Current Applied Physics最新文献

Applying Cs_xFA_1-xPbI₃ perovskite is a useful strategy for synthesizing high-efficiency organic-inorganic lead halide perovskite solar cells because it improves the stability of the perovskite structure. High concentration of cesium (Cs) in CsFAPbI₃ synthesized under ambient conditions typically lead to phase separation due to δ-CsPbI₃ formation and moisture, thereby reducing light absorption and increasing non-radiative recombination. To counter this, we fabricated the mixed halide Cs_0.22FA_0.78Pb(I_1-xBr_x)₃ perovskite films. Introducing bromine (Br) content effectively reduced the δ-CsPbI₃ formation and grain boundaries, thus suppressing the non-radiative recombination between perovskite and charge transport layers. Employing this approach, our perovskite solar cells with a 10 % Br concentration achieved a power conversion efficiency of 15.81 %. This demonstrates the potential of Br incorporation in enhancing the stability and efficiency of perovskite solar cells.

This work introduces an ultra-thin tunable ultra-wideband (UWB) metasurface absorber (MSA) for the terahertz (THz) gap. The polarization-insensitive MSA provides an absorptivity ($A\left(f\right)$) ≥ 90% from 0.1 to 11.5 THz, corresponding to 196.6% fractional bandwidth. The usage of resonant slots engraved on top patterned graphene sheet ($G_{pat}$) and strong plasmonic coupling in the Fabry-Perot cavity formed between top $G_{pat}$ and bottom continuous graphene ($G_{cont}$) in bilayer stack configuration ensures absorptivity over a UWB THz spectrum. An equivalent circuit model (ECM) closely follows the $A\left(f\right)$ response of the proposed MSA. The proposed DC-biasing mechanism can regulate the chemical potential (${\mu }_c$) of the connected $G_{cont}$ efficiently. A DC bias voltage of 0 to 6.1 V is adequate to vary ${\mu }_c$ of $G_{cont}$ from 0 to 0.6 eV for achieving tunable $A\left(f\right)$. The structure maintains its ultra-thin nature and has a thickness of only ${\lambda }_0$/1500, where ${\lambda }_0$ is the free space wavelength calculated at 0.1 THz. In addition, the periodicity is only ${\lambda }_0$/300. The MSA also provides stable absorption response from 0.1 to 11.5 THz with $A\left(f\right)$ ≥ 80% for incidence angle (θ) up to ${60}^{\circ }$ under both transverse magnetic (TM) and transverse electric (TE) polarization.

Solution-processed amorphous oxide semiconductor thin films contain poor metal-oxygen-metal (M-O-M) networks and numerous impurities, making it difficult to manufacture high-performance semiconductor devices with excellent stability. In this study, we enhance the electrical performance and device stability of solution-processed oxide thin-film transistors (TFTs) by incorporating water molecular oxidants. In solution, a water molecule can be easily incorporated by adding deionized water (DW) to the precursor solution. The DW-incorporated precursor solutions induced the production of oxide semiconductor thin films with improved M-O-M networks and fewer defect states. Therefore, compared to conventional case, the DW-incorporated indium zinc oxide (InZnO) TFT showed improved device performances and significantly reduced changes of threshold voltage under positive gate bias stress and negative gate bias/illumination stress conditions. This approach of incorporating DW into the precursor solutions provides a promising route for fabricating high-quality amorphous semiconductor films and transistor devices.

Recent advancements in artificial intelligence (AI) techniques have significantly influenced daily life and the forefront of research and development. Data-driven research using AI accelerates the resolution of complex problems and aids in uncovering previously unknown knowledge and scientific discoveries. In this study, we propose a data-driven approach for investigating perovskite solar cells, a vibrant area within renewable energy applications. This approach incorporates the generation of a robust dataset, developing an interpretable machine learning model based on knowledge-based feature selection, and analyzing the impacts of material properties on the device performance. Through this framework, we successfully constructed accurate predictive models for the efficiency of perovskite solar cells and assessed the importance of each feature. Our analysis demonstrates that our models effectively capture existing knowledge about perovskite solar cells and can potentially inform the design of new perovskite solar cell configurations.

Pulsed laser epitaxy (PLE) has emerged as a pivotal technique in the fabrication of complex oxide thin films, offering unprecedented control over material composition and myriads of properties. Complex oxides exhibit various functionalities, such as high-T_c superconductivity, colossal magnetoresistance, and ferroelectricity, making them essential for advanced electromagnetic and optical applications. PLE facilitates the epitaxial growth of complex oxides using a high-power pulsed laser to ablate a solid target, generating a plume of material that is deposited onto a heated substrate. The process is highly adaptable and capable of achieving stoichiometric material in thin film form with high quality. This review explores the fundamental principles, system configurations, and essential growth parameters of PLE and highlights its role in advancing the field of complex oxide thin films.

Iron (Fe), nickel (Ni), and cobalt (Co) coated cellulose papers were synthesized via the electroless plating method, and their electrochemical properties were investigated for flexible supercapacitor applications. Three different concentrations of FeCoNi to distilled water on cellulose paper were prepared, and it affected morphology and crystal structure, resulting in different surface area, porosity, and impedance. The best performance obtained was specific capacitance of 75 ± 0.5 Fg^-1 at 1 Ag^-1, specific energy of 7 Whkg⁻¹, and specific power of 400 Wkg^-1 with capacitance retention of 88.2 % and coulombic efficiency of 83 % after 1000 cycles.

With the development of flexible electronics, ion gel has numerous applications in flexible devices, and it is crucial to explore the properties of ion gels. In this study, the ion gel is generated by loading the ionic liquid 1-Ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl) imide in polymer Poly (vinylidene fluoride). The electrical characteristics were studied as a function of ionic liquid concentration, thickness, and temperature. The results show that the capacitance value with 20 % ionic liquid concentration can be as high as 2 μF/cm² at 1 Hz, and the capacitance value is not affected by the gel thickness at frequencies lower than 1 kHz; the capacitance exhibits a positively correlated with the temperature in the temperature range of 30–80 °C; the capacitance is unaffected by bending curvature less than 1.67 mm⁻¹. Meanwhile, we also established different circuit models to simulate the ion gel capacitors with different ionic concentrations, which provides a theoretical basis for flexible transistors.

Scanning tunneling microscopy (STM) is a pivotal surface-imaging technique that reveals intricate atomic and electronic structures. Its remarkable subatomic spatial resolution, coupled with the energy-resolved local density of states, provides insights into both the local electronic properties and global band structures. Recent advancements in STM, including a breakthrough in charge-density manipulation, have broadened the scope of its research. This review delves into the experimental methodologies for probing the electronic structures of various topological materials, including topological insulators, semimetals, and superconductors. It explores techniques such as Landau-level spectroscopy and quasi-particle interference measurements. Additionally, it examines the influence of topological phase transitions and electron correlations that can be modulated by in situ electrical fields in two-dimensional samples.

We present a machine learning method for swiftly identifying nanobubbles in graphene, crucial for understanding electronic transport in graphene-based devices. Nanobubbles cause local strain, impacting graphene's transport properties. Traditional techniques like optical imaging are slow and limited for characterizing multiple nanobubbles. Our approach uses neural networks to analyze graphene's density of states, enabling rapid detection and characterization of nanobubbles from electronic transport data. This method swiftly enumerates nanobubbles and surpasses conventional imaging methods in efficiency and speed. It enhances quality assessment and optimization of graphene nanodevices, marking a significant advance in condensed matter physics and materials science. Our technique offers an efficient solution for probing the interplay between nanoscale features and electronic properties in two-dimensional materials.

Au/Ba_0.6Sr_0.4TiO₃ (BST)/La_0.5Sr_0.5CoO₃ (LSCO) and Pt/BST/LSCO ferroelectric capacitors were successfully constructed on (001) LaAlO₃ substrates via off-axis magnetron sputtering. X-ray diffraction (XRD) and Phi scan patterns confirmed that the BST film was epitaxial with an out-of-plane tetragonal phase. The ferroelectric and dielectric measurements reveal that, compared with the Pt/BST/LSCO capacitor, the Au/BST/LSCO capacitor exhibits a larger coercive field (∼139.7 kV/cm), smaller permanent polarization (∼2.94 $\mu C/{cm}^2$), and lower tunability (∼65.22 %), which may be attributed to the higher difference in work function and weaker depolarization field screen effect of the top electrode, as well as smaller interfacial capacitance of the Au/BST interface than those of the Pt/BST interface. Therefore, based on series capacitor model and leakage behavior analysis, the thickness and dielectric constant of interfacial layer are quantitatively determined to be 3.52 nm and 12.13 for Pt/BST, and 4.42 nm and 5.82 for Au/BST, respectively. Our results pave a way for improving the dielectric performance in electrically tunable microwave devices.