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Two-dimensional Kagome Lattices Made of Hetero Triangulenes are Dirac Semimetals or Single-Band Semiconductors
摘要： Here we discuss, based on first-principles calculations, two-dimensional (2D) kagome lattices composed of polymerized hetero-triangulene units, planar molecules with D3h point group containing a B, C or N center atom and CH2, O or CO bridges. We explore the design principles for a functional lattice made of 2D polymers, which involves control of π-conjugation and electronic structure of the knots. The former is achieved by the chemical potential of the bridge groups, while the latter is controlled by the heteroatom. The resulting 2D kagome polymers have a characteristic electronic structure with a Dirac band sandwiched by two flat bands and are either Dirac semimetals (C center), or single-band semiconductors - materials with either exclusively electrons (B center) or holes (N center) as charge carriers of very high mobility, reaching values of up to ~8×103 cm2V-1s-1, which is comparable to crystalline silicon.
关键词： high mobility,charge carriers,single-band semiconductors,hetero-triangulene units,Dirac semimetals,two-dimensional kagome lattices
更新于2025-09-23 15:21:21
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Visible Light TiO <sub/>2</sub> Photocatalyst Composite Based on Carbon Microfiber Derived from Human Hair
摘要： The present work reports titanium dioxide (TiO2) photocatalyst composite based on human hair that can operate efficiently under visible light. The human hair melanin structure contains active sites, which can be described as a carbon compound derived from a Quinone where one of two oxygen atoms is bonded to a hydrogen radical and that can be reversibly photogenerated under visible or ultraviolet irradiation. The human hair-derived microfibers (HHDMs) were created by the pyrolyzing hair at 850 °C, resulting in a rod-like hollow structure. TiO2 was immobilized on the pyrolyzed hair by a simple self-template method. The resulting composite was calcined at five different temperatures (150 to 350 °C). The HHDM and HHDM-TiO2 morphologies and the chemical compositions were characterized using scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). The HHDM-TiO2 photocatalytic efficiency in degrading methylene blue was investigated and compared to that of a conventional TiO2 catalyst (P25). HHDM-TiO2 was more effective for methylene blue degradation under visible light than the conventional P25 catalyst suspension due to the unique photosensitivity and porous structure of the composite. The catalyst calcined at 300 °C showed the best performance, which was 71% higher than that of the P25 catalyst.
关键词： Semiconductors,Immobilization,Titanium Dioxide,Waste prevention,Photocatalysis
更新于2025-09-23 15:21:21
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Core-shell Structured TiO2@In2O3 for Highly Active Visible-light Photocatalysis
摘要： Core-shell structured TiO2@In2O3 with high visible-light photocatalytic activity have been successfully fabricated by solvothermal method. The as-obtained products were characterized by field transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-visible diffuse reflectance spectra (UV-vis DRS). Structural characterizations demonstrated that the In2O3 layers were comprised of nanocrystallites ca. 14 nm in size and displayed rough surfaces. The UV-vis DRS data showed that In2O3 greatly expanded the visible light absorption band edge of TiO2. The results revealed that the obtained TiO2@In2O3 with core-shell structure showed enhancement of the visible-light photocatalytic activity to degrade methyl orange (MO) comparing with the pure TiO2 and In2O3 products.
关键词： TiO2@In2O3,Nanocomposites,Semiconductors,Core-shell structure
更新于2025-09-23 15:21:21
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Insight into the Z-scheme heterostructure WO3/g-C3N4 for enhanced photocatalytic degradation of methyl orange
摘要： WO3 nanosheets and its hybridized nanocomposite, WO3/g-C3N4, were prepared by a simple direct precipitation method. The as-prepared WO3/g-C3N4 showed enhanced photocatalytic activity toward degrading methyl orange (MO). The ?O2 ?, which played key role in the photocatalytic oxidation process, were clearly identified and quantitationally determined by the trapping experiment and nitroblue tetrazolium (NBT) probing method. Z-scheme photocatalytic mechanism was proposed accordingly.
关键词： photocatalysis,WO3/g-C3N4,Nanocomposites,Semiconductors
更新于2025-09-23 15:21:21
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Hole transporting properties of discotic liquid-crystalline semiconductor confined in calamitic UV-crosslinked gel
摘要： The influence of polymer network on hole transport in discotic liquid crystal (LC) is investigated by the time of flight charge carrier mobility measurements. Composites of discotic LC and nematic reactive mesogen undergo UV-activated polymerization in columnar phase which yields the formation of chemical gels. Polarized optical microscopy allows us to observe alignment effect, whether scanning electron microscopy helps us to obtain characteristic imprint of polydomain columnar phase in created polymeric network. Hole mobility is improved, presumably due to the stabilization of the alignment of discotic LC. This type of composite is relevant for potential multilayer and flexible device applications.
关键词： reactive mesogens,discotic liquid crystals,photopolymers,gels,organic semiconductors
更新于2025-09-23 15:21:21
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Formation of Occupied and Unoccupied Hybrid Bands at Interfaces between Metals and Organic Donors/Acceptors
摘要： Efficient charge transport in organic semiconductors and at their interfaces with electrodes is crucial for the performance of organic molecule-based electronic devices. Band formation fosters effective transport properties and can be found in organic single crystals of large π-stacking aromatic molecules. However, at molecule/metal interfaces hybrid band formation and band dispersion is a rarely observed phenomenon. Using angle-resolved two-photon photoemission supported by density functional theory calculations we demonstrate such band formation for two different molecule/metal systems, namely tetrathiafulvalene (TTF)/Au(111) and tetrafluoro-tetracyanoquinodimethane (F4TCNQ)/Au(111), in the energy region of occupied as well as unoccupied electronic states. In both cases strong adsorbate/substrate interactions result in formation of interface states due to hybridization between localized molecular states and delocalized metal bands. These interface states exhibit significant dispersions. Our study reveals that hybridization in combination with an extended well-ordered adsorption structure of the π-conjugated organic molecules is a striking concept to receive and experimentally observe band formation at molecule/metal interfaces.
关键词： band formation,organic semiconductors,molecule/metal interfaces,hybridization,charge transport,density functional theory,angle-resolved two-photon photoemission
更新于2025-09-23 15:21:21
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Tuning the Cross-Linker Crystallinity of a Stretchable Polymer Semiconductor
摘要： The cross-linking of conjugated polymers has been demonstrated to be an effective strategy to improve its elastic properties to give deformable semiconductors for plastic electronics. While there have been extensive studies of the structural requirements of the polymer host for good film ductility, no work to date has focused on the relevance of the structural design or chemistry of these cross-linker additives. In this study, urethane groups and tertiary carbon atoms are inserted into the alkyl backbone of perfluorophenyl azide-based cross-linkers to investigate the importance of cross-linker crystallinity with respect to polymer morphology and hence mechanical and electrical properties. Linear cross-linkers with hydrogen bonding from urethane groups readily phase separate and recrystallize in the polymer network to form cross-linked domains that obstruct the strain distribution of the polymer film. Branch cross-linkers with tertiary carbon on the other hand form an evenly cross-linked network in the polymer blend stemming from excellent miscibility and show a 4-fold increase in fracture strain. Furthermore, a stable hole mobility of 0.2 cm2 V?1 s?1 is achieved up to ε = 100%, and a stable hole mobility of 0.1 cm2 V?1 s?1 after 2000 cycles of ε = 25% on fully stretchable organic field-effect transistors.
关键词： cross-linking,deformable semiconductors,cross-linker crystallinity,electrical properties,polymer morphology,elastic properties,plastic electronics,conjugated polymers,mechanical properties
更新于2025-09-23 15:21:21
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D-??-D molecular semiconductors for perovskite solar cells: the superior role of helical versus planar ??-linker
摘要： Controlling the mode of molecular packing and the size of molecular aggregate are of fundamental importance for high-performance charge transporting materials in next-generation optoelectronic devices. To clarify the peculiar role of helicene as kernal blocks in the exploration of unconventional organic semiconductors, in this work thia[5]helicene (T5H) is duplicately aminated with electron-donating dimethoxydiphenylamine to afford T5H-OMeDPA, which is systematically compared with its perylothiophene (PET) congener (PET-OMeDPA). On the basis of quantum theory of atoms in molecules and energy decomposition analysis of single-crystals, it is suprisingly found that while π-π stacking of planar PET is stronger than that of helical T5H, this desirable effect for charge transport of organic semiconductors is completely lost for donor-π-donor (D-π-D) typed PET-OMeDPA, but is retained for T5H-OMeDPA to a large extent. Consequently, T5H-OMeDPA single-crystal presents an about 5 times higher theoretical hole-mobility than PET-OMeDPA. More critically, the solution-processed racemic glassy film of T5H-OMeDPA displays a 3 times higher hole-mobility in comparison with the PET-OMeDPA counterpart, due to a larger domain of molecular aggregate. With respect to PET-OMeDPA, there is a weaker electronic coupling of helical T5H-OMeDPA with perovskite, leading to a reduced interfacial charge recombination. Due to reduced transport resistance and enhanced recombination resistance, perovskite solar cells with T5H-OMeDPA exhibit a power conversion efficiency of 21.1%, higher than that of 19.8% with PET-OMeDPA and that of 20.6% with spiro-OMeTAD control.
关键词： charge transport,perovskite solar cells,helicene,molecular semiconductors,π-π stacking
更新于2025-09-23 15:21:01
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Lead-free perovskite/organic semiconductor vertical heterojunction for highly sensitive photodetectors
摘要： In recent years, photodetectors based on organic-inorganic lead halide perovskites have been studied extensively. However, the inclusion of lead in those materials can cause severe human health and environmental problems, which is undesirable for practical applications. Here, we report high-performance photodetectors with a tin-based perovskite/PEDOT:PSS vertical heterojunction. The device demonstrates broadband photo-response from NIR to UV. The maximum responsivity and gain are up to 2.6 × 106 A/W and 4.7 × 106, respectively. Moreover, a much shorter response time and higher detectivity can be achieved by reducing the thickness of PEDOT:PSS. The outstanding performance is due to the excellent optoelectronic properties of the perovskite and the photo-gating effect originated from the heterojunction. Furthermore, devices fabricated on flexible substrates can demonstrate not only high sensitivity but also excellent bending stability. This work opens up the opportunity of using lead-free perovskite in highly sensitive photodetectors with vertical heterojunctions.
关键词： Photo-gating,heterojunction,organic semiconductors,Photodetectors,Lead free perovskites
更新于2025-09-23 15:21:01
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Photovoltaic organic interface for neuronal stimulation in the near-infrared
摘要： Organic materials, such as conjugated polymers, are attractive building blocks for bioelectronic interfaces. In particular, organic semiconductors show excellent performance in light-mediated excitation and silencing of neuronal cells and tissues. However, the main challenges of these organic photovoltaic interfaces compared to inorganic prostheses are the limited adhesion of conjugated polymers in aqueous environments and the exploitation of materials responsive in the visible spectrum. Here, we show a photovoltaic organic interface optimized for neuronal stimulation in the near-infrared spectrum. We adjusted the organic materials by chemical modification in order to improve the adhesion in an aqueous environment and to modulate the photoelectrical stimulation efficiency. As proof-of-principle, we tested this interface on explanted degenerated mice retinas, thus providing results on the efficiency and reliability of the device as an implant for neural stimulation.
关键词： organic semiconductors,bioelectronic interfaces,neuronal stimulation,near-infrared spectrum,photovoltaic interfaces
更新于2025-09-23 15:21:01