Excessive Aggregation Research Articles

Effects of the main media of wind and water on the biodiversity pattern of grassland and its driving mechanism in Poyang Lake

AbstractAs important media for species diffusion, water and wind are two important factors for grassland biodiversity conservation in lake areas. Exploring their driving mechanism on grassland biodiversity is crucial for maintaining the lake ecosystem's equilibrium. Our study utilizes the data of wind velocity and water level, which are significant performance factors for wind and water respectively in Poyang Lake from 2000 to 2020 to reveal their interannual time‐series fluctuation characteristics and their influence mechanism on the grassland biodiversity pattern. Landscape pattern indices and biodiversity indicators, such as the number of patches (NP), patch density (PD), landscape spreading index (CI), landscape fragmentation index (LSD), landscape aggregation index (AI), Simpson diversity index (MSIDI) and Simpson evenness index (MSIEI) were analysed, trend analysis, redundancy analysis and structural equation modelling were applied in this study. The main results were: (1) From 2000 to 2020, Poyang Lake's wind velocity decreased gradually, and the water level first decreased and then rose. NP in Poyang Lake fluctuated substantially, LSD fluctuated frequently and obvious temporal heterogeneity existed. (2) CI and AI increased from low to high value, facilitating species dispersal and migration. The dominant species with high aggregation gradually established stronger connectivity. Moderate spreading degree and aggregation degree maintained high biodiversity and evenness, whereas excessive spreading degree and aggregation degree led to homogenization of species, decrease in biodiversity, reduction in species evenness, and increase in dominance. (3) As the landscape transformed from having no obvious dominant species to being dominated by several dominant species, MSIEI and landscape dominance changed from high to low and low to high respectively. Moreover, the biodiversity shifted from high to low, and species distribution in the landscape shifted from balanced to unbalanced. (4) The effect of water level on PD, AI, LSD, MSIDI and MSIET was significantly higher than that of wind velocity. LSD was mainly regulated by the minimum wind velocity affecting the maximum and average water levels. MSIDI and MSIET were primarily governed by the minimum wind velocity affecting the minimum water level. The minimum water level decreased as the minimum wind velocity increased, and MSIDI and MSIET weakened as the minimum water level decreased.

Carboxymethylcellulose and rare earth metal cation self-assembly: Tunable encapsulation of carbon dots in a multifunctional transparent film

Due to their unique properties, carbon dots have attracted significant interest across diverse fields. However, obstacles such as uneven size distribution in the course of synthesis and excessive aggregation lead to fluorescence quenching during solidification process. Moreover, conventional doping procedures frequently yield carbon dot films with constrained functionality, inferior durability, and harsh environments, thereby restricting their practical applications. To address these issues, this study fabricates N-doped carbon dots via a straightforward hydrothermal approach and incorporates them into CMC films by metathesis with CeCl3·7H2O, resulting in a unique carbon dot-encapsulated film. This film overcomes the problem of fluorescence quenching caused by excessive aggregation of carbon dots and allows for size control by adjusting the concentration of Ce(III). The resulting film achieves extreme transparency and superior performance compared to existing UV-blocking films. In addition, the film exhibits exceptional resistance to acids and bases, bleaching, excellent mechanical properties, and good thermal and water stability. Based on these properties, the film achieves size-controlled in-situ photoluminescence, full UV shielding, Cu2+ ion detection, anti-counterfeiting, and information encryption. The water-processable and water-adhesive characteristics of CMC enable its use in real-life situations, opening the door to wider use of solid-state carbon dots for multifunctional and intelligent applications.

Fluorinated Naphthalene Diimides as Buried Electron Transport Materials Achieve Over 23% Efficient Perovskite Solar Cells.

Naphthalene diimides (NDI) are widely serving as the skeleton to construct electron transport materials (ETMs) for optoelectronic devices. However, most of the reported NDI-based ETMs suffer from poor interfaces with the perovskite which deteriorates the carrier extraction and device stability. Here, a representative design concept for editing the peripheral groups of NDI molecules to achieve multifunctional properties is introduced. The resulting molecule 2,7-bis(2,2,3,3,4,4,4-heptafluorobutyl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (NDI-C4F) incorporated with hydrophobic fluorine units contributes to the prevention of excessive molecular aggregation, the improvement of surface wettability and the formation of strong chemical coordination with perovskite precursors. All these features favor retarding the perovskite crystallization and achieving superior buried interfaces, which subsequently promote charge collection and improve the structural compatibility between perovskite and ETMs. The corresponding PSCs based on low-temperature processed NDI-C4F yield a record efficiency of 23.21%, which is the highest reported value for organic ETMs in n-i-p PSCs. More encouragingly, the unencapsulated devices with NDI-C4F demonstrate extraordinary stability by retaining over 90% of their initial PCEs after 2600 h in air. This work provides an alternative molecular strategy to engineer the buried interfaces and can trigger further development of organic ETMs toward reliable PSCs.

Leveraging Compatible Iridium(III) Complexes to Boost Performance of Green Solvent‐Processed Non‐Fullerene Organic Solar Cells

AbstractIn organic solar cells (OSCs), the short exciton lifetime poses a significant limitation to exciton diffusion and dissociation. Extending exciton lifetime and suppressing recombination are crucial strategies for improving the OSC performance. Herein, an effective approach is proposed by introducing the phosphorescent emitter, tris(2‐(4‐(tert‐butyl)phenyl)‐5‐fluoropyridine)Iridium(III), with long‐lived triplet exciton lifetime in OSCs. This research reveals that the steric structure of fac‐Ir(tBufppy)3 exhibits excellent compatibility with both the donor PM6 and acceptor BTP‐eC9, maintaining efficiencies of over 90% even with a 30% third component loading. Moreover, a 10% addition of fac‐Ir(tBufppy)3 mitigates excessive aggregation in the acceptor BTP‐eC9, optimizing the active layer morphology and improving the fill factor. Transient absorption spectroscopy and transient photoluminescence measurements demonstrate that the introduction of fac‐Ir(tBufppy)3 significantly extends exciton lifetimes and suppresses recombination, which increases the short‐circuit current (JSC). Ultimately, employing the non‐halogenated solvent o‐xylene for processing, an impressive power conversion efficiency (PCE) of 18.54% is achieved in devices based on PM6:10%fac‐Ir(tBufppy)3:BTP‐eC9, surpassing the efficiency of binary PM6:BTP‐eC9 devices (17.41%). This work provides a promising approach to further improve the PCEs in binary OSCs by introducing a phosphorescent iridium(III) complex as the third component.

Amplifying High‐Performance Organic Solar Cells Through Differencing Interactions of Solid Additive with Donor/Acceptor Materials Processed from Non‐Halogenated Solvent

AbstractDeveloping non‐halogenated solvent‐processed organic solar cells (OSCs) demands precise control over the bulk‐heterojunction (BHJ) morphology of the photoactive layer. However, the limited solubility of halogen‐free solvents to photoactive materials hinders microstructure morphology fine‐tuning for boosting photovoltaic performance. This study not only examines the debated intermolecular interactions between the DBrDIB solid additive and photoactive materials but also analyzes the substantial influence of volatile solid additive on the BHJ morphological properties. The DBrDIB effectively restricts the excessive aggregation of Y6‐BO and regulates the phase separation, which is attributed to strong intermolecular interactions with Y6‐BO and rapid quenching during morphology formation. It then achieves a well‐mixed D/A phase with favorable domain size, resulting in a balanced aggregation and dispersion of D/A, ultimately leading to markedly enhanced charge transfer and transport as well as suppressed charge recombination. The transformative use of the o‐xylene/DBrDIB solvent system propels PM6:Y6‐BO and PM6:Y6‐HU OSCs to impressive efficiencies of 17.9% and 19.1%, respectively, outperforming those of the control devices. These findings provide crucial insights into theoretical and experimental areas, offering actionable guidelines for designing high‐performance OSCs processed from halogen‐free solvent.

A triple-benefit strategy of microstructure, electronic property and active site modulation on ZnIn2S4 photocatalyst by Sn atom doping

To overcome the high cost and complex preparation of cocatalysts in photocatalytic H₂ production, this study pioneers a triple-benefit strategy in visible-light-absorbing semiconductors through microstructure optimization, electronic property modulation, and active site modification in two-dimensional (2D) hexagonal ZnIn₂S₄ (ZIS) via Sn atom doping. Facilely synthesized through a one-step hydrothermal method without surfactants, 4–6 nm thick Sn-doped ZIS nanosheets exhibit reduced charge recombination by preventing excessive self-assembly and aggregation. Density Functional Theory (DFT) and X-ray Absorption Fine Structure (XAFS) confirm Sn’s substitution for Zn on (001) surface, shifting the Fermi level into the conduction band to facilitate electron migration and charge separation. This adjustment also modulates the electronic properties of adjacent S atoms, triggering the inert basal plane for an enhanced H₂ evolution reaction kinetics. Consequently, Sn-ZIS achieves a H₂ evolution rate of 62.18 μmol h−1 under visible light, significantly outperforming pure ZIS and Pt@ZIS by 6.7 and 3.5 times, respectively.

Er2O3 doped ZnO–Cr2O3-based varistors with high voltage gradient

ZnO varistors are widely used in modern intelligent electrical equipment, and the preparation of miniaturized varistors with high voltage gradient has become a top priority. This work investigated the preparation of high voltage gradient ZnO–Cr2O3-based varistors doped with Er2O3 and analyzed the relationship between their microstructure and electrical properties. As the doping amount of Er2O3 increases from 0.00 to 0.75 mol%, Er2O3 phase obviously dissolving element Co distributed at the trigeminal grain boundaries increases, leading to the grain size d decreases from 3.16 to 1.70 μm, the nonlinear coefficient α increases from 6.22 to 50.48, the voltage gradient E1mA increases from 428.37 to 1616.76 V/mm, and the leakage current density JL decreases from 375.75 to 0.79 μA/cm2, achieving optimal comprehensive electrical performance of the sample with Er2O3 doping of 0.75 mol%, for which, the residual voltage ratios K reaches the minimum value of 1.14 under the impulse current density Jp of 63.7 A/cm2. When the doping amount of Er2O3 further increases to 1.00 mol%, the excessive Er2O3 phase aggregates at the trigeminal grain boundaries and distributes unevenly, leading to the growth of ZnO grains and performance deterioration of the samples. The ZnO–Cr2O3-based varistors have the advantages of much easier doping, and there is no dopant volatilization during the sintering process. This research provides an important reference for the development of high-performance, miniaturized ZnO–Cr2O3-based varistors.

Role of ultrasonic freezing­treated pork dumpling filling during frozen storage: Insights from protein oxidation, aggregation, and functional properties

The effects of air freezing (AF), immersion freezing (IF), and ultrasonic freezing (UF) on the oxidation, aggregation, and functional properties of myofibrillar protein (MP) in pork dumpling filling during frozen storage were investigated. The findings demonstrated that, compared to AF and IF treatments, UF treatment had higher total and reactive sulfhydryl content, solubility, and absolute zeta potential. Conversely, it exhibited lower values in carbonyl content, dityrosine content, turbidity, and particle size within the same storage time (p < 0.05). SDS-PAGE revealed that UF treatment delayed the oxidation and excessive aggregation of MP during frozen storage. Moreover, samples treated with UF at 180 days (d) displayed similar functional and qualitative characteristics to those treated with IF at 90 d or AF at 60 d, as per the hierarchical cluster analysis findings. In conclusion, UF effectively delayed the oxidation, aggregation, and loss of functional properties of MP in pork dumpling filling during frozen storage.

Functionally Modified Polymer Electrolyte Based on Noncovalent Interaction for Stable Lithium Metal Batteries.

The charge transfer efficiency of the solid electrolyte depends on the number of lithium ions that can be effectively transported and participate in the electrode reaction. However, limited by the strong coupling relationship between Li+ and Lewis basic sites on the polymer chain, the Li+ transference number (tLi+) of the solid polymer electrolyte (SPE) based dual-ion conductor is typically low, resulting in excessive anion aggregation at the electrode side and inducing concentration polarization. In this study, we present a functionalized modified polymer electrolyte (FMPE) with selective cation transport, which was synthesized by embedding 4-(trifluoromethyl)styrene (TFS) functionalized groups onto the poly(diethylene glycol diacrylate) polymer chain. The TFS group formed noncovalent couplings with TFSI- anions through hydrogen bondings and dipole-dipole interactions, which effectively limited the migration of the anions and contributed to the elevated tLi+ of the FMPEs to 0.595 and 0.699 at 25 and 60 °C, respectively. Density functional theory (DFT) calculations were performed to verify the increased anion migration barriers for different noncovalent interactions and revealed that the conjugated system formed by the delocalized π electrons of the benzene ring and the C═O groups helped to disperse the electron distribution of the polymer chains. Consequently, the decrease in the degree of Li+ immobilization promotes the decoupling and migration of Li+ between the polymer chains. Benefiting from optimized Li+ transport behavior, the lithium metal batteries (LMBs) assembled by FMPEs and LiFePO4 exhibit excellent rate performance (discharge specific capacity of 88.8 mAh g-1 at 5 C) and stable long-term cycle performance (capacity decay rate of only 0.064% per cycle for 500 cycles at 25 °C and 0.5 C).

Surface modified FeCoZn-ZIF derived polyhedral electrocatalysts for ORR under alkaline and acidic conditions

Electrocatalysts for catalyzing oxygen reduction reactions at variable pH conditions are essential for energy conversion and storage. Herein, Fe@FeCoZn–CN electrocatalysts were prepared with internal and external doping approach. The Fe@FeCoZn–CN electrocatalyst exhibits a desirable ORR performance in both acid and alkaline electrolytes. Specifically, the half-wave potential (E1/2) of Fe@FeCoZn–CN electrocatalyst is 0.890 V which far beyond Pt/C electrocatalyst (0.839 V) in alkaline electrolyte. In addition, Fe@FeCoZn–CN electrocatalyst also exhibits improved ORR activity (E1/2 = 0.801 V) compared to Pt/C (0.797 V) electrocatalysts in acidic electrolytes. What's exciting is that the rechargeable ZABs based on Fe@FeCoZn–CN electrocatalysts exhibit an impressive performance with a favorable open-circuit potential of 1.517 V and a promising specific capacity is 833.7 mA h gzn−1, good charge/discharge cycle stability. The remarkable ORR catalytic performance of Fe@FeCoZn–CN electrocatalysts can be traced to the internal doping of metals which prevent excessive metal aggregation and surface modified which can increase the metal loading to expose more active sites.

Optimizing the formation of myosin/high-density lipoprotein composite gels: PH-dependent effects on heat-induced aggregation

This study investigated impact of high-density lipoprotein (HDL) on thermal aggregation and gelling behavior of myosin in relation to varied pHs. Results revealed that HDL modified myosin structure before and after heating, with distinct effects observed at varied pH. Under pH 5.0, both myosin and HDL-MS exhibited larger aggregates and altered microstructure; at pH 7.0 and 9.0, HDL inhibited myosin aggregation, resulting in enhanced solubility, reduced turbidity and particle size. Comparative analysis of surface hydrophobicity, free sulfhydryl groups and secondary structure highlighted distinct thermal aggregation behavior between MS and HDL-MS, with the latter showing inhibitory effects under neutral or alkaline conditions. Gelation behavior was enhanced at pH 7.0 with maximum strength, hardness, water-holding capacity and rheological properties. Under acidic pH, excessive protein aggregation resulted in increased whiteness and rough microstructure with granular aggregates. Under alkaline pH, gel network structure was weaker, possibly due to higher thermal stability of protein molecules. Scanning electron microscopy revealed expanded HDL protein particles at pH 7.0, accounting for decreased gel strength and altered rheological properties compared with myosin gel. Overall, the results indicated a positive role of HDL at varied pH in regulating thermal aggregation of myosin and further impacting heat-induced gel characteristics.

Optimizing Alkyl Side Chains in Difluorobenzene-Rhodanine Small-Molecule Acceptors for Organic Solar Cells.

A series of small molecules, T-2FB-T-ORH, T-2FB-T-BORH, and T-2FB-T-HDRH, were synthesized to have a thiophene-flanked difluorobenzene (T-2FB-T) core and alkyl-substituted rhodanine (RH) end groups for their use as nonfullerene acceptors (NFAs) in organic solar cells (OSCs). Octyl, 2-butyloctyl (BO), and 2-hexyldecyl (HD) alkyl side chains were introduced into RHs to control the material's physical properties based on the length and size of the alkyl chains. The optical properties of the three NFAs were found to be almost the same, irrespective of the alkyl chain length, whereas the molecular crystallinity and material solubility significantly differed depending on the alkyl side chains. Owing to the sufficient solubility of T-2FB-T-HDRH, OSCs based on PTB7-Th and T-2FB-T-HDRH were fabricated. A power conversion efficiency of up to 4.49% was obtained by solvent vapor annealing (SVA). The AFM study revealed that improved charge mobility and a smooth and homogeneous film morphology without excessive aggregation could be obtained in the SVA-treated film.

Insight Into Designing High‐Performance Polythiophenes for Reduced Urbach Energy and Nonradiative Recombination in Organic Solar Cells

AbstractIn the pursuit of high‐efficiency polythiophene (PT) organic solar cells (OSCs), a critical challenge is the reduction of nonradiative recombination. This study comprehensively explores polydithienylthiazolothiazole (PTTz)‐based PT terpolymers: PTTz‐Tz and PTTz‐TzT, in which it is demonstrate that molecular structure alterations greatly influence the aggregation kinetics and orientation of these polymers. Specifically, PTTz‐TzT achieves rapid ordering aggregation during spin coating, effectively suppressing excessive polymer aggregation and facilitating appropriate phase separation upon mixing with the acceptor. Meanwhile, PTTz‐TzT inherently adopts a face‐on orientation, resulting in more structured π–π stacking in the vertical direction after acceptor integration, compared to the intrinsic edge‐on orientation of PTTz‐Tz. These factors collectively contribute to lower Urbach energy and a substantial reduction of nonradiative recombination in PTTz‐TzT‐based OSCs, culminating in a high photovoltaic conversion efficiency (PCE) exceeding 16%. Furthermore, a prominent PCE of 19.11% is obtained by PTTz‐TzT via ternary blend strategy, which is among the highest values reported for the OSCs. This investigation underscores the significance of aggregation kinetics and orientation in PT‐based polymers, especially regarding Urbach energy and nonradiative recombination, and offers novel insights for designing high‐performance polythiophene donors.

Non-halogenated Solvent-Processed Organic Solar Cells with Approaching 20 % Efficiency and Improved Photostability.

The development of high-efficiency organic solar cells (OSCs) processed from non-halogenated solvents is crucially important for their scale-up industry production. However, owing to the difficulty of regulating molecular aggregation, there is a huge efficiency gap between non-halogenated and halogenated solvent processed OSCs. Herein, we fabricate o-xylene processed OSCs with approaching 20 % efficiency by incorporating a trimeric guest acceptor named Tri-V into the PM6:L8-BO-X host blend. The incorporation of Tri-V effectively restricts the excessive aggregation of L8-BO-X, regulates the molecular packing and optimizes the phase-separation morphology, which leads to mitigated trap density states, reduced energy loss and suppressed charge recombination. Consequently, the PM6:L8-BO-X:Tri-V-based device achieves an efficiency of 19.82 %, representing the highest efficiency for non-halogenated solvent-processed OSCs reported to date. Noticeably, with the addition of Tri-V, the ternary device shows an improved photostability than binary PM6:L8-BO-X-based device, and maintains 80 % of the initial efficiency after continuous illumination for 1380 h. This work provides a feasible approach for fabricating high-efficiency, stable, eco-friendly OSCs, and sheds new light on the large-scale industrial production of OSCs.

Non‐halogenated Solvent‐Processed Organic Solar Cells with Approaching 20 % Efficiency and Improved Photostability

AbstractThe development of high‐efficiency organic solar cells (OSCs) processed from non‐halogenated solvents is crucially important for their scale‐up industry production. However, owing to the difficulty of regulating molecular aggregation, there is a huge efficiency gap between non‐halogenated and halogenated solvent processed OSCs. Herein, we fabricate o‐xylene processed OSCs with approaching 20 % efficiency by incorporating a trimeric guest acceptor named Tri‐V into the PM6:L8‐BO‐X host blend. The incorporation of Tri‐V effectively restricts the excessive aggregation of L8‐BO‐X, regulates the molecular packing and optimizes the phase‐separation morphology, which leads to mitigated trap density states, reduced energy loss and suppressed charge recombination. Consequently, the PM6:L8‐BO‐X:Tri‐V‐based device achieves an efficiency of 19.82 %, representing the highest efficiency for non‐halogenated solvent‐processed OSCs reported to date. Noticeably, with the addition of Tri‐V, the ternary device shows an improved photostability than binary PM6:L8‐BO‐X‐based device, and maintains 80 % of the initial efficiency after continuous illumination for 1380 h. This work provides a feasible approach for fabricating high‐efficiency, stable, eco‐friendly OSCs, and sheds new light on the large‐scale industrial production of OSCs.

Low‐Temperature Processed Efficient and Reproducible Blade‐Coating Organic Photovoltaic Devices with γ‐Position Branched Inner Side Chains‐Containing Nonfullerene Acceptor

Recent advancements in blade‐coating organic photovoltaic (OPV) devices utilizing eco‐friendly nonhalogenated solvents have demonstrated high power conversion efficiencies (PCEs) when processed at high substrate temperatures. However, this method poses challenges in device reproducibility and stability. Herein, a BTP‐eC9‐γ nonfullerene acceptor (analogous to BTP‐eC9) with γ‐position‐branched inner side chains within the BTP‐eC9‐based structural motif is developed. This pin‐sized extension in the branching position enhances the solubility of BTP‐eC9‐γ in nonhalogenated toluene solvent. This improvement not only mitigates excessive aggregation in the film state but also facilitates device fabrication at lower substrate temperatures. Optimized at a substrate temperature of 40 °C, the BTP‐eC9‐γ‐based blade‐coating devices with toluene achieve remarkable PCEs of 16.43% (0.04 cm2) and 14.95% (1.0 cm2). Furthermore, these devices retain their high film uniformity at 40 °C, which contributes to superior device reproducibility. This is attributed to the minimized alteration in the evolution kinetics of fluid flow. These findings signify a promising direction for the industrial production of blade‐coating OPV devices.

Zombie Credit and (Dis‐)Inflation: Evidence from Europe

ABSTRACTWe show that “zombie credit”—subsidized credit to nonviable firms—has a disinflationary effect. By keeping these firms afloat, zombie credit creates excess aggregate supply, thereby putting downward pressure on prices. Granular European data on inflation, firms, and banks confirm this mechanism. Markets affected by a rise in zombie credit experience lower firm entry and exit, capacity utilization, markups, and inflation, as well as a misallocation of capital and labor, which results in lower productivity, investment, and value added. If weakly capitalized banks were recapitalized in 2009, inflation in Europe would have been up to 0.21 percentage points higher post‐2012.

Homogeneous Organic Crystal Nucleation Rates in Solution from the Perspective of Chemical Reaction Kinetics

It is demonstrated for 11 different combinations of organic solutes and solvents that the supersaturation dependence of homogeneous organic crystal nucleation rates from solution can be predicted from the solubility, bar a single empirical rate constant, when it is assumed that nucleation takes place in reversible aggregates of solvated solutes formed in supersaturated solutions. Reversible solute aggregation represents natural solute density fluctuations that take place in any solute/solvent system. For thermodynamically ideal solutions, the steady state size distribution, and thus the population of reversible aggregates in supersaturated solution, can be predicted quantitatively from the overall solute concentration by a simple mathematical expression. Supersaturation creates an excess of reversible aggregates with sizes exceeding that of the largest aggregate in saturated solution. It is shown that the number of these excess aggregates is proportional to experimental homogeneous nucleation rates, suggesting a rate equation for homogeneous nucleation that has only one empirical parameter, namely, a rate constant specific to the solute/solvent combination. This rate constant can be determined from standard nucleation rate data. The system-specificity of homogeneous nucleation rates thus appears to be encoded solely in a rate constant for the transformation of the large excess aggregates into crystal nuclei. The driving force for triggering nucleation events in these aggregates is likely the extremely high local supersaturation, which provides the conditions for spatiotemporally aligned bond-breaking (e.g., de-solvation) and bond-forming (e.g., solute–solute bonding) events that create stable crystal nuclei. The possible influence of heterogeneous nucleation by solid impurities is considered.

Heterogeneous Nucleating Agent for High-Boiling-Point Nonhalogenated Solvent-Processed Organic Solar Cells and Modules.

High-boiling-point nonhalogenated solvents are superior solvents to produce large-area organic solar cells (OSCs) in industry because of their wide processing window and low toxicity; while, these solvents with slow evaporation kinetics will lead excessive aggregation of state-of-the-art small molecule acceptors (e.g. L8-BO), delivering serious efficiency losses. Here, a heterogeneous nucleating agent strategy is developed by grafting oligo (ethylene glycol) side-chains on L8-BO (BTO-BO). The formation energy of the obtained BTO-BO; while, changing from liquid in a solvent to a crystalline phase, is lower than that of L8-BO irrespective of the solvent type. When BTO-BO is added as the third component into the active layer (e.g. PM6:L8-BO), it easily assembles to form numerous seed crystals, which serve as nucleation sites to trigger heterogeneous nucleation and increase nucleation density of L8-BO through strong hydrogen bonding interactions even in high-boiling-point nonhalogenated solvents. Therefore, it can effectively suppress excessive aggregation during growth, achieving ideal phase-separation active layer with small domain sizes and high crystallinity. The resultant toluene-processed OSCs exhibit a record power conversion efficiency (PCE) of 19.42% (certificated 19.12%) with excellent operational stability. The strategy also has superior advantages in large-scale devices, showing a 15.03-cm2 module with a record PCE of 16.35% (certificated 15.97%).

GUIDE: Training Deep Graph Neural Networks via Guided Dropout Over Edges.

Graph neural networks (GNNs) have made great progress in graph-based semi-supervised learning (GSSL). However, most existing GNNs are confronted with the oversmoothing issue that limits their expressive ability. A key factor that leads to this problem is the excessive aggregation of information from other classes when updating the node representation. To alleviate this limitation, we propose an effective method called GUIded Dropout over Edges (GUIDE) for training deep GNNs. The core of the method is to reduce the influence of nodes from other classes by removing a certain number of inter-class edges. In GUIDE, we drop edges according to the edge strength, which is defined as the time an edge acts as a bridge along the shortest path between node pairs. We find that the stronger the edge strength, the more likely it is to be an inter-class edge. In this way, GUIDE can drop more inter-class edges and keep more intra-class edges. Therefore, nodes in the same community or class are more similar, whereas different classes are more separated in the embedded space. In addition, we perform some theoretical analysis of the proposed method, which explains why it is effective in alleviating the oversmoothing problem. To validate its rationality and effectiveness, we conduct experiments on six public benchmarks with different GNNs backbones. Experimental results demonstrate that GUIDE consistently outperforms state-of-the-art methods in both shallow and deep GNNs.