB-TF-based PSCs were further improved mainly due to the significantly enhanced Voc. Importantly, the DTCFO-ICCl-based PSCs achieved a high PCE of up to 11.03% along with an increased Voc (0.93 V), a further increased Jsc (18.80 mA cm−2), and almost retained FF (63.1%). The enhanced device performance could be attributed to better charge transport and collection abilities, less charge recombination and more optimal active layer morphology. These results argue that combining the halogenation on the A group of an A–D–A acceptor and variation of the paired polymer donor could be an effective strategy to enhance the device efficiency by balancing photovoltaic parameters.

Summary A “face-on” molecular orientation is essential for photovoltaic materials with efficient vertical carrier transport, but understanding how the molecular structures control their orientations remains challenging. Based on a ladder-type fused-ring core without sp3-hybridized bridging atoms, novel acceptor-donor-acceptor (A-D-A or ADA)-type nonfullerene acceptors (M3 and M32) are developed, and their molecular orientation behaviors are successfully controlled by the neighboring side chains. With linear n-cetyl chains on the nitrogen atoms, the acceptor (M32) tends to adopt an “edge-on” molecular orientation, whereas with bulky branched 2-hexyldecyl chains, the acceptor (M3) has a preferred “face-on” orientation. Blended with a donor polymer of PM6, M3 shows optimal phase separation and dramatically improved electron transport, consequently leading to a much higher device performance than M32. Further optimization of the M3-based devices yields an outstanding efficiency of 16.66%. The strategy of molecular orientation control proposed here will inspire many other innovative designs and syntheses of high-performance nonfullerene acceptors.

Density functional theory (DFT) calculations are carried out to investigate the effect of point defects on acetylene hydrogenation reaction over Ni(111) surface with three different defect concentrations (DC = 0.0500, 0.0625, and 0.0833), compared with the perfect Ni(111) surface. The adsorptions of C2 species and H atoms and the mechanism of acetylene hydrogenation via the ethylene pathway are systematically analyzed. The results indicate that the existence of defects will make C2 species and H atoms more inclined to adsorb near the defects. Introducing an appropriate amount of point defect concentration can enhance the catalytic activity and ethylene selectivity of Ni. In this work, DC = 0.0625 Ni(111) surface has the highest catalytic activity and selectivity of ethylene. This work provides useful theoretical information on the effect of defects on acetylene hydrogenation and is helpful for the design of Ni and related metal catalysts with defects.

Nonfullerene acceptors are being investigated for use in polymer solar cells (PSCs), with their advantages of extending the absorption range, reducing the energy loss and therefore enhancing the power conversion efficiency (PCE). However, to further boost the PCE, mobilities of these nonfullerene acceptors should be improved. For nonfullerene acceptors, the π–π stacking distance between cofacially stacked molecules significantly affects their mobility. Here, we demonstrate a strategy to increase the mobility of heteroheptacene-based nonfullerene acceptors by reducing their π–π stacking distances via control over the bulkiness of lateral side chains. Incorporation of 2-butyloctyl substituents into the nonfullerene acceptor (M36) leads to an increased mobility with a reduced π–π stacking distance of 3.45 Å. Consequently, M36 affords an enhanced PCE of 16%, which is the highest among all acceptor-donor-acceptor-type nonfullerene acceptors to date. This strategy of control over the bulkiness of side chains on nonfullerene acceptors should aid the development of more efficient PSCs.

Semitransparent organic solar cells (OSCs) have great potential for vehicle-integrated and building-integrated photovoltaics with their rapidly increased power conversion efficiencies (PCEs). For these purposes, the efficiency of semitransparent OSCs at an adequate transparency should be further increased. In this work, a ladder-type dithienonaphthalene-based acceptor (DTNIF) with a high-lying lowest unoccupied molecular orbital energy level is used as a third component material for ternary OSCs which show increased PCEs with enlarged values in open-circuit voltage, short-circuit current and fill factor. Consequently, outstanding PCEs of 16.73% and 13.49% are achieved for the corresponding opaque and semitransparent ternary OSCs, respectively. The efficiency of 13.49% for the semitransparent OSCs at an average visible transmittance (AVT) of 22.58% is the highest reported to date, to the best of our knowledge. This work provides an effective strategy to fabricate high-performance semitransparent OSCs at high AVT values by using an excellent third component acceptor material.

Along with the rapidly increasing power conversion efficiency (PCE) of polymer solar cells (PSCs), the stability of PSCs has become one of the crucial issues for the commercial application of this technology. Ternary PSCs exhibit great potential in improving the device efficiency and stability. However, the main cause behind the improvement in the efficiency and stability has been a lack of in-depth investigation. Moreover, the basic working mechanism of ternary solar cells is still ambiguous and it is urgently necessary to further understand it. Here, a small-molecule acceptor (SMA) IDT-OT was developed and introduced into a binary system containing polymer donor PBDB-T (donor) and fullerene acceptor (FA) PC71BM to construct donor/FA/SMA ternary PSCs. The results reveal that the incorporation of IDT-OT into the PBDB-T/PC71BM binary system can improve the PCE up to 9.09% and enhance the thermal stability of the ternary PSCs relative to all the binary systems. In-depth investigations indicate that the enhanced device performance and stability are closely related to an intermixed small-molecule/fullerene acceptor alloy formed by IDT-OT and PC71BM in which the structural nature of the two acceptors is remarkably different. This distinctive alloy system is verified via investigating the dependence of the LUMO energy level and open-circuit voltage on the weight ratio of IDT-OT in the acceptor blend and the miscibility of the two acceptors by morphological characterization and water contact angle measurements. This small-molecule/fullerene acceptor alloy phase is beneficial for improving charge dissociation, collection and transport as well as the carrier mobility, and suppressing bimolecular recombination, thus leading to the increase of Jsc and FF of the ternary PSCs. Interestingly, photoluminescence and donor-free device performance studies demonstrate that there exists not only efficient charge transfer but also Forster resonance energy transfer between PC71BM and IDT-OT, which has rarely been found in previously reported ternary PSCs. Moreover, we suppose the stable active layer morphology benefitting from the formation of this small-molecule/fullerene acceptor alloy as the main reason behind the observed improvement in the thermal stability of the ternary PSCs. This work suggests that introducing an SMA into an FA to form a small-molecule/fullerene acceptor alloy could be a powerful tool to realize high-performance and stable PSCs.

The mechanism of a low-temperature water-gas shift reaction (LT-WGSR) over supported gold catalysts has long been disputed, with the two prevailing ones being redox and associative mechanisms, due to the rather limited direct and reliable evidence for the actual reaction route. Herein, a typical supported gold-based catalyst (Au@TiO2−x/ZnO) was obtained via a structural topotactic transformation from hydrotalcite precursors, exhibiting an extremely high catalytic performance towards LT-WGSR. A series of experimental measurements involving in situ/operando DRIFTS, in situ Pulse-MASS and in situ/operando EXAFS as well as density functional theory (DFT) calculations were carried out to monitor the dynamic evolution of active sites, detect reaction intermediates and identify the reaction route. A new redox reaction route derived from the interfacial synergistic catalysis was verified: one H2O molecule undergoes dissociation at an Auδ−–Ov–Ti3+ (Ov: oxygen vacancy) interfacial active site, accompanied with the production of one H2 molecule and the oxidation of the interfacial structure to Au0–Or–Ti4+ (Or: the interfacial reactive oxygen species). Subsequently, one chemisorbed CO molecule captures Or to produce CO2 with the recovery of Auδ−–Ov–Ti3+. The present understanding and identification of the reaction mechanism of LT-WGSR would offer inspiration for further material exploration and catalyst design in gold-based heterogeneous catalysis.

The design and exploitation of high-performance catalysts as well as understanding the structure-property correlation have gained considerable attention in selective hydrogenation reactions, but remain a huge challenge. Herein, we report a RuNi single atom alloy (SAA) in which Ru single atoms are anchored onto Ni nanoparticle surface via Ru–Ni coordination accompanied with electron transfer from sub-surface Ni to Ru. The optimal catalyst 0.4% RuNi SAA exhibits simultaneously improved activity (TOF value: 4293 h− 1) and chemoselectivity toward selective hydrogenation of 4-nitrostyrene to 4-aminostyrene (yield: >99%), which is, to the best of our knowledge, the highest level compared with reported heterogeneous catalysts. In situ experimental researches based on XAFS, FT-IR measurements and theoretical calculations reveal that the Ru–Ni interfacial sites as intrinsic active centers facilitate the preferential cleavage of N–O bond in nitro group with a decreased energy barrier by 0.35 eV. In addition, the Ru–Ni synergistic catalysis promotes the formation of intermediates (C8H7NO* and C8H7NOH*) and accelerates the rate-determining step (hydrogenation of C8H7NOH*), resulting in the extraordinary activity and chemoselectivity toward nitroarenes hydrogenation.

In this paper, TiB reinforced Ti-6Al-4V matrix composites were successfully fabricated using a spark plasma sintering, hot rolling and heat treating process. (Transformed β-Ti + secondary α-Ti) domains were formed in TiB/TMCs after heat treatment. The size of these domains increases from 2.5 μm to 4.6 μm with the increase of solution time. The aspect ratio of whiskers monotonously decreases along with the solution time extending. The highest ultimate tensile strength of 1332 MPa and yield-strength of 1315 MPa were achieved by (940 °C, 15min+ water-quenching+537 °C, 4h) TMC.

The Isa/Ausmelt smelting technology with a top submerged lance (TSL) has been extensively used in copper smelting processes. However, the TSL is extremely vulnerable to damage and failure because of bending and tip burning. Frequent lance replacement is time-consuming and limits the copper production capacity. Here, a numerical simulation method is used to study the influence of lance failure on the flow field, splashing of slag, and wall shear of the lance as well as furnace body for exploring the factors that limit the service life of the lance. The simulation results reveal that the fluid flow is weak on the reverse bending side, which is is not conducive to mixing of raw materials when the lance is bent, resulting in a significant amount of slag splashing. After the lance tip is burned out, the utilization of agitation energy decreases because of an increase in the lance outlet area, resulting in poor stirring of the molten bath and a considerable loss of heat. In addition, this study shows that the lance wall shear varies because of slag splashing, implying that the wall shear can be reduced by reducing slag splashing.

Taking account of the fascinating properties of photovoltaic materials with conjugated side chains and the great influence of side-chain engineering on molecular structures and optoelectronic properties, we herein successfully developed three novel A–D–A (A = acceptor unit, D = donor unit) type small molecular acceptors (SMAs), IDTV-PhIC, m-IDTV-PhIC, and IDTV-ThIC, based on a methylene-modified indacenodithiophene (IDT) donor building block (IDTV), in which four flanking aryls were introduced as the conjugated side chains by grafting onto the two ethylene bridges of the IDT unit. The effects of the conjugated side chain and its type (phenyl vs. thienyl) as well as the substitution position (para vs. meta) on the molecular structures, physicochemical properties, charge transport properties, film morphology and photovoltaic performance of these SMAs have been investigated systematically. Compared to the control molecule IDT-PhIC based on IDT, the three IDTV-based acceptors exhibit extended conjugation in the vertical direction, which can enlarge the π-electron delocalization region along the molecular backbone and thus broaden the absorption spectra, reduce the bandgaps and elevate energy levels. Additionally, the conjugated side chains far away from the framework of the IDTV segment can enhance the rigidity, resulting in decreased solubility and improved charge transport properties of the SMAs. Because of the synergistic effects of changing the conjugated side-chain type and substitution position, m-IDTV-PhIC with meta-hexyloxyphenyl as the conjugated side chains exhibits relatively good solubility, a broad absorption spectrum and a high-lying LUMO energy level, moderate molecular planarity and better charge transport properties and film morphology, which are beneficial for achieving higher Voc, Jsc, and FF in devices compared to the control IDT-PhIC and the other IDTV-based SMAs IDTV-PhIC and IDTV-ThIC. As a result, among these acceptors, a polymer solar cell (PSC) fabricated with m-IDTV-PhIC as an acceptor and polymer PBDB-T as the donor delivers the best PCE of 5.85% with both the highest Voc (0.99 V) and Jsc (11.58 mA cm−2). This work not only provides a simple and effective strategy for developing new A–D–A type SMAs with conjugated side chains but also proves that the side-chain modification is an effective approach to optimize photovoltaic performance of the acceptors in PSCs.

A ultra-high temperature diffusion process with thin oxide layer capped with polysilicon film to get a deep VLD (Variable Lateral Doping) junction edge termination of 4500V trench-gated IGBT platform is presented in this paper. Conventionally, the VLD high temperature drive-in process is performed with oxide cap layer only, during which severe segregation of boron occurs at Si/Oxide interface, resulting in most of the implanted boron ions loss from silicon to oxide. Subsequently, the effective dose of VLD is decreased significantly with a poor controllability. As the consequence, it is difficult to get a uniform distribution of breakdown characteristics of the edge termination. Thru the proposed process disclosed in this paper, the segregation of boron at Polysilicon/Oxide interface acts as an effective barrier for the boron diffusion in underlying layers and the boron loss from silicon is considerably reduced. Both simulated and experimental results confirm that the improved process is highly manufacturable and can achieve excellent breakdown characteristics with a high production yield.

To develop new conjugated polymers (CPs) based on heteroepines, a soluble azepine moiety of benzo [d]-dithieno [3,2-b; 2′,3′-f]azepine was copolymerized with different building blocks to obtain a series of CPs. A broad absorption range of 300–850 nm and the desired optical bandgaps (1.54–2.42 eV) are easily accessible by varying different copolymerization units. The HOMO levels of polymers are observed as an almost identical value of −5.21 eV and the LUMO levels range from −2.82 to −3.52 eV. Polymer solar cells (PSCs) with these polymers as donor materials were fabricated to explore application potentials in organic photovoltaics. Preliminary study exhibits the best power conversion efficiency of 1.28% for PSCs based on these polymers with a relatively high Voc of 0.84 V. Although photovoltaic performance of these new polymers is not as high as our expected, the first daring attempt provides some good references to expand application fields of azepine-based polymers.

We have synthesized two photovoltaic molecules (HEX-3TVT-ID and EH-3TVT-ID) based on vinylene-bridged oligothiophene applied as donor for the solution-processable bulk-heterojunction organic solar cells (OSCs). Vinylene unit was introduced as π-bridge in the oligothiophenes with 1,3-indenedione as end group and 4,4′-dihexyl-2,2′:5′,2′-terthiophene or 3′,4′-di(octan-3-yl)-2,2′:5′,2′-terthiophene as core, respectively. Due to the different substituent positions of the alkyl group relative to the vinylene unit in the terthiophene, HEX-3TVT-ID and EH-3TVT-ID show different optical and electrochemical properties, corresponding to the photovoltaic performance of the OSCs devices. The power conversion efficiency (PCE) of the OSCs based on a blend of HEX-3TVT-ID and PC71BM (1:0.8, weight ratio, 0.5% CN) reached 2.3%. In comparison, the OSCs based on the blend of EH-3TVT-ID and PC71BM in the weight ratio of 1:1 without the additive show a higher PCE of 2.7%, with a typically high VOC of 0.93 V, under the illumination of AM 1.5, 100 mW cm−2.

Nowadays, constructing ternary polymer solar cells (PSCs) and developing non-fullerene acceptors (NFAs) have emerged as two powerful and efficient means to propel the device efficiency further forward. However, the incorporation of NFAs into a fullerene-based binary PSC to form high-performance donor : fullerene : NFA type ternary PSCs with a thick active layer and large area is still a challenge due to their inferior charge transport properties, complicated blend morphology and unclear aggregation behavior. In this contribution, a new low bandgap NFA (DTCFOIC) based on a fused heptacyclic core (dithienocyclopentafluorene) is developed and blended with a medium bandgap polymer donor PBDB-T to form a binary PSC achieving a power conversion efficiency (PCE) of 6.92%. When a small amount of DTCFOIC was employed as the additional acceptor combined with fullerene-based PC71BM to construct the PBDB-T : PC71BM : DTCFOIC ternary PSCs, an enhanced PCE of 9.40% was obtained after carefully optimizing the blend composition and the amount of the additive 1,8-diiodooctane (DIO) with a thin active layer (100 nm) and normal area (0.04 cm2). This could be mainly attributed to the extended absorption range, improved charge transfer, dissociation and collection properties, and suppressed charge recombination as well as optimized blend morphology in the ternary blend after the addition of NFA and DIO. Moreover, the photovoltaic performance of the ternary PSCs could be further optimized to achieve a higher PCE of 10.13% with a thicker active layer (160 nm) and eventually the highest PCE of 10.41% can be achieved with a thick active layer of 190 nm and a large area of 0.1 cm2, which is among the highest efficiencies of both thick layer and large area ternary PSCs. Besides, the ternary PSCs preserved a high PCE over 9% even with a larger active area of 1 cm2 using a thick active layer (172 nm). This observation demonstrates that incorporating a NFA to construct donor : fullerene : NFA type ternary PSCs is a feasible and effective approach to significantly enhance the performance of the resulting ternary system. Meanwhile, our results related to the thick active layer and large area suggest that this ternary system has a promising application prospect for mass manufacturing high-performance PSCs with a roll-to-roll process.

Benzo[1,2-b:4,5-b′]dithiophene (BDT) is demonstrated as a very effective building block to construct acceptor-donor-acceptor (A-D-A) small-molecule acceptors (SMAs) involving one BDT unit for high-performance polymer solar cells (PSCs). Herein, we successfully developed two new A-D-A SMAs, namely IDBDT-O and IDBDT-T, with the same BDT-fused nonacyclic indacenobis(benzo[1,2-b:4,5-b′]dithiophene) (IDBDT) central D unit and 1,1-dicyanomethylene-3-indanone (IC) terminal A group, but different side chains (alkoxyl vs alkylthiophene) attached on the BDT units. The IDBDT central core is formed by the fusion of one indacene segment and two BDT moieties, which obviously differs from the previously studied BDT-fused SMAs. Compared to IDBDT-T with alkylthiophene side chains, IDBDT-O with alkoxyl side chains exhibits a broader absorption, smaller band gap, and higher-lying HOMO energy level. Moreover, these IDBDT-based SMAs have upshifted LUMO energy levels relative to the reported BDT-fused SMAs, which is beneficial to increase open-circuit voltage (Voc). Bulk-heterojunction PSCs fabricated from polymer donor PBDB-T and IDBDT-T achieve the best power conversion efficiency (PCE) of 7.14% with a high Voc of 0.96 V, a short-circuit current density (Jsc) of 15.20 mA cm−2, much larger than a PCE of 1.83%, a Voc of 0.89 V and a Jsc of 5.21 mA cm−2 for the counterpart of PBDB-T:IDBDT-O. The enhanced device performance could be ascribed to higher and more balanced carrier mobility, more efficient exciton dissociation, and weaker bimolecular recombination as well as better active layer morphology in the IDBDT-T-based PSCs relative to IDBDT-O. Our results provide a new molecular design strategy to exploit BDT-fused A-D-A SMAs for high-performance PSCs.

Control over the molecular orientation of organic semiconductors with respect to the substrate plays a critical role in determining the performance of organic electronic devices. In this work, three ladder-type heteroheptacene-based small molecules with branched or unbranched side chains flanked in different positions of their conjugated backbone (M11, M12, and M13), were designed and synthesized to investigate the effect of side-chains on the crystallinity, molecular orientation, and optoelectronic properties of the organic semiconductors. When linear n-dodecyl side-chains are attached to the nitrogen atoms of the heteroheptacene core, the resulting molecule (M11) exhibits high crystallinity and edge-on molecular orientation, thus leading to excellent horizontal charge transport with a field-effect transistor (FET) mobility of 3.95 × 10−2 cm2 V−1 s−1. Replacing the linear n-dodecyl chains on the nitrogen atoms with the branched 2-butyloctyl chains leads to the organic semiconductors (M12 and M13) with the face-on dominated molecular orientation thereby leading to two orders of magnitude enhancement in the vertical charge transport in comparison with M11. Consequently, M12 and M13 show much higher power conversion efficiencies (PCEs) of 11.55% and 13.14%, respectively, compared to M11 which exhibits a PCE of 2.26% under the same device fabrication conditions. Optimization on the M13-based solar cells yields a further improved PCE of 15.63% which is among the highest values for the A-D-A type nonfullerene acceptors. The results reported in this work highlight that modulating the molecular orientation of organic semiconductors is a highly effective molecular design strategy to boost the performance of optoelectronic devices, thus also providing new insights into the molecular design guidelines for the next generation of high-performance semiconductors for the FET and photovoltaic applications.

Three low bandgap conjugated copolymers ( PB-DPP , PDFB-DPP , and PTFB-DPP ) based on 1,4-dithienylphenylene and diketopyrrolopyrrole units were synthesized and characterized as the donor materials for polymer solar cells. The effect of the number of fluorine atoms on thermodynamic, crystalline, physicochemical and photovoltaic properties of the copolymers was comparatively investigated. Results indicate that the absorption peaks of polymer solutions are blue-shifted and optical bandgaps are gradually decreased along with the increase of the number of fluorine atoms. Moreover, PDFB-DPP and PTFB-DPP show better light-harvesting abilities, higher crystallinities and lower-lying HOMO energy levels than those of PB-DPP . Photovoltaic performances of these copolymers were studied and optimized. PDFB-DPP and PTFB-DPP deliver a power conversion efficiency of 5.31% and 4.93%, respectively, both of which are higher than that of PB-DPP (4.13%) due to the increased J sc and V oc . This work demonstrates that the number of fluorine substitution is crucial to improving optoelectronic properties.

In this study, a water-model experiment and numerical simulation were carried out in a pilot ISASMELT furnace to study the factors affecting mixing time. The experimental results were compared to the simulation results to test the accuracy of the latter. To study the internal factors that affect the mixing time, the turbulent viscosity and flow field were calculated using simulation. In addition, following previous research, external factors that influence the mixing time including the depth of the submerged lance, lance diameter, gas flow rate, and the presence of a swirler were studied to investigate their effect on the flow regime. The results indicated that the mixing time is controlled by the turbulent viscosity and velocity vector. In addition, it was found that the lance diameter should not exceed 3.55 cm to maintain sufficient energy for stirring the bath. Finally, the optimal gas flow rate that offers the best mixing efficiency was found to be 50 Nm3/h.

Recently, Ni-Sn intermetallic compounds (IMCs) with unique geometric structures have been proved to be selective catalysts for acetylene hydrogenation to ethylene, but the origin of the selectivity remains unclear. In this work, a density functional theory (DFT) study has been carried out to investigate the mechanism of acetylene hydrogenation on six surfaces of Ni-Sn IMCs, and the geometric effects towards ethylene selectivity were revealed. Two key parameters (adsorption energy and the hydrogenation barrier of ethylene), which determine the ethylene selectivity, were studied quantitatively. The adsorption sites for C2Hy (y = 2, 3, 4) can be classified into three types: Type 1 (Ni3Sn(111) and Ni3Sn2(101)-2) with Ni trimers, Type 2 (Ni3Sn(001) and Ni3Sn2(001)) with Ni monomers, and Type 3 (Ni3Sn2(101) and Ni3Sn2(001)-2) with reconstructed metal trimers. The adsorption energy (Ead) decreases following the order: Type 1 > Type 3 > Type 2, which indicates that the adsorption strength depends significantly on site ensemble: a more isolated Ni site would facilitate the desorption of ethylene. However, the surface roughness mainly dominates the hydrogenation barrier of ethylene. Either low or high roughness decreases the interactions between H and C2H4 (Eint), resulting in an enhanced energy barrier for over-hydrogenation of C2H4 (Ea,hydr); while moderate roughness benefits Eint and lowers Ea,hydr. The selectivity to ethylene is denoted as ΔEa = Ea,hydr - |Ead|, thus depending on the interplay of site ensemble effects and surface roughness. From this point of view, Ni3Sn(001) and Ni3Sn2(101) surfaces with well-isolated Ni ensembles and low (or high) surface roughness exhibit decreased |Ead| and increased Ea,hydr, giving rise to excellent selectivity to ethylene. This work provides significant understanding of the origin of ethylene selectivity in terms of geometric effects, which gives helpful instruction for the design and preparation of intermetallic catalysts for acetylene semi-hydrogenation.

We constructed a 1:10 cold water experimental model by geometrically scaling down an Isa smelting furnace. The mixing processes at different liquid heights, lance diameters, lance submersion depths, and gas flow rates were subsequently measured using the conductivity method. A new criterion was proposed to determine the mixing time. On this basis, the quasi-equations of the mixing time as a function of different parameters were established. The parameters of the top-blown smelting process were optimized using high-speed photography. An excessively high gas flow rate or excessively low liquid height would enhance the fluctuation and splashing of liquid in the bath, which is unfavorable for material mixing. Simultaneously increasing the lance diameter and the lance submersion depth would promote the mixing in the bath, thereby improving the smelting efficiency.

The scale-up of a solid–liquid stirred tank with an Intermig impeller was characterized via experiments. Solid concentration, impeller just-off-bottom speed and power consumption were measured in stirred tanks of different scales. The scale-up criteria for achieving the same effect of solid suspension in small-scale and large-scale vessels were evaluated. The solids distribution improves if the operating conditions are held constant as the tank is scaled-up. The results of impeller just-off-bottom speed gave X = 0.868 in the scale-up relationship ND X = constant. Based on this criterion, the stirring power per unit volume obviously decreased at N = N js, and the power number (N P) was approximately equal to 0.3 when the solids are uniformly distributed in the vessels.

Besides high short-circuit current density (Jsc) and fill factor (FF), high open-circuit voltage (Voc) is urgently necessary for obtaining high overall efficiencies of polymer solar cells (PSCs). In order to produce high Voc PSCs, herein, we developed three wide-bandgap donor–acceptor (D-A) alternate copolymers (PBDTO-TPTI, PBDTT-TPTI, and PBDTS-TPTI ) of benzodithiophene (BDT) and thienopyridothieno-isoquinoline-5,11(4H,10H)-dione (TPTI) moieties. These copolymers possess a uniform BDT-TPTI framework, but various side chains (alkoxyl, alkylthienyl, alkylthiothienyl) on the BDT unit. The resultant data convincingly reveal that the spectral absorption, optical bandgap (Egopt), aggregation characteristic, energy levels, charge transport properties and active layer morphology of the D–A copolymers can be effectively manipulated via side-chain engineering on the BDT segment. The gradually increased Egopt (1.92–1.95 and then to 1.97 eV) and gradually decreased HOMO/LUMO levels (−5.43/−3.47 to −5.54/−3.53 and then to −5.56/−3.76 eV) are found while the side group on the BDT unit is varied from alkoxyl (PBDTO-TPTI) to alkylthieyl (PBDTT-TPTI) and then to alkylthiothienyl (PBDTS-TPTI). Importantly, the geometric and optoelectronic properties of these polymers are supported by theoretical predictions. PSCs based on all the three copolymers with a fullerene-based acceptor (PC71BM) exhibit power conversion efficiencies (PCEs) exceeding 5% and a Voc over 0.93 V. Notably, PBDTS-TPTI-based PSC achieves the highest PCE of 5.35% accompanied with the highest Voc as far as 0.99 V and Jsc up to 12.60 mA cm−2. This work indicates side-chain engineering on polymers is an impactful and feasible approach to realize high Voc PSCs by manipulating electronic levels of D–A copolymers.

Three new A-π-D-π-A type small molecules ( DIP-T , DIP-HT , and DIP-HTT ) employing diindole[3,2- b :4,5- b ′]pyrrole (DIP) as the electron-rich donor (D) block, indenedione as the electron-deficient acceptor (A) group, and thiophene, 3-hexylthiophene, or 4-hexyl-2,2′-dithiophene as the conjugated π-bridge, are designed, synthesized and characterized as donor materials for organic solar cells (OSCs). The effects of the length and steric hindrance of the thiophene-containing π-bridges on the molecular configuration, optical, electrochemical and charge-transport properties were investigated by theory calculations, UV–vis spectroscopy, cyclic voltammetry, and the space-charge-limited current method, respectively. These DIP-based small molecules (SMs) show excellent solubility and good thermal stability. DIP-T with thiophene as π-bridge shows wider and stronger absorption, higher-lying HOMO energy level, higher hole mobility and superior active layer morphology in comparison with that of DIP-HT and DIP-HTT with 3-hexylthiophene and 4-hexyl-2,2′-dithiophene as the conjugated π-bridge, respectively. As a result, the optimized OSC based on DIP-T exhibits an obviously higher power conversion efficiency (PCE) of 4.65% with relative to the other two SMs. So far, this is the first report of developing the A-π-D-π-A type SMs with a DIP donor core for application in organic electronic devices. Our results indicate that the pentacyclic DIP can be a potential and attractive donor building block for developing efficient A-π-D-π-A type SMs donor materials.

To obtain low-bandgap polymers paired well with fullerene and nonfullerene acceptors, here we adopted a D-A1-D-A2 motif to develop two new low-bandgap copolymers PTPTI-T-BDD and PTPTI-T-FBT, where thiophene was used as the D unit, thieno[2′,3′:5,6]pyrido[3,4-g]thieno[3,2-c]-isoquinoline-5,11(4H,10H)-dione (TPTI) was used as the A1 unit, and benzo[1,2-b:4,5-c′]dithiophene-4,8-dione (BDD) and 5,6-difluoro-2,1,3-benzothiadiazole (FBT) were employed as the A2 unit, respectively. Effects of the electron-withdrawing strength of A2 unit on optoelectronic and photovoltaic properties of the PTPTI-T-BDD- and PTPTI-T-FBT-based fullerene and nonfullerene polymer solar cells (PSCs) were systematically investigated. When blended with PC71BM and ITIC, PTPTI-T-FBT-based PSCs showed a power conversion efficiency (PCE) of 6.20% and 6.03%, respectively, both of which are higher than that of PTPTI-T-BDD-based PSCs. Furthermore, ternary PSCs based on PBDB-T:PTPTI-T-FBT:PC71BM exhibited an improved PCE of 7.92%. This work suggests that constructing D-A1-D-A2 copolymers is a promising strategy to develop low-bandgap copolymers for efficient fullerene and nonfullerene PSCs with a reduced energy loss.

The experimental advanced superconducting tokamak (EAST) is being constructed at the Institute of Plasma Physics of Chinese Academy of Sciences (CASIPP). The EAST project, approved by the Chinese government as a national mega project of science research is a fully superconducting tokamak. The most key component for EAST is the superconducting magnet coils (SMCs), which consists of 16 toroidal field coils (TFCs) and 14 poloidal field coils (PFCs). In 2003, three prototypes, one TFC and two PFCs, were successfully completed and passed a series of cryogenic tests. Batch production, needed for the SMCs has begun at CASIPP since 2002. Up to now, all 58 CIC conductors with a total length of 32 km, 12 TFCs out of 16 and 10 PFCs out of 14 have been fabricated. This paper emphasizes on the various technology issues that must be faced and solved for four R&D lines of SMCs after transforming to batch production. Quality control methods in process are also described.

The Toroidal Field (TF) coil case of the HT-7U superconducting tokamak device is made of austenitic stainless steel 316LN and is designed to operate at cryogenic temperature (4 K). 316LN can retain high strength and fracture toughness at 4 K. Feasibility study on technical process of welding has been experimentally considered as a hopeful joint method for suppression of post-welding deformation and reduction of over-heating. Meanwhile the final range of stress intensity and the stress intensity factor (K) for pre-cracks of welding structure have been determined by using J-integral. These related results are optimistic and have shown that there's no problem in strength and fracture toughness at the vicinity of the pre-crack tip. This paper introduces the welding structure of TF coil case in detail.

A special winding machine with high accuracy has just been developed and applied to the construction of HT-7U Tokamak. It is one of the critical facilities for R & D of HT-7U construction. The machine mainly consists of five parts, including a CICC pay-off spool, a four-roller correcting assembly, a four-roller forming/bending assembly, a continuous winding structure and a CNC control system with three-axis AC servo motors. The facility is used for Cable in Conduit Conductor (CICC) magnet fabrication of HT-7U. The main requirements of the winding machine are: continuous winding to reduce joints inside the coils; pre-forming CICC conductor to avoid winding with tension; suitable for all TF & PF coils of various coil shapes and within the dimension limit; improving the configuration tolerance and the special flatness of the CICC conductor. This paper emphasizes on the design and fabrication of the special winding machine for HT-7U. Some analyses and techniques in winding process for trial D-shape coil are also presented.

In this paper, the theoretical expressions of modulation depth of moire signal under the incoherent illumination are derived. It follows as a concequence that, the modulation depth of moire signal is in relation to the following factors: the geometric share and size of light source, the diffraction effect of grating,which relates to the line numbers of grating, the line and space ratio, the gap of grating pairs, the geometric shape and size of receiving window, etc. In addition, the influences of grating fair on the period and inclination of moire fringes under the noncollimated illumination are discussed, and the comparisons of the changes of modulation depth of moire signals and the noncollimated illumination with that under the collimated illumination are made. Finally, some exoeriment results are given to verify the theoretical expressions. This parer is useful to the actual design of grating sensors.© (1986) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.