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Mechanistic insights into the effect of polymer regioregularity on thermal stability of polymer solar cells
摘要： Thermal stability is a bottleneck toward commercialization of polymer solar cells (PSCs). The effect of PCBM aggregation in multi-length-scale on the bulk-heterojunction (BHJ) structure, performance, and thermal stability of PSCs is studied here by grazing-incidence small- and wide-angle X-ray scattering. The evolution of hierarchical BHJ structures of the blend film tuned by regioregularity of polymers from the as-cast state to the thermally unstable state was systematically investigated. The thermal stability of PSCs with high polymer regioregularity value can be improved because of the good mutual interaction between polymer crystallites and fullerene aggregation. The insights obtained from this study provide an approach to manipulate the film structure in a multi-length scale and to enhance the thermal stability of P3HT-based PSCs.
关键词： PCBM aggregation,bulk heterojunction,nanostructure,polymer solar cell,GIXRD,thermal stability
更新于2025-09-19 17:13:59
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Effect of low-intensity laser radiation on hemostasis in patients with chronic obstructive pulmonary disease
摘要： Objective. The study presents results of the low-intensity intravenous (IV) laser radiation effect on some indicators of the hemostasis system and respiratory function of 83 patients with a chronic lung disease (COPD), stable phase, II-III (after GOLD scale), including 51 men and 32 women. The average COPD duration was 9.6±4.4 years. Materials and methods. All patients with COPD were randomly divided into 2 groups - comparison (30 people) and main (53 people). The control group consisted of 20 practically healthy people, matched by sex and age. Patients in the control group received only standard drug therapy with IGCC/DBA combination (budesonide/formoterol, salmeterol/fluticasone propionate inhalation at a therapeutic dose corresponding to the COPD clinical symptoms severity). Result and Discussion. In addition to the basic treatment, the main group received a course of intravenous low-intensity laser radiation. As established before the treatment initiation, patients with COPD experienced a decrease in FEV1, Tiffno index, SaO2. Conclusion. The respiratory function disruption was accompanied by a significant activation of plasma hemostasis (prothrombin time shortening, thrombin time, activated partial thromboplastin time) and a significant increase in platelet aggregation (increase in the aggregation degree, aggregation rate, decrease in the aggregation time). At the same time, in patients with COPD, a significant decrease in anticoagulant activity was observed before treatment, particularly antithrombin III decrease when compared with the control group (p <0.05) and CRP (main group: 0.86±0.02; control group: 0.85±0.02). The introduction of low-intensity laser radiation into the patients complex with COPD led to the these parameters normalization.
关键词： platelet aggregation,low-intensity intravenous laser radiation,COPD,plasma hemostasis
更新于2025-09-19 17:13:59
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Achievement of Higha??Performance Nondoped Blue OLEDs Based on AIEgens via Construction of Effective Higha??Lying Chargea??Transfer State
摘要： There remains an urgent demand for high-quality blue luminogens that can simultaneously achieve high photoluminescence quantum yield (PLQY) in film and high exciton utilization efficiency (EUE) in the electroluminescence (EL) process. In this study, a referable molecular design strategy is developed for blue luminogens via constructing low-lying locally excited (LE) state with an aggregation-induced emission (AIE) characteristic and high-lying charge-transfer (CT) state for the effective triplet-to-singlet conversion channel. 2TriPE-BPI-MCN with the insertion of p-cyano and o-methyl groups is designed to compare with its matrix framework (2TriPE-BPI). They have analogous properties of the lowest singlet (S1) states with blue emission and free of concentration quenching in film; however, 2TriPE-BPI-MCN exhibits unusual response for hydrostatic pressure owing to its S2 state CT characteristics. Therefore, 2TriPE-BPI-MCN can harness more electrogenerated excitons than 2TriPE-BPI, resulting in a better EL performance in nondoped blue organic light-emitting diodes (OLEDs) (CIEx,y = 0.153, 0.147) with high external quantum efficiency of 4.6% and negligible efficiency roll-off. These findings could open a feasible avenue to develop high-quality blue luminogens for high-performance nondoped blue OLEDs.
关键词： organic light-emitting diodes,blue emission,hydrostatic pressure,aggregation-induced emission,charge-transfer state
更新于2025-09-19 17:13:59
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Effect of Side Substituents Incorporated into <i>??</i> a??Bridges of Quinoxalinea??Based Sensitizers for Dyea??Sensitized Solar Cells
摘要： ZW003, has been synthesized and applied in dye-sensitized solar cells (DSSCs). Both dyes have broad absorption and large molar absorption coefficients. The sensitizer with the HQ core effectively restrains intermolecular aggregation owing to steric hindrance of numerous alkyl chains. A thienyl unit with or without a hexyl branch is used as a π-bridge. Incorporation of only thienyl groups as a π-bridge into the sensitizer increases the dye-loading amount on TiO2 film owing to the smaller molecular size. Using the ZW002 dye with the Co (II/III) redox couple results in DSSCs that exhibits a high photovoltaic conversion efficiency of 8.23% and short-circuit current density (Jsc) of 12.43 mA cm?2, an open-circuit voltage (Voc) of 960 mV, and a fill factor (FF) of 0.69. Although ZW003 shows a wider absorption range than that of ZW002, the two additional phenyl groups on the quinoxaline unit contributes to poorer performance (PCE of 7.43%) due to more serious dye aggregation.
关键词： Quinoxaline,Additional acceptors,Intermolecular aggregation,Dye-loading amount,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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Charge-Transfer Character in Excimers of Perylenediimides Self-Assembled on Anodic Aluminum Oxide Membrane Walls
摘要： Chromophore aggregation strongly impacts the efficiency of organic photovoltaics (OPVs). Perylene-3,4:9,10-bis(dicarboximide) (PDI)-based electron acceptors have been shown to be excellent alternatives to fullerenes in OPVs, provided their supramolecular assemblies do not form excimers. In order to study this phenomenon in a controlled fashion, we have prepared two PDI derivatives that were incorporated into an anodic aluminum oxide (AAO) membrane. In one system, the PDI molecule has an n-propyl silatrane attached to one of its imide nitrogens, while a 12-tricosanyl group is attached to the other imide nitrogen. The silatrane reacts with the AAO surface to covalently bind the PDI. The other PDI has 12-tricosanyl groups on both imide nitrogens, which intercalate with n-octadecylsilane chains covalently bound to an AAO membrane. Since aluminum oxide is a wide bandgap semiconductor, photoexcitation of PDI does not result in charge injection into the AAO membrane; thus, the intrinsic electronic properties of the aggregated PDI molecules within the membrane can be studied. Both PDI derivatives form excimers upon photoexcitation with and without solvent in the AAO membrane pores which display increasing charge transfer character with increasing solvent polarity. Since the AAO membrane allows for any choice of solvent to be infiltrated into its pores, the PDI photophysics can be modulated over an arbitrary range of solvent polarities, irrespective of whether PDI is soluble in a particular solvent. The results presented here show how to tune the intermolecular interactions of PDI and related rylene dyes attached to walls of the AAO pores to understand the intermediate regime between solution and the solid state.
关键词： Excimers,Anodic aluminum oxide membrane,Perylene-3,4:9,10-bis(dicarboximide),Chromophore aggregation,Charge transfer character,Organic photovoltaics
更新于2025-09-19 17:13:59
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Elucidating Roles of Polymer Donor Aggregation in All-Polymer and Non-Fullerene Small-Moleculea??Polymer Solar Cells
摘要： The aggregation behavior of polymers plays a crucial role in determining the optical, electrical, and morphological properties of donor-acceptor blends in both all-polymer solar cells (all-PSCs) and non-fullerene small molecule acceptor-polymer solar cells (NFSMA-PSCs). However, direct comparison of the impacts on two different systems has not been reported, although it is important to design universal polymer donors (PDs). Herein, three PDs with different side chains (P-EH, P-SEH and P-Si) are designed to study the PD aggregation effects on the blend morphology and device performance of both all-PSCs and NFSMA-PSCs. It is observed that the aggregation property of PDs is a critical factor in determining the optimal blend morphologies and ultimately the device performances in both the PSC systems. Furthermore, PD aggregation effects on device performance is significantly more impactful in all-PSCs than in NFSMA-PSCs. The P-Si PD exhibiting the strongest aggregation behavior in a processing solvent produces the most severe phase separation in the blend with a polymer acceptor, resulting in the lowest power conversion efficiency (PCE) of all-PSCs. In contrast, when P-Si is used in an NFSMA-PSC, a well-mixed blend morphology is observed, which results in the highest PCE of over 12%. These different roles dependent on PD aggregation mainly originate from the difference in molecular size of polymer acceptor and small molecule acceptor, which influences the entropic contribution to the formation of blend morphology. Our work provides a comprehensive understanding on the PD aggregation-blend morphology relationship in different all-PSC and NFSMA-PSC systems, which serves as an important guideline for the design of universal PDs for both all-PSCs and NFSMA-PSCs.
关键词： polymer solar cells,all-polymer solar cells,non-fullerene small molecule acceptor-polymer solar cells,polymer donor aggregation,blend morphology,power conversion efficiency
更新于2025-09-19 17:13:59
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Bioinspired Simultaneous Changes in Fluorescence Color, Brightness, and Shape of Hydrogels Enabled by AIEgens
摘要： Development of stimuli-responsive materials with complex practical functions is significant for achieving bioinspired artificial intelligence. It is challenging to fabricate stimuli-responsive hydrogels showing simultaneous changes in fluorescence color, brightness, and shape in response to a single stimulus. Herein, a bilayer hydrogel strategy is designed by utilizing an aggregation-induced emission luminogen, tetra-(4-pyridylphenyl)ethylene (TPE-4Py), to fabricate hydrogels with the above capabilities. Bilayer hydrogel actuators with the ionomer of poly(acrylamide-r-sodium 4-styrenesulfonate) (PAS) as a matrix of both active and passive layers and TPE-4Py as the core function element in the active layer are prepared. At acidic pH, the protonation of TPE-4Py leads to fluorescence color and brightness changes of the actuators and the electrostatic interactions between the protonated TPE-4Py and benzenesulfonate groups of the PAS chains in the active layer cause the actuators to deform. The proposed TPE-4Py/PAS-based bilayer hydrogel actuators with such responsiveness to stimulus provide insights in the design of intelligent systems and are highly attractive material candidates in the fields of 3D/4D printing, soft robots, and smart wearable devices.
关键词： stimuli-responsive hydrogels,complex shape,simultaneous changes,fluorescence,aggregation-induced emission luminogens
更新于2025-09-19 17:13:59
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Towards Blue AIE/AIEE: Synthesis and Applications in OLEDs of Tetra-/Triphenylethenyl Substituted 9,9-Dimethylacridine Derivatives
摘要： Aiming to design blue fluorescent emitters with high photoluminescence quantum yields in solid-state, nitrogen-containing heteroaromatic 9,9-dimethylacridine was refined by tetraphenylethene and triphenylethene. Six tetra-/triphenylethene-substituted 9,9-dimethylacridines were synthesized by the Buchwald-Hartwig method with relatively high yields. Showing effects of substitution patterns, all emitters demonstrated high fluorescence quantum yields of 26–53% in non-doped films and 52–88% in doped films due to the aggregation induced/enhanced emission (AIE/AIEE) phenomena. In solid-state, the emitters emitted blue (451–481 nm) without doping and deep-blue (438–445 nm) with doping while greenish-yellow emission was detected for two compounds with additionally attached cyano-groups. The ionization potentials of the derivatives were found to be in the relatively wide range of 5.43–5.81 eV since cyano-groups were used in their design. Possible applications of the emitters were demonstrated in non-doped and doped organic light-emitting diodes with up to 2.3 % external quantum efficiencies for simple fluorescent devices. In the best case, deep-blue electroluminescence with chromaticity coordinates of (0.16, 0.10) was close to blue color standard (0.14, 0.08) of the National Television System Committee.
关键词： aggregation induced emission enhancement,electroluminescence,tetra-/triphenylethene,acridan
更新于2025-09-19 17:13:59
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Self-Assembled Extended ??-Systems for Sensing and Security Applications
摘要： Molecules and materials derived from self-assembled extended π-systems have strong and reversible optical properties, which can be modulated with external stimuli such as temperature, mechanical stress, ions, the polarity of the medium, and so on. In many cases, absorption and emission responses of self-assembled supramolecular π-systems are manifested several times higher when compared with the individual molecular building blocks. These properties of molecular assemblies encourage scientists to have a deeper understanding of their design to explore them for suitable optoelectronic applications. Therefore, it is important to bring in highly responsive optical features in π-systems, for which it is necessary to modify their structures by varying the conjugation length and by introducing donor?acceptor functional groups. Using noncovalent forces, π-systems can be put together to form assemblies of different shapes and sizes with varied optical band gaps through controlling intermolecular electronic interactions. In addition, using directional forces, it is possible to bring anisotropy to the self-assembled nanostructures, facilitating efficient exciton migration, resulting in the modulation of optical and electron-transport properties. In this Account, we mainly summarize our findings with optically tunable self-assemblies of extended π-systems such as p-phenylenevinylenes (PVs), p-phenyleneethynylenes (PEs), and diketopyrrolopyrroles (DPPs) as different stimuli-responsive platforms to develop sensors and security materials. We start with how PV self-assemblies and their coassemblies with appropriate electron-deficient systems can be used for the sensing of analytes in contact mode or in the vapor phase. For example, whereas the PV having electron-deficient terminal groups has high sensitivity toward trinitrotoluene (TNT) in contact mode, the supercoiled fibers formed by the coassembly of self-sorted stacks of C3-symmetrical PV and C3-symmetrical electron-deficient perylene bisimide are capable of sensing vapors of nitrobenzene and o-toluidine. The power of different functional groups in combination with PVs has been further illustrated by attaching CO2-sensitive tertiary amine moieties to a cyano-substituted PV, which allowed the bimodal detection of CO2 using fluorescence and Raman spectroscopy. Interestingly, the functionalization of PVs with terminal amide groups and chiral alkoxy side chains provided a mechanochromic system that allows self-erasable imaging. Whereas PVs exhibit quenching of fluorescence in most cases during self-assembly, PE derivatives exhibit aggregation-induced emission. This property of PEs has been exploited for the development of stimuli-responsive security materials, especially for currency and documents. For instance, the blue fluorescence of a PE attached to hydrophilic oxyethylene side chains coated on a filter paper upon contact with water changes to cyan emission due to the change in the molecular packing. Interestingly, the molecular packing of a Bodipy-attached PE-based gelator allowed a stress-induced change in the emission behavior, resulting in strong near-infrared (NIR) emission upon the application of mechanical stress or gelation. Finally, the use of DPP-based π-systems for the development of NIR transparent optical filters that block UV?vis light and their security- and forensic-related applications are described. These selected examples of the π-system self-assemblies provide an idea of the current status and future opportunities for scientists interested in this field of self-assembly and soft materials research.
关键词： self-assembly,sensors,π-systems,NIR transparent optical filters,stimuli-responsive,mechanochromism,fluorescence,security materials,aggregation-induced emission
更新于2025-09-19 17:13:59
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Analysis on FM-to-AM conversion of SSD beam induced by etalon effect in a high-power laser system
摘要： Malondialdehyde (MDA) was selected to represent a secondary by-product of lipid peroxidation during rice ageing. This study aimed to investigate the effects of MDA modification on the structural characteristics of rice protein. The results showed that as MDA concentration increased, rice protein carbonyl and disulphide groups increased, but sulphydryl content decreased. The blue shift of maximum fluorescence peak, the decrease of rice protein intrinsic fluorescence intensity and the reduction of surface hydrophobicity indicated the formation of protein aggregates caused by MDA oxidative modification. The results of molecular weight distribution and particle size distribution showed that MDA modification resulted in the formation of soluble protein aggregates, and the decrease of rice protein solubility indicated that insoluble protein aggregates were formed. Results of protein electrophoresis showed that MDA modification contributed to rice protein aggregation via non-disulphide covalent bonds. The results showed that rice protein gradually aggregated with increasing MDA concentration.
关键词： Aggregation,rice protein,protein oxidation,lipid peroxidation,rice ageing,malondialdehyde
更新于2025-09-19 17:13:59