MRS Communications最新文献

Abstract

Co₃O₄ nanorods and nanosheets were prepared via a facile fluorine-mediated hydrothermal method, followed by thermal conversion. Both the Co₃O₄ nanorods and nanosheets exhibited a spinel structure, assembling by 30 nm nanograin along one and two dimensions. The primary exposed facet of the Co₃O₄ nanorods was identified as (110), while the main exposed plane of the Co₃O₄ nanosheets was (112). Gas sensing results showed the Co₃O₄ nanorods sensor exhibited higher sensitivity. The Co₃O₄ nanorods sensor demonstrated excellent sensitivities to toluene and xylene at 200°C, making it a promising candidate for the detection of these specific volatile organic compounds.

We present our findings on organic field-effect transistors (OFETs) that utilize the conjugated copolymer poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b′]-dithiophen-2-yl)alt[1,2,5]thiadiazolo[3,4-c]pyridine] as the active material, with electrodes composed of arrays of carbon nanotubes (CNTs). We employed three types of source and drain electrodes: gold, titanium, and CNT array electrodes with titanium contact pads. A comparison of characteristics of OFETs using these three different electrodes revealed the effectiveness of CNTs in enhancing charge carrier injection for OFETs. The OFETs based on CNT electrodes showed a twofold increase in the drain current and a threefold increase in charge carrier mobility compared to those with gold electrodes.

Graphical abstract

With their remarkably low thresholds, organic polariton lasers are a promising alternative to organic photonic lasers. However, device stability remains a challenge, in part due to material degradation during deposition of the top dielectric mirror. We demonstrate polariton lasers based on 4,4′-Bis(4-(9H-carbazol-9-yl)styryl)biphenyl (BSBCz) as active material that achieve a low lasing threshold of 8.7 μJ/cm², and we show that a ZrO₂ protection layer between active layer and top mirror significantly improves stability. Optimized devices exhibit minimal degradation after 100,000 excitation pulses at 3.8 times above threshold. Our findings establish BSBCz as an attractive candidate for future injection driven polariton lasers.

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Abstract

This study introduces a method to create porous carbon structures with intricate internal voids. 3D-printed PLA acts as an internal sacrificial template, combined with carbonized whey powder as the porous carbon matrix. Sintering whey powder at 150°C yields solid pieces that, upon carbonization, result in highly porous carbon objects while maintaining the original mold shape. Temperature control ensures successful whey powder sintering before PLA melting. The use of PLA sacrificial templates, along with whey carbonization, allows for developing devices with finely tailored internal voids, as demonstrated through a double Archimedean spiral reactor with porous carbon walls.

Abstract

We present the analytic workflow to understand the temperature and illumination-intensity-dependent recombination of the photoinduced charge carriers in organic–inorganic hybrid perovskite solar cells based on methylammonium lead iodide (CH₃NH₃PbI₃) thin films. The temperature-dependent, open-circuit voltage analysis reveals that the recombination of photoinduced charge carriers predominantly occurs at our PEDOT:PSS/CH₃NH₃PbI₃ interface as well as in the depletion region. Taking into account the structural phase transition in CH₃NH₃PbI₃ films, as confirmed using temperature-dependent x-ray diffraction spectra and dielectric constant measurements, the illumination-dependent short-circuit current and open-circuit voltage analysis shows both bimolecular and trap-assisted recombination is dominant in our solution-processed perovskite solar cells.

While efforts have been made to optimize organic semiconducting materials to achieve low-power-consumption organic field-effect transistors (OFETs), it is important to note that the choice of gate dielectric materials is equally critical. In general, a high-k polymer dielectric material is highly preferred for low-power-consumption OFETs. In this perspective, we highlight several newly emerged strategies for high dielectric constant polymer dielectrics. By exploiting the recent advances in molecular modulation and morphology control, these new strategies enable remarkably high dielectric constant up to 25–30 for polymer dielectrics, while still maintaining dielectric losses below 0.01 at 1 kHz. We further analyze the advantages and disadvantages of these strategies and propose four design principles—side-chain dipole, rigid free volume, self-assembly, and thermosets—for future polymer gate dielectrics in OFETs.

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This study examines the effects of Mn²⁺ doping on the microstructure, morphology, and thermoresistive properties of the Zn_x-1Mn_xO system (x = 0.8, 0.15 mol), synthesized via a combustion reaction. After uniaxial pressing (191 MPa) and sintering (1373 K), the samples exhibited NTC thermistor characteristics without a second phase. The decrease in the energy gap to 2.9 eV (Mn08) and 2.69 eV (Mn15), along with average particle sizes of 8.79 µm and 2.91 µm, respectively. The parameters α, β, A, B, C, and SF highlight the influence of Mn²⁺ doping on the properties of these materials, with potential applications in NTC thermistor devices.

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A series of titanium dioxide nanotubes were synthesized via a hydrothermal method. By varying the preparation conditions, nanotubes with different morphologies or textural properties were produced. Various characterization techniques were used to clarify the various features of the as-prepared nanotubes. Samples with surface areas ranging between 200 and 230 m²/g in specific surface area exhibit the maximum photocatalytic activity in the degradation of formic acid. Detailed analysis of the structural characteristics emphasizes the complex role played by surface structural defects in the tuning of their photocatalytic performance helping in this way to achieve optimal activity in photooxidation.

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An alloy based on the Laves phase, which hydrogenated at room temperature, and magnesium powder were used to create the composite material. Using the method of hydrogen dispersion, the alloy was crushed into a powder with a size of 30 μm. Composite materials were obtained by mixing magnesium with a size of 100 μm and the resulting powders from the alloy for 8 h, followed by pressing. This made it possible to obtain a new type of materials for hydrogen batteries, since they cannot be produced by the traditional casting method, because they do not have mutual solubility.

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Bridgman grown CsPbBr₃ single crystals have demonstrated γ-ray spectra with a high resolution, making them a highly promising competitor for the current benchmark room-temperature radiation detector Cd_1−xZn_xTe. However, CsPbBr₃ crystal growth is a very slow process that oftentimes results in cracked ingots due to phase transitions from cubic to orthorhombic crystal systems. In this report, we demonstrate the stabilization of a room-temperature cubic phase in Cs(Pb_1−xSn_x)(Br_3−yCl_y) solid solutions to overcome this issue. Cs(Pb_0.75Sn_0.25)(Br_1.00Cl_2.00) was identified as the most promising composition and grown as a crack-free ingot using Bridgman growth in around one week.

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