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A wide-bandgap nonplanar small molecule acceptor having indenofluorene core for non-fullerene polymer solar cells
摘要： Recently, the nonplanar non-fullerene acceptors (NFAs) are attractive in active layers in highly efficient polymer solar cells (PSCs) because of their up-shifted energy levels, improved absorption as well as charge transportation performances. However, presently nonplanar NFAs always absorb the lights in the long-wavelength region and even to near-infrared (NIR) region, which limits their further utilization in low-bandgap polymer donor-based PSCs. To further probe the performances of nonplanar NFAs in low-bandgap polymer-based PSCs, a new twisted NFA (i-IF-4F) having indenofluorene derivatives as the electron-donating fused-ring core was synthesized. Due to the relatively weak electron-donating ability of the indenofluorene core, this newly designed NFA has wide optical bandgap (1.79 eV) with absorption spectrum ranged from 450 to 690 nm, suitable lowest unoccupied molecular orbital (LUMO, -3.71 eV) and highest occupied molecular orbital (HOMO, -5.55 eV) energy levels, which ensure its matching well with the typically low-bandgap polymer (PTB7-Th) to achieve complementary absorption and proper differences in energy levels. After thermal annealing treatment, the film morphologies, charge transfer properties and charge recombination performances of i-IF-4F:PTB7-Th-based device was improved to a certain degree, leading to an optimized power conversion efficiency (PCE) of 6.47%. The work in this manuscript demonstrates the applicability of wide-bandgap twisted acceptors in PSCs and the possible approach to further improve the performances of wide-bandgap nonplanar acceptors in PSCs.
关键词： Polymer solar cells,Indenofluorene,Main-chain twisted small molecules,Wide bandgap non-fullerene acceptors
更新于2025-09-23 15:21:01
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Effect of molecular weight on the feature size in organic ice resists
摘要： The feature size of patterns obtained by electron beam lithography (EBL) depends critically on resist properties, beam parameters, development process, and instrument limitations. Frozen layers of simple organic molecules such as n-alkanes behave as negative tone resists for EBL. With the unique advantage of an in-situ thermal treatment replacing chemical development, the entire lithographic process can be performed within a single instrument, thus removing the influence of chemical developers on the feature size. By using an environmental transmission electron microscope, we can also minimize the influence of instrumental limitations and explore the fundamental link between resist characteristics and feature size. Our results reveal that the onset dose of organic ice resists correlates with the inverse molecular weight, and that in the thermal development the role of change in solubility of polymers is mirrored in a shift in the solid/vapour critical temperature of organic ices. With a 0.4 pA beam current we obtained 4.5 nm, 5.5 nm, 8.5 nm, lines with frozen octane, undecane, and tetradecane, respectively, consistent with the predictions of a model we developed that links beam profile and feature size. The knowledge acquired on the response of small organic molecules to electron irradiation, combined with the flexibility and operational advantages of using them as qualified EBL resists, provide us with new opportunities for the design and production of nanodevices, and broadens the reach of EBL especially towards biological applications.
关键词： crosslinking,exposure mechanism,organic ice resist,transmission electron microscopy,E-beam lithography,condensed organic molecules
更新于2025-09-23 15:21:01
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<i>Ab initio</i> study of parity and time-reversal violation in laser-coolable triatomic molecules
摘要： Electronic structure enhancement factors of simultaneous parity and time-reversal violation (P, T violation) caused by an electric dipole moment of the electron (eEDM) and scalar-pseudoscalar nucleon-electron current (SPNEC) interactions are reported for various metal monohydroxides, several of which are considered laser-coolable and promising candidates for an eEDM measurement. Electronic structure enhancements are calculated ab initio within zeroth-order regular approximation (ZORA) for CaOH, SrOH, BaOH, RaOH, and YbOH. Scaling behavior with respect to nuclear charge numbers and the ratio of enhancement factors for both discussed sources of P, T violation are analyzed, which are crucial to obtaining stringent bounds on parameters for new physics from experiments.
关键词： laser-coolable molecules,electric dipole moment,ab initio calculation,scalar-pseudoscalar nucleon-electron current,parity and time-reversal violation,ZORA
更新于2025-09-23 15:21:01
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Strong angular dependence of resonant states in 2D dielectric cylinder rings
摘要： We investigate collective resonators made of dielectric cylinders assembled as two-dimensional regular octagons and decagons. These structures exhibit collective resonance states that change their intensity with the incident radiation angle. While most parts of the spectra present small or even null variation, one of these resonances presents high-sensitivity to the incidence angle. This strong variation is well characterized in terms of the electric field intensity distribution of a resonant state where all the cylinders show the lowest order Mie resonance and the neighbors alternate their polarities. The collective state is optimally excited when radiation impinges on a vertex of the polygonal arrangement of cylinders, while the response decreases to its minimum when the incident field hits an edge (two cylinders at the same time). The resonant state and its high dependence on the excitation incidence angle have been found in both octagonal and decagonal configurations for different dielectric permittivity values. In addition, the scalability of Maxwell equations warranties the same behavior if the whole system is downscaled to terahertz or optic frequencies. The study was performed by finite integration time domain calculations of scattering and transmission for different incidence angles. Experimental measures in the microwave range were taken from photonic molecule prototypes made of centimeter-scale glass cylinders (ε = 4.5). We find an overall excellent agreement between measurements and simulations. We propose that photonic molecules made of polygonal rings of dielectric cylinders are an ideal structure to build angle sensors using the strongly varying state that they present.
关键词： resonance states,angle sensors,incident radiation angle,collective resonators,photonic molecules,dielectric cylinders
更新于2025-09-23 15:21:01
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Fluorescent Platforms Based on Organic Molecules for Chemical and Biological Detection
摘要： Fluorescent platforms based on organic molecules have attracted great attention in the field of chemical and biological detection because of their high detection efficiency and sensitivity. Strategies in fluorescent platform design with controlled luminescence properties based on F?rster resonance energy transfer, excimer/exciplex formation, and metal-enhanced fluorescence mechanisms are reviewed herein. Attention is focused on the photophysical processes of fluorescent molecules in their interactions with other components as well as with the target. Color- and intensity-tunable luminescence from energy or electron transfer and the electronic structures of fluorescent molecules are discussed. On the basis of the photophysical properties of fluorescent molecules, their responsive fluorescence signals, which reflect specific inter- and intra-molecular interactions, are particularly effective for chemical and biological detection.
关键词： detection,fluorescent platform,fluorescent molecules,photophysical property,tunable luminescence
更新于2025-09-23 15:21:01
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Harnessing Natural Product Diversity for Fluorophore Discovery: Naturally Occurring Fluorescent Hydroxyanthraquinones from the Marine Crinoid <i>Pterometra venusta</i>
摘要： Fluorescent small molecules are important tools in many aspects of modern biology. A two-stage evaluation process involving fluorescence screening and live-cell imaging was developed to facilitate the identification of new fluorescent probes from extracts housed within the NCI Natural Products Repository. To this end, over 2000 extracts and prefractionated samples were examined, including an extract from the marine crinoid Pterometra venusta. An optically guided evaluation involving stepwise fluorescence screening and live-cell imaging was developed to enable the isolation of fluorescent natural products. These efforts resulted in the isolation of six hydroxyanthraquinone compounds, three of which are new natural products. These purified metabolites were examined for their potential as cellular imaging probes, and they demonstrate that natural product libraries can be a good source of new fluorescent agents.
关键词： natural products,fluorescent small molecules,Pterometra venusta,hydroxyanthraquinones,cellular imaging
更新于2025-09-23 15:21:01
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Quasi-phase-matched third harmonic generation in organic multilayers
摘要： We report the first realization of quasi-phase-matched (QPM) third harmonic generation in isotropic polymer films. Spin-coated thin films of ethyl-violet molecules dispersed in a polymer host (EV) were used as cubic nonlinear optical media because of their transparency at both the fundamental (1230 nm) and the third harmonic (410 nm) wavelengths. A passive layer of a UV-curable material was formed to compensate the phase shift between the two light waves after propagating through each EV layer. We fabricated a series of samples with 1~4 EV layers (0~3 alternatingly coated passive layers). The third harmonic output power showed a quadratic increase with the number of layers, providing a strong evidence for successful quasi-phase-matching. A conversion efficiency of 0.15% was observed with a 190 fs pulse input.
关键词： third harmonic generation,ethyl-violet molecules,quasi-phase-matched,isotropic polymer films,UV-curable material
更新于2025-09-23 15:21:01
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Theories of Molecular Optical Spectra and Chemical Transformations: Algorithm for ab initio Calculation of the Probabilities of Chemical Reactions Using a Multiminimum Gaussian Potential
摘要： The possibility of formulating and solving the problem of chemical reaction probabilities as a problem of the molecular energy levels and their transition probabilities is considered. The features of using multiminimum Gaussian potentials in such problems are discussed. An algorithm for ab initio calculation of the chemical transformation probabilities with given initial conditions and a list of structures participating in the process is proposed. It is shown that the algorithm can be constructed using a variational procedure with basis functions corresponding to solutions of both one-dimensional problems with a multiminimum potential and problems for each well separately.
关键词： Gaussian function,molecular spectrum,chemical reaction,quantum theory of molecules
更新于2025-09-23 15:21:01
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Multilayer plasmonic photonic structures embedding photochromic molecules or optical gain molecules
摘要： We study the optical properties of different functional molecular systems in order to embed them in properly designed photonic structures for photochromic switching and lasing. We study the light absorption of two photochromic molecules and of 4,4’-bis[(N-carbazole)styryl]biphenyl (BSB-Cz) with density functional theory. For the photochromic diarylethene we derivate the refractive index with Kramers-Kronig relations and we design multilayer photonic structures alternating diarylethene with either poly vinyl carbazole or fluorine indium co-doped cadmium oxide (FICO) nanoparticle-based layers. For BSB-Cz we design a one-dimensional photonic crystal alternating BSB-Cz layers wit SiO2 layers and a microcavity embedding BSB-Cz between indium tin oxide (ITO) / FICO nanoparticle-based multilayers.
关键词： multilayer plasmonic photonic structures,photochromic molecules,density functional theory,Kramers-Kronig relations,optical gain molecules
更新于2025-09-23 15:19:57
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Negative Differential Resistance and Hysteresis in Selfa??Assembled Nanoscale Networks with Tunable Moleculea??toa??Nanoparticle Ratios
摘要： Electronic transport is investigated through self-assembled benzenedithiol–gold nanoparticle networks with tunable molecule-to-particle ratios (1:5–50:1) deposited between planar electrodes. Two-terminal current–voltage measurements of the networks display linear behavior at low bias, which is described using a circuit model that accounts for different network morphologies, tunable via molecule-to-nanoparticle ratio, and defects. At larger biases, nonlinear negative differential resistance and hysteresis behavior are observed for different molecular concentrations, which can be attributed to a combination of ?eld-assisted tunneling and charge trapping occurring in the nanoscale networks. The directed self-assembly of benzenedithiol–metal nanoparticle molecular electronic networks is suggested for molecular integrated circuits in applications such as memory, switching, hardware security, and computing.
关键词： molecules,electronic transport,self-assembly,negative differential resistance,nanoparticles
更新于2025-09-23 15:19:57