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Suppressing the nonradiative recombination in the bulk and surface of perovskite film is highly desired to improve the power conversion efficiency (PCE) and stability of halide perovskite solar cells (PSCs). In this study, a benzotriazole derivative (6-chloro-1-hydroxybenzotriazole, Cl-HOBT) is applied to improve the crystallinity and reduce the trap density of methylammonium lead iodide (MAPbI3) perovskite film. Meanwhile, incorporation of Cl-HOBT elongates the photoluminescence carrier lifetime and charge-recombination lifetime, implying the trap-assisted nonradiative recombination is greatly suppressed. Besides, the improved energy level alignment and enhanced built-in potential are conducive to the charge carrier separation and transfer process with Cl-HOBT. Consequently, a PCE of 20.27% and an open-circuit voltage (Voc) of 1.09 V are achieved for the inverted MAPbI3 PSCs, along with an 85% maintaining of the initial PCE under stored at relative humidity of 20% for 500 h. Furthermore, the existence of Cl-HOBT could inhibit the formation of Pb0 defect under prolonged UV illumination to retard the degradation of perovskite film. It is believed that this study paves a novel path for the realization of high-efficiency PSCs with UV-stability.

In order to overcome the shuttling effect of soluble polysulfides in lithium-sulfur (Li-S) batteries, we have designed and synthesized a creative MoS2-MoO3/carbon shell (MoS2-MoO3/CS) composite by a H2O2-enabled oxidizing process under mild conditions, which is further used for separator modification. The MoS2-MoO3 heterostructures can conform to the CS morphology, forming two-dimensional nanosheets, and thus shorten the transport path of lithium ion and electrons. Based on our theoretical calculations and experiments, the heterostructures show strong surface affinity toward polysulfides and good catalytic activity to accelerate polysulfide conversion. Benefiting from the above merits, the Li-S battery with a MoS2-MoO3/CS modified separator exhibits good electrochemical performance: it delivers a high discharge capacity of 1531 mAh g-1 at 0.2 C; the initial capacity can be maintained by 92% after 600 cycles at 1 C, and the discharge capacity decay rate is only 0.0135% per cycle. Moreover, the MoS2-MoO3/CS battery still achieves good cycling stability with 78% capacity retention after 100 cycles at 0.2 C with a high sulfur loading of 5.9 mg cm-2. This work offers a facile design to construct the MoS2-MoO3 heterostructures for high-performance Li-S batteries, and may also improve one's understanding on the heterostructure contribution during polysulfide adsorption and conversion.

The charge carrier dynamics in hybrid perovskite solar cells (PSCs), especially the carrier generation, transfer, interface recombination and collection, are in the femtosecond to millisecond range...

We report charge recombination rates in lead iodide perovskites with alloys of formamidinium (FA) and methylammonium (MA) cations, FAxMA1–xPbI3, 0 ≤ x ≤ 0.9, prepared through ion exchange with mini...

The morphology and optoelectronic properties of perovskite films are the key to high-performance perovskite solar cells (PSCs). Here, a facile non-destructive interface ethanol/chlorobenzene (EtOH/CB) post treatment was established for the lateral grain growth of MAPbI3 perovskite films and fabrication of efficient solar cells. The alcoholic treatment leads to perovskite grain coarsening and a secondary growth in the average grain size from 38.88 μm to 89.59 μm. The enlargement of the perovskite crystals induced a notable defect passivation and attenuated charge recombination centers as confirmed by photoluminescence, electrochemical impedance spectroscopy, and photocharge extraction by a linearly-increasing voltage. Accordingly, inverted planar PSC devices showed an 18% enhancement in the overall power conversion efficiency using this alcoholic post-treatment under ambient fabrication conditions. Our results demonstrate a versatile strategy for the lateral growth of perovskite photovoltaics and beyond.

Carrier transport layers have been recognized as a key factor to determine the performance of perovskite solar cells (PSCs) by dominating the charge carrier extraction, transport and recombination process. Metal oxides have been widely used as electron transport layers (ETLs) in PSCs for high performance and stability, of which TiO2 and SnO2 are the most popular choices. However, the large-scale implementation of TiO2 and SnO2 ETLs is hindered by their own deficiencies, such as low electron mobility, poor stability against UV light and surface defects. Therefore, binary and ternary metal oxide alternatives have been widely investigated recently. Here, we review the recent advances of these metal oxide ETLs in PSCs with a special focus on the nanostructuring, elemental doping, surface modification, and multi-layer ETLs and large-scale fabrication of these ETLs. Furthermore, the state-of-the-art progress towards high-efficiency and stable PSCs using these novel ETLs is summarized and future perspectives are discussed.

Halide perovskite solar cells (PSCs) have been materialized as a hotspot in the next-generation photovoltaic technology due to their low-cost manufacturing process and high-efficiency characteristics. However, the defects within the bulk or in the grain boundaries and surface hinder ambipolar charge transport as non-radiative recombination centers. Efficacious defect passivation is therefore highly desired for high-efficiency and stable PSCs. Herein, a feasible Lewis acid/base passivation strategy and its effects on energy level alignment, recombination kinetics, hysteresis behavior and operational stability for efficient PSCs are comprehensively reviewed. These additives have been widely used to coordinate with unwanted defects and form Lewis adducts by dative bonds, where the Lewis acid contributes to passivate negatively charged defects (e.g., under-coordinated I− ions and Pb–I anti-sites) and the Lewis base plays a significant role in passivating positively charged defects (e.g., under-coordinated Pb2+ and Pb2+ interstitials), whereas zwitterions could passivate negatively and positively charged defects simultaneously. This highly executable Lewis adduct passivation would enable scalable deposition techniques for efficient and stable PSCs like inkjet printing, doctor-blade coating, screen printing, laser pattering and roll-to-roll deposition. Additionally, we also discuss the prospects of the maturity of this passivation strategy towards upscaling manufacture of perovskite photovoltaic and related optoelectronic devices.

A novel gas separation approach is proposed in this work by combining an amine-based solid adsorbent with a zeolitic imidazolate framework-8 (ZIF-8) membrane. This was achieved by incorporating the amine-based solid adsorbent during the fabrication of the ZIF-8 membrane on a macroporous substrate. An amine-based solid adsorbent was prepared using porous ZIF-8-3-isocyanatopropyltrimethoxysilane (IPTMS) and N-[(3-trimethoxysilyl)propyl]diethylenetriamine (3N-APS) amine compounds. The as-prepared porous amine-based solid adsorbent (denoted as ZIF-8-IPTMS-3N-APS) possessed excellent adsorptive CO2/N2 and CO2/CH4 separation performances. As the adsorbent needs to be regenerated, this could indicate that the CO2 adsorption separation process cannot be continuously operated. In this work, an amine-based solid adsorbent was applied during the preparation of the ZIF-8 membranes owing to the following reasons: (i) gas separation by the membrane can be operated continuously; (ii) the amino group provides a heterogeneous nucleation site for ZIF-8 to grow; and (iii) the reparation of surface defects on the macroporous substrate can be performed prior to the growth of the ZIF-8 membrane. Herein, the ZIF-8 membrane was successfully fabricated, and it possessed excellent CO2/CH4, CO2/N2, and H2/CH4 separation performances. The 0.6 μm ultrathin ZIF-8 membrane demonstrated a high CO2 permeance of 4.75 × 10−6 mol m−2 s−1 Pa−1 at 35 °C and 0.1 MPa, and ideal CO2/N2 and CO2/CH4 selectivities of 4.67 and 6.02, respectively. Furthermore, at 35 °C and 0.1 MPa, the ideal H2/CH4 selectivity of the ZIF-8 membrane reached 31.2, and a significantly high H2 permeance of 2.45 × 10−5 mol m−2 s−1 Pa−1.

MoS2/ZnIn2S4 nanocomposite was prepared via photoreduction of (NH4)2MoS4 in the presence of hexagonal ZnIn2S4. The as-obtained MoS2/ZnIn2S4 nanocomposite showed superior activity for acceptorless photocatalytic semi-dehydrogenation of 1,2,3,4-tetrahydroisoquinoline to produce 3,4-dihydroisoquinoline, with quantitative hydrogen evolved. In addition to MoS2/ZnIn2S4, a series of MS/ZnIn2S4 nanocomposites (MS = PtS and NiS) were also found to be active for this reaction, indicating that ZnIn2S4-based nanocomposites are effective photocatalysts for acceptorless semi-dehydrogenation of 1,2,3,4-tetrahydroisoquinoline to produce 3,4-dihydroisoquinoline. This study not only provides an efficient, green and cost effective strategy to produce 3,4-dihydroisoquinoline, but also highlights the great potential of semiconductor-based photocatalysis for light-driven organic syntheses.

Utilization of non-lithium-ion batteries in next-generation renewable energy storage is hindered by the lack of appropriate electrode materials with desired electrochemical performance. Motivated by low peeling-off energy (Jing et al. Nano Lett. 2017, 17(3), 1833−1838), an experimentally available two-dimensional material, nominated as GeP3, is investigated as the anode for non-lithium-ion batteries (Na+, K+, Ca2+, Mg2+, Al3+) based on density functional theory calculations. The electrochemical properties, i.e., ion intercalation mechanism, diffusion behavior, and theoretical capacities of different metal ions in GeP3, are systematically investigated. A semiconductor-to-metal transition and improved conductivity are observed due to ions intercalation in the GeP3 electrode. Even though the charge storage mechanism of Na and Ca ions is quite different, the GeP3 monolayer has exhibited a high theoretical capacity of 1295.42 mAh g–1 for both Na+ and Ca2+ ions. Furthermore, collective Na ions transport at the ...

Metal halide perovskites have demonstrated strong potential for optoelectronic applications. Particularly, two-dimensional (2D) perovskites have emerged to be promising materials due to their tunable properties and superior stability compared to their three-dimensional counterparts. For high device performance, 2D perovskites need a vertical crystallographic orientation with respect to the electrodes to achieve efficient charge transport. However, the vertical orientation is difficult to achieve with various compositions due to a lack of understanding of the thin film nucleation and growth processes. Here we report a general crystallization mechanism for 2D perovskites, where solvent evaporation and crystal growth compete to influence the level of supersaturation and a low supersaturation is necessary to crystallize vertically oriented thin films starting from nucleation at the liquid–air interface. Factors influencing the supersaturation and crystallization dynamics, such as choices of organic spacers, s...

Most of the electron transport layers (ETLs) used in inverted perovskite solar cells (PSCs) are fullerene derivatives, which are relatively expensive due to the complex synthesis process. Here we report coenzyme Q10, composed of quinone as the acceptor group and an alkyl chain as the donor group, which can be used as a low cost ETL alternative in inverted PSCs. The energy level alignments, carrier transport and recombination dynamics were systematically studied in comparison with the benchmark PC61BM. By optimizing the device structure and thickness of the ETL, the device with Q10 exhibits a comparable power conversion efficiency to the PC61BM device under the standard irradiation conditions. The carrier transport and recombination processes were further evaluated through steady state and time-resolved photoluminescence spectroscopy, space-charge-limited current, and Mott–Schottky measurements. An accelerated carrier injection ability and a passivated interface defect density between the perovskite and Q10 ETL were observed. Charge density difference from DFT calculations also determined that the band alignment of Q10 promoted easier charge transport from the perovskite. Moreover, the long alkyl chain of the Q10 molecule endows it with excellent hydrophobic properties, which largely improves the water-resistance capability of the Q10 ETL. This work highlights the great potential of Q10 as a cheap alternative for the most popular PC61BM ETL for inverted PSCs.

Metal halide perovskite materials have drawn worldwide attention for application in a variety of optoelectronic devices, especially in the emerging photovoltaic devices. In recent years, remarkable progress has been achieved in the device performance and stability. The optoelectronic properties of metal halide perovskites can be further tuned by ion doping. Herein, a comprehensive review of the incorporation of alkali metal ions (Li+, Na+, K+ and Rb+) in emerging perovskite solar cells for a longer carrier lifetime, lower interfacial defect density, faster charge transfer, no hysteresis, higher stability and higher power conversion efficiency is presented. The detailed mechanism behind these beneficial effects has been discussed in terms of electronic properties, film morphology, energy level alignment, carrier recombination dynamics and stability. On the basis of these latest advances and breakthroughs in alkali ion doped perovskite thin films, future research directions and prospects are also discussed, which include further understanding of the underlying photophysical mechanism and extension to other optoelectronic devices where a longer carrier lifetime and lower trap density are needed.

Solution-processed TiO2 and other metal-oxide electron-transporting layers (ETLs) for perovskite solar cells commonly require high-temperature annealing (>450 °C), causing the underlying indium-tin...

Polycrystalline samples of CoAsSb were prepared by annealing a stoichiometric mixture of the elements at 1073 K for 2 weeks. Synchrotron powder X-ray diffraction refinement indicated that CoAsSb adopts arsenopyrite-type structure with space group P21/c. Sb vacancies were observed by both elemental and structural analysis, which indicate CoAsSb0.883 composition. CoAsSb was thermally stable up to 1073 K without structure change but decomposed at 1168 K. Thermoelectric properties were measured from 300 to 1000 K on a dense pellet. Electrical resistivity measurements revealed that CoAsSb is a narrow-band-gap semiconductor. The negative Seebeck coefficient indicated that CoAsSb is an n-type semiconductor, with the maximum value of −132 μV/K at 450 K. The overall thermal conductivity is between 2.9 and 6.0 W/(m K) in the temperature range 300–1000 K, and the maximum value of figure of merit, zT, reaches 0.13 at 750 K. First-principles calculations of the electrical resistivity and Seebeck coefficient confirmed ...

In light of low atomic mass, three types of experimentally synthetized borophene including β12, χ3 and striped t-sheet have been predicted to be promising anode materials for lithium-ion batteries (LIBs) with extremely high capacity. However, the rate performances of β12 and χ3 are quite poor with high diffusion barrier of 0.66–0.81 eV on β12 and 0.60–0.85 eV on χ3 in contrast with that in t-sheet (typically

Co9S8 can catalyze polysulfides conversion in Lithium sulfur batteries (LSBs) owing to its metallic nature and rich catalytic sites. However, its catalytic activity and chemical adsorption is not strong enough to suppress the shuttle effect of Lithium polysulfides (LiPS) under high sulfur loading. Herein, Phosphorous (P)-doped Co9S8 nanoparticle was synthesized and embedded into 3D Spongy carbon (SC) sheets as electrochemical catalyst for LSBs. Our Density functional theory (DFT) calculations and experimental results revealed that moderate P doping can modulate the electronic structure of Co9S8 and simultaneously improve its interaction with LiPS and promote LiPS conversion. When P-doped Co9S8 nanoparticles are in situ formed and homogeneously distributed on 3D spongy carbon sheet matrix, the resulting P-Co9S8@SC can ensure good exposure of their adsorption and catalytic sites. As a result, the LSB based on an optimized P-Co9S8@SC modified polypropylene separator exhibited excellent cycling stability (capacity decay of 0.05% per cycle over 900 cycles at 1 C) and high areal capacity (4.38 mAh cm−2 at 5.6 mg cm−2 sulfur loading at 0.1 C). Our work demonstrates that moderate heteroatom doping is a promising strategy to develop effective polysulfides catalysis.

The commercialization process of metal hybrid perovskite solar cells (PSCs) is hindered by the poor quality of perovskite films, imperfect carrier extraction, and inferior stability. Organic or inorganic molecules have been widely used to overcome these limitations. Herein, 5-(ethylthio)-1H-tetrazole (ETT) is applied for the deposition of perovskite films with high crystallinity and smooth surface. Due to the interaction between the lone pair electrons of tetrazole and Pb2+, the surface defects of perovskite films were passivated, thus leading to facilitated charge transport and inhibited carrier recombination. The improved crystallinity and defect passivation enabled a power conversion efficiency over 20% in the ETT-modified inverted MAPbI3 PSC device, along with notably enhanced moisture stability. Our work provides a feasible strategy for the crystallization modulation and humidity stability enhancement of PSCs.

In order to realize high-throughput roll-to-roll manufacturing of flexible perovskite solar cells, low-temperature processing of all device components must be realized. However, the most commonly used electron transporting layer in high-performance perovskite solar cells is based on TiO2 thin films processed at high temperature (>450 °C). Here, we demonstrate room temperature solution processing of the TiOx layer that performs as well as the high temperature TiO2 layer in perovskite solar cells, as evidenced by a champion solar cell efficiency of 16.3%. Using optical spectroscopy, electrical measurements, and X-ray diffraction, we show that the room-temperature processed TiOx is amorphous with organic residues, and yet its optical and electrical properties are on par with the high-temperature TiO2. Flexible perovskite solar cells that employ a room-temperature TiOx layer with a power conversion efficiency of 14.3% are demonstrated.

The utilization of solar energy for CO2 conversion to produce valuable chemicals or fuels is extremely appealing since it can simultaneously reduce the greenhouse effect and relieve the energy shortage pressure. In addition to the commonly used semiconductor-based photocatalysts, metal–organic frameworks (MOFs), a class of micro-mesoporous hybrid materials, are recently emerging as new types of photoactive materials for CO2 reduction due to their excellent adsorption capability toward CO2 and unique structural characteristics. In this review, we summarized the recent applications of MOFs for photocatalytic CO2 reduction, in which MOFs either act directly as the photocatalysts for CO2 reduction or as components in a hybrid photocatalytic system to promote CO2 reduction. This review starts with a brief introduction of the background of photocatalytic CO2 reduction, followed by a summarization of CO2 reduction catalyzed by photoactive ligands and metal nodes in MOFs, respectively. Thereafter, the construction of hybrid photocatalytic systems in which MOFs play a role in promoting photocatalytic CO2 reduction is described. Finally, the limitations, challenges and future prospects of the application of MOFs to CO2 reduction are addressed. We hope that this review not only can serve as a starting point to get into this largely unexplored field but can also stimulate intensive research on the rational design and development of more creative MOF systems for light induced CO2 conversion, which is a green and sustainable strategy for CO2 utilization.

Here, we report a combined study of transport and thermodynamic measurements on the layered pnictide material ${\mathrm{SrAg}}_{4}{\mathrm{As}}_{2}$. Upon cooling, a drop in electrical and Hall resistivity, a jump in heat capacity, and an increase in susceptibility and magnetoresistance are observed around 110 K. All suggest nonmagnetic phase transitions emerge at around 110 K, likely associated with structural distortions. In sharp contrast with the first-principles calculations based on the crystal structure at room temperature, quantum oscillations reveal small Fermi pockets with light effective masses, suggesting significant change in the Fermi surface topology caused by the low-temperature structural distortion. No superconductivity emerges in ${\mathrm{SrAg}}_{4}{\mathrm{As}}_{2}$ down to 2 K under pressures up to 2.13 GPa; instead, the low-temperature structural distortion moves up linearly to high temperature at a rate of $\ensuremath{\approx}13$ K/GPa above 0.89 GPa.

In highly efficient halide perovskite solar cells (PSCs), nickel oxide (NiOx) have been widely used as an inorganic hole transport layer (HTL). However, the solution-processed NiOx films always have pinholes, along with inferior contact with perovskite layer. Herein, a surfactant of hexadecylbenzene (HAB) was applied to improve the hole extraction from perovskite to NiOx HTL. With the modification of HAB, a high quality perovskite layer was obtained. Due to the enhanced hole extraction, the HAB modified device showed a higher short-circuit current density (JSc ) and a power conversion efficiency of 17.11%. Therefore, this work offers a novel strategy in interfacial engineering for high-efficiency PSCs.

Lithium-sulfur batteries (LSBs) have gained intense research enthusiasm due to their high energy density. Nevertheless, the ‘shuttle effect’ of soluble polysulfide (a discharge product) reduces their cycling stability and capacity, thus restricting their practical application. To tackle this challenging issue, we herein report a sulfonated covalent organic framework modified separator (SCOF-Celgard) that alleviates the shuttling of polysulfide anions and accelerates the migration of Li+ ions. Specifically, the negatively charged sulfonate can inhibit the same charged polysulfide anion through electrostatic repulsion, thereby improving the cycle stability of the battery and preventing the Li-anode from being corroded. Meanwhile, the sulfonate groups may facilitate the positively charged lithium ions to pass through the separator. Consequently, the battery assembled with the SCOF-Celgard separator exhibits an 81.1% capacity retention after 120 cycles at 0.5 C, which is far superior to that (55.7%) of the battery with a Celgard separator. It has a low capacity degradation of 0.067% per cycle after 600 cycles at 1 C, and a high discharge capacity (576 mAh g−1) even at 2 C. Our work proves that the modification of a separator with a SCOF is a viable and effective route for enhancing the electrochemical performance of a LSB.

Anion exchange membranes (AEMs) are an important component in anion exchange membrane fuel cells, and their side chain structures have a significant impact on membrane performance. Here, we construct a series of poly(phenylene oxide) (PPO)-based AEMs with varied side chain structures and investigate the effects of alkyl or alkoxyl extenders (or “tail” of the cation) and spacers (or the link between backbone and cation head group) on AEM performance. Our investigations demonstrate that the simultaneous introduction of alkoxyl extender and spacer can significantly improve water absorption and ion conductivity of membrane; this is attributed to the good hydrophilicity of alkoxyl group and flexibility of spacer that benefit the formation hydrophilic domains. At an IEC (ion exchange capacity) of 1.13 mmol/g, the AEM containing both spacer and alkoxyl extender exhibits a hydroxide conductivity of 87.3 mS/cm (80 °C), which is much higher than that of other spacer-containing membranes at similar IECs. The H2/O2 single cell constructed with this membrane exhibits a good peak power density of 292 mW/cm2 at 60 °C. In addition, the steric hindrance of the extender gives rise to higher alkali stability of the AEM than that of the membrane which does not have the extender. Our work provides a meaningful direction of side chain design which can effectively improve conductivity and alkaline stability of AEMs.

Development of inorganic metal halide perovskites solar cells (PSCs) has been hampered by the inherent phase instability of inorganic perovskites. Herein, an ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) is proposed to stabilize the CsPbI2Br phase and reduce the surface defect density. From experimental analyzes and density functional theory calculations, the BMIMBF4 interlayer could reduce the energy loss and stabilize the cubic -phase of CsPbI2Br. The interaction between BMIMBF4 and CsPbI2Br could improve the perovskite film quality and the interfacial charge transport. Accordingly, the BMIMBF4-modified device enables a 37.18% and 18.89% improvement in the power conversion efficiency and open-circuit voltage compared to the control CsPbI2Br device, along with an 86.9% retaining of its initial performance over 1000 h storage in N2 atmosphere, while the control device drops to zero in 200 h. The work provides a novel cogitation for the defect passivation and energy loss reduction to improve both the stability and efficiency of inorganic perovskite solar cells.

Perovskite solar cells (PSCs) have been widely investigated in the past decade with a certificated record efficiency up to 25.2%, which is comparable to the inorganic thin-film and crystalline silicon photovoltaics. Further improving the device photovoltaic performance and long-term stability has been pursued to impel commercial application. Ionic liquids, an old class of compounds that contain large asymmetric organic cations coupled with organic or inorganic anions, have been used in high-performance PSC devices with enhanced efficiency and stability due to their unique physicochemical properties. Herein, the recent progress of ionic liquids engineering in PSCs is comprehensively reviewed and the potential mechanisms on device performance and stability are illustrated. Specifically, the main beneficial effects of ionic liquids including crystallization process modulation, energy level alignment, independent charge extraction layer or dopant, enhancing the moisture and thermal stability are summarized. Future prospects towards the realization of ultra-stable and efficient PSCs with ionic liquid engineering are also discussed and presented.

Crystal orientation of perovskite film and interface modification plays an important role in the efficient operation and stability of perovskite solar cells (PSC). Herein, a high quality perovskite film with large grain size, high crystallinity and preferred crystal orientation on (100) plane is deposited on an aqueous solvent (H2O and DMF) pretreated nickel oxide (NiOx) substrate (HDP). The aqueous solvent treatment increases the wettability and conductivity of NiOx layer during perovskite growth. Steady-state and time-resolved photoluminescences reveals a significantly increased charge extraction efficiency in the HDP perovskite films. In addition, the HDP devices exhibit impressively improved photovoltaic performance as well as enhanced long-term stability under high moisture, UV irradiation and thermal stress. Therefore, our work provides a versatile strategy to introduce preferred orientation and interfacial modification to enhance the crystal quality and stability of halide perovskite thin films and related optoelectronic devices.

Excess PbI2 has been widely introduced in halide perovskite precursor solution to passivate the grain boundary defects in high efficient perovskite solar cells (PSCs). However, the passivation effect is highly sensitive to the PbI2 content and overmuch PbI2 affects the crystalline growth and charge transport. We report here a precious control of excess PbI2 into perovskite grain boundaries by methylamine treatment for efficacious defects passivation and charge extraction. The crystallization of the deposited perovskite films was carefully evaluated and the charge recombination dynamics were systematically analyzed through time-resolved photoluminescence spectroscopy, space charge limited current, electrochemical impedance spectroscopy and Mott-Schottky analysis. The precise PbI2 introduction to the grain boundaries results in a significantly lower defect state density, efficient charge extraction and prolonged carrier lifetime, causing a notable increase of short-circuit current density and negligible hysteresis in the corresponding device. Our work demonstrates a reliable method to alleviate the rigorous tolerance of PbI2 excess in high efficient PSCs.

Metal sulfides (MS) have been widely explored in lithium-sulfur batteries (LSB) owing to their stronger affinity with lithium polysulfide species (LPS) than carbon materials and higher electronic conductivity compared with metal oxides. However, practical application of MS based sulfur cathodes is hindered by a slow conversion of sulfur species due to limited catalytic effect of MS for redox reactions of sulfur, and by the absence of a continuous conducting network in the cathode. To address these issues, we herein report the design and fabrication of a heterostuctured Co3S4/MnS nanotube array grown on carbon cloth (CC@CMS-NA) as a catalytic sulfur host for high performance LSB. According to the theoretical calculations and electrochemical test, Mn dopants can tune the electronic structure of Co3S4 to adsorb soluble LPS more effectively and engineer a catalytic heterogeneous surface to facilitate charge transport and enhance the conversion kinetics of sulfur species. Meanwhile, the 3D array structure avoids “dead” sites caused by the use of binder and conductive additive, and also provides rapid electron transport path. As a result, the CC@CMS-NA based sulfur cathodes with 3.2 mg cm−2 sulfur loading exhibits an excellent cycle performance at a current density of 2.67 mA cm−2 (95% retention of initial specific capacity after 200 cycles, namely 0.02% decay per cycle). Our work demonstrates that reasonable construction of heterogeneous structures is a promising strategy to improve the performance of MS based LSB.

Silicon surface passivation is highly important for solar cells and other optoelectronic devices. In order to achieve a high-performance, low-cost, room-temperature, and nonvacuum surface passivati...

Metal halide perovskite thin films have achieved remarkable performance in optoelectronic devices but suffer from spatial heterogeneity in their electronic properties. To achieve higher device performance and reliability needed for widespread commercial deployment, spatial heterogeneity of optoelectronic properties in the perovskite thin film needs to be understood and controlled. Clear identification of the causes underlying this heterogeneity, most importantly the spatial heterogeneity in charge trapping behavior, has remained elusive. Here, a multimodal imaging approach consisting of photoluminescence, optical transmission, and atomic force microscopy is utilized to separate electronic heterogeneity from morphology variations in perovskite thin films. By comparing the degree of heterogeneity in highly oriented and randomly oriented polycrystalline perovskite thin film samples, we reveal that disorders in the crystallographic orientation of the grains play a dominant role in determining charge trapping and electronic heterogeneity. This work also demonstrates a polycrystalline thin film with uniform charge trapping behavior by minimizing crystallographic orientation disorder. These results suggest that single crystals may not be required for perovskite thin film based optoelectronic devices to reach their full potential.

Pb2MReO6 (M = Co, Cr) perovskites were prepared by high pressure–high temperature method. Rietveld refinements of synchrotron powder X-ray diffraction show that the crystal structure of Pb2CoReO6 is trigonal (space group R-3) with almost complete ordering of Co and Re cations, while Pb2CrReO6 (space group Pm-3m) is a cubic perovskite with one single site for Cr and Re atoms. The difference between the symmetry and the degree of order was further clarified by X-ray absorption spectroscopy that establishes formal oxidation states in these phases as Pb2Co2+Re6+O6 and Pb2Cr3+Re5+O6. Pb2CrReO6 is a simple perovskite with a high magnetic ordering temperature of 643 K. Pb2CoReO6 is a double perovskite with −23% high field negative magnetoresistance at 10 K and 9 T. First-principles calculations of Pb2CoReO6 indicate a half metallic electronic structure.

We report on the emergence of robust superconducting order in single crystal alloys of TaSe2− x S x (0 ≤ × ≤ 2). The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe2 and TaS2. The evolution of superconducting critical temperature T c(x) correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high-temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe2 and/or 2H-TaS2. It is known that in these materials superconductivity is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order. Substituting sulfur into TaSe2 induces disorder, which further helps to enhance superconductivity, with a higher transition temperature. It is higher than that of either TaSe2 or TaS2. An international team of researchers led by Cedomir Petrovic at Brookhaven national laboratory of USA synthesized single crystal alloys of TaSe2− x S x and measured the electrical conductivity and superconducting transition temperature as a function of x. They found that the transition temperature optimally increased when a maximal disorder is introduced by substituting sulfur into TaSe2. The role of such a disorder was understood as to suppress other competing orders while keeping superconductivity intact. By breaking other orders, conducting carriers were released so that they contributed further to superconductivity. These results highlight a benefit role of disorder and provide a possible way to enhance superconductivity.

We introduce a temperature-dependent parameterization in the modified embedded-atom method and combine it with molecular dynamics to simulate the diverse physical properties of the \delta - and \epsilon - phases of elemental plutonium. The aim of this temperature-dependent parameterization is to mimic the different magnitudes of correlation strength of the Pu 5f electrons at different temperatures. Compared to previous temperature independent parameterization, our approach captures the negative thermal expansion and temperature dependence of the bulk moduli in the \delta -phase. We trace this improvement to a strong softening of phonons near the zone boundary and an increase of the f-like partial density and anharmonic effects induced by the temperature-dependent parameterization upon increasing temperature. Our study suggests it is important to include temperature-dependent parameterization in classical force field methods to simulate complex materials such as Pu.

LiV 3 O 8 is a very promising cathode material for lithium secondary batteries. An EDTA-sol-gel method was proposed for the first time to obtain LiV 3 O 8 at low temperature. LiAc · 2H 2 O, NH 4 VO 3 and EDTA were used as raw materials to prepare the precursor, and then the precursor was sintered to obtain the layered structure of LiV 3 O 8 . The effect of sintering temperature and duration on the quality of LiV 3 O 8 was investigated. We also tested the electrochemical performances of LiV 3 O 8 obtained through the method. The sample heated at 550 °C for 15 h has a single-phase layered structure and it has a first cycle discharge capacity of 251.7 mA h g −1 at the range of 1.8 – 3.6 V at 0.1 mA and an average capacity decay rate of 0.43% per cycle after 30 cycles.

The structure, transport, thermodynamic properties, x-ray absorption spectra (XAS), and electronic structure of a new barium titanate suboxide, Ba1+δTi13−δO12 (δ = 0.11), are reported. It is a paramagnetic poor metal with hole carriers dominating the transport. Fermi liquid behavior appears at low temperature. The oxidization state of Ti obtained by the XAS is consistent with the metallic Ti2+ state. Local density approximation band structure calculations reveal the material is near the Van Hove singularity. The pseudogap behavior in the Ti-d band and the strong hybridization between the Ti-d and O-p orbitals reflect the characteristics of the building blocks of the Ti13 semi-cluster and the TiO4 quasi-squares, respectively.

An ultrasound system is provided which includes a therapy ultrasound transducer and a diagnostic ultrasound transducer and operates in accordance with a method to direct the application of the therapy ultrasound. The method includes operating the diagnostic ultrasound transducer to acquire a first ultrasound image; simultaneously operating the diagnostic ultrasound transducer and therapy ultrasound transducer for a second interval to acquire a second ultrasound image; and determining a difference in the first and second images indicative of the pattern of the therapy ultrasound transducer signal. The difference in the images, which result from enhanced non-linearities and propagation distortions induced by the high intensity therapy ultrasound, can be obtained by subtracting the two images. A method is also provided for monitoring the progress of high intensity therapy ultrasound which evaluates transient changes due to in-situ heating as well as permanent changes which result from cell microstructure alteration.

A dual-frequency band ultrasonic apparatus provides a first ultrasound signal to a region at a first frequency band and a second ultrasound signal at a second frequency band for monitoring the region. A processor controls the first and second ultrasound signals such that a predetermined phase relationship is achieved between the first frequency band signal and the second frequency band signal. The apparatus can employ a single transducer operable at both frequency bands or separate transducers for the first and second frequency bands.