Current Applied Physics最新文献

Choosing FA⁺/MA⁺ mixed-ion perovskite material as the active layer of the perovskite solar cells hold out the prospect of high efficiency and high stability. In this paper, the FA⁺/MA ⁺ ratio is modified to optimize the performance of FA_xMA_1-xPbI₃-based perovskite solar cells utilizing SCAPS-1D. The results indicate that the PCE of the devices reached a minimum of 21 % when x is greater than or equal to 0.6 in FA_xMA_1-xPbI₃(FTO/NiO_x/FA_xMA_1-xPbI₃/C₆₀/BCP/Al). When x = 0.6, the impact of the bottom interface defects on the solar cell performance is dominant and the thickness of the active layer should be controlled within a range of 0.4 μm–0.8 μm, while the defect density of the layer is expected to be between 10¹³ 1/cm³ and 10¹⁴ 1/cm³. By optimizing the perovskite layer thickness, defect density and changing the type of back electrode material, the efficiency is reaching 25.74 % based on the device(FTO/NiO_x/FA₆MA₄PbI₃/C₆₀/BCP/Au). This study provides theoretical guidance for experimental research on interface modification, defect passivation and manufacturing of high-efficiency FA_xMA_1-xPbI₃-based perovskite solar cells.

Doping is one of the effective strategies to modulate the optoelectronic properties and photocatalytic activity of photocatalysts. In this study, the effect of Fe doping (0–10 %) on morphology, optical and electronic properties, and photocatalytic activity of ZnO nanostructures is studied. The X-ray diffraction analysis shows that >5 % Fe doping, ZnFe₂O₄ is segregated as a secondary phase. The crystalline size decreases from 50.8 nm to 21.4 nm and the micro-strain increases with increasing the Fe concentration. The Fe doping-induced electronic restructuring facilitates visible light absorption through the O 2p → Fe 3d transition and the suppression of charge recombination by efficiently trapping conduction band electrons. Density functional theory (DFT) calculations are employed to unravel the underlying electronic changes induced by Fe doping in ZnO. The formation of shallow donor levels below the conduction band originates from the Fe 3d state. Photoluminescence spectra of pristine and Fe-doped ZnO nanostructures show characteristic emission peaks at approximately 384 nm and 570 nm, indicating the recombination of free excitons and oxygen interstitial defects, respectively. The results of the photocatalytic activity tests confirm that the 1 % Fe-doped ZnO nanostructures can exhibit the highest efficiency compared to the heavily doped ZnO nanostructures. The high efficiency in photocatalytic activity of 1 % Fe-doped ZnO nanostructures is ascribed to the modulated electronic structure and defect density. The adsorption affinity of methylene blue and water molecules to the surfaces of pristine and Fe-doped ZnO is simulated using the Monte-Carlo method. This study emphasizes the importance of controlling the dopant concentration to enhance the photocatalytic activity of various photocatalysts.

The density functional theory (DFT) data-driven approach to generating potential energy surfaces using machine learning has been proven to quickly and accurately predict the molecular and crystal structures of various elements. However, training databases consisting of hundreds of well-known symmetric structures have shown fatal weaknesses in calculating amorphous or nano-scale structures. Ab-initio molecular dynamics (AIMD) simulations create a training set that compensates for these shortcomings, but there are still many rare event structures. Here we introduce a new method to easily enlarge the data diversity and dramatically reduce data points based on the highly defected nano structures for universal machine learned potential. Our potential applies to bulk and nano systems and has been shown to high accuracy and computational efficiency while requiring minimal DFT training data. The developed potential is expected to help observation of structural changes in the Pt-based nano-catalysts that have been difficult to simulate at the DFT-level.

In recent years, electrochemical energy storage devices, including lithium batteries, supercapacitors, and fuel cells, have surged in development. They play indispensable roles across various domains and significantly enhance the quality of life. Electrochemical energy storage is vital to power systems, managing supply and demand dynamics, mitigating challenges such as intermittent energy fluctuations, and fostering the sustainable advancement of clean energy solutions. Among burgeoning research avenues, DNA is a green biological macromolecule with biodegradability and a unique double-helix structure, attracting attention across diverse fields. This review discusses the myriad applications of DNA in electrochemical energy storage devices and offers insights into novel approaches to leveraging DNA for electrochemical applications. Exploring these potential applications of DNA may unlock innovative pathways to enhancing the efficiency, sustainability, and versatility of electrochemical energy storage technologies. As these efforts continue, DNA promises to transform the ongoing quest for robust and eco-friendly energy solutions.

High-performance transparent quantum-dot light-emitting diodes (TQLEDs) are achieved through fine-tuning the top dielectric/metal/dielectric (DMD) anode structure. The transparent DMD electrodes are utilized as both the bottom cathode and top anode of TQLEDs. Employing WO_x/Ag/WO_x DMD anodes serves a dual purpose of transparency and hole injection, thereby streamlining the TQLED design. Investigation into the effects of the thicknesses of WO_x and Ag layers on the device characteristics reveals an optimal configuration of 10-nm WO_x/27-nm Ag/40-nm WO_x for the DMD anode. The resulting TQLED exhibits a remarkable device light transmittance of 47 % at 530 nm. With maximum bottom and top emission current efficiencies of 34.0 and 9.42 cd/A, respectively, the total emission obtained by summing the bottom and top emissions reaches the maximum current efficiency of 41.8 cd/A, surpassing that of conventional opaque quantum-dot light-emitting diodes. This advancement underscores the successful fabrication of TQLEDs boasting higher efficiency alongside substantial light transmittance.

Developing feasible Ag nanowire (NW) transparent conductive thin films (TCFs) with good conductivity, transparency, mechanical durability, strong adhesion, and high stability is a great challenge. Herein, novel TCFs composed of Ag NWs/Al₂O₃ on polyethylene terephthalate (PET) substrates with synchronously improved conductivity, transparency, mechanical durability, adhesion, and stability, are prepared. The corresponding values (before coating Al₂O₃: 13.0 Ω/sq. at 86.1 %, after coating Al₂O₃: 11.7 Ω/sq. at 87.7 %) indicate that the deposition of Al₂O₃ enhances the transparency and conductivity of Ag NW networks. Moreover, the resistance does not change significantly after 50 taping cycles and 2000 bending cycles with a bending radius of 5.0 mm, indicating the strong adhesion and good mechanical flexibility of Al₂O₃/Ag NWs composites. In addition, Al₂O₃/Ag NWs composites possess excellent stability to resist strong oxidizing, hot and humid environments. As a proof of concept, the flexible transparent heater prepared by Al₂O₃/Ag NWs composites is successfully demonstrated, verifying the practicability.

Solution-processable perovskite solar cells (PSCs) have the potential to revolutionize solar cell technology by enabling low power generation costs via low-cost device fabrication. However, most existing research regarding PSCs relies on the spin-coating method, which is not conducive to large-area film deposition. Therefore, the development of an alternative deposition method for perovskite films has become increasingly important for commercialization, for which electrospray deposition is a promising technique. This study investigates the two-step preparation of methylammonium lead triiodide (MAPbI₃) perovskite films via the electrospray deposition of a methylammonium iodide (MAI) solution on a spin-coated PbI₂ film. The gradual conversion of PbI₂ to MAPbI₃ with increasing MAI deposition time was revealed, accompanied by an increase in the size of the perovskite crystals. In addition, PSCs were successfully fabricated by electrospraying MAI, achieving a considerable power conversion efficiency of 7.86 % at the optimal MAI deposition time.

The accuracy of modern scientific research and technological advancement is highly reliant on the ability to accurately measure weak signals. The lock-in amplifier (LIA) represents an indispensable instrument, skillfully extracting these faint signals from a backdrop of noise. As the pursuit of accuracy intensifies, LIA technology has been continuously adapted and optimized. This review offers a comprehensive analysis of the evolution and applications of LIAs in weak signal measurements. It presents a structured introduction to the historical development of LIAs and evaluates their diverse applications across various domains, including impedance, optical, electrochemical, thermal, and biosensing methods. By examining specific examples in each field, it showcases the significant impact of LIAs on enhancing measurement precision. The review concludes by highlighting persistent challenges encountered by LIAs in practical settings and explores potential avenues for their future advancement. Future research aims to address practical challenges, including further noise reduction, improved system stability, and ease of use, ensuring LIAs continue to play a pivotal role in scientific and technological progress.

In this study, we developed a simple and facile synthesis method for producing CuS films at low temperatures. The method uses self-reducible complex inks comprising copper formate (Cuf) as the copper source and thioacetamide (TA) as both the sulfur source and complexing agent. The thermal properties of complex inks with different TA/Cuf ratios (0.5–2.0) were analyzed. The ink with a TA/Cuf ratio of 1 exhibited a significant decrease in the reduction temperature. The synthesis of a CuS film involved calcination of the ink at 140 °C; however, some residual Cuf was observed. Introducing hexanol to the ink, aimed at prolonging the liquid-phase reaction, yielded a pure CuS film that contained agglomerated particles. The thermal reduction pathway of Cuf to CuS was analyzed through thermogravimetric–mass spectrometric analysis, and the results revealed that the low-temperature synthesis was attributed to the formation of acetonitrile and formic acid during thermal decomposition of the ink.

First-principles calculations on phonon dynamics using density functional theory (DFT) have proven powerful in estimating the phonon dispersion of crystalline structures. However, it remains a challenging task for defective structures due to the computational cost. The main computational bottleneck of the phonon calculation is obtaining the interatomic force constants in many supercells with different configurations of displacements. Here, we employed a machine learning-based force fields (MLFFs) to accelerate DFT calculations of interatomic force constants of Si-doped HfO₂. We find that the specific phonon band originated from ferroelectric phase disappears, and imaginary modes are enhanced upon the introduction of a 10 % concentration of Si dopants, which is in good agreement with experimental results. This work demonstrates that MLFFs can be a promising application for predicting the phonon dispersion of both crystalline and defective structures.