Expandable polystyrene (EPS) foam is widely used in external wall insulation, packaging, logistics, and other fields, but it is limited by high fire hazard. To enhance the flame retardancy of EPS foam, this study fabricated a green and efficient biomass-based multifunctional flame-retardant coating (PDA@xLC@yAPP) through dopamine (DA)-mediated combination of lignocellulose (LC) and ammonium polyphosphate (APP). Specifically, LC was functionally modified, and APP was anchored on its surface via DA; the resulting coating was then applied to the surface of EPS foam, successfully constructing an EPS composite material with excellent flame-retardant and smoke-suppressant properties as well as green and environmentally friendly characteristics. The results show that the limiting oxygen index (LOI) of E-PDA@6LC@6APP exceeds 60 vol%, and it achieves V-0 grade in the vertical burning (UL-94) test, effectively inhibiting melt dripping. In the cone calorimeter test, compared with pure EPS, the peak heat release rate (pHRR) is reduced by 50.71%, the peak smoke production rate (pSPR) is decreased by 14.29%, and the smoke release is delayed by approximately 170 s. Additionally, the fire growth index (FGI) is 1.29, and the fire performance index (FPI) is 0.1446. This biomass-based LC flame-retardant coating not only fills the research gap in the field of biomass-based LC for EPS flame retardancy but also exhibits broad application prospects.

Small-molecule organic photovoltaic materials offer advantages of precise molecular definition, high purity, and excellent reproducibility, making them promising for large-scale applications. However, almost all-small-molecule organic solar cells (ASM-OSCs) rely on fused-ring electron acceptors and halogenated solvents, whose complex synthesis, high cost, and environmental hazards hinder commercialization. To address these challenges, we report halogen-free ASM-OSCs based on nonfused-ring acceptors (NFREAs). Using the nonfused acceptor 2BTh-2F and donor MPhS-C6, we systematically investigated various halogen-free processing solvents. The blend film processed with high-boiling-point toluene exhibited optimal nanoscale morphology, with balanced molecular self-assembly and well-defined nanofibrillar domains that promoted efficient charge transport. As a result, the corresponding device achieved a power conversion efficiency of 13.89%, substantially exceeding the 11.58% achieved with chloroform and representing the highest device performance reported for halogen-free ASM-OSCs employing NFREAs. This work provides a practical and environmentally friendly strategy toward scalable, high-performance, halogen-free OSCs.

Molecular aggregation and phase morphology of the active layer in bulk-heterojunction (BHJ) solar cells are crucial to attain efficient and stable organic solar cells (OSCs). Most studies of solid additives in high-efficiency OSCs have primarily focused on the impact of these additives on the acceptors, while largely neglecting the synergistic effects of additives on donor and acceptor. Herein, we introduce a synergistic morphology regulation approach by utilizing two isomeric solid additives (4-bromobenzothiadiazole (4-BBT) and 5-bromobenzothiadiazole (5-BBT)). 4-BBT or 5-BBT promotes both the crystallinity and u03C0u2013u03C0 stacking of the polymer donor PM6 while effectively suppressing excessive aggregation of the acceptor L8-BO, which leads to a favorable phase morphology. When mixed additives are loaded simultaneously, synergistic regulation can be achieved, enabling finer nanoscale phase separation with enhanced donoru2013acceptor miscibility and well-ordered packing. Further analyses indicate that the mixed additives effectively slow down the film formation and charge relaxation dynamics, thereby prolonging crystallization time and enhancing u03C0u2013u03C0 stacking while effectively suppressing recombination losses. Consequently, modified by the mixed additives, the PM6:L8-BO device demonstrates high efficiency of 19.32%, coupled with improved short-circuit current (JSC) and fill factor (FF). Besides, the D18:L8-BO-C4-based devices treated with 4-BBT+5-BBT delivered a remarkable efficiency of 20.13%, with an outstanding FF of 83.01%. Furthermore, the optimized device shows excellent photostability and thermal stability. This study provides a versatile and effective strategy for accurate regulation of the molecular aggregation and phase morphology through synergistic isomeric solid additive engineering, thereby offering insights into the rational design of efficient and stable organic photovoltaic materials.

Aiming at the low utilization rate of copper tailings (CTS), this study proposes using CTS as a flame-retardant material, leveraging its content of silicon, aluminum, iron and other metallic elements. By introducing the composite system of CTS and aluminum hypophosphite (AHP) into the preparation process of rigid polyurethane foam (RPUF), flame-retardant RPUF composites were successfully developed. Flame-retardant tests show that the R-CTS/2AHP sample achieves a limiting oxygen index (LOI) of 23.7 vol

Building-integrated photovoltaics (BIPVs) is a promising application for semitransparent organic solar cells (ST-OSCs). However, conventional ultra-thin (<80 nm) active layers for ST-OSCs, while balancing transmittance and efficiency, limit the cell-to-module efficiency remaining ratio (CTM) below 56%. Here, we achieve high semitransparency and efficiency in ST-OSCs with reasonable active layer thickness by manipulating the aggregation of acceptors in various donor-diluted blends processed with non-halogen solvent in ambient air. Using PM6:Qx-p-4Cl as a model system, we elucidate a unique film-formation mechanism and charge generation process, demonstrating that the fiber network and suitable aggregation size are crucial for ensuring higher performance in donor-diluted ST-OSCs. The 1 cm2 donor-diluted ST-OSCs with active layer thicknesses of 119 and 301 nm exhibit high light utilization efficiencies (LUEs) of 4.04% and 3.02%, respectively. Notably, a 100 cm2 module demonstrates a CTM ratio of ~85% and a LUE of 3.32%, owing to its high film thickness tolerance, setting a new benchmark for large-area semitransparent modules. Furthermore, we demonstrate the feasibility of BIPVs in terms of power generation, energy storage, and temperature control through a scale-down model with a 600 cm2 power-generating window. These results reveal promising prospects for ST-OSCs in real-world applications.

Molecular aggregation and phase morphology of the active layer in bulk-heterojunction (BHJ) solar cells are crucial to attain efficient and stable organic solar cells (OSCs). Most studies of solid additives in high-efficiency OSCs have primarily focused on the impact of these additives on the acceptors, while largely neglecting the synergistic effects of additives on donor and acceptor. Herein, we introduce a synergistic morphology regulation approach by utilizing two isomeric solid additives (4-bromobenzothiadiazole (4-BBT) and 5-bromobenzothiadiazole (5-BBT)). 4-BBT or 5-BBT promotes both the crystallinity and rr-rr stacking of the polymer donor PM6 while effectively suppressing excessive aggregation of the acceptor L8-BO, which leads to a favorable phase morphology. When mixed additives are loaded simultaneously, synergistic regulation can be achieved, enabling finer nanoscale phase separation with enhanced donor-acceptor miscibility and well-ordered packing. Further analyses indicate that the mixed additives effectively slow down the film formation and charge relaxation dynamics, thereby prolonging crystallization time and enhancing rr-rr stacking while effectively suppressing recombination losses. Consequently, modified by the mixed additives, the PM6:L8-BO device demonstrates high efficiency of 19.32%, coupled with improved short-circuit current (JSC) and fill factor (FF). Besides, the D18:L8-BO-C4-based devices treated with 4-BBT+5-BBT delivered a remarkable efficiency of 20.13%, with an outstanding FF of 83.01%. Furthermore, the optimized device shows excellent photostability and thermal stability. This study provides a versatile and effective strategy for accurate regulation of the molecular aggregation and phase morphology through synergistic isomeric solid additive engineering, thereby offering insights into the rational design of efficient and stable organic photovoltaic materials. Without additive treatment With 4-BBT or 5-BBT treatment With 4-BBT + 5-BBT treatment Current density (mAcm-2) 0-5-10-15-20-25-30 D18/L8-BO-C4 4-BBT+5-BBT FF = 83.01% PCE = 20.13% 0.0 0.2 0.4 0.6 0.8 1.0 Voltage (V)

Organic solar cells (OSCs) offer unique advantages like flexibility and lightweight design, making them suitable for solar-extended unmanned aerial vehicles (SUAVs). However, conventional transparent electrodes limit their performance due to high sheet resistance. To address this, a flexible, transparent electrode with ultra-low sheet resistance (<1 Ω/□) and 90% transmission was developed. Utilizing non-halogenated solvent processing and slot-die coating, a 1 cm2 single cell achieved 17.12% (certified 16.88%) power conversion efficiency (PCE), while a 42 cm2 module achieved 15.60%. Stability tests showed unencapsulated devices retained 90% efficiency after 1080 h (ISOS-D-1) and 97% after 1000 bending cycles. SUAVs equipped with the flexible OSC modules, combined with a lithium battery and power management system, demonstrated a flight time extension of 24.2%. Outdoor testing confirmed reliable sensor performance and data transmission. This study validates flexible OSCs for SUAV applications, advancing renewable energy solutions in lightweight mobile systems.

The oligomeric acceptor is an intrinsically stable and efficient organic photovoltaic material because it combines the advantages of monomeric and polymeric acceptors. The connection site significantly influences the oligomeric acceptor properties; however, the design principles are still unclear. Herein, center-linked (C-Dimer and C-Trimer) and end-linked (E-Dimer and E-Trimer) oligomeric acceptors are designed and synthesized based on high-performance quinoxaline-based acceptors. We systematically investigated their differences in electronic structural properties, film-formation dynamics, and morphology through calculation, in situ UV-vis and dynamic light scattering, and morphology characterizations. It is found that end-linked acceptors have the following advantages: 1) superior electronic properties: higher super-exchange coupling and smaller reorganization energy facilitate intra-molecular charge transport; 2) stronger molecular interactions: pre-aggregation in dilute or concentrated solution and stronger miscibility enable slow assembly into dense fibrous morphology, achieving concurrent efficient exciton dissociation and charge transport. Hence, the PM6: E-Dimer-based device achieves the optimal efficiency of 18.02% with a t 80 of 4096 hours. E-Dimer also acts as an effective third in the classical D18: L8-BO system to improve efficiency from 18.77% to 19.73%. Our results demonstrate the enormous potential of E-oligomers in engineering high-performance OSCs and provide guidance for further design of highly efficient oligomeric acceptors.

Organic solar cells (OSCs) have experienced remarkable performance progress up to 20

Organic solar cells (OSCs) based on small molecular donor and polymer acceptor (SD/PA-type) show low photovoltaic performance due to the unideal morphology. However, previous work mainly focused on the aspects of donors, but how the polymer acceptor influences its morphology and device performances is lacking in study. In this work, we apply three polymerized nonfullerene small molecules as acceptors, combining film-forming kinetics and microstructure characterization to investigate the efficient SD/PA-type OSCs requirements on polymers. We found the following two results: Strong miscibility between donor and acceptor would facilitate the acceptor inducing the donor to adopt a face-on packing; under similar miscibility, the inferior crystallinity of the acceptor facilitates a more proper phase separation. Hence, the DTBDT-C3-D6:PY2S-F-based SD/PA-type OSCs with the best miscibility achieve an impressive PCE of 13.65% with both high short-circuit current density (Jsc) of 20.73 mA cm-2 and fill factor (FF) of 72.93%, which are among the highest values in the reported binary SD/PA-type OSCs so far. Our work provides a new perspective for the development of highly efficient SD/PA-type OSCs with polymer acceptor matched to small molecule donor.

All-small-molecule organic solar cells (ASM-OSCs) with completely definite chemical structure are an ideal model to establish the relationship between molecular structure and device performance via aggregates. The end-capped acceptor unit is of great significance in the regulation of aggregates by essential molecular interactions. However, the successful end-capped acceptor units for small-molecule donors have been rather poorly studied and only focused on the alkyl substituted rhodamine, limiting further development for ASM-OSCs. In this study, three novel end-capped acceptors are designed by fluorinating the benzyl-substituted rhodamine, and results show that both the fluorinated position and quantity make significant effect on the dynamic film formation, aggregation and photoelectric properties in both the pure and blend films. Pairing with BTP-eC9, the MPhS-m-1F with single meta-fluorinated end groups performs a satisfactory PCE of 16.10% with the most efficient charge carrier management, which is one of the highest efficiencies in additive-free ASM-OSCs. These results open a window for the diverse of efficient end-capped units and provide design guidance for their further improvements.

With the continuous growth in demand for flame-retardant materials in the construction and insulation industries, flame-retardant modification of rigid polyurethane foam (RPUFs) has become critical for their safe application in scenarios such as building energy conservation, cold chain refrigeration, and pipeline insulation. However, the high loading levels of traditional flame retardants often result in reduced mechanical strength and/ or increased thermal conductivity of RPUFs. To address this issue, this study aims to enhance the flame retardancy, smoke suppression performance, mechanical strength, and thermal insulation properties of RPUFs by synthesizing an organic flame retardant additive containing phosphorus and silicon (PSiFR) and blending it with diatomaceous earth into RPUFs, leveraging the synergistic effects of the two materials. The optimal formulation is RPUFs containing 9.6 wt% PSiFR and 0.4 wt% diatomaceous earth (RPUF-3). Specifically, the peak heat release rate, total heat release, and total smoke generation of RPUF-3 are 47.2 %, 40.6 %, and 27.0 % lower than those of unmodified RPUFs, respectively. Compared with the compressive strength of unmodified RPUF (6.12kN center dot m/kg), the compressive strength of RPUF-3 is increased to 6.72 kN center dot m/kg. And also, its thermal conductivity (0.044 W/(m center dot K)) shows a downward trend compared with that of unmodified RPUF (0.044 W/(m center dot K)). The synergistic addition of PSiFR and diatomite successfully achieved simultaneous improvements in the flame retardancy, smoke suppression capability, mechanical strength, and thermal insulation performance of RPUF. This method provides an efficient and feasible modification strategy for fields such as building energy conservation and cold chain refrigeration.

ABSTRACT In this work, piperazine pyrophosphate (PAPP) and metallurgical solid steel slag (SS) are used to fabricate flame‐retardant rigid polyurethane foam (RPUF) composites through a one‐step all‐water foaming technology. The thermal stability, combustion properties, and flame retardancy of the PAPP/SS composite were investigated by thermogravimetric (TG) analysis, cone calorimetry, limiting oxygen index testing (LOI), and UL‐94 vertical burn testing. RPUF‐3 showed a char residue of 28.6 wt% at 750°C compared with 24.9 wt% of the pure sample, indicating better thermal stability of the FRPRUF composites. RPUF‐3 possessed an LOI of 21.5 vol% and achieved a V‐0 level in the UL‐94 test. Cone calorimetry displayed the peak heat release rate and fire growth rate index of RPUF‐3 were decreased by 12.66% and 41.6%, respectively, compared with those of pure RPUF. PAPP/SS incorporation led to the formation of compact char layer structures during combustion. Pyrophosphoric acid, generated from the decomposition of PAPP, promotes the formation of esters, ethers, and alcohols, whereas metal oxides in SS enhance the compactness of the char layer. This enhanced structural integrity obstructs mass and heat transmission in the combustion zone, effectively improving condensed‐phase flame retardancy. This approach offers a novel strategy for the fabrication of high‐performance RPUF composites and the high‐value utilization of SS.

Small molecule donor/polymer acceptor(SMD/PA)solar cells demonstrate high stability and notable performance advantages due to reduced molecular weight distribution variability,indicating potential breakthroughs in power conversion efficiency(PCE).However,research in this area is limited.This manuscript synthesizes two novel small donor molecules,DTBDT-C1-D6 and DTBDT-C3-D6(DTBDT represents dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene,C3 denotes a three-carbon spacer between the alkyl chain's branching point and the core linkage site,C1 denotes a one-carbon spacer between the alkyl chain's branching point and the core linkage site,and D6 represent π bridge has two alkyl chains with six carbon atoms each),combined additives of chloronaphthalene(CN),to investigate their effects on packing properties,film formation dynamics,and device performance.Interestingly,the CN significantly impact the packing modes and ability of the donors,and ultimately the intermolecular interaction and the dynamics of film forming,making the device performance fluctuate wildly with the CN ratio.The DTBDT-C3-D6 molecule,with alkyl chains branching away from the donor core,with 1%CN in volume,forms an interpenetrating framework by the proper hetero/homo molecular interaction,promoting a PCE of 13.4%,significantly exceeding the 5.65%of the DTBDT-C1-D6 blend and also other CN volume ratios.This PCE is the highest reported for SMD/PA-type organic solar cells(OSCs).The findings highlight the importance of alkyl side chain branching and additives in modulating intermolecular interactions and film dynamics,offering insights into morphology control in OSCs.

Wood materials have been basic building and structural materials for thousands of years, but because of their particular composition, the flammability and flame retardant modification of wood composites have attracted widespread attention. In this study, a new strategy was designed for flame retardant modification of commercial wood boards, and a series of wood samples were prepared with improved hydrophobic and flame retardant properties via delignification, impregnation of phytic acid (PA) and 3, 5-diamino-1,2,4-triazole (ATA-N), and surface hydrophobic modification of trimethoxymethylsilane. After impregnation with PA and ATA-N, the wood samples exhibited outstanding flame retardant properties, and the Wood@PA/ATA-N sample presented a limit oxygen index (LOI) of more than 80 % and a UL-94 V-0 rating. In addition, the peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) of Wood@PA were 92.0 %, 68.0 % and 63.0 % lower than those of the untreated wood. Moreover, surface treatment with organosilane significantly improved the hydrophobicity of the wood surface, and the water contact angle of the surface for Wood@PA/ATA-N/MTMS reached 93.4 degrees, indicating a highly hydrophobicity. In conclusion, the strategies of delignification, flame retardant impregnation and surface modification could significantly improve the flame retardancy and hydrophobic properties of wood samples, thereby increasing their useful life and application value in construction and structural materials.

Giant dimeric donors possess definite chemical structures and regulatable molecular skeletons and are expected to become alternative photovoltaic materials for polymer donors with batch differences. However, the design of giant dimeric donors is still at an early stage and needs to be further explored. Here, through creative semi-flexible and flexible linker design, we synthesized three interesting giant dimeric donors with relative monomer positions ranging from parallel to staircase to perpendicular in their optimized conformation. Unusually, the hyperconjugation effect in the semi-flexible linker stabilizes the perpendicular conformation, which results in the strongest homo-molecular interactions exhibiting non-planar molecular conformation. Combining calculations and multiple morphology characterization on dynamic and thermal packing, we systematically analyze the hyperconjugation effects, flexibility, and hetero-molecular interaction on the assembly. As a result, applying Y6 as an acceptor, the giant dimeric donor of BDT-Dimer3 with a semi-flexible non-planar linker achieved a satisfactory efficiency of 15.68% with a cutting-edge short-circuit current of 27.39 mA cm-2 and an improved photostability with a T80 of 630 hours. Our results provide hyperconjugated linker design for efficient and stable OSC devices with definite structures, as well as a deep understanding of the assembly in both pure and mixed systems.

A novel bio-based flame retardant(Furan-2DOPO)was synthesized from 5-hydroxymethylfurfural,furfuramine,phosphorus oxychloride and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO).Its struc-ture was characterized by Fourier transform infrared spectroscopy,proton-and phosphorus-nuclear magnetic resonance spectroscopy.A series of cured flame retarded epoxy products was obtained by modification of epoxy resin with Furan-2DOPO.The effects of the loading of Furan-2DOPO on the mechanical properties,thermal stability and flame retardant properties of the cured epoxy products were investigated.The results showed that when the addition amount of Furan-2DOPO was only 5%(mass fraction,phosphorus mass fraction was 0.47%),the oxygen index of the cured epoxy product reached 31.0%,and can pass the UL-94 V-0 test;compared with the unmodified epoxy resin,the peak heat release rate of the cured epoxy products containing 2.5%(mass fraction)and 5%(mass fraction)Furan-2DOPO was decreased by 31%and 35%,respectively.In addition,the tensile strength of the cured epoxy products containing 2.5%and 5%Furan-2DOPO was about 28%higher than that of the unmodified epoxy resin,respectively.The results of char analysis indicated that Furan-2DOPO possessed excellent catalytic charring performance,which was conducive to reducing the escape of combustible gases during combustion,so as to improve the flame retardant performance.

In addition to the donor-acceptor nano phases, the intermixed phase within the organic blends is crucial for the photovoltaic performance and stability of the bulk-heterojunction organic solar cells (OSCs). Here, the intermixed phase of a representative M-PhS:BTP-eC9 all-small-molecule organic solar cell was investigated by a concentration-dependent ultraviolet-visible (UV-vis) absorption spectroscopy method, where a shift of the absorption maximum wavelength was measured for the acceptor component with the increase of the acceptor concentration. The blend ratios of the acceptor to the donor in the intermixed phase, corresponding to the critical concentration for the formation of the acceptor nanophase (CAP), were determined to be 0.35, 0.20, and 0.15 for the as-cast, thermal annealing (TA), and the combined TA and solvent vapor annealing films. These results indicated that M-PhS and BTP-eC9 are kinetically well intermixed during spin coating, whereas TA and the following solvent annealing promote the crystallization of BTP-eC9 molecules out of the intermixed phase. The photovoltaic performance of the M-PhS:BTP-eC9 cells with different blend ratios was investigated. The formation of the BTP-eC9 nano phase in the blend film leads to stable VOC and fast increased JSC, which can be understood by the reduction of bimolecular charge recombination and the formation of electron transporting pathways within the photoactive layer. Similarly, the critical concentration for the formation of the donor phase was estimated to be 0.15 by measuring the stabilized VOC and increased JSC values of the cells with different donor blending ratios. More importantly, after a fast "burn-in" thermal degradation, the M-PhS:BTP-eC9 cell showed excellent thermal stability aging at 85 °C for over 1128 h, which is in good accordance with the unchanged intermixed phases measured by the UV-vis spectra of the annealed films. The current work demonstrates the feasibility of the spectroscopy method to investigate the intermixed phases for organic bulk-heterojunction solar cells and proves that all-small-molecule solar cells can be intrinsically very stable.

A tris(DOPO-grafted piperazine)-triazine phosphoramide (DOPO-TPT) was synthesized, and its structure was well characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. DOPO-TPT was used as a flame retardant additive to modify the epoxy resin to obtain a series of flame retardant epoxy thermosets. The effects of DOPO-TPT on the thermomechanical properties, thermal stability and flame retardancy of the resulting epoxy thermosets were investigated. The results showed that when the addition of DOPO-TPT was 5 mass

Increasing the molecular weight while maintaining mono-dispersity has been proved crucial in innovating high-performance photovoltaic materials in giant oligomeric acceptors. However, developing efficient giant oligomeric donors to replace the batch-varied polymers remains challenging due to a lack of design principles. Here, by designing two unique isomeric rhodanine-based linkers, we successfully regulate the assembly behaviors of giant dimeric donors (G-Dimer-Ds) and fabricate the first all-giant-oligomer OSCs pairing with giant dimeric acceptor DY. Multiple characterizations demonstrate the small homo-molecular interaction with strong thermal-driven assembly capability in G-Dimer-D2 simultaneously facilitates reducing energetic disorder, improving charge transport and obtaining stable morphology, resulting in a satisfactory efficiency of 15.70% and long-term photostability with an extrapolated T80 of ca.10,000 hours, and further enhancing thermal-driven assembly promotes efficiency of 16.05%. Our results provide construction approaches on efficient giant donors, and propose a promising type of OSC with completely definite structures, high efficiency and superior stability. The development of giant oligomeric donors to replace batch-varied polymer remains challenging. Here, the authors regulate the assembly behaviour of giant dimeric donors, realizing all-giant-oligomeric-based organic solar cells with promising device efficiency and stability.