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Optical Tweezers: A Force to Be Reckoned With
摘要： The 2018 Nobel Prize in Physics has been awarded jointly to Arthur Ashkin for the discovery and development of optical tweezers and their applications to biological systems and to Ge′ rard Mourou and Donna Strickland for the invention of laser chirped pulse ampli?cation. Here we focus on Arthur Ashkin and how his revolutionary work opened a window into the world of molecular mechanics and spurred the rise of single-molecule biophysics.
关键词： Arthur Ashkin,Optical Tweezers,Single-Molecule Biophysics,Nobel Prize,Physics
更新于2025-09-23 15:21:01
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System Composed of Three Types of Electronic Angular Momenta: A <b>J</b> – <b>S</b> – <b>L</b> Triad in a Photoexcited π-Radical Bis(phthalocyaninato)terbium Single-Molecule Magnet
摘要： Interactions of three different types of electronic angular momenta, namely, spin, orbital, and total angular momenta from different origins in a photoexcited neutral bis(phthalocyaninato)terbium single-molecule magnet (Pc2Tb, where Pc2? denotes a phthalocyaninato anion) have been studied. We have conducted varied-temperature and varied-magnetic-field magnetic circular dichroism (MCD) measurements on the highest occupied molecular orbital?lowest unoccupied molecular orbital electronic transition in the ligand side of the neutral Pc2Tb to reveal the quantum nature of the system composed of a π-radical with a spin angular momentum S, the 4f system with a total angular momentum J, and the cyclic π conjugate system with a photoinduced orbital angular momentum L. We have constructed a new theoretical model that gives a quantitative agreement to the temperature and magnetic field dependence of MCD. The theoretical analysis revealed that the system takes eight quantum states that can be expressed as |JzSzLz? = |±±±?, where the three angular momenta are quantized along the fourfold symmetry axis. Thus, we have identified the existence of the magnetic interactions among the three angular momenta and quantitatively determined their magnitudes for the first time.
关键词： single-molecule magnet,electronic angular momenta,quantum states,magnetic circular dichroism,magnetic interactions
更新于2025-09-23 15:21:01
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Photoassociative spectroscopy of a halo molecule in
摘要： We present two-photon photoassociation to the least-bound vibrational level of the X 1Σ+g electronic ground state of the 86Sr2 dimer and measure a binding energy of Eb = ?83.00(7)(20) kHz. Because of the very small binding energy, this is a halo state corresponding to the scattering resonance for two 86Sr atoms at low temperature. The measured binding energy, combined with universal theory for a very weakly bound state on a potential that asymptotes to a van der Waals form, is used to determine an s-wave scattering length a = 810.6(3)(9) a0, which is consistent with, but substantially more accurate than, the previously determined a = 798(12) a0 found from mass scaling and precision spectroscopy of other Sr isotopes. For the intermediate state, we use a bound level on the metastable 1S0-3P1 potential. Large sensitivity of the dimer binding energy to light near resonant with the bound-bound transition to the intermediate state suggests that 86Sr has great promise for manipulating atom interactions optically and probing naturally occurring Efimov states.
关键词： scattering length,binding energy,Efimov states,photoassociation,halo molecule,86Sr
更新于2025-09-23 15:21:01
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Atomic Force Microscopy in Molecular and Cell Biology || In Situ Single Molecule Detection on Cell Membrane and Label Molecule Distributions Using AFM/NSOM
摘要： Consisting of viscous phospholipid bilayer, different kinds of proteins and various nano/micrometer-sized domains, cell membranes have proven to play very important roles in ensuring the stability of the intracellular environment and order of cellular signal transductions. The developments of modern cell biology, immunology, and medicine urge us to explore more precise cell membrane structures and detailed functions of biomolecules on cell membranes. Due to the minuscule size of biomolecules and their clusters on cell membranes (varying from several nanometers to hundreds of nanometers), a high resolution microscopy is needed to explore the cell membrane biomolecule distribution.
关键词： single molecule detection,biomolecule distribution,AFM,cell membrane,NSOM
更新于2025-09-23 15:21:01
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Over 15% Efficiency Polymer Solar Cells Enabled by Conformation Tuning of Newly Designed Asymmetric Smalla??Molecule Acceptors
摘要： The prosperous period of polymer solar cells (PSCs) has witnessed great progress in molecule design methods to promote power conversion efficiency (PCE). Designing asymmetric structures has been proved effective in tuning energy level and morphology, which has drawn strong attention from the PSC community. Two hepta-ring and octa-ring asymmetric small molecular acceptors (SMAs) (IDTP-4F and IDTTP-4F) with S-shape and C-shape confirmations are developed to study the relationship between conformation shapes and PSC efficiencies. The similarity of absorption and energy levels between two SMAs makes the conformation a single variable. Additionally, three wide-bandgap polymer donors (PM6, S1, and PM7) are chosen to prove the universality of the relationship between conformation and photovoltaic performance. Consequently, the champion PCE afforded by PM7: IDTP-4F is as high as 15.2% while that of PM7: IDTTP-4F is 13.8%. Moreover, the S-shape IDTP-4F performs obviously better than their IDTTP-4F counterparts in PSCs regardless of the polymer donors, which confirms that S-shape conformation performs better than the C-shape one. This work provides an insight into how conformations of asymmetric SMAs affect PCEs, specific functions of utilizing different polymer donors to finely tune the active-layer morphology and another possibility to reach an excellent PCE over 15%.
关键词： small-molecule acceptors,power conversion efficiencies,polymer solar cells
更新于2025-09-23 15:19:57
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Effect of Solvent Additives on the Morphology and Device Performance of Printed Non-fullerene Acceptor Based Organic Solar Cells
摘要： Printing of active layers of high-efficiency organic solar cells and morphology control by processing with varying solvent additive concentrations are important to realize real-world use of bulk-heterojunction photovoltaics as it enables both, up-scaling and optimization of the device performance. In this work, active layers of the conjugated polymer with benzodithiophene units PBDB-T-SF and the non-fullerene small molecule acceptor IT-4F are printed using meniscus guided slot-die coating. 1,8-diiodoctane (DIO) is added to optimize the power conversion efficiency (PCE). The effect on the inner nano-structure and surface morphology of the material is studied for different solvent additive concentrations with grazing incidence small angle X-ray scattering (GISAXS), grazing incidence wide angle X-ray scattering (GIWAXS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties are studied with photoluminescence (PL), UV/Vis absorption spectroscopy and external quantum efficiency (EQE) measurements and correlated to the corresponding PCEs. The addition of 0.25 vol% DIO enhances the average PCE from 3.5 to 7.9 % whereas at higher concentrations the positive effect is less pronounced. A solar cell performance of 8.95 % is obtained for the best printed device processed with an optimum solvent additive concentration. Thus, with the large-scale preparation method printing similarly well working solar cells can be realized as with the spin-coating method.
关键词： slot-die coating,solvent additives,small molecule acceptor,high-efficiency organic solar cells,printed organic solar cells
更新于2025-09-23 15:19:57
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Alkyl Side-Chain Dependent Self-Organization of Small Molecule and its Application in High-Performance Organic and Perovskite Solar Cells
摘要： The molecular self-organization of organic semiconductors, which is mainly determined by the structural design, film processing, and device configuration, is one of the crucial factors for achieving high-performance organic photovoltaics (OPVs) and perovskite solar cells (PvSCs). In this study, we newly synthesized and developed strongly self-organized small molecules via alkyl side-chain engineering. Replacing “H” to “C6H13” on the thienyl group, SM2 showed a well-ordered face-on orientation. Due to favorable self-organization leading to effective charge carrier dynamics, including enhanced charge transfer/transport and suppressed recombination, SM2-based OPVs and PvSCs exhibited improved device performance compared to the devices based on SM1 without an additional hexyl side-chain. The best fullerene-based OPV and planar PvSC with SM2 as a small-molecule donor and as a hole transport layer (HTL) achieved an unprecedentedly high efficiency of 9.38% and 20.56%, in contrast with SM1-based devices showing lower efficiency of 8.70% and 15.37%. Furthermore, the planar PvSCs based on undoped-SM2 HTL exhibited comparable efficiency but provided excellent heat and humidity stability compared with doped spiro-OMeTAD-based devices. These results clearly indicated that SM2 with highly-ordered and favorable self-organization is a promising organic semiconductor for future applications of high-performance organic and inorganic-organic hybrid electronics.
关键词： small molecule,organic photovoltaics,alkyl side-chain,self-organization,perovskite solar cells
更新于2025-09-23 15:19:57
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The Phase Behavior in the Active Layer of Small Molecule Organic Photovoltaics: The State Diagram of p-DTS(FBTTh <sub/>2</sub> ) <sub/>2</sub> :PC <sub/>71</sub> BM
摘要： A comprehensive study was undertaken to obtain a more fundamental understanding of the phase behavior of the p-DTS(FBTTh2)2:PC71BM system, used in small molecule organic solar cells, with a strong focus on the amorphous phase and its influence on crystallinity. Three dedicated thermal protocols were used in combination with advanced thermal analysis, solid-state NMR, and wide angle X-ray diffraction. Rapid cooling, to avoid structure formation and gain insight in the amorphous phase, and slow cooling, to promote structure formation, were used as limiting cases to explain the intermediate behavior after device processing from solution. A complete state diagram was developed and the glass transition (Tg) - composition relationship was determined. In the case of slow cooling and the procedure used for device processing, the rapid crystallization of p-DTS(FBTTh2)2 leads to an enrichment of the amorphous phase in PC71BM, increasing its Tg and causing vitrification of the mixed amorphous phase before crystallization when the total amount of PC71BM exceeds 70 wt%. The common processing additive 1,8-diiodooctane (DIO) was found to lead to a lower p-DTS(FBTTh2)2 crystallinity and smaller average crystal size. More importantly, it acts as a strong plasticizer, lowering Tg significantly and thus reducing the morphological stability of the p-DTS(FBTTh2)2:PC71BM mixtures.
关键词： p-DTS(FBTTh2)2:PC71BM,glass transition temperature,wide angle X-ray diffraction,phase behavior,crystallinity,amorphous phase,small molecule organic photovoltaics,thermal analysis,solid-state NMR,1,8-diiodooctane (DIO)
更新于2025-09-23 15:19:57
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Double Fano resonances in hybrid disk/rod artificial plasmonic molecules based on dipole-quadrupole coupling
摘要： Fano resonance can be achieved by the destructive interference between a superradiant bright mode and a subradiant dark mode. A variety of artificial plasmonic oligomers have been fabricated to generate Fano resonance for its extensive applications. However, the Fano resonance in plasmonic oligomer systems comes from the interaction of all metal particles, which greatly limits the tunability of the Fano resonance. Besides, only a single Fano resonance is supported by many existing plasmonic oligomers, while multiple Fano resonances mostly occur in complex and multilayer structures, whose fabrication is greatly challenging. Here, a simple asymmetric plasmonic molecule consisting of a central metal disk and two side-coupled parallel metal rods is demonstrated. The simulation and experimental results clearly show that double Fano resonances appear in the transmission spectrum. In addition, the two Fano peaks can be independently tuned and single/double Fano peak switching can be achieved by changing one rod length or the gap distances between the rods and the disk. The modulation method is simple and effective, which greatly increases the tunability of the structure. The proposed asymmetric artificial plasmonic molecule can have applications in multi-channel optical switches, filters and biosensors. Moreover, the controllable plasmonic field intensity in the gap between the disk and rods also provides a new control means for plasmon-induced photocatalytic reactions and biosynthesis.
关键词： plasmonic oligomers,biosynthesis,Fano resonance,filters,optical switches,biosensors,asymmetric plasmonic molecule,plasmon-induced photocatalytic reactions,double Fano resonances
更新于2025-09-23 15:19:57
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Modulation of the properties of dinuclear lanthanide complexes through utilizing different ?2-diketonate co-ligands: near-infrared luminescence and magnetization dynamics
摘要： A family of new dinuclear lanthanide complexes as the simplest entities showing intramolecular magnetic interactions, [Ln2(dbm)2(L)2(CH3OH)2] (Ln = Tb (1), Dy (2), Ho (3), Er (4), Yb (5), Lu (6)), [Ln2(acac)2(L)2(EtOH)2] (Ln = Dy (7), Er (8)), [Dy2(TTA)2(L)2(CH3OH)2]·2CH2Cl2 (9) and [Dy2(tfa)2(L)2(CH3OH)2] (10) (H2L = N’-(2-hydroxy-5-methylphenyl)-pyrazine-2-carbohydrazide, Hdbm = 1,3-diphenyl-1,3-propanedione, Hacac = acetylacetone, HTTA = 2-thenoyltrifluoroacetone, Htfa = trifluoroacetylacetone), were constructed successfully by the reaction of a Schiff base ligand H2L and four different β-diketonate salts. As for complexes 4, 5 and 8, all exhibit the characteristic emission peaks of the corresponding Er3+, Yb3+ and Er3+ ions, respectively. Meanwhile, the excitation wavelength (510 nm) of 5 is located in the visible region, confirming its significant potential application value. Magnetic studies indicate that complexes 9 and 10 exhibit characteristic slow relaxation of magnetization with the energy barriers (Ueff) of 102 K for 9 and 140 K for 10 under a zero dc field. Under the optimized dc fields, slow magnetic relaxations are present in 2 and 7, and the Ueff values of 9 and 10 have been improved. This proves that the β-diketonate co-ligands deserve an important role in regulating Dy-SMMs influenced by the diverse perturbations of the axial crystal field originating from minor changes in the coordination environment.
关键词： single-molecule magnets,dinuclear lanthanide complexes,β-diketonate co-ligands,near-infrared luminescence,magnetization dynamics
更新于2025-09-23 15:19:57