Voltage Loss Research Articles

Li, Ag Co‐Doping Enables Efficient Kesterite Solar Cell with a High Fill Factor of 74.30%

AbstractIn addition to open‐circuit voltage (VOC) loss, fill factor (FF) loss is considered another major factor restricting the further optimization of Cu2ZnSn(S,Se)4 (CZTSSe) device efficiency. In this work, a comprehensive investigation into the loss mechanisms of FF has been conducted, and implemented a Li&Ag co‐doping approach to enhance FF. The results indicate that the FF loss caused by insufficient carrier extraction is higher than that caused by non‐radiative recombination. The carrier extraction capability is significantly influenced by the band alignment of the CdS/CZTSSe interface and has little relationship with the carrier concentration of the absorber. Therefore, although Ag doping reduces the hole concentration and conductivity, it reduces the FF loss caused by carrier extraction due to the improvement of band alignment. Ag doping is also superior to Li in passivating harmful defects, which helps reduce FF losses caused by non‐radiative recombination. Correspondingly, Li performs better than Ag in increasing the hole carrier concentration and optimizing band alignment, greatly reducing FF losses caused by insufficient carrier transport. Finally, the Li and Ag co‐doping strategy enables a 14.91% efficient kesterite solar cell with the highest reported FF to date of 74.30% through collaborative optimization of carrier extraction and suppression of non‐radiative recombination.

Boosting the Durability of High-Pt-Content Fuel Cell Cathode Catalysts Through TaOx Decorating.

Enhancing the durability of carbon-supported platinum catalysts (Pt/C) for the oxygen reduction reaction remains a significant challenge in the field of proton exchange membrane fuel cells (PEMFCs), especially for catalysts with high-Pt contents. Herein, a TaOx decorating strategy that is capable of effectively boosting the durability of Pt/C catalysts even with a high-Pt content of 50 wt.% is introduced. This strategy involves introducing reducible Ta2O5 nanoparticles into carbon supports, depositing Pt nanoparticles, and finally conducting high-temperature H2 annealing to convert reducible Ta2O5 nanoparticles into amorphous TaOx decorating the Pt nanoparticles. The annealing temperature found in the Ta2O5 incorporation step is critical for the formation of reducible Ta2O5 nanoparticles, which, in turn, determines the continuity of the TaOx subsequently formed around the Pt nanoparticles. By controlling annealing temperature, the formation of a relatively continuous TaOx distribution on the Pt nanoparticle surface is achieved, thereby maximizing the interaction between Pt and TaOx and enhancing the electrochemical stability of Pt nanoparticles. Following the accelerated durability test, the resulting high-Pt-content catalyst demonstrates an array of exceptional durability metrics, including an electrochemical surface area loss of 30%, a mass activity loss of 35%, and a voltage loss of 22mV at 0.8 A cm‒2.

Tuning the bandgap without compromising efficiency: ambient solution processing of Ge-alloyed (Ag,Cu)2Zn(Sn,Ge)(S,Se)4 kesterite thin-film solar cells

The photovoltaic sector currently experiences a growing demand for deeply-integrated technologies in agriculture, buildings, vehicles, among others. Kesterite compounds provide a versatile solution through their tunable bandgap via isovalent alloying. However, this should be done while preserving material opto-electronic quality and device performance, which is an unresolved challenge. Indeed, tuning the bandgap of kesterites must ensure low crystalline disorder to counteract the associated open-circuit voltage (Voc) losses when used in solar cells. To achieve this goal, this work introduces a simple molecular ink recipe realized in ambient air to process single-phase high-quality Ag,Gealloyed kesterite absorbers. By varying the Ge content from 0 to 100%, the absorber bandgap covers the range from 1.15 to 1.5 eV, in which the Urbach energy remains close to 20 meV and promisingly low Voc deficits are observed. In particular, the champion efficiency of 12.1% obtained with 40% Ge breaks the record for Ge-alloyed kesterites with a 1.2 eV bandgap by remarkably reaching 62% of the Shockley-Queisser limit for Voc. This study demonstrates a promising strategy to solve the issue of large band tailing and low opto-electronic quality in widebandgap kesterites while establishing a foundation for solution-processed kesterite solar cells with tunable bandgap and promising performance.

A comprehensive optimization of highly efficient MA-Free wide-bandgap perovskites for 4-T Perovskite/Silicon tandem solar cells

Perovskite/silicon tandem solar cells have emerged as a highly promising strategy for surpassing the Shockley–Queisser limit. Among these tandem solar cells, the wide-bandgap perovskite plays a key role in highly efficient tandem solar cells. However, the wide bandgap perovskite material suffers from considerable voltage loss due to a high trap density and phase instability under light illumination. In this study, we present a comprehensive set of optimization procedures designed to enhance the power conversion efficiency of methylammonium-free (MA-free) wide-bandgap perovskites. Following this procedure, the opaque MA-free wide-bandgap perovskite solar cells demonstrate an impressive efficiency of 22.11 % with a minimal open-circuit voltage deficit of 0.47 V. Moreover, the efficiency of the semi-transparent wide-bandgap perovskite solar cells reached 19.21 %, and these semi-transparent cells were subsequently integrated into a 4-terminal perovskite/Si tandem solar cell, yielding a remarkable efficiency of 29.98 %. Our study paves a facile way towards highly efficient wide-bandgap perovskite solar cells for the application of semi-transparent and tandem solar cells.

U-Shaped Dimeric Acceptors for Balancing Efficiency and Stability in Organic Solar Cells.

Despite significant improvements in power conversion efficiencies (PCEs) of organic solar cells (OSCs), achieving excellent stability remains a great challenge to their commercial feasibility. Here, U-shaped dimeric acceptors (5-IDT and 6-IDT) with different molecular lengths are introduced into the binary OSCs as a third component, respectively. The introduction of the third component effectively reduces the energetic disorder and non-radiative voltage losses and improves the exciton dissociation and charge transport of the devices. Consequently, the PCEs of the 6-IDT- and 5-IDT-treated OSCs are significantly improved to 19.32% and 19.96%, respectively, which is the highest PCE for oligomeric acceptors-based ternary OSCs to date. Meanwhile, the thermal stability of the treated devices is dramatically improved, with the initial efficiency retention of the 6-IDT- and 5-IDT-treated devices increasing from 18% to 32% and 75%, respectively, after 1000h of thermal stress. This is mainly attributed to the ability of the smaller molecular length of 5-IDT to stabilize the phase-separated morphology of the polymeric donor and small molecular acceptor, rather than the high glass transition temperature and low diffusion coefficient.

Seed-Mediated Synthesis of High Loading PtCo Intermetallic Compounds Enhanced Catalytic Efficacy and Long-Term Stability for Oxygen Reduction Reaction.

Atomically ordered intermetallic Pt-based nanoparticles, recognized as advanced electrocatalysts, exhibit superior activity for the oxygen reduction reaction (ORR) in fuel cell cathodes. Nevertheless, the formation of these ordered structures typically necessitates elevated annealing temperatures, which can accelerate particle growth and diminished reactivity. In this study, we synthesized carbon-supported platinum-cobalt intermetallic compounds (PtCo-IMCs) with sub-4 nm particle sizes and uniform distribution. These catalysts, characterized by high platinum content and exceptional ORR activity, are specifically tailored for heavy-duty vehicle (HDV) applications. The PtCo-IMCs exhibited significantly enhanced catalytic performance and durability compared to conventional Pt-based catalysts, utilizing platinum nanoparticles as nucleation sites to promote growth. This method effectively retained smaller particle sizes while achieving a higher degree of ordering and alloying during high-temperature annealing. Optimization of the annealing temperature resulted in peak activity and stability at 800 °C. The mass activity (MA) of the PtCo-800 catalyst was 2.7-fold and 1.8-fold that of the commercial Pt/C and disordered PtCo catalysts, respectively. Additionally, the single cell employing the PtCo-800 catalyst showed a minimal voltage loss of only 27 mV at a current density of 2 A cm-2 after 30,000 cycles of the accelerated durability test (ADT), underscoring its long-term stability.

Boost efficiency with buffer and bottom stack optimization in Cu2BaSn(S,Se)4 solar cells by simulation

Cu2BaSn(S,Se)4 is gaining tremendous attention as a potential absorber due to its non-toxicity, earth abundance, and low antisite defects opposing Cu2ZnSn(S,Se)4. However, the highest experimental efficiency of 6.17 % is achieved with the device structure Al:ZnO/Mg:ZnO/Zn1-xCdxS/Cu2BaSn(S,Se)4/Mo where the drawback is large open circuit voltage (VOC) loss stemming from the large cliff at the absorber/buffer interface and back contact recombination. Therefore, finding a suitable non-toxic buffer with modification of the bottom stack is crucial. In this regard, Cu2BaSn(S,Se)4 solar cells based on diverse buffers are numerically simulated using SCAPS-1D with Ni as back contact and introducing back surface field (BSF) at the absorber/Ni interface. At first, a baseline model validating the experimental efficiency is designed. The application of Ni enhanced efficiency to 7.92 % due to the formation of ohmic contact. Further, it is improved to 9.91 % with anti-reflection coating. Afterward, a total of 780 solar cells were designed with six buffer and eight BSF combinations by optimizing the absorber, buffer, and interface properties where the highest efficiency of 28.11 % with incredible fill factor (90 %) and less VOC loss (0.24 V) is accomplished for the Al:ZnO/Mg:ZnO/TiO2/Cu2BaSn(S,Se)4/CuI/Ni solar cell. Further, the importance of BSF is analyzed via energy band diagrams, Mott-Schottky and Nyquist plots. The outcomes disclosed that the BSF greatly influences the energy band alignment, built-in potential, depletion width, and recombination resistance of solar cells, underscoring its significance in improving performance. Overall, the present work proposes an efficient strategy to modify the device configuration of Cu2BaSn(S,Se)4 solar cells to enhance their efficiency.

Dual-Passivation Strategy of Bulk and Surface Enables Highly Efficient and Stable Inverted Perovskite Solar Cells.

Inverted perovskite solar cells (PSCs) have captured significant interest due to their outstanding stability, cost-effective fabrication process, and good compatibility with flexible and tandem devices. The presence of bulk and surface defects is key factor in PSCs that cause non-radiative recombination and degradation. To improve the efficiency and stability of inverted PSCs, a bulk-to-surface dual-passivation strategy is employed by utilizing Oleylamine Iodide (OAmI) as additives and 4-Fluorobenzylamine Hydroiodide (4-F-PMAI) as surface passivating agents. Utilizing OAmI as bulk passivation can enhance the crystallinity of perovskite films and reduce lattice defects. Meanwhile, 4-F-PMAI further suppresses non-radiative recombination and reduces open-circuit voltage (VOC) loss through bidentate anchoring. Consequently, the dual-passivation strategy significantly enhances device performance, boosting the power conversion efficiency (PCE) of PSCs to 24.26%, with a VOC of 1.15V. Moreover, the unencapsulated PSCs show excellent long-term stability maintaining over 85% and 90% of the initial efficiency under 85°C thermal annealing in N2 for 1000 hours and after storage in ambient conditions (RH: 30 ± 5%) for 1000 hours.

Emerging Bi‐Based Multicationic Ternary Chalcogenides as Promising Photoabsorbers for Solar Cells

Bismuth‐based multicationic chalcogenide solar cells of class ABiX2 (A–Ag, Cu; X–S, Se) have attracted substantial interest within the photovoltaic research community mainly due to their nontoxic nature and rising power conversion efficiencies. Although a good amount of research on these materials is underway, it calls for an intense and comprehensive approach to address the poor performance (PCE 10%) compared to its reported theoretical efficiency of 29%. Hence a review in this direction to address various unexplored concerns of these materials particularly, the defects and unfavorable band positions that give rise to enormous nonradiative recombinations, leading to major voltage losses in these devices is necessary. The article also discusses the structural and electronic properties, deposition techniques, device optimization strategies, impact of grain size, interface engineering, cationic disorder, transport layers, and light‐harvesting techniques that may be required to enhance the device performance. Additionally, a comprehensive analysis of stability and cost considerations of the emerging AgBiS2 solar devices is conducted to unveil their real‐time applications in comparison to current state‐of‐the‐art devices.

Minimizing Voltage Deficit in Perovskite Indoor Photovoltaics by Interfacial Engineering.

Metal halide perovskites with bandgap of ≈1.8eV are competitive candidates for indoor photovoltaic (IPV) devices, owing to their superior photovoltaic properties and ideal absorption spectra matched to most indoor light sources. However, these perovskite IPVs suffer from severe trap induced non-radiative recombination, resulting in large open-circuit voltage (VOC) losses, particularly under low light intensity. Herein, an effective approach is developed to minimizing trap density by modifying the buried interface of perovskite layer with bifunctional molecular 2-(4-Fluorophenyl)ethylamine Hydrobromide (F-PEABr). The benzene ring of F-PEABr molecules can firmly anchor at the hole transporting layer by π-π stacking interaction, and the other ends can passivate the defects on the buried interface of perovskite layer. Based on that, the F-PEABr modified perovskite IPVs achieved power conversion efficiency (PCE) of 42.3% with a remarkable VOC of 1.13V under 1000 lux illumination from a 4000K LED lamp. Finally, perovskite IPV mini-modules with area of 10.40cm2 are demonstrated with a PCE of 35.2%. This interface modification strategy paves the way for crafting high-performance perovskite IPVs, holding great potential for self-powered internet of things applications.

A universal reverse‐cool annealing strategy makes two‐dimensional Ruddlesden‐popper perovskite solar cells stable and highly efficient with Voc exceeding 1.2 V

AbstractTwo‐dimensional Ruddlesden‐Popper (2D RP) layered metal‐halide perovskites have garnered increasing attention due to their favorable optoelectronic properties and enhanced stability in comparison to their three‐dimensional counterparts. Nevertheless, precise control over the crystal orientation of 2D RP perovskite films remains challenging, primarily due to the intricacies associated with the solvent evaporation process. In this study, we introduce a novel approach known as reverse‐cool annealing (RCA) for the fabrication of 2D RP perovskite films. This method involves a sequential annealing process at high and low temperatures for wet perovskite films. The resulting RCA‐based perovskite films show the smallest root‐mean‐square value of 23.1 nm, indicating a minimal surface roughness and a notably compact and smooth surface morphology. The low defect density in these 2D RP perovskite films with exceptional crystallinity suppresses non‐radiative recombination, leading to a minimal non‐radiative open‐circuit voltage loss of 149 mV. Moreover, the average charge lifetime in these films is extended to 56.3 ns, thanks to their preferential growth along the out‐of‐plane direction. Consequently, the leading 2D RP perovskite solar cell achieves an impressive power conversion efficiency of 17.8% and an open‐circuit voltage of 1.21 V. Additionally, the stability of the 2D RP perovskite solar cell, even without encapsulation, exhibits substantial improvement, retaining 97.4% of its initial efficiency after 1000 hours under a nitrogen environment. The RCA strategy presents a promising avenue for advancing the commercial prospects of 2D RP perovskite solar cells.image

Integrated Omnidirectional Design of Non‐Volatile Solid Additive Enables Binary Organic Solar Cells with Efficiency Exceeding 19.5 %

AbstractSolid additives have drawn great attention due to their numerous appealing benefits in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). To date, various strategies have been reported for the selection or design of non‐volatile solid additives. However, the lack of a general design/evaluation principles for developing non‐volatile solid additives often results in individual solid additives offering only one or two efficiency‐boosting attributes. In this work, we propose an integrated omnidirectional strategy for designing non‐volatile solid additives. By validating the method on the 4,5,9,10‐pyrene diimide (PyDI) system, a novel non‐volatile solid additive named PyMC5 was designed. PyMC5 is capable of enhancing device performance by establishing synergistic dual charge transfer channels, forming appropriate interactions with active layer materials, reducing non‐radiative voltage loss and optimizing film morphology. Notably, the binary device (PM6 : L8‐BO) treated by PyMC5 achieved a PCE over 19.5 %, ranking among the highest reported to date. In addition, the integration of PyMC5 mitigated the degradation process of the devices under photo‐ and thermal‐stress conditions. This work demonstrates an efficient integrated omnidirectional approach for designing non‐volatile solid additives, offering a promising avenue for further advancements in OSC development.

Rational Design of Two Well‐Compatible Dimeric Acceptors Through Regulating Chalcogen‐Substituted Conjugated Backbone Enable Ternary Organic Solar Cells with 19.4% Efficiency

AbstractTo enhance the performance of dimeric acceptors (DMAs) based organic solar cells (OSCs), two new DMAs, designated as DC9‐HD and DYSe‐3, are rationally developed and employed to fabricate ternary OSCs. The substitution of the sulfur atom on the outer ring of the fused‐ring core of DC9‐HD with a selenium atom resultes in the red‐shifted DYSe‐3. Despite these minor differences, DC9‐HD and DYSe‐3 possess nearly identical conjugated skeletons, which contribute to their similar packing motifs and crystallinities, ultimately enabling a high degree of miscibility between two DMAs. Upon incorporating DYSe‐3 into the host PM6:DC9‐HD binary blend, fibril‐like morphologies featured with diameters of ≈16.9 nm and reduced charge recombination are observed in the PM6:DC9‐HD:DYSe‐3 ternary blend. More importantly, owing to their long exciton diffusion lengths and low voltage losses, a remarkable power conversion efficiency of 19.4% is achieved for the ternary OSCs, alongside a delicate balance between open‐circuit voltage and short‐circuit current density. This super result is comparable to the best performance of oligomer acceptor based OSCs reported to date. Furthermore, the proposed ternary strategy, which combines one polymer donor and two well‐compatible DMAs, not only retains the advantages of DMAs but also offers a streamlined approach for fabricating high‐performance ternary OSCs.

Integrated Omnidirectional Design of Non-Volatile Solid Additive Enables Binary Organic Solar Cells with Efficiency Exceeding 19.5 .

Solid additives have drawn great attention due to their numerous appealing benefits in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). To date, various strategies have been reported for the selection or design of non-volatile solid additives. However, the lack of a general design/evaluation principles for developing non-volatile solid additives often results in individual solid additives offering only one or two efficiency-boosting attributes. In this work, we propose an integrated omnidirectional strategy for designing non-volatile solid additives. By validating the method on the 4,5,9,10-pyrene diimide (PyDI) system, a novel non-volatile solid additive named PyMC5 was designed. PyMC5 is capable of enhancing device performance by establishing synergistic dual charge transfer channels, forming appropriate interactions with active layer materials, reducing non-radiative voltage loss and optimizing film morphology. Notably, the binary device (PM6 : L8-BO) treated by PyMC5 achieved a PCE over 19.5 %, ranking among the highest reported to date. In addition, the integration of PyMC5 mitigated the degradation process of the devices under photo- and thermal-stress conditions. This work demonstrates an efficient integrated omnidirectional approach for designing non-volatile solid additives, offering a promising avenue for further advancements in OSC development.

Voltage enhancement and loss minimization in a radial network through optimal capacitor sizing and placement based on Crow Search Algorithm

In power systems, the distribution network is crucial as it serves as the final stage in delivering energy from generation plants to end users. However, reactive power demand from consumers can create challenges such as low power factor, voltage drops, and increased power losses depending on the distribution system used. This study aims to enhance the performance of radial distribution networks (RDNs) by optimizing capacitor placement and sizing based on the Crow Search Algorithm (CSA). Additionally, the study addresses the Optimal Power Flow (OPF) within the network by employing the Backward/Forward Sweep (BFS) method. The study accesses CSA’s effectiveness compared to other metaheuristic optimization techniques through simulation. The simulation results showed that the Voltage Stability Index improved from 0.61 for base case to 0.68 pu with CSA, compared to 0.66 for Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), Genetic Algorithm (GA), and Teacher Learner Based Optimization (TLBO and 0.67 for Invasive Weed Optimization (IWO). CSA also achieved a 30.41 % reduction in active power losses, outperforming PSO, ABC, GA, and TLBO having 26.61 %, and IWO at 24.92 %. Additionally, application of CSA led to a 29.33 % reduction in reactive power losses, compared to 21.91 % for PSO, ABC, GA, and TLBO, 18.2 % for IWO. In the simulated IEEE 33 bus Radial Distribution Network (RDN) topology, the lowest bus voltage at bus 18 increased from 0.8820 in the base case to 0.9080 with CSA, indicating a 32.9 % improvement in voltage deviation. Furthermore, the optimization resulted in a significant reduction of 3.841 pu in capacitor cost, demonstrating CSA’s efficiency in both technical and economic aspects. CSA not only showed favorable results in minimizing power losses and improving voltage profiles but also provided substantial cost savings in capacitor implementation, making it a robust and cost-effective solution for enhancing RDN performance.

Halogenated Polycyclic Aromatic Hydrocarbon for Hole Selective Layer/Perovskite Interface Modification and Passivation for Efficient Perovskite‐Organic Tandem Solar Cells with Record Fill Factor

AbstractPerovskite whentandemed with organic photovoltaics (OPV) for double‐junctions have efficiencypotentials over 40%. However, there is still room for improvement suchas better current matching, higher fill factor, as well as lower voltage and fill factor losses in the top perovskite cell. Here weaddress the issue associated with the top perovskite cell by utilising anovel halogenated polycyclic aromatic hydrocarbon compound, 1‐naphthylammoniumchloride (NA─Cl) playing dual roles of surface modification for the hole selectivelayer (HSL) and passivation of HSL/perovskiteinterface. Results of X‐ray photoelectron spectroscopy and density functionaltheory calculations reveal that NA─Cl retains self‐assembly property for the HSLwhile demonstrating high dipole moment and polarizability. This induces asurface dipole at the HSL/perovskite interface reducing the energetic barrierfor hole extraction by 210 meV thereby enhancing voltage output and fill factorof the device. Such scheme when implemented in a high bandgap (1.78 eV)perovskite solar cell, results in a respectable efficiency of 19.7% and thehighest fill factor of 85.4% amongst those of 1.78 eV perovskite cells reported.We have also achieved 23% cell efficient monolithic perovskite‐OPV tandem withan impressive fill factor of 84%, which is the highest for perovskite‐OPVtandem cells reported to‐date.

Enhancing the photovoltaic performance of dithienobenzodithiophene based polymer donors through backbone fluorination and radical polymer additives

Unveiling the corresponding relationship between the molecular architecture of organic semiconductor materials and the morphology within the active layer of the organic solar cells (OSCs) is essential for the innovation of novel optical materials and the refinement of device optimization strategies to overcome the bottlenecks in efficiency. In this work, three dithieno[3,2-b]benzo[1,2-b;4,5-b’]dithiophene(DTBDT)-alt-benzothiadiazole (BT) based polymer donors (PDTBDT-F-BT, PDTBDT-F-FBT, and PDTBDT-F-2FBT) with varying fluorine atom content within their acceptor segments were designed and synthesized, and the photovoltaic performances of these polymers when blended with Y6 were meticulously investigated. Incorporating fluorine atoms into the BT segment was observed to not only incrementally increase the optical bandgap, lower the HOMO energy level, and bolster the self-aggregation of the polymer, but also effectively reduce the surface energy of the resulting polymer, thereby altering the donor-acceptor (D-A) interfacial spacing and the phase separation in the blend films as illustrated by molecular dynamic simulations and morphology characterization. As a result, the OSCs fabricated using PDTBDT-F-FBT, which incorporates a single fluorine substitution in the BT unit, demonstrated the highest power conversion efficiency (PCE) of 9.92 %. More importantly, this blend film's morphology is likely to be more conducive to the incorporation of the radical polymer additive, GDTA. This has resulted in a notable reduction in voltage loss, ultimately achieving a higher PCE of 11.55 % for the PDTBDT-F-FBT:Y6 based OSCs. This research uncovered a synergistic impact of backbone fluorination and the incorporation of radical polymer additives, which contributed to reducing the energy loss and enhancing the efficiency of OSCs from DTBDT-based polymer donors.

A novel leaf bionic flow field with structured multi-level channel based on Murray's law in proton exchange membrane fuel cell for enhanced mass transfer

The design of flow field has a significant impact on the performance of proton exchange membrane fuel cells (PEMFCs). In this study, a novel leaf bionic flow field is designed and optimized based on Murray's law. The power consumption ratio is first used in the bionic PEMFC. Additionally, an evaluation criterion, the mass transfer efficiency evaluation criterion (MTEEC), is proposed to characterize mass transfer efficiency, and field synergy theory is used to analyze performance differences in mass transfer among various flow fields. The results demonstrate that adding multi-level channel and obstacles in the flow field significantly enhances cell output performance and reduces voltage losses in mass transfer regions. Applying Murray's law to distribute multi-level channel improves the uniformity of oxygen concentration distribution in the flow field and alleviates under-rib water accumulation. Compared to the secondary stream flow field (SSFF), the structure mesh of leaf bionic flow field (SMLBFF) demonstrates a nearly 19% increase in current density output at 0.45 V. SMLBFF exhibits an 81.51% increase in convective mass transfer rate compared to SSFF at 0.4 V. Moreover, the MTEEC of SMLBFF shows improvements of 179.68% at 0.5 A/cm2 and 135.43% at 1.0 A/cm2, compared to SSFF.

Stability analysis and voltage improvement in DG-integrated distribution networks using VCPI-based critical buses and lines detection considering uncertain power factor

Voltage stability ensures reliable and efficient power transmission to end-users, making it essential for power system efficiency. Dynamic load changes and rising power requirements might cause voltage instability and strain performance. This paper investigates the voltage stability Indicators of distribution systems to address the voltage stability issue in power systems. The uncertain power factor and other numerous technical parameters that affect the voltage drop or voltage collapse are involved in predicting the system’s voltage stability. First, the analysis uses the voltage collapse proximity index (VCPI) technique, which considers bus voltage, impedance, uncertain power factor of load buses, and transmission line impedance at both ends. The applied technique correctly predicts and detects weak buses and transmission lines using different voltage stability indices since technical parameters are correlated with the VCP index. The index and line impedance correspond; consequently, the recommended indication compensates for voltage loss owing to impedance. Therefore, the VCPI is a better index for anticipating voltage collapse and finding network weak busses and lines. The implemented approach is simple, precise, and economical; the index technique detects weak buses and forecasts system collapse. Second, this work introduces EMFO-FPSO, a hybrid metaheuristic that improves voltage stability by combining Fractional-order particle swarm optimization (PSO) and Entropy design mouth flame optimization (MFO). The proposed approach is validated on the IEEE 33 bus system by identifying weak buses and optimizing distributed generation placement in the distribution system. The implemented solution approach based on VCPI and EMFO-FPSO optimization achieves a significant power loss reduction of 71.5% compared to the base case, whereas the reductions for ABC, ACO-ABC, and PSO are 57.3%, 60.7%, and 64.4%, respectively. Moreover, the proposed method attains a stable VCPI Index of 0.90, indicating a 10% enhancement in voltage stability relative to the base case. The study’s results, key findings, and comparisons show the relevance of the proposed method for voltage stability enhancement.

Continuous Graded Catalyst Layers for PEM Fuel Cells with Improved Humidity Range Tolerance

Grading electrodes is a promising approach to reduce ohmic and mass transport-related voltage losses in proton exchange membrane fuel cells. In graded electrodes, the ionomer and/or catalyst are spatially non-uniformly distributed to optimize performance over a wide operating range. In this study, through-plane ionomer gradients were fabricated with a simple wet-layer deposition technique that can readily be adapted in a roll-to-roll process. The presence of ionomer gradients was verified using scanning transmission electron microscopy and the profiles were found to be continuous despite using only two coating steps. Single cell tests revealed that the gradients outperform conventional electrodes and maintain the optimal performance for different relative humidities. These improvements were traced back to enhanced mass transport and protonic conduction properties identified by detailed electrochemical analysis. This manufacturing approach for electrodes offers an accessible toolbox to produce versatile and specialized multi-layered catalyst layers for different applications.