Search

We fabricated SrRuO3/PbZr0.52Ti0.48O3 heterostructures with an in-plane tensile-strained SrRuO3 layer and investigated the effect of an applied electric field on the anomalous Hall effect. The four-fold symmetry of anisotropic magnetoresistance and the nonmonotonic variation of anomalous Hall resistivity were observed. By applying positive and negative electric fields, the intersecting hump-like features are suppressed and enhanced, respectively. The sign and magnitude of the anomalous Hall conductivity can be effectively controlled with an electric field at a high magnetic field. The electric-field-modulated anomalous Hall effect is associated with the magnetization rotation in SrRuO3. The experimental results are helpful to realize magnetization rotation modulation in spintronic devices based on SrRuO3 heterostructures.

Orientation control of oxygen vacancy channel (OVC) is a highly desirable for tailoring oxygen diffusion as it serves fast transport channel in ion conductors, which is widespread exploited in solid-state fuel cells, catalysts, and ion-batteries. Direct observation of oxygen-ions hopping towards preferential vacant sites is a key to clarifying migration pathways. Here we report the anisotropic oxygen-ion migration mediated by strain in ultrathin cobaltites via in-situ thermal activation in an atomic-resolved transmission electron microscopy. Oxygen migration pathways are constructed on the basis of the atomic structure during the OVC switching, which is manifested as the vertical-to-horizontal OVC switching under tensile strain, but the horizontal-to-diagonal switching under compression. We evaluate the topotactic structural changes to OVC, determine the crucial role of tolerance factor for OVC stability and establish the strain-dependent phase diagram. Our work provides a practical guide for engineering OVC orientation that is applicable ionic-oxide electronics.

Due to its relatively high inertness and presence as a key component of the greenhouse gases, CO2 reduction is highly significant from both scientific and socioeconomic points of view but is very c...

More and more attention has been paid to CsPbIBr2 material for perovskite solar cells (PSCs), owing to the trade-off between bandgap and stability. However, the reported maximum power conversion efficiency (PCE) of CsPbIBr2 PSCs is lag behind that of the congeners due to the serious interface recombination of charge carriers. In this work, the effects of interface defect density and interface band offset on the properties of CsPbIBr2 PSCs are investigated. It is found that the characteristic of the front electron transfer layer (ETL)/perovskite interface has a significant influence on the performance of PSCs than that of the back perovskite/hole transfer layer (HTL) interface. Additionally, a PCE of 15.05% with a high open-circuit voltage (VOC) of 1.54 V is obtained for the PSCs with FTO/ZnOS/CsPbIBr2/CuAlO2/Au structure. Finally, two-terminal monolithic all-perovskite double-junction tandem solar cells (TSCs) with the architecture of FTO/ZnOS/CsPbIBr2/CuAlO2/ITO/TiO2/MAPbI3/Spiro-MeOTAD/Au are constructed, and a maximum PCE of 27.4% (VOC of 2.60 V, JSC of 12.21 mA/cm2, and FF of 86.42%) is obtained for the TSCs with top and bottom absorber thicknesses of 600 nm and 500 nm respectively. Furthermore, four-terminal triple-junction TSCs are designed with silicon solar cells as bottom sub-cell, and a maximum PCE of 35.35% is achieved. These results will provide theoretical guidance for the fabrication of high performance TSCs.

Thermoelectric (TE) devices exhibit considerable application potential in Internet of Things and personal health monitoring systems. However, TE self-powered devices are expensive and their fabrication process is complex. Therefore, large-scale preparation of the TE devices remains challenging. In this work, simple screen-printing technology is used to fabricate a user-friendly and high-performance paper-based TE device, which can be used in both stamp-like paper-based TE generators and infrared displays. When used as a paper-based TE generator, an output power of 940.8 µW is achieved with a temperature difference of 40 K. The programmable infrared pattern based on the TE array display could be used to realize encryption and anti-counterfeiting properties. Moreover, a visual extraction algorithm is used to develop a mobile application for processing and decoding the infrared quick response code information. These findings offer an exciting approach to using paper-based TEGs in applications such as energy harvesting devices, optical encryption, anti-counterfeiting, and dynamic infrared display.

Interfaces formed by correlated oxides offer a critical avenue for discovering emergent phenomena and quantum states. However, the fabrication of oxide interfaces with variable crystallographic orientations and strain states integrated along a film plane is extremely challenging by conventional layer-by-layer stacking or self-assembling. Here, the creation of morphotropic grain boundaries (GBs) in laterally interconnected cobaltite homostructures is reported. Single-crystalline substrates and suspended ultrathin freestanding membranes provide independent templates for coherent epitaxy and constraint on the growth orientation, resulting in seamless and atomically sharp GBs. Electronic states and magnetic behavior in hybrid structures are laterally modulated and isolated by GBs, enabling artificially engineered functionalities in the planar matrix. This work offers a simple and scalable method for fabricating unprecedented innovative interfaces through controlled synthesis routes as well as providing a platform for exploring potential applications in neuromorphics, solid-state batteries, and catalysis.

Formic acid oxidation (FAO) is a typical anode reaction in fuel cells that can be facilitated by modulating its direct and indirect reaction pathways. Herein, PtAu bimetallic nanoparticles loaded onto Co and N co-doping carbon nanoframes (CoNC NFs) were designed to improve the selectivity of the direct reaction pathway for efficient FAO. Based on these subtle nanomaterials, the influences of elemental composition and carbon-support materials on the two pathways of FAO were investigated in detail. The results of fuel cell tests verified that the appropriate amount of Au in PtAu/CoNC can promote a direct reaction pathway for FAO, which is crucial for enhancing the oxidation efficiency of formic acid. In particular, the obtained PtAu/CoNC with an optimal Pt/Au atomic ratio of 1:1 (PtAu/CoNC-3) manifests the best catalytic performance among the analogous obtained Pt-based electrocatalysts. The FAO mass activity of the PtAu/CoNC-3 sample reached 0.88 A·mgPt−1, which is 26.0 times higher than that of Pt/C. The results of first-principles calculation and CO stripping jointly demonstrate that the CO adsorption of PtAu/CoNC is considerably lower than that of Pt/CoNC and PtAu/C, which indicates that the synergistic effect of Pt, Au, and CoNC NFs is critical for the resistance of Pt to CO poisoning. This work is of great significance for a deeper understanding of the oxidation mechanism of formic acid and provides a feasible and promising strategy for enhancing the catalytic performance of the catalyst by improving the direct reaction pathway for FAO.

It is well known that the phase stability of CsPb(I1−xBrx)3 (0 ≤ x ≤ 1) perovskite materials is enhanced under humid environments with the increase of Br− concentration in film, however, the bandgap (Eg) is also widened synchronously, resulted in limiting the light harvesting and then reducing the power conversion efficiency (PCE) of devices. Hence, how to realize the compatibility of high stability and high PCE is a challenge for device based on CsPb(I1−xBrx)3. In this work, the two- (2-T) and four-terminal (4-T) tandem solar cells (TSCs) consisting of a CsPb(I1−xBrx)3 top sub-cell and a crystalline silicon (c-Si) bottom sub-cell are constructed and compared. It is found that in the case of 2-T configuration, performance of device is very sensitive to the Eg and the thickness of top sub-cell, and a maximum PCE of 29.23% is achieved only for the CsPbI3 top sub-cell at an optimum thickness of 275 nm. However, in the 4-T formation, devices present a weak dependence on the Eg and the thickness of top sub-cell, and PCEs above 28.5% can be obtained when CsPbBr3 is used as top sub-cell. These results highly underline the application potential of 4-T CsPb(I1−xBrx)3/Si TSCs, especially for CsPbBr3/Si TSC.

Lead-free halide double perovskites (HDPs) have recently been proposed as potential stable and environment-friendly alternatives to lead-based halide perovskites. Bandgap engineering plays a vital role in the optoelectronic applications of HDP materials. In this study, methods combining high-pressure techniques with density functional theory calculations were employed to implement the bandgap engineering of a classic HDP-based (NH4)2SnBr6. Under high pressure, (NH4)2SnBr6 exhibits a redshift of the bandgap with increasing pressure up to 6.3 GPa and a sudden blueshift up to 20.2 GPa, followed by a redshift at higher pressures, which is relevant to the cubic-tetragonal phase transition, direct-indirect transition, and amorphization, respectively. Our results enrich the understanding of the structural-optical properties of (NH4)2SnBr6 and reveal the special role of NH4+ cations in pressure-induced bandgap engineering, thus providing important information for application in optoelectronic devices and helping to design ideal materials with higher efficiency.

In recent years, inorganic CsPbBr3-based perovskites have accomplished considerable progress owing to their superior stability under harsh humid environment. The power conversion efficiency (PCE) of CsPbBr3 perovskite solar cells (PSCs) has seen an unprecedented development from 5.74% to 10.91% with the improvement of the CsPbBr3 crystal quality. Despite extensive research efforts, the device efficiency of the CsPbBr3-based PSCs still lags behind that of other hybrid perovskite materials. Therefore, there is a significant interest in further boosting the performance of all-inorganic CsPbBr3 PSCs by the synergic optimization of films and device interfaces. In this review, we have discussed and summarized recent advances and methodologies related to CsPbBr3 films and PSCs. Furthermore, we discuss different fabrication strategies such as solution-based and vapor-based methods and their influence on the properties of CsPbBr3, particularly the morphology of films. Moreover, the timeline of improvement of the device efficiency from 2015 to 2020 is comprehensively addressed and developments are clearly sorted out by addressing critical factors influencing the photovoltaic performance. We further highlight state-of-the-art engineering strategies for CsPbBr3 PSCs that facilitate the crystallization control, charge extraction, suppression of charge recombination, and defect passivation in a systematic manner. At the end of the review, the summary and perspectives are presented along with beneficial guidelines for developing highly efficient and stable CsPbBr3 PSCs.

Solvent effects are important for photovoltaic systems like dye-sensitized solar cells (DSCs) but remain largely unexplored, partly due to the complexity of explicitly including solvent molecules in atomistic simulations. To address these issues, we have systematically investigated the solvent effects in practical solar cells using ab initio excited state dynamics simulations. In this computational protocol and the extended model system, we considered giving a novel perspective on the excited state changes in response to solvation and finite temperature at the heterointerface of DSCs. By directly comparing the geometric stability of interface bonding, photoabsorption, interfacial electronic structure, and dynamics of vacuum and solvent systems, we obtain useful insights into how solvents influence the key factors that determine the efficiency of DSCs. Solvents significantly enhance the intensity of visible light absorption of chromophores (∼2 times) through two effects: (a) by inducing changes to the dye molecule structure due to intermolecular dye-solvent interactions, and (b) by the dielectric screening of the solvent. Furthermore, by adsorbing onto the TiO2 surface, solvent molecules adjust the interfacial band alignment to a favorable level and screen out the attraction force between injected electrons in the semiconductor substrate and holes left on the chromophore to a large extent, dramatically slowing down the recombination process (>8 times). Our findings provide a comprehensive picture of the explicit solvent effects on individual energy conversion steps in DSCs at the microscopic scale and lead to more accurate prediction of the performance of nanodevices in practical environments, contributing to the optimization of realistic renewable energy devices.

Recently, inorganic perovskite solar cells (PSCs) based on CsPbBr3 have triggered incredible interest due to the demonstrated excellent stability against thermal and high humidity environmental conditions. However, the power conversion efficiency (PCE) of the CsPbBr3-based PSCs is still lower than that of the organic-inorganic hybrid one, because of the large band gap and serious charge recombination at the interface or inside the device. Here, the working mechanism of the devices with normal n-i-p planar structure is modeled and investigated using SCAPS 1D simulation software. The simulation results state that the proper band structure of PSCs is crucial to carrier separation and transport. The high interface recombination, originated from the large band offsets of the electron transport material (ETM)/absorber and absorber/hole transport material (HTM) respectively, can be effectively diminished with the continuous gradient junction design of the absorber, and a PCE of 11.58% is obtained with a high open-circuit voltage (VOC) of 1.68 V. Moreover, by building a heterojunction bilayer absorption scenario of CsPbIBr2/CsPbBr3 and employing ZnOS and Cu2ZnSnS4 films as the ETM and HTM respectively, the PCE of PSCs is further increased to 15.89%, caused mainly by the enhancement in short-current density (JSC). Moreover, reducing the interface defect density is also very important to improve the performance of PSCs. These results will provide theoretical guidance for improving the performance of the CsPbBr3-based PSCs.

Nanoscale phase mixtures in transition-metal oxides (TMOs) often render these materials susceptible to external stimuli (electric field, mechanical stress, etc.), which can lead to rich functional properties and device applications. Here, direct observation and multifield manipulation of a nanoscale mixture of brownmillerite SrFeO

CuxO (Cupric Oxide) nanotubes (NTs) were synthesized by using thermal oxidation of Cu nanowires (NWs) for 2 and 4 hours, respectively, and the effect of the components on their photo-electrical properties due to the infrared (IR) light with a wavelength of 1064 nm were investigated. In the 2-h CuxO NTs, the main component was Cu2O; however, the 4-h CuxO NTs were composed of a mixture of CuO and Cu2O. The photoelectric properties showed that the voltage difference and the sensitivity of 4-h CuxO NTs were more than 3 times those of the 2-h CuxO NTs, and its linear range was only about one-third that of the 2-h CuxO NTs. The above results were caused by the 4-h CuxO NTs containing a higher content of CuO, which had a suitable bandgap of 1.2 eV for light with a wavelength of 1064 nm. In addition, the response and the recovery times for the 4-h NTs were on the same order as those of the 2-h NTs. The conclusions from this article indicated that 4-h and 2-h NTs were very promising for the design of IR photodetector device with higher sensitivity and a larger detection range respectively.

Heterointerfaces have led to the discovery of novel electronic and magnetic states because of their strongly entangled electronic degrees of freedom. Single-phase chromium compounds always exhibit antiferromagnetism following the prediction of Goodenough-Kanamori rules. So far, exchange coupling between chromium ions via hetero-anions has not been explored and the associated quantum states is unknown. Here we report the successful epitaxial synthesis and characterizations of chromium oxide (Cr2O3)-chromium nitride (CrN) superlattices. Room-temperature ferromagnetic spin ordering is achieved at the interfaces between these two antiferromagnets, and the magnitude of the effect decays with increasing layer thickness. First-principles calculations indicate that robust ferromagnetic spin interaction between Cr3+ ions via anion-hybridizations across the interface yields the lowest total energy. This work opens the door to fundamental understanding of the unexpected and exceptional properties of oxide-nitride interfaces and provides access to hidden phases at low-dimensional quantum heterostructures., 21 pages, 4 figures

Pt nanocatalysts play a critical role in direct methanol fuel cells (DMFCs) due to their appropriate adsorption/desorption energy, yet suffer from an unbalanced relationship between size-dependent activity and stability. Herein, mixed-dimensional Pt-Ni alloy polyhedral nanochains (Pt-Ni PNCs) with an ordered assembly of a nanopolyhedra-nanowire-nanopolyhedra architecture are fabricated as bifunctional electrocatalysts for DMFCs, effectively alleviating the size effect. The Pt-Ni PNCs exhibit 7.23 times higher mass activity for the anodic methanol oxidation reaction (MOR) than that of commercial Pt/C. In situ Fourier transform infrared spectroscopy and CO stripping measurements demonstrate the prominent stability of the Pt-Ni PNCs to resist CO poisoning. For the cathodic oxygen reduction reaction (ORR), a positive half-wave potential exceeding Pt/C is achieved by the Pt-Ni PNCs, and it can be well maintained for 10 000 cycles with negligible activity decay. The designed nanostructure can alleviate the agglomeration and dissolution problems of 0D small-sized Pt-Ni alloy nanocrystals and enrich surface atom steps and active facets of 1D chain-like nanostructures. This work provides a proposed strategy to improve the catalytic performance of Pt-based nanocatalysts by constructing novel interfacial relationships in mixed dimensions to alleviate the imbalance between catalytic activity and catalytic stability caused by size effects.

Interfacial magnetism stimulates the discovery of giant magnetoresistance (MR) and spin-orbital coupling across the heterointerfaces, facilitating the intimate correlation between spin transport and complex magnetic structures. Over decades, functional heterointerfaces composed of nitrides have seldom been explored due to the difficulty in synthesizing high-quality nitride films with correct compositions. Here, the fabrication of single-crystalline ferromagnetic Fe

Understanding hot carrier dynamics between plasmonic nanomaterials and its adsorbate is of great importance for plasmon‐enhanced photoelectronic processes such as photocatalysis, optical sensing and spectroscopic analysis. However, it is often challenging to identify specific dominant mechanisms for a given process because of the complex pathways and ultrafast interactive dynamics of the photoelectrons. Here, using CO2 reduction as an example, the underlying mechanisms of plasmon‐driven catalysis at the single‐molecule level using time‐dependent density functional theory calculations is clearly probed. The CO2 molecule adsorbed on two typical nanoclusters, Ag20 and Ag147, is photoreduced by optically excited plasmon, accompanied by the excitation of asymmetric stretching and bending modes of CO2. A nonlinear relationship has been identified between laser intensity and reaction rate, demonstrating a synergic interplay and transition from indirect hot‐electron transfer to direct charge transfer, enacted by strong localized surface plasmons. These findings offer new insights for CO2 photoreduction and for the design of effective pathways toward highly efficient plasmon‐mediated photocatalysis., Upon illumination, hot electrons generated by the plasmon decay around the silver clusters transfer into the molecular orbitals of CO2, resulting in activation of the asymmetrical stretching and bending mode of CO2 and leading to its final splitting. Cooperative interaction and transition from indirect hot‐electron transfer to direct charge transfer cause the nonlinear relationship between laser intensity and reaction rate.

Oxygen-vacancy-induced topotactic phase transformation between the ABO

Lead-free halide double perovskites (HDPs) have recently been proposed as potential stable and environment-friendly alternatives to lead-based halide perovskites. Bandgap engineering plays a vital role in the optoelectronic applications of HDP materials. In this study, methods combining high-pressure techniques with density functional theory calculations were employed to implement the bandgap engineering of a classic HDP-based (NH

Controlling oxygen redox reactions in transition metal oxides offers an attractive route to tune their physical properties; a topotactic structural transformation from their parent phases effectively modifies the electronic state. In this work, infinite-layered SrFeO2 thin films were produced from brownmillerite SrFeO2.5 via low-temperature hydro-reduction. After the structural transition, their out-of-plane lattice constants dramatically shrank by ∼12%; tensilely strained samples exhibited metallic character, whereas the compressively strained ones maintained the insulating behavior of their bulk form. According to X-ray linear dichroism results, this strain-mediated electronic anisotropy may be attributed to electron redistribution within degenerated orbitals. This suggests a possible mechanism for the metallic conductivity of infinite-layered SrFeO2, giving a hint for understanding emergent quantum phenomena, such as the recently discovered superconductivity in nickelates, and stimulating various applications, including in ionic conductivity and oxygen catalysis.

Formamidinium tin iodide (FASnI3), as one promising Pb-free halide perovskite, has received extensive attention. But perovskite solar cells (PSCs) based on FASnI3 films have yet to realize the high power conversion efficiency (PCE) achieved in its Pb-based counterparts. To investigate the limitation of FASnI3-based perovskite solar cells with inverted p-i-n planar structures, the influences of various parameters on the device performance are analyzed through device simulation. The results reveal that defect density at front hole transport material (HTM)/absorber interface is critical for high efficiency. And it is interesting to note that the doping density, rather than the doping type and its space distribution, dominates the device properties, and an upper limit of 1 × 1016 cm−3 is achieved. In addition, the response of device to band offset is investigated, and an optimum electron affinity of 3.9 eV is obtained. Finally, the effects of relative permittivity and thickness of the absorber with different carrier lifetime are studied. A maximum PCE of 9.75% is achieved at absorber thickness of 300 nm with carrier lifetime of 0.1 ns? These results show that optimizing the interface property and band offset, improving the stability of Sn2+ and reducing the defect density of absorber layer are the main challenges for high-performance FASnI3-based PSCs in the future research.

Single-atom catalysts (SACs) are of great scientific and technical importance due to their low cost, high site density, and high specificity to enhance chemical reactions. Nevertheless, a major issue that severely limits the practical exploration of SACs is their instability, i.e., the preference of sintering and clustering over a defect-free substrate during operation. Here, we employ first-principles calculations to investigate how substrate engineering can stabilize SACs by strain-tuning the electronic interactions between the metal and the substrate using two Pd adatoms on a defect-free, single-layer MoS2 as a typical example. It is identified that the Pd2 dimer is prone to dissociate and form highly efficient SACs for CO oxidation due to the enhanced charge transfer and orbital hybridization with the MoS2 substrate under a suitable tensile strain. The straining induces a semiconductive-to-metallic phase transition of the substrate. Moreover, low-cost elements, such as Ag, Ni, Cu, and Cr, can also be stabilized into high-performance SACs for CO oxidation with tunable reaction barriers by straining. The present findings offer a new avenue to inhibit the transition metal atoms from clustering into nanoclusters/particles and provide a clear guidance for the development of highly cost-efficient and stable SACs on defect-free substrates.

Photocatalytic studies performed on well-defined epitaxial thin films and heterostructures allow the direct investigation of crystallographic-dependent reactivity, and can provide fundamental insights into the reaction mechanisms. In this work, we show that phase-pure, monoclinic BiVO4 nanoislands with a truncated pyramid shape with the (010) top surface and {110} sidewalls can be grown on (001)-oriented yttria-stabilized zirconia (YSZ) substrates with an epitaxial relationship of BiVO4(010)[001] // YSZ(001)[100]. The resulting nanostructures show a strong size-dependent mass-normalized photocatalytic activity, with highly dispersed nanoislands at low coverage being the most active. Pb(NO3)2 photooxidation or photoreduction reactions can be controlled in aqueous solution with and without adding NaIO3 as a electron scavenger, leading to the selective deposition of PbO2 or Pb on {110} or (010) surfaces of BiVO4, respectively.

Polar metals with ferroelectric-like displacements in metals have been achieved recently, half a century later than Anderson and Blount’s prediction. However, genuine ferroelectricity with electric...

Ionic defects, such as oxygen vacancies, play a crucial role in the magnetic and electronic states of transition metal oxides. Control of oxygen vacancy is beneficial to the technological applications, such as catalysis and energy conversion. Here, we investigate the electronic structure of SrCoO3−x as a function of oxygen content (x). We found that the hybridization extent between Co 3d and O 2p increased with the reduction of oxygen vacancies. The valence band maximum of SrCoO2.5+δ has a typical O 2p characteristic. With further increasing oxygen content, the Co ions transform from a high spin Co3+ to an intermediate spin Co4+, resulting in a transition of SrCoO3−x from insulator to metal. Our results on the electronic structure evolution with the oxygen vacancies in SrCoO3−x not only illustrate a spin state transition of Co ions, but also indicate a perspective application in catalysis and energy field.

For ferroelectric photovoltaics, it is challenging to enhance the power conversion efficiency (PCE) without sacrificing the photoresponse switchability. Here, we demonstrate that enhanced PCE and good photoresponse switchability can be simultaneously achieved in perovskite heterostructures comprising narrow-gap semiconductor LaVO3 (LVO) and ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT). The LVO(24 nm)/PZT(120 nm) based device exhibits a ∼5-fold enhancement in PCE compared with the PZT-only based device, which is attributed to the enhanced absorption from the LVO layer and the built-in field at the LVO/PZT interface facilitating the separation of photo-generated e–h pairs. In addition, the switched photovoltage of the LVO/PZT based device is above 1 V, which is as large as that of the PZT-only based device. This persisted photoresponse switchability is obtained because the polarization can be fully switched in the LVO/PZT based devices when the LVO thickness is less than 24 nm. Our finding therefore provides a promising route for the development of high-efficiency and highly switchable ferroelectric photovoltaic devices.

Fuel cells are highly efficient conversion devices to alleviate energy crisis and environmental pollution, but still encounter technical challenges to further improve catalytic efficiency of Pt-based electrocatalysts. In this work, PtNi multi-branched nanostructures (PtNi MBNs) were successfully prepared by a simple and economical one-step solvothermal method. The average diameter of the branches is about 9 nm, with numerous atom steps and Pt-rich surface. The prepared electrocatalyst shows excellent bifunctionality in acidic electrolytes, catalyzing both oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The half-wave potential of 0.966 V for ORR is much higher than that of commercial Pt/C (0.931 V), and only decreases 14 mV after 8000 cycles. For MOR, the specific activity of PtNi MBNs is 18.1 A m Pt − 2 , better than that of commercial Pt/C (7.8 A m Pt − 2 ), indicating an optimal intrinsic activity. The remarkable bifunctionality of PtNi MBNs is attributed to the exposed electrochemical surface area, abundant atomic steps, and Pt-rich surface provided by the unique MBN. This facile preparation technique offers a promising application for designing high-performance electrocatalyst for acid direct methanol fuel cell in the future.

Misfit strain delivered from single-crystal substrates typically modifies the ground states of transition metal oxides, generating increasing interest in designing modern transducers and sensors. Here, we demonstrate that magnetotransport properties of La0.67Sr0.33MnO3 (LSMO) films were continuously tuned by uniaxial strain produced by a home-designed bending jig. The electrical conductivity and Curie temperature of LSMO films are enhanced by bending stresses. The resistivity of u-shape bended LSMO decays three times faster than that of n-shape bended LSMO as a response to the same magnitude of strain. The asymmetric magnetic states in uniaxially strained LSMO are attributed to the dual actions of Jahn–Teller distortion and strain gradient mediated flexoelectric fields in an adjacent ferroelectric layer. These findings of multi-field regulation in a single material provide a feasible means for developing flexible electronic and spintronic devices.

Since the first report in 2009, the certified power conversion efficiency (PCE) of organic-inorganic halide perovskite solar cells (PSCs) has rapidly risen to 23.3%, which successfully demonstrates the importance of film morphology and quality management, especially for the planar heterojunction architecture based on solution-processed method. In this paper, the morphology, structure, optical and electrical properties of perovskite films treated by two different multi-step thermal annealing methods have been studied and compared. For the conventional multi-step (CMS) annealing method, the surface morphologies and optical properties of films are significantly influenced by the annealing temperature due to the decomposition of CH3NH3PbI3. When the modified multi-step (MMS) method is adopted, the decomposition of CH3NH3PbI3 can be effectively suppressed. The best device treated by MMS method at 180 °C showed a short circuit current density of 20.85 mA/cm2, an open circuit voltage of 0.96 V, a fill factor of 72.7%, and a PCE of 14.7%, which is a 23.5% enhancement in PCE relative to the maximum 11.9% treated by CMS method at 160 °C. These findings suggest that the efficiency of PSCs can be further improved by optimizing the preparation process.