| 181. |
- Zhang, Youwei, et al.
(författare)
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Competing Mechanisms for Photocurrent Induced at the Monolayer-Multilayer Graphene Junction
- 2018
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Ingår i: Small. - : WILEY-V C H VERLAG GMBH. - 1613-6810 .- 1613-6829. ; 14:24
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Tidskriftsartikel (refereegranskat)abstract
- Graphene is characterized by demonstrated unique properties for potential novel applications in photodetection operated in the frequency range from ultraviolet to terahertz. To date, detailed work on identifying the origin of photoresponse in graphene is still ongoing. Here, scanning photocurrent microscopy to explore the nature of photocurrent generated at the monolayer-multilayer graphene junction is employed. It is found that the contributing photocurrent mechanism relies on the mismatch of the Dirac points between the monolayer and multilayer graphene. For overlapping Dirac points, only photothermoelectric effect (PTE) is observed at the junction. When they do not coincide, a different photocurrent due to photovoltaic effect (PVE) appears and becomes more pronounced with larger separation of the Dirac points. While only PTE is reported for a monolayer-bilayer graphene junction in the literature, this work confirms the coexistence of PTE and PVE, thereby extending the understanding of photocurrent in graphene-based heterojunctions.
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| 182. |
- Zhang, Yuning
(författare)
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Novel Therapeutic Platform of Micelles and Nanogels from Dopa-Functionalized Triblock Copolymers
- 2021
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Ingår i: Small. - : Wiley. - 1613-6829 .- 1613-6810. ; 17:17, s. 2007305-
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Tidskriftsartikel (refereegranskat)abstract
- Multi-drug delivery systems constructed from a basic polymeric scaold, and which have the ability to target a variety of biomedical applications, can streamline the development of nanomedicine to provide both environmental and economical relief. Herein, amphiphilic ABA-triblock copolymers are synthesized and assembled sequentially into micelles and nanogels as drug delivery systems following a thorough evaluation on advanced in vitro models to explore their potential for the treatment of cancer and bacterial infections. Short blocks of -methyl--allyloxycarbonyl-,-dioxan--one (MAC) are oli-gomerized from PEGk and thereafter functionalized with dihydroxyphenyla-lanine (dopa)-functional thiols using thiol-ene coupling (TEC) click chemistry. The copolymers self-assemble into well-defined micelles in aqueous solution and are further formulated into nanogels via UV-induced TEC. The resulting spherical micelles and nanogels are stable nanoparticles, with sizes ranging between and nm. The nanogels are found to be non-toxic to a panel of cell lines and mask the toxicity of the potent drugs until their release. The nanogels would be superior to micelles for the elimination of cancer cells supported by both D cell culture and a D spheroid model. The opposite conclusion could be drawn for bacteria inhibition.
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| 183. |
- Zhao, Haiguang, et al.
(författare)
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Absorption Enhancement in “Giant” Core/Alloyed-Shell Quantum Dots for Luminescent Solar Concentrator
- 2016
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 12:38, s. 5354-5365
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Tidskriftsartikel (refereegranskat)abstract
- Luminescent solar concentrators (LSCs) can potentially reduce the cost of solar cells by decreasing the photoactive area of the device and boosting the photoconversion efficiency (PCE). This study demonstrates the application of “giant” CdSe/CdxPb1–xS core/shell quantum dots (QDs) as light harvesters in high performance LSCs with over 1.15% PCE. Pb addition is critical to maximize PCE. First, this study synthesizes “giant” CdSe/CdxPb1–xS QDs with high quantum yield (40%), narrow size distribution (<10%), and stable photoluminescence in a wide temperature range (100–300 K). Subsequently these thick alloyed-shell QDs are embedded in a polymer matrix, resulting in a highly transparent composite with absorption spectrum covering the range 300–600 nm, and are applied as active material for prototype LSCs. The latter exhibits a 15% enhancement in efficiency with respect to 1% PCE of the pure-CdS-shelled QDs. This study attributes this increase to the contribution of Pb doping. The results demonstrate a straightforward approach to enhance light absorption in “giant” QDs by metal doping, indicating a promising route to broaden the absorption spectrum and increase the efficiency of LSCs.
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| 184. |
- Zhao, Haifeng, et al.
(författare)
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Efficient and High-Luminance Perovskite Light-Emitting Diodes Based on CsPbBr3 Nanocrystals Synthesized from a Dual-Purpose Organic Lead Source
- 2020
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Ingår i: Small. - : WILEY-V C H VERLAG GMBH. - 1613-6810 .- 1613-6829.
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Tidskriftsartikel (refereegranskat)abstract
- Rational engineering of the surface properties of perovskite nanocrystals (PeNCs) is critical to obtain light emitters with simultaneous high photoluminescence efficiency and excellent charge transport properties for light-emitting diodes (LEDs). However, the commonly used lead halide sources make it hard to rationally optimize the surface compositions of the PeNCs. In addition, previously developed ligand engineering strategies for conventional inorganic nanocrystals easily deteriorate surface properties of the PeNCs, bringing additional difficulties in optimizing their optoelectronic properties. In this work, a novel strategy of employing a dual-purpose organic lead source for the synthesis of highly luminescent PeNCs with enhanced charge transport property is developed. Lead naphthenate (Pb(NA)(2)), of which the metal ions work as lead sources while the naphthenate can function as the surface ligands afterward, is explored and the obtained products under different synthesis conditions are comprehensively investigated. Monodispersed cesium lead bromide (CsPbBr3) with controllable size and excellent optical properties, showing superior photoluminescence quantum yields up to 80%, is obtained. Based on the simultaneously enhanced electrical properties of the Pb(NA)(2)-derived PeNCs, the resultant LEDs demonstrate a high peak external quantum efficiency of 8.44% and a superior maximum luminance of 31 759 cd cm(-2).
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| 185. |
- Zhao, Haiguang, et al.
(författare)
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Solar Concentrators : Absorption Enhancement in “Giant” Core/Alloyed-Shell Quantum Dots for Luminescent Solar Concentrator
- 2016
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 12:38
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- On page 5354, H. G. Zhao, F. Rosei, A. Vomiero, and co-workers, demonstrate the application of “giant” core/shell quantum dots as light harvesters in high-performance luminescent solar concentrators (LSCs) with over 1.15% power conversion efficiency. Metal doping approach can tune the absorption spectra of QDs to better match the solar spectrum, and represents a significant advance for the development of high-efficiency LSCs for cost-effective photovoltaic applications.
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| 186. |
- Zhao, Haiguang, et al.
(författare)
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Tailoring the Heterostructure of Colloidal Quantum Dots for Ratiometric Optical Nanothermometry
- 2020
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Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 16:28
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Forskningsöversikt (refereegranskat)abstract
- Colloidal quantum dots (QDs) are a fascinating class of semiconducting nanocrystals, thanks to their optical properties tunable through size and composition, and simple synthesis methods. Recently, colloidal double‐emission QDs have been successfully applied as competitive optical temperature sensors, since they exhibit structure‐tunable double emission, temperature‐dependent photoluminescence, high quantum yield, and excellent photostability. Until now, QDs have been used as nanothermometers for in vivo biological thermal imaging, and thermal mapping in complex environments at the sub‐microscale to nanoscale range. In this Review, recent progress for QD‐based nanothermometers is highlighted and perspectives for future work are described.
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| 187. |
- Zhao, Haiguang, et al.
(författare)
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Temperature Sensors : Ultrasensitive, Biocompatible, Self-Calibrating, Multiparametric Temperature Sensors
- 2015
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 11:43, s. 5740-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- PbS/CdS core/shell quantum dots are applied as ultrasensitive, biocompatible, self-calibrating, multi-parametric temperature sensors by H. Zhao, A. Vomiero, and F. Rosei. On page 5741, they show how part of the colour emission comes from the PbS core and part from the CdS shell. The relative intensity of these emissions is temperature-dependent, inducing color changes when the temperature varies. The lifetime and peak position of PbS emission also monotonically change with the temperature, offering a platform for a multi-parametric detection system.
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| 188. |
- Zhao, Haiguang, et al.
(författare)
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Ultrasensitive, Biocompatible, Self-Calibrating, Multiparametric Temperature Sensors
- 2015
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 11:43, s. 5741-5746
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Tidskriftsartikel (refereegranskat)abstract
- Core–shell quantum dots serve as self-calibrating, ultrasensitive, multiparametric, near-infrared, and biocompatible temperature sensors. They allow temperature measurement with nanometer accuracy in the range 150–373 K, the broadest ever recorded for a nanothermometer, with sensitivities among the highest ever reported, which makes them essentially unique in the panorama of biocompatible nanothermometers with potential for in vivo biological thermal imaging and/or thermoablative therapy.
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| 189. |
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| 190. |
- Zhi, L., et al.
(författare)
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Solid-state pyrolyses of metal phthalocyanines : A simple approach towards nitrogen-doped CNTs and metal/carbon nanocables
- 2005
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 1:8-9, s. 798-801
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Tidskriftsartikel (refereegranskat)abstract
- Solid-state pyrolysis of organometallic precursors has emerged as an alternative method for preparing carbon nanostructures such as carbon nanotubes (CNT) and carbon anions. The morphology of the tubes can be controlled by the nature of the precursors and the pyrolysis procedures, and micrometer long nanotubes, composed of metal carbide wires encased in a graphitic sheath. Cobalt phthalocyanine (CoPc) as well as iron phthalocyanine were pyrolyzed at different temperatures to obtain CNTs. HRTEM and energy-dispersion X-Ray analysis disclosed that the core consisted of long, iron-containing single crystals and that the core was fully surrounded by crystallized graphic carbon. Iron-filled carbon nanotubes were also obtained from the pyrolysis of ferrocene by CVD method. Encapsulated iron carbide were also observed inside the carbon nanotubes formed after pyrolysis of FePc. These nanotubes and nanocables were considered useful for assembling miniaturized electronic device and sensors.
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