| 60041. |
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| 60042. |
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| 60043. |
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| 60044. |
- Liu, Xianjie, et al.
(författare)
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Electronic Structure Characterization of Soft Semiconductors
- 2019
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Ingår i: Advanced Materials Interfaces. - : WILEY. - 2196-7350. ; 6:16
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Tidskriftsartikel (refereegranskat)abstract
- Soft semiconductors are a class of materials that have seen increased interest in terms of both basic research and development of technology, in particular optoelectronic devices. These materials, organic semiconductors and metal halide perovskites, are defined by being more mechanically malleable than the traditional crystalline inorganic semiconductors and with thin film fabrication done at lower temperatures and often from solution. In this short perspective article, basic properties of the materials are introduced, as well as their typical applications and a number of advanced characterization techniques that offer distinct advantages for studying soft semiconductor thin films.
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| 60045. |
- Liu, Xianjie, et al.
(författare)
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Interfacial electronic properties of pentacene tuned by a molecular monolayer of C-60
- 2009
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - College Park, MD, United States : American Physical Society. - 1098-0121 .- 1550-235X. ; 80:11, s. 115401-1-115401-7
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Tidskriftsartikel (refereegranskat)abstract
- Fine-tuning charge injection barriers between organic materials and electrodes is critical to optimize organic electronic device performance. Here we demonstrate that by modifying gold substrates with a monolayer of fullerene, significant decrease in the hole-injection barrier into pentacene films can be achieved. The insertion of the fullerene monolayer modifies the interfacial dipole and produces an interface where the pentacene molecules form a standing-up orientation with their long axis parallel to the surface normal. The latter effect lowers the vertical ionization energy of the pentacene molecules at the interface as compared to the pentacene-on-Au case, as well as improves the pi-pi overlap between the pentacene molecules that will likely enhance the transport properties in corresponding devices.
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| 60046. |
- Liu, Xiaoke, et al.
(författare)
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Metal halide perovskites for light-emitting diodes
- 2021
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Ingår i: Nature Materials. - : NATURE PUBLISHING GROUP. - 1476-1122 .- 1476-4660. ; 20:1, s. 10-21
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Forskningsöversikt (refereegranskat)abstract
- The development of perovskite emitters, their use in light-emitting devices, and the challenges in enhancing the efficiency and stability, as well as reducing the potential toxicity of this technology are discussed in this Review. Metal halide perovskites have shown promising optoelectronic properties suitable for light-emitting applications. The development of perovskite light-emitting diodes (PeLEDs) has progressed rapidly over the past several years, reaching high external quantum efficiencies of over 20%. In this Review, we focus on the key requirements for high-performance PeLEDs, highlight recent advances on materials and devices, and emphasize the importance of reliable characterization of PeLEDs. We discuss possible approaches to improve the performance of blue and red PeLEDs, increase the long-term operational stability and reduce toxicity hazards. We also provide an overview of the application space made possible by recent developments in high-efficiency PeLEDs.
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| 60047. |
- Liu, Xiaobin, et al.
(författare)
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Molecular Fingerprint of Neuropeptide S-Producing Neurons in the Mouse Brain
- 2011
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Ingår i: JOURNAL OF COMPARATIVE NEUROLOGY. - : John Wiley and Sons, Ltd. - 0021-9967. ; 519:10, s. 1847-1866
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide S (NPS) has been associated with a number of complex brain functions, including anxiety-like behaviors, arousal, sleep-wakefulness regulation, drug-seeking behaviors, and learning and memory. In order to better understand how NPS influences these functions in a neuronal network context, it is critical to identify transmitter systems that control NPS release and transmitters that are co-released with NPS. For this purpose, we generated several lines of transgenic mice that express enhanced green-fluorescent protein (EGFP) under control of the endogenous NPS precursor promoter. NPS/EGFP-transgenic mice show anatomically correct and overlapping expression of both NPS and EGFP. A total number of similar to 500 NPS/EGFP-positive neurons are present in the mouse brain, located in the pericoerulear region and the Kolliker-Fuse nucleus. NPS and transgene expression is first detectable around E14, indicating a potential role for NPS in brain development. EGFP-positive cells were harvested by laser-capture microdissection, and mRNA was extracted for expression profiling by using microarray analysis. NPS was found co-localized with galanin in the Kolliker-Fuse nucleus of the lateral parabrachial area. A dense network of orexin/hypocretin neuronal projections contacting pericoerulear NPS-producing neurons was observed by immunostaining. Expression of a distinct repertoire of metabotropic and ionotropic receptor genes was identified in both NPS neuronal clusters that will allow for detailed investigations of incoming neurotransmission, controlling neuronal activity of NPS-producing neurons. Stress-induced functional activation of NPS-producing neurons was detected by staining for the immediate-early gene c-fos, thus supporting earlier findings that NPS might be part of the brain stress response network.
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| 60048. |
- Liu, Xiaoke, et al.
(författare)
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Organic-Inorganic Hybrid Ruddlesden-Popper Perovskites: An Emerging Paradigm for High-Performance Light-Emitting Diodes
- 2018
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Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 9:9, s. 2251-2258
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Tidskriftsartikel (refereegranskat)abstract
- Recently, lead halide perovskite materials have attracted extensive interest, in particular, in the research field of solar cells. These materials are fascinating "soft" materials with semiconducting properties comparable to the best inorganic semiconductors like silicon and gallium arsenide. As one of the most promising perovskite family members, organic-inorganic hybrid Ruddlesden-Popper perovskites (HRPPs) offer rich chemical and structural flexibility for exploring excellent properties for optoelectronic devices, such as solar cells and light-emitting diodes (LEDs). In this Perspective, we present an overview of HRPPs on their structural characteristics, synthesis of pure HRPP compounds and thin films, control of their preferential orientations, and investigations of heterogeneous HRPP thin films. Based on these recent advances, future directions and prospects have been proposed. HRPPs are promising to open up a new paradigm for high-performance LEDs.
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| 60049. |
- Liu, X. P., et al.
(författare)
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In-Situ Neutron Diffraction Studies of Micromechanical Behavior in a Friction Stir Welded AA7475-T761
- 2011
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer-Verlag New York. - 1073-5623 .- 1543-1940. ; 42A:1, s. 89-94
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Tidskriftsartikel (refereegranskat)abstract
- An in-situ neutron diffraction technique was used to investigate the lattice strain distributions and micromechanical behavior in a friction stir welded (FSW) sheet of AA7475-T761. The neutron diffraction experiments were performed on the spectrometer for material research, STRESS-SPEC, at FRM II (Garching, Germany). The lattice strain profiles around the weld center were measured as a function of the applied strain during the tensile loading and unloading. The anisotropic elastic and plastic properties of the FSW aluminum alloy were simulated by elasto-plastic self-consistent (EPSC) model to predict the anisotropic deformation behaviors involving the grain-to-grain interactions. Material parameters used for describing the constitutive laws of each test position were determined from the measured lattice strain distributions for different diffraction hkl planes as well as the macroscopic stress-strain curve of the FSW aluminum alloy. A good agreement between experimental results and numerical simulations was obtained. The present investigations provided a reliable prediction of the anisotropic micromechanical behavior of the FSW aluminum alloy during tensile deformation.
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| 60050. |
- Liu, Xianjie, et al.
(författare)
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Tunable Interface Properties between Pentacene and Graphene on the SIC Substrate
- 2013
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society. - 1932-7447 .- 1932-7455. ; 117:8, s. 3969-3975
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Tidskriftsartikel (refereegranskat)abstract
- Understanding energy-level alignment and molecular growth characteristics of an organic semiconductor on the graphene surface is crucial for graphene-related device performance. Here we demonstrate that tunable interface properties and molecular orientation can be achieved by modifying graphene films on a SiC substrate with monolayer copper-hexadecafluorophthalocyanine (F16CuPc) molecules. On clean graphene, pentacene molecules form a tilted configuration even at very low coverage (one or two monolayers) rather than flat-lying as on the graphite surface. Pentacene molecules prefer to grow with a (022) plane parallel to the clean graphene surface. With increasing coverage, X-ray adsorption data indicate there is no obvious change of molecular stacking orientation. The corresponding hole injection barrier is about 0.7 eV. On the modified graphene where thin (one or two monolayers) F16CuPc molecules are flat-lying on graphene, an almost perfect up-standing molecular stacking of pentacene film was formed on the modified surface. A low hole injection barrier of 0.3 eV was observed. Furthermore, the interface of dirty graphene upon pentacene was also discussed.
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