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Wide band-gap organic molecules containing benzodithiophene and difluoroquinoxaline derivatives for solar cell applications
摘要： Two new semiconducting organic small molecules, namely BDTQ-BDT(EH) and BDTQ-BDT(OC), were prepared by attaching electron accepting 2,3-didodecyl-6,7-difluoro-5,8-di(thiophen-2-yl)quinoxaline (DTQ) unit on 2,6-position of electron donating 4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b’]dithiophene (BDT(EH)) and 4,8-bis(octyloxy)-benzo[1,2-b:4,5-b’]dithiophene (BDT(OC)) units. Molecule BDTQ-BDT(EH) showed higher thermal stability (5% weight loss temperature, Td “349 jC), slightly lower band-gap (Eg “2.10 eV) and deeper highest occupied molecular orbital energy level (HOMO “–5.36 eV) level compared to those (Td “336 jC, Eg “2.11 eV, and HOMO “–5.30 eV, respectively.) of the molecule BDTQ-BDT(OC). The organic solar cells (OSCs) made with the synthesized molecules as an electron donor and [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) as an electron acceptor gave a maximum power conversion efficiency (PCE) of 1.20% and 0.83%, respectively, for BDTQ-BDT(EH) and BDTQ-BDT(OC). This study confirmed that the substituents attached on the 4,8-position of BDT unit greatly alter the properties of the resulting molecules.
关键词： small molecule solar cells,wide band-gap molecules,quinoxaline-based molecules,benzodithiophene-based molecules,organic solar cells
更新于2025-09-16 10:30:52
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Laser detection of nuclear spin isomers of ethylene molecules
摘要： We report the making of a double-beam laser spectrometer to measure absorption spectra in the n5 + n9 combination vibrational band of ethylene in the region of l = 1.6 mm. The spectrometer is used to find a portion of the spectrum that has well-resolved absorption lines of all four nuclear spin isomers of ethylene molecules. The rotational quantum numbers of these absorption lines and the nuclear spin isomers of ethylene molecules responsible for them are identified.
关键词： spectroscopy of ethylene molecules,nuclear spin isomers of molecules,laser spectroscopy
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Dispersion-Managed Soliton Molecules in An All-Fiber Mode-Locked Fiber Laser With Near Zero Dispersion
摘要： Characterized by particle-like behaviors, soliton molecules interesting further unveil vivid multi-soliton dynamics and the research pulse-interaction scenarios community of ultrafast fiber lasers. Here, we report the formation of dispersion-managed solitons (DMSs) in an all-fiber laser passively mode-locked by a 45° tilted fiber grating (45° TFG) near the zero-dispersion regime. Particularly, typical DMS singlets are observed, possessing a broadband and smooth spectral shape. reinforced Besides, on stretching-compressing process during the pulse propagation, various multi-pulse DMS molecules are also discovered. Moreover, transient soliton dynamics of dual-pulse and triple-pulse DMS molecules covering the timescale over hundreds of round trips are illustrated based on dispersive Fourier transformation (DFT) technique. The investigation of multi-soliton compounds, caused by direct soliton interaction, probably paves access to the explorations of nonlinear dynamics in mode-locked lasers.
关键词： mode-locked fiber laser,45° tilted fiber grating,soliton molecules,dispersion-managed soliton
更新于2025-09-16 10:30:52
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Laser switching contrast microscopy to monitor free and restricted diffusion inside the cell nucleus
摘要： A novel microscopic technique termed laser switching contrast microscopy (LSCM) allows for the imaging of the dynamics of optically switchable proteins in single cell compartments. We present an application for the monitoring of diffusive properties of single molecules of the photo-switchable fluorescent protein Dreiklang (DRK). LSCM in the cell nucleus of Chinese hamster ovary (CHO) cells cytoplasmically expressing DRK unravels quick diffusive equilibration of the DRK molecules inside the whole cytoplasm and inside the cell nucleus within seconds. The nuclear membrane is also highly permeable for DRK. Inside the nucleus entirely distinct regions are found that only partially enable diffusive protein redistribution with mean square displacement proportional to time while in other regions the mobility of the proteins seems to be restricted. After photo-switching string like patterns of light DRK molecules are observed in the cell nucleus. In addition a fraction of these DRK molecules appears immobile. The findings support recent theories of the cell interior described as a random obstacle model with an additional immobile fraction of DRK. Numerical simulations show that at different illumination intensity and different distance from the laser focus similar patterns for fluorescence recovery might be obtained in spite of strongly varying diffusion constants.
关键词： random walk,Fluorescence microscopy,diffusion constant,nanofluidics,Dreiklang,superresolution microscopy,fluorescent protein,photo-switchable molecules
更新于2025-09-16 10:30:52
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Inactivation of Bacteria during Stimulation of Sensitizers with High-Power Nanosecond Laser Pulses
摘要： The results of a study of photoinactivation of bacteria during stimulation of sensitizers with nanosecond laser pulses with a power density within 1–30 MW/cm2 are presented. The irreversible damage to living cells by shock waves developed during the formation and collapse of vapor bubbles in locally heated microregions of the medium is discussed. The local heating of the medium occurred due to heat release during nonradiative relaxation of high electronic states of sensitizer molecules.
关键词： local heating,highly excited electronic states of molecules,photoinactivation of bacteria,acoustic waves
更新于2025-09-16 10:30:52
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“Twisted” conjugated molecules as donor materials for efficient all-small-molecule organic solar cells processed with tetrahydrofuran
摘要： High-performance organic semiconductors that can be processed with environmentally benign solvents are highly desirable for printable optoelectronics. Herein, four acceptor–donor–acceptor conjugated molecules, i.e., DRTT-T, DRTT-R, DRTT-OR and DRTT, with 3-ethylrhodanine as acceptor terminal units and 2,5-bis(4,8-di(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophen-2-yl)thieno[3,2-b]thiophene derivatives as donor units were synthesized. 5-(2-Ethylhexyl)thiophen-2-yl, 2-ethylhexyl and 2-ethylhexyloxy were introduced at the b-positions of the central thieno[3,2-b]thiophene (TT) units in DRTT-T, DRTT-R and DRTT-OR, respectively, and unsubstituted TT was used as the central unit in DRTT. As revealed by density functional theory calculations, DRTT-OR and DRTT adopt an almost planar geometry, while DRTT-T and DRTT-R have “twisted” backbones due to the introduction of bulky substituents on TT units. Di?ering from DRTT-OR and DRTT which are only well soluble in chlorinated solvents such as chloroform, DRTT-T and DRTT-R also show high solubility in “greener” solvents, including toluene and tetrahydrofuran (THF). Non-fullerene small molecule (NFSM) organic solar cells (OSCs) were fabricated with these molecules as donor materials. The molecules (DRTT-T and DRTT-R) with twisted backbones displayed remarkably higher device performance compared to more planar ones (DRTT-OR and DRTT), attributed to the formation of ordered face-on microstructures with p–p stacking distances of 3.7–3.8 ?A and interpenetration networks of donor and acceptor components in the blend ?lms based on DRTT-T and DRTT-R. Most importantly, the power conversion e?ciencies (PCEs) of DRTT-T and DRTT-R based devices processed with THF reached 9.37% and 10.45%, respectively. This study demonstrates that “twisting” conjugated backbones is an appropriate strategy to design eco-friendly solvent processable organic semiconductors for high-e?ciency OSCs.
关键词： conjugated molecules,tetrahydrofuran,organic solar cells,donor materials,power conversion efficiencies
更新于2025-09-16 10:30:52
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Tailoring a Molecule’s Optical Absorbance Using Surface Plasmonics
摘要： Understanding the interaction of light with molecules physisorbed on substrates is a fundamental problem in photonics, with applications in biosensing, photovoltaics, photocatalysis, plasmonics, and nanotechnology. However, the design of novel functional materials in silico is severely hampered by the lack of robust and computationally efficient methods for describing both molecular absorbance and screening on substrates. Here we employ our hybrid G0[W0 + ?W]-BSE implementation, which incorporates the substrate via its screening ?W at both the quasiparticle G0W0 level and when solving the Bethe-Salpeter equation (BSE). We show this method can be used to both efficiently and accurately describe the absorption spectra of physisorbed molecules on metal substrates and thereby tailor the molecule’s absorbance by altering the surface plasmon’s energy. Specifically, we investigate how the optical absorption spectra of three prototypical π-conjugated molecules: benzene (C6H6), terrylene (C30H16) and fullerene (C60), depends on the Wigner-Seitz radius rs of the metallic substrate. To gain further understanding of the light–molecule/substrate interaction, we also study the bright exciton’s electron and hole densities and their interactions with infrared active vibrational modes. Our results show that (1) benzene’s bright E1 2u exciton at 7.0 eV, whose energy is insensitive to changes in rs, could be relevant for photocatalytic dehydrogenation and polymerization reactions, (2) terrylene’s bright B3u exciton at 2.3 eV hybridizes with the surface plasmon, allowing the tailoring of the excitonic energy and optical activation of a surface plasmon-like exciton, and (3) fullerene’s π ? π? bright and dark excitons at 6.4 and 6.8 eV hybridize with the surface plasmon, resulting in the tailoring of their excitonic energy and the activation of both a surface plasmon-like exciton and a dark quadrupolar mode via symmetry breaking by the substrate. This work demonstrates how a proper description of interfacial light–molecular/substrate interactions enables the prediction, design, and optimization of technologically relevant phenomena in silico.
关键词： Plasmonics,Optical Absorbance,π-conjugated molecules,Fullerene,Excitons,Hybrid Materials,Benzene,Surface Plasmonics,Magnetic,Infrared active vibrational modes,Wigner-Seitz radius,Optical,Terrylene
更新于2025-09-16 10:30:52
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Polarization of high-order harmonic generation in oriented molecules with intense ultrashort laser pulses
摘要： Using numerical solutions of the time-dependent Schr?dinger equation we show that in oriented molecules one can control the polarization of molecular high-order harmonic generation (MHOHG) by intense linearly polarized pulses. For oriented triangular molecules, H3+/H32+, one obtains even-order harmonics perpendicular to the laser polarization, whereas all odd-order harmonics have the same polarization as the laser polarization. For H2+/H2 we show that only odd-order harmonics are generated for any orientation and their polarization is nearly parallel to the molecular axis. We describe these phenomena based on perturbation theory. Redshifts of the MHOHG spectra occur due to laser induced electron localization in non-Born-Oppenheimer dissociating molecules, reflecting the effect of nuclear dynamics. The numerical results illustrate the sensitivity of harmonic polarization to molecular geometry and nuclear dynamics.
关键词： oriented molecules,ultrashort laser pulses,perturbation theory,nuclear dynamics,high-order harmonic generation,polarization
更新于2025-09-16 10:30:52
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Ternary small molecules organic photovoltaics exhibiting 12.84% efficiency
摘要： Small molecules organic photovoltaics (SMPVs) were prepared with DR3TSBDT as donor, narrow band gap material Y6 and broad band gap material PC71BM as acceptor. The Y6 based binary SMPVs exhibits a power conversion efficiency (PCE) of 10.53%, with short-circuit density (JSC) of 21.67 mA cm-2, open circuit voltage (VOC) of 0.879 V and fill factor (FF) of 55.21%. A 12.84% PCE is achieved from the optimized ternary SMPVs with 40 wt% PC71BM in acceptors, which is attributed to the enhanced JSC of 22.19 mA cm-2 and FF of 67.27% resulting from the well-optimized phase separation with PC71BM as morphology regulator. Hollow spherical structure of PC71BM with high electron mobility may connect Y6 molecules to form the more continuous electron transport channels in ternary active layers. Meanwhile, DR3TSBDT molecular arrangement can be markedly adjusted by incorporating PC71BM to form 3D texture structure. The well-optimized phase separation degree and molecular arrangement in ternary active layers can well support the enhanced FFs of ternary SMPVs compared with that of binary SMPVs. Over 21% PCE improvement is achieved by employing ternary strategy with 40 wt% PC71BM in acceptors, the 12.84% PCE should be among the highest values of SMPVs.
关键词： Small molecules organic photovoltaics,Ternary strategy,Morphology regulator,Power conversion efficiency
更新于2025-09-16 10:30:52
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Controlling circularly polarized high-order harmonic generation in molecules by intense tricircular laser pulses
摘要： We present a scheme to control circularly polarized high-order harmonic generation (HHG) in molecules, the source of extreme ultraviolet and x-ray pulses, by multiple frequency co- and counter-rotating circularly polarized laser pulses. Simulations are performed on the oriented single electron molecular ions with cyclic equilateral geometry, H2+ 3 , as benchmark models, by numerically solving time-dependent Schr?dinger equations. Results show that circularly polarized HHG can be produced with extended harmonic order cutoffs, which depend on the intensity ratio of ?elds and the ?eld-molecule symmetry. We describe the laser induced electron dynamics in a rotating frame to examine recollision dynamics and Coriolis effects. The resulting modulation of HHG spectra arises from a combination of two bicircular ?elds with counter-rotating and co-rotating components. It is also found that harmonic polarization is a function of the pulse frequencies and helicities, illustrating the importance of matching the ?eld-molecule symmetry. The results in principle illustrate a method for controlling circular polarization properties of harmonics in molecules.
关键词： tricircular laser pulses,molecules,electron dynamics,high-order harmonic generation,circularly polarized
更新于2025-09-16 10:30:52