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High-Resolution Label-Free Studies of Molecular Distribution and Orientation in Ultrathin, Multicomponent Model Membranes with Infrared Nano-Spectroscopy AFM-IR
摘要： Biological membranes are undoubtedly very interesting systems. Unfortunately, their analysis is very complicated and therefore simplified artificial models, like Langmuir monolayers, are frequently applied. In this work a novel method of label-free monomolecular films analysis based on infrared nano-spectroscopy (AFM-IR) is presented. In order to verify applicability of this approach well-defined referential system of sphingomyelin (SM), cholesterol (Chol) and cyclosporin A (CsA) is applied. AFM-IR method allows to directly and chemoselectively map the distribution of components in model lipid membranes. Additionally the orientation of Chol and SM molecules in the monolayer is determined by application of two perpendicular infrared laser polarizations. This paper is the first report of using AFM-IR to analyze LB films with extremely high sensitivity.
关键词： phase separation,lipid rafts,Langmuir-Blodgett films,Cyclosporin A,AFM-IR
更新于2025-09-19 17:15:36
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Imaging the local electronic and magnetic properties of intrinsically phase separated Rb<sub>x</sub>Fe<sub>2-y</sub>Se<sub>2</sub> superconductor using scanning microscopy techniques
摘要： The discovery in 2008 of the iron-based superconducting pnictide and chalcogenide compounds has provided an entirely new family of materials for studying the crucial interplay between superconductivity and magnetism in unconventional superconductors. The alkali-metal-intercalated iron selenide (AxFe2?ySe2, A = alkali metal) superconductors are of particular interest owing to their relatively high transition temperatures of 30 K and the co-existence of the superconducting state with antiferromagnetic ordering. Intrinsic phase separation on the mesoscopic scale is known to occur in “single crystals” of these compounds, adding to the complexity of interpretation of bulk property measurements. In this study, we investigate the local electronic structure and chemistry of RbxFe2?ySe2 crystals using scanning microscopy techniques. Nano-focussed angle-resolved photoemission spectroscopy (NanoARPES) has enabled the band structure of the minority superconducting phase and the non-superconducting matrix to be measured independently and linked to the surface chemistry from the same regions using core-level spectroscopy. Valence band mapping reveals the characteristic microstructure of these crystals, but does not have sufficient spatial resolution to enable the precise morphology of the superconducting phase to be elucidated. Cryogenic magnetic force microscopy (MFM) has shown that the superconducting phase has a fine-scale stripey morphology that was not resolved in the SPEM experiment. The correlation of these findings with previous microstructural studies, bulk measurements and first-principles DFT calculations paves the way for understanding the intriguing electronic and magnetic properties of these compounds.
关键词： RbxFe2?ySe2,phase separation,magnetism,superconductivity,scanning microscopy
更新于2025-09-19 17:15:36
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Enhancement of Light Extraction from Organic Light-Emitting Diodes by SiO <sub/>2</sub> Nanoparticle-Embedded Phase Separated PAA/PI Polymer Blends
摘要： Using the phase separation of a binary immiscible polymer blend of poly(amic acid) and polyimide in combination with SiO2 nanoparticles, we have designed random nanopore and nanopillar patterns by a simple spin-coating technique. The spontaneously formed pattern structure was investigated by an atomic force microscope technique, which enhanced the external quantum efficiency of conventional green OLEDs up to a highest factor of 1.42. This enhancement is mainly attributed to the reduction of the total internal reflection at the interface of glass and air by the polymer hybrid layer on the backside of OLED devices. This work provides a new and practical approach to the development of efficient external outcoupling structures for OLEDs.
关键词： Poly(amic acid)/Polyimide (PAA/PI),phase separation,light extraction,nanoparticles,nanopores and nanopillars
更新于2025-09-19 17:13:59
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Understanding the Morphology of High-performance Solar Cells Based on a Low Cost Polymer Donor
摘要： A low cost and high performance bulk heterojunction (BHJ) solar cell comprising an emerging polymer donor, poly[(thiophene)-alt-(6,7-difluoro-2-(2-hexyldecyloxy)quinoxaline)] (PTQ10), shows an efficiency of 12.7%. To improve performance of the solar cells, a better understanding of the structure-property relationships of the PTQ10-based devices is crucial. Here, we fabricate PTQ10/nonfullerene and fullerene BHJ devices, including PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC71BM, processed with or without thermal annealing and additive, provide detailed descriptions of the relationships between the morphology and performance. PTQ10 is found to be highly miscible with nonfullerene IDIC and ITIC acceptors, and poorly miscible with fullerene PC71BM acceptors. Thermal annealing promotes the crystallization of PTQ10 and phase separation of all PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC71BM devices, leading to an increased power conversion efficiencies (PCE) of the PTQ10/IDIC and PTQ10/ITIC devices but a decreased PCE of PTQ10/PC71BM devices with 1,8-di-iodooctane (DIO) additive. Without thermal annealing, DIO greatly improves the morphology of PTQ10/PC71BM, leading to a higher PCE. The results show that the degree of phase separation and ordering in the PTQ10-based devices significantly influence device performance. The morphology-property correlations demonstrated will assist in the rational design of this low cost polymer donor based solar cells to achieve even higher performance.
关键词： morphology,phase separation,polymer solar cells,miscibility,crystallization
更新于2025-09-19 17:13:59
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Optimizing the Phase-Separated Domain Size of the Active Layer via Sequential Crystallization in All-Polymer Solar Cells
摘要： Proper domain size of the active layer plays a key role in determining the exciton dissociation and charge transport in all polymer solar cells (all-PSCs). However, fine-tuning the domain size remains challenging due to low glass transition temperature and negligible mixing entropy in polymer blends. Herein, we systematically studied the influence of “crystallization kinetics” on the domain size and proposed that if donor and acceptor crystallize simultaneously, it is prone to form large domain size; while if sequential crystallization of donor and acceptor occurs, a fine phase separation structure with proper domain size can be obtained. Taking PBDB-T/PNDI blends for instance, the domain size was decreased by using sequential crystallization, meanwhile, the crystallinity and molecular orientation were optimized as well, boosting the power conversion efficiency (PCE) from 6.55% to 7.78%. This work provides a novel way to finely tune the heterojunction phase separation structures.
关键词： domain size,crystallization kinetics,sequential crystallization,all-polymer solar cells,phase separation
更新于2025-09-19 17:13:59
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All-Small-Molecule Organic Solar Cells with an Ordered Liquid Crystalline Donor
摘要： A new small-molecule donor, namely BTR-Cl, which possesses a strong liquid crystalline property and high crystallinity, works well with the non-liquid crystalline acceptor Y6 and gives a record-high power conversion efficiency (PCE) of 13.6% in single-junction all-small-molecule organic solar cells. The BTR-Cl:Y6-based device was certified at the National Institute of Metrology, certifying a PCE of 13.0%.
关键词： All-small-molecule organic solar cells,Phase separation,Liquid crystalline donor,Power conversion efficiency,High crystallinity
更新于2025-09-19 17:13:59
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Nonfullerene organic photovoltaic cells exhibiting 13.76% efficiency by employing upside‐down solvent vapor annealing
摘要： Organic photovoltaic cells (OPVs) are fabricated with a polymer donor PM7 and a nonfullerene acceptor IT‐4Cl; the morphology of active layers is optimized by employing upside‐down solvent vapor annealing (UD‐SVA) method with different annealing solvents. The OPVs with CS2 as annealing solvent exhibit optimized power conversion efficiency (PCE) of 13.76%, with simultaneously increased short‐circuit current density (JSC) of 20.53 mA cm?2 and fill factor (FF) of 77.05%. More than 15% PCE improvement can be achieved by employing CS2 UD‐SVA treatment, which should be attributed to slightly enhanced photon harvesting, efficient exciton separation, charge transport, and collection, resulting from the well‐developed morphology of active layer. Moreover, the PM7:IT‐4Cl–based OPVs with CS2 as annealing solvent still can maintain PCE more than 13% in a wide treatment time range from 20 to 90 seconds. This work demonstrated that UD‐SVA has great potential in improving the performance of nonfullerene OPVs.
关键词： phase separation,organic photovoltaic cells,solvent vapor annealing,nonfullerene
更新于2025-09-19 17:13:59
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Effect of polymer donor aggregation on active layer morphology of amorphous polymer acceptor-based all-polymer solar cells
摘要： Most of polymer acceptors for all-polymer solar cells (all-PSCs) are semi-crystalline. Amorphous polymer acceptors containing B←N unit represent a new kind of acceptor materials and possess unique phase separation behaviours in all-PSCs. In this work, to study their phase separation morphology and all-PSC device performance, we select three polymer donors with identical polymer backbone but different side chains to blend with an amorphous polymer acceptor (rr-PBN). Among the three polymer donors, J91 exhibits the strongest aggregation tendency in solution and moderate crystallinity in thin film. The J91:rr-PBN blend shows the most optimal phase separation morphology and the best all-PSC device performance. In comparison, J51 shows the least aggregation tendency in solution and the highest crystallinity in thin film. The all-PSC device of J51:rr-PBN blend exhibits sub-optimal active layer morphology and poor photovoltaic performance. These results indicate that the aggregation tendency in solution of polymer donor is the dominant factor in the phase separation of semi-crystalline polymer donor/amorphous polymer acceptor blend in all-PSCs.
关键词： crystallinity,morphology,all-polymer solar cells,aggregation in solution,phase separation
更新于2025-09-19 17:13:59
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Green-light-induced melting of self-assembled azobenzene nano/microstructures
摘要： We report the formation of green-light-responsive fluorescent aggregates composed of trigonal molecules having three ortho-dialkylated azobenzene wings at the periphery (a green-light-responsive 3BuES and an aggregation-induced emission/aggregation-induced emission enhancement [AIE/AIEE]-active 3BuAz). Exposure of the respective (3BuES and 3BuAz) spheres to green light leads to color tuning and/or fluorescence switching. The results can be rationalized in terms of green-light-induced molecular conformational changes of the trigonal azobenzene molecules and the resulting phase transition of the self-assembled structures. For instance, irradiation of 3BuES with green light produces B35% of U-shaped cis forms (i.e., approximately one-third of the trans-azobenzene units isomerizes to the cis forms), which seems to be su?cient to weaken the degree of the molecular packing of the trigonal azobenzene frameworks and lower the melting temperatures. Moreover, to apply the excellent fluorescence switching functions of 3BuAz aggregates to create new fluorescent organic materials, we used a co-assembly of 3BuES–3BuAz binary mixtures. Our important approach for obtaining green-light-responsive fluorescent nano/microstructures from the binary mixtures is phase separation based on the structural difference between 3BuES (having a planar central core) and 3BuAz (having a distorted conformation), which helps retain the fluorescence functions of the AIE/AIEE-active 3BuAz chromophore. Scanning electron microscopy (SEM), optical microscopy (OM), and fluorescence optical microscopy (FOM) observations prove apparent green-light-induced melting, color tuning and fluorescence switching of the phase-separated structures (i.e., microspheres and nanoparticles).
关键词： green-light-responsive,AIE/AIEE,azobenzene,fluorescent aggregates,fluorescence switching,phase separation
更新于2025-09-16 10:30:52
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Phase separation of vector solitons in spin-orbit-coupled spin-1 condensates
摘要： We study the phase separation in three-component bright vector solitons in a quasi-one-dimensional spin-orbit-coupled hyperfine spin F = 1 ferromagnetic Bose-Einstein condensate upon an increase of the strength of spin-orbit (SO) coupling px(cid:2)z above a critical value, where px is the linear momentum and (cid:2)z is the z component of the spin-1 matrix. The bright vector solitons are demonstrated to be mobile and dynamically stable. The collision between two such vector solitons is found to be elastic at all velocities with the conservation of density of each vector soliton. The two colliding vector solitons repel at small separation and at very small colliding velocity, they come close and bounce back with the same velocity without ever encountering each other. This repulsion produced by SO coupling is responsible for the phase separation in a vector soliton for large strengths of SO coupling. The collision dynamics is found to be completely insensitive to the relative phase of the colliding solitons. However, in the absence of SO coupling, at very small velocity, the two colliding vector solitons attract each other and form a vector soliton molecule and the collision dynamics is sensitive to the relative phase as in scalar solitons. The present investigation is carried out through a numerical solution and an analytic variational approximation of the underlying mean-field Gross-Pitaevskii equation.
关键词： Bose-Einstein condensate,spin-orbit coupling,collision dynamics,vector solitons,phase separation
更新于2025-09-16 10:30:52