Efficient Modulation Research Articles

Holistic Analysis for Mismatch Losses in Photovoltaic Modules: Assessing the Impact of Inhomogeneity from Operational Conditions and Degradation Mechanisms on Power and Yield

ABSTRACTThis study investigates mismatch losses in PV modules, analyzing the impact of operational conditions and degradation mechanisms on power generation across different module designs: full‐cell, half‐cell, string‐shingled, and matrix‐shingled. A bottom‐up multi‐physics model assesses inhomogeneities like partial shading, temperature inhomogeneity, soiling, encapsulation aging, and bypass diode failure. Module design related analysis reveals that parallel connections within modules minimize current mismatch losses, enhancing power under partial shading. Furthermore, modules exhibit a temperature profile with maximum temperatures at the center and minimum at the corners, impacting power differently based on the module's internal geometry, cell size, and electrical layout. Degradation analysis reveals significant power reduction due to soiling width and orientation, with encapsulation aging causing a 2% power loss after 3000 h. Findings indicate that partial shading and bypass diode failure can reduce full‐cell module power to zero under vertical shading; half‐cell and shingled modules retain varying power under horizontal and diagonal shading. Matrix‐shingled modules perform best under partial shading due to additional lateral current paths. Yield analysis shows a 1.7‐kWh annual yield increase for the matrix‐shingled module, attributed to changes in cell‐specific irradiance and temperature from its unique design, compared to a 0.5‐kWh increase for the full‐cell module. It was observed that shingled modules have a 1.6% higher specific yield under accumulating soiling along the long edge, which drops to 0.4% when considering module cleaning. For soiling along the short edge, results show that full‐cell modules exhibit the highest specific yield. Furthermore, findings indicate that portrait mounting reduces annual yield by about 5% for shingled modules, compared to 3% for full‐cell and half‐cell modules, with landscape mounting having a lower negative impact on yield. Overall, this research identifies the strengths and weaknesses of various PV module designs under different degradation and inhomogeneity scenarios, advancing the development of more efficient modules and enhancing accurate energy yield predictions, thus significantly contributing to the sustainability of solar energy.

Facile Strategy for Reducing Cell-to-Module Efficiency Gap in Organic Solar Cells by Controlling the Preaggregation of Photoactive Solutions.

Organic solar cells (OSCs) have recently achieved efficiencies of >20% in single-junction unit cells owing to rapid advancements in materials and device technologies. Large-area OSCs face several challenges that adversely affect their efficiency compared to small unit cells. These challenges include increased resistance loads derived from their larger dimensions, as well as limitations related to morphology, miscibility, and crystallinity. In this study, a preaggregation control technique was employed to develop efficient OSC modules. This was achieved by incorporating a low-concentration D18 solution into a high-performance donor-acceptor combination of PM6 and L8-BO facilitating optimal chain entanglement. As a result, macroscopically clean films and microscopically phase-separated morphologies were obtained. For devices with a small area of 0.04 cm2, the device incorporating D18 exhibited a marginally higher power conversion efficiency (PCE) of 17.82% compared to 17.32% for the device without D18. For devices with significantly larger areas of 4.725 and 30.24 cm2, the PCEs increased significantly with the introduction of D18, rising from 14.85 to 15.31% and from 12.77 to 13.49%, respectively. In particular, the module with the largest area of 30.24 cm2 demonstrated a significant decrease in load resistance, leading to a substantial reduction in the cell-to-module efficiency gap, which decreased from 26.3 to 24.3%.

Low-power high-stability all-optical modulator based on PtSe2 nanosheet integrated micro-nano fibers

All-optical modulators based on two-dimensional (2D) materials hold promising application as key components in the fields of all-optical signal processing and fiber optic communications. In this study, we present an all-optical modulator based on PtSe2 nanosheets integrated with micro-nano fibers (PtSe2-MF) with low power and high stability. PtSe2 nanosheets were deposited on the surface of micro-nano fibers with a diameter of approximately 6 µm using an optical deposition method. A tunable laser with a wavelength of 1550 nm was used as the signal light for modulation, and the 980 nm pump light was coupled with the 1550 nm signal light into the micro-nano fibers (MFs). And the all-optical intensity modulation effect at mW level power was achieved by varying the optical power of the pump light and taking advantage of the absorption of light by PtSe2, to produce light matter interaction. The modulation depth of PtSe2-MF for signal light was measured to be 11.8 dB, the modulation efficiency was 0.295 dB/mW, and the rise and fall response times of the modulation were 22.5 ms and 24.2 ms, respectively. The modulation efficiency of the device only changed by 4.4% after being exposed to the environment for three months, indicating that it still has long-term stability for more than three months. Research has shown that PtSe2-MF has advantages of low power, fast response, high modulation efficiency, and high stability. It has broad application prospects in the field of all-optical modulation.

Chip warpage and stress analysis in power modules of different substrate configurations

Purpose This paper aims to use rigorous finite element simulations to investigate the impact of different substrate systems on the warpage behavior of silicon (Si) chips of power modules exposed to thermal loading. Design/methodology/approach Three common substrate systems: direct copper bonded (DCB), insulated metal substrate (IMS) and printed circuit board (PCB) configurations examined. In addition, three lead-free bonding materials: silver-tin transient liquid phase (TLP), sintered silver (Ag) and sintered copper (Cu). This results in nine assembly configurations. Finite element models of the electronic modules are developed using ANSYS to apply thermal loads from room temperature to 250°C to induce deformations, strains and stresses in the electronic structure. Accordingly, the silicon chip deformations and maximum principal stresses of each assembly configuration are thoroughly examined. Findings The results indicate that DCB-based power modules markedly reduce Si die warpage and maximum principal stresses, suggesting enhanced resistance to thermal loads. In contrast, IMS systems exhibit the highest levels of die warpage and out-of-plane deformation. PCB substrates, however, induce the highest maximum principal stress values in the silicon die, potentially leading to accelerated crack initiation and propagation. While the die attach system has a minimal effect on die warpage, the silver-tin TLP bonds generate significantly higher die stresses compared with sintered Ag and sintered Cu, which both result in reduced stresses. Originality/value Power electronics exceptionally rely on ceramic-based and polymer-based substrate systems due to their superior thermal conductivity, heat resistance and electrical insulation properties. The strategic selection of substrate structures can significantly enhance the robustness of power. Ultimately, the findings of this research provide valuable insights for the design of highly reliable and efficient power modules subjected to thermal stress.

Coherent Optics for Passive Optical Networks: Flexible Access, Rapid Burst Detection, and Simplified Structure

With the development of the Internet of Things, cloud networking, and 4K/8K high-definition video, global internet traffic has seen a dramatic increase. This surge in traffic has placed higher demands on the performance of optical networks, featuring higher data rates, lower latency, and lower cost. The passive optical network (PON) is a representative scenario of optical access networks. Issues such as burst-mode detection in upstream PON scenarios, flexible rate allocation in downstream scenarios, and the simplification of hardware complexity at the optical network unit (ONU) side have attracted considerable attention. Compared to intensity modulation/direct detection (IM/DD), a recently proposed coherent PON incorporates a local oscillator laser at the receiver, enabling superior receiver sensitivity, spectrally efficient modulation, linear optical field recovery, and flexible channel selection. These features significantly enhance the flexibility and data rates of PON systems. This paper provides a comprehensive review of the development of coherent PONs, particularly in aspects of preamble design for burst-mode detection in upstream scenarios, the design of flexible rate PONs in downstream scenarios, and solutions for reducing hardware complexity at the ONU side.

Enhancing charge carrier dynamics with an N-type polymer guest for printable ternary organic solar modules

The ternary strategy offers a promising route to enhance the power conversion efficiencies (PCEs) of organic solar cells (OSCs). In this contribution, we focus on the state-of-the-art binary system PM6:L8-BO and reveal how the n-type polymer guest (PYIT) in the PM6:L8-BO:PYIT ternary system enhances carrier dynamics, thereby improving both efficiency and scalability for large-area printable OSC modules. These benefits are primarily attributed to two key factors: (i) the excellent miscibility of the PYIT guest with the host materials, coupled with the chain-dominant structure and high crystallinity nature of the PYIT polymer, which creates additional pathways for carrier transport and charge transfer; (ii) the incorporation of PYIT, which limits the excessive aggregation of L8-BO, improves molecular packing, and reduces film defects, thereby enhancing exciton dynamics. These optimizations lead to an increase in PCEs from 17.58% in the binary system to 18.59% in the ternary OSC, with improvements across all photovoltaic parameters. More importantly, the PM6:L8-BO:PYIT ternary system exhibits excellent compatibility with large-area printing processes, as demonstrated by a doctor blading OSC module achieving 15.57% PCE over an area of 11.7 cm2. This work highlights the potential of the ternary methodology in tuning the physical properties of OSCs while enhancing both performance and scalability.

Durable, Transparent, and Superhydrophobic Film Design for Flexible Substrate

Transparent superhydrophobic films/coatings have recently gained significant attention in the solar energy field due to their ease of preparation, low cost, self‐cleaning process, and high effectiveness in reducing dust adhesion to the surface. Compared to the rigid glass cover, the organic one has an advantage of flexibility and light weight, but the dust deposition impact is more serious. The aim of the present study is to design a transparent and superhydrophobic film with good durability on the organic glass surface, to recover the module efficiency reduction caused by dust deposition. Based on a soft photolithography and hot‐pressing process, periodic microcavities are prepared on the organic glass surface as an armor structure, and hydrophobic SiO2 nanoparticles are sprayed into the microcavities to achieve anti‐reflection and superhydrophobicity. The experimental test results show that the designed film possesses a large contact angle around 160°, a sliding angle of 3°, and a high visible transmittance over 90%. The unique armor structure design greatly improves the wear resistance of the film, and after encountering harsh conditions such as sandpaper friction, water flow impact, acid immersion, UV exposure, and repeatable bending, it still maintains excellent superhydrophobicity.

Damp‐Heat–Induced Degradation of Lightweight Silicon Heterojunction Solar Modules With Different Transparent Conductive Oxide Layers

ABSTRACTLightweight photovoltaic applications are essential for diversifying the solar energy supply. This opens up vast new scenarios for solar modules and significantly boosts the capacity of renewable energy. To ensure high efficiency and stability of the solar modules, several challenges need to be overcome. Degradation due to elevated temperature and/or humidity is a critical concern for silicon heterojunction (SHJ) solar modules. Here, we investigated the stability and degradation mechanism of encapsulated cells with lightweight configurations where the cells are based on three different types of transparent‐conductive oxide (TCO): indium tin oxide (ITO), aluminum‐doped zinc oxide (AZO), and a combination of ITO/AZO/ITO under humid and thermal environmental conditions. A damp heat (DH) test at a temperature of 85°C and relative humidity (RH) of 85% was performed on lightweight modules for 1000 h. Our results show that AZO is the most susceptible to DH degradation. The AZO film was damaged by the combined effects of moisture ingress and delamination of the interconnection foil, resulting in a decrease in the conductivity of the AZO film, leading to a dramatic increase in Rs and a decrease in FF of the modules. Consequently, moisture has a greater chance of percolating through the damaged AZO layer into the a‐Si:H passivation layer, causing passivation degradation, which leads to an increase in recombination, resulting in a decrease in Voc of the modules. In particular, after capping the AZO film with an ITO film, the efficiency loss of the ITO/AZO/ITO module was significantly reduced. This suggests that the ITO film could be a promising protective capping layer for the AZO‐based solar cells.

Synergistic Boronic Acid and Photoredox Catalysis: Synthesis of C-Branched Saccharides via Selective Alkylation of Unprotected Saccharides.

Here we present a regio- and stereoselective alkylation approach for unprotected saccharides using synergistic boronic acid and photoredox catalysis. Targeting the equatorial C-H bond of the cis-1,2-diol motif, this method employs MeB(OH)2 as a catalyst. Mechanistic investigations indicate that the formation of a tetracoordinate boron species, resulting from the interaction between the cyclic boronic diol ester and a free hydroxyl group in the saccharide, is critical to this transformation. Notably, this method enables efficient late-stage modification of complex carbohydrates, such as raffinose and the drug digoxin, expanding opportunities for carbohydrate functionalization.

All-Fiber Micro-Ring Resonator Based p-Si/n-ITO Heterojunction Electro-Optic Modulator

With the rapid advancement of information technology, the data demands in transmission rates, processing speed, and storage capacity have been increasing significantly. However, silicon electro-optic modulators, characterized by their weak electro-optic effect, struggle to balance modulation efficiency and bandwidth. To overcome this limitation, we propose an electro-optic modulator based on an all-fiber micro-ring resonator and a p-Si/n-ITO heterojunction, achieving high modulation efficiency and large bandwidth. ITO is introduced in this design, which exhibits an ε-near-zero (ENZ) effect in the communication band. The real and imaginary parts of the refractive index of ITO undergo significant changes in response to variations in carrier concentration induced by the reverse bias voltage, thereby enabling efficient electro-optic modulation. Additionally, the design of the all-fiber micro-ring eliminates coupling losses associated with spatial optical-waveguide coupling, thereby resolving the high insertion loss of silicon waveguide modulators and the challenges of integrating MZI modulation structures. The results demonstrate that this modulator can achieve significant phase shifts at low voltages, with a modulation efficiency of up to 3.08 nm/V and a bandwidth reaching 82.04 GHz, indicating its potential for high-speed optical chip applications.

A Study on the Performance of Soiled Solar Photovoltaic Panels at Different Tilt Angles in Al Seeb, Oman

Climate and weather conditions greatly affect photovoltaic (PV) module performance and efficiency, particularly in desert environments. Dust accumulation, which significantly reduces power generation efficiency, is currently the main issue facing photovoltaic modules since it affects the return on investment of PV systems. It is believed that the tilt angle of solar PV panels can be helpful in reducing the effect of soiling using the gravitational force experienced by the dust particles, mainly in dry environments. In this work, experimental studies were conducted to investigate the effects of the tilt angle and dust deposition on the electrical power generation performance of photovoltaic modules under weather conditions in Al Seeb, Oman. The study was conducted by exposing solar PV panels to outdoor sunlight for two weeks. Two of the PV panels with fixed and different tilt angles were cleaned on a daily basis, while another panel was left uncleaned. A comparison was made with the panel that was not cleaned for an extended time. Measurements included solar irradiance, solar panel temperature, voltage, and current. The output power and efficiency reached 93.5 W and 24.5%, respectively, for the panel cleaned daily. Furthermore, soiling resulted in an 18.8% power loss. The results showed that the highest output power of 79.75 W was observed at an angle of 25°, with an efficiency of up to 20.5%. Moreover, the power generated was up to 9.8% higher than that at different tilt angles.

A Wenzel Interfaces Design for Homogeneous Solute Distribution Obtains Efficient and Stable Perovskite Solar Cells.

The coffee-ring effect, caused by uneven deposition of colloidal particles in perovskite precursor solutions, leads to poor uniformity in perovskite films prepared through large-area printing. In this work, the surface of SnO2 is roughened to construct a Wenzel model, successfully achieving a super-hydrophilic interface. This modification significantly accelerates the spreading of the perovskite precursor solution, reducing the response delay time of perovskite colloidal particles during the printing process. Additionally, the micro-spherical depression structure on the SnO2 surface effectively inhibits the migration of colloidal particles toward the edges of liquid film, trapping perovskite colloidal particles at the buried interfaces and improving film uniformity. Due to the synergistic effect of super-hydrophilicity and micro-rough structure on the surface of SnO2, leading to a substantial improvement in the quality of perovskite crystals. Therefore, the efficiency of printing prepared flexible devices (0.101 cm2) reached 25.42% (certified 25.12%). Moreover, the efficiency of rigid and flexible large-scale perovskite solar modules (PSMs) based on meniscus-coating manufacture reached 21.34% and 16.99% (100 cm2), respectively, and demonstrated superior environmental stability by maintaining an initial efficiency of 91% after being stored in atmospheric conditions for 2000 h, offering practical guidance for fabricating high-performance and stable large-scale perovskite solar cells (PSCs).

Ship target detection method based on improved YOLOv8 for SAR images

ABSTRACT Due to the complex background and less effective information in low-resolution and noisy images, the detection of small ships in SAR images suffers from low detection rate and high false alarm rate. In order to solve the above problems, this paper proposes a method to detect the small ship targets in SAR images based on improved YOLOv8. Firstly, the deformable convolutional networks are added to the leading network to improve feature extraction. Then, the efficient multi-scale attention module is fused with the backbone network to enhance the detection effect of small targets. The weighted intersection over union loss function is used to optimize the regression process of the prediction frame and the detection frame to enhance the localization capacity of small targets. Finally, there is an addition of a specialized small target detection layer, and a reconstruction of the feature extraction and fusion network to enhance the detection performance of small ship targets in SAR images. To verify the effectiveness and robustness of the method, we conduct experiments on SSDD and HRSID. The proposed method achieves high detection accuracy while also offering a more compact model size and less computation time compared to other prevalent methods.

Dual-function applications of photochromic BiNbO4:Er3+ ceramics based on reversible upconversion luminescence modulation

This research introduces a photochromic luminescent BiNbO4:Er ceramic, showing good coloration contrast and efficient upconversion luminescence modulation rate. The dual-functional applications in security and fingerprint acquisition are developed.

A spiro-type self-assembled hole transporting monolayer for highly efficient and stable inverted perovskite solar cells and modules.

Self-assembled monolayers (SAMs) have significantly contributed to the advancement of hole transporting materials (HTMs) for inverted perovskite solar cells (PSCs). However, uneven distribution of SAMs on the substrate largely decreases the PSC performance, especially for large-scale devices. Herein, the first spiro-type SAM, termed 4PA-spiro, with an orthogonal spiro[acridine-9,9'-fluorene] as the skeleton and phosphonic acid as the anchoring group were proposed. Compared to the reference 4PACz, the twisted configuration with larger steric hindrance of 4PA-spiro inhibited the intermolecular aggregation, enabling a uniform and homogeneous anchoring on the substrate. Moreover, the suitable highest occupied molecular orbital (HOMO) level of 4PA-spiro is beneficial in promoting hole extraction and reducing charge non-radiative recombination. As a result, compared to 4PACz with a power conversion efficiency (PCE) of 22.10%, the 4PA-spiro-based PSCs exhibited a superior PCE of 25.28% (certified 24.81%, 0.05 cm2), along with excellent long-term stability. More importantly, 4PA-spiro-enabled larger-area PSCs and modules achieved PCEs of 24.11% (1.0 cm2) and 21.89% (29.0 cm2), respectively, one of the highest PCEs for inverted PSC modules, providing an effective SAM candidate for the commercialization of efficient, stable and large-scale inverted PSCs.

Photocatalytic regioselective C-H bond functionalizations in arenes.

The direct functionalization of C-H bonds has revolutionized the field of synthetic organic chemistry by enabling efficient and atom-economical modification of arenes by avoiding prefunctionalization. However, the inherent challenges of inertness and regioselectivity in different C-H bonds, particularly for distal positions, necessitate innovative approaches. In this aspect, photoredox catalysis by utilizing both transition metal and organic photocatalysts has emerged as a powerful tool for addressing these challenges under mild reaction conditions. This review provides a comprehensive overview of recent progress in regioselective C-H functionalization in arenes via photocatalysis. Emphasizing the strategies for achieving ortho-, meta-, and para-selectivity, we explore the mechanistic insights, catalyst designs, and the novel methodologies that have expanded the scope of C-H bond functionalization. This discussion aims to offer valuable perspectives for advancing the field and developing more efficient and sustainable synthetic methodologies.

Heterologous expression of a highly thermostable L-asparaginase from Thermococcus zilligii in Aspergillus niger for efficient reduction of acrylamide in French fries

L-asparaginase (L-ASNase) can hydrolyze L-asparagine, a precursor to acrylamide, thereby reducing toxic acrylamide formation in fried foods. Currently, commercial L-ASNases are primarily produced by wild-type (WT) filamentous fungi; however, these enzymes often exhibit rapid activity loss during high-temperature processing due to limited thermal stability. In this study, we screened a thermostable L-ASNase gene from thermophile bacteria and expressed it in Aspergillus niger to reduce acrylamide content in French fries. Initially, four genes encoding thermostable L-ASNases were selected and integrated into the A. niger genome via non-homologous end joining. Among these, the L-ASNase gene tzi from Thermococcus zilligii was successfully expressed in A. niger, yielding an extracellular activity of 114 U·mg−1. The recombinant enzyme (An-Tzi) displayed the same optimal temperature and pH as its WT counterpart but exhibited superior catalytic efficiency, likely due to the efficient post-translational modifications in A. niger. To further enhance expression, the tzi gene was integrated into the amylase (amyA) locus of the A. niger genome using the CRISPR-Cas9 system, resulting in increased activity of 128 U·mg−1. Additionally, various lengths of the highly expressed glucoamylase (glaA) protein from A. niger AG11 were fused to the N-terminus of the Tzi. Notably, fusing the 500-amino-acid catalytic domain of glaA led to a substantial 3.3-fold increase in enzyme activity. Despite the metabolic stress induced by high-level expression of glaA, supplementing the culture medium with metal ions and sophorose resulted in an extracellular activity of 486.74 U·mg−1, the highest reported yield of L-ASNase in shake flasks. Finally, applying the An-Tzi to French fries achieved a 32 % greater reduction in acrylamide compared to the commercial enzyme. Overall, the recombinant A. niger strain expressing thermostable An-Tzi demonstrates significant potential for industrial applications targeting acrylamide reduction in fried and baked foods.

Recent advances in valorization of lignocellulosic waste into biochar and its functionalization for the removal of chromium ions.

Lignocellulosic waste is a prevalent byproduct of agricultural and forestry activities which is an excellent feedstock for the preparation of biochar. This research area is of interest to the scientific community due to its potential in environmental remediation. In this regard, this review examines the latest advancements in transforming lignocellulosic waste into biochar and explores recent innovations in enhancing its functionality for chromium ion removal. It gives analysis on current methods for biochar production from lignocellulosic materials such as pyrolysis. Additionally focusing on improvements in production efficiency, structural properties, and surface modifications. The review also highlights various functionalization techniques, such as chemical activation and impregnation with metal oxides, that were innovated to improve adsorptive nature of biochar for chromium ions. While progress has been made, achieving scalability in lignocellulosic biochar production presents challenges, such as the high energy demands of pyrolysis, inconsistencies in feedstock quality, and the need for cost-effective functionalization methods. By summarizing recent research and technological progress, this paper aims to offer a clear perspective on the effectiveness of biochar derived from lignocellulosic waste in addressing contamination. Additionally, it discusses the ongoing challenges and future research directions needed to optimize biochar applications in environmental cleanup.

Molten salt-assisted synthesis of a nitrogen-doped biochar catalyst at low temperature for enhanced degradation of acetaminophen

Nitrogen (N) doping is an efficient modification route to improve the catalytic performance of biochar in peroxymonosulfate (PMS) activation, and molten salt-assisted pyrolysis is an effective and eco-friendly approach to increase the N doping level.

Potential development of thermally stable polycrystalline photovoltaic modules utilizing biocomposite materials

Abstract Solar energy has become a vital source for generating and harvesting electricity. Enhancing the efficiency of solar modules is an essential factor for successful transition to a sustainable and green energy production. Since natural fiber composites (NFCs) possess various outstanding properties, they can be used as an adequate alternative to synthetic fibers and environmentally harmful materials that are used in photovoltaic (PV) applications and module components. Solar modules are believed to undergo a decline in efficiency when exposed to excessive sun radiation, which eventually caused by a gradual escalation in temperature. Therefore, utilizing appropriate NFCs in the rear components and backsheets of solar modules could significantly contribute to the overall efficiency of these modules and enhance their thermal stability.