| 1. |
- Benetti, Daniele, et al.
(författare)
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Direct Measurement of Electronic Band Structure in Single Quantum Dots of Metal Chalcogenide Composites
- 2018
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Ingår i: Small (Weinheim an der Bergstrasse, Germany). - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 14:51
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Tidskriftsartikel (refereegranskat)abstract
- Metal chalcogenide quantum dots (QDs) are among the most promising materials as light harvesters in all-inorganic systems for applications in solar cells and production of solar fuels. The electronic band structure of composite QDs formed by lead and cadmium chalcogenides directly grafted on highly oriented pyrolytic graphite surfaces through successive ionic layer absorption and reaction is investigated. Atomic force microscopy and Kelvin probe force microscopy (KPFM) are applied to investigate PbS, CdS, and PbS/CdS QD systems. The variation of the surface potential of individual QDs is measured, investigating the evolution of the electronic band structure as a function of QD size and composition. A shift of the Fermi level toward more negative values occurs when QD size is increased. The shift is more pronounced in CdS than in PbS, while the composite PbS/CdS exhibits an intermediate behavior. The calculated shift is in good agreement with the experiments. These results highlight the ability of KPFM to directly measure the electronic band structure in individual QDs of metal chalcogenide composites. This feature regulates charge dynamics in composite systems, thereby affecting device performance. This work provides valuable insights for applications in several fields, in which charge injection plays a major role.
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| 2. |
- Concina, Isabella, et al.
(författare)
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Metal Oxide Semiconductors for Dye- and Quantum-Dot-Sensitized Solar Cells
- 2015
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 11:15, s. 1744-1774
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Tidskriftsartikel (refereegranskat)abstract
- This Review provides a brief summary of the most recent research developments in the synthesis and application of nanostructured metal oxide semiconductors for dye sensitized and quantum dot sensitized solar cells. In these devices, the wide bandgap semiconducting oxide acts as the photoanode, which provides the scaffold for light harvesters (either dye molecules or quantum dots) and electron collection. For this reason, proper tailoring of the optical and electronic properties of the photoanode can significantly boost the functionalities of the operating device. Optimization of the functional properties relies with modulation of the shape and structure of the photoanode, as well as on application of different materials (TiO2, ZnO, SnO2) and/or composite systems, which allow fine tuning of electronic band structure. This aspect is critical because it determines exciton and charge dynamics in the photoelectrochemical system and is strictly connected to the photoconversion efficiency of the solar cell. The different strategies for increasing light harvesting and charge collection, inhibiting charge losses due to recombination phenomena, are reviewed thoroughly, highlighting the benefits of proper photoanode preparation, and its crucial role in the development of high efficiency dye sensitized and quantum dot sensitized solar cells.
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| 3. |
- Concina, Isabella, et al.
(författare)
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Solar Cells : Metal Oxide Semiconductors for Dye- and Quantum-Dot-Sensitized Solar Cells
- 2015
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 11:15, s. 1743-
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Tidskriftsartikel (refereegranskat)abstract
- Metal oxide semiconductors are an appealing class of material, extensively used as photoanodes in excitonic solar cells such as dye- and quantum dot-sensitized solar cells. On page 1744, I. Concina and A. Vomiero describe how proper tailoring of the shape, composition, and crystalline structure of these materials can significantly boost the performances of these solar energy converting devices by ameliorating the processes of exciton separation, charge transport, and collection, while reducing charge losses due to recombination and back reactions.
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| 4. |
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| 5. |
- Ibrahim, Kassa Belay, et al.
(författare)
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Facile Electron Transfer in Atomically Coupled Heterointerface for Accelerated Oxygen Evolution
- 2023
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Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- An efficient and cost-effective approach for the development of advanced catalysts has been regarded as a sustainable way for green energy utilization. The general guideline to design active and efficient catalysts for oxygen evolution reaction (OER) is to achieve high intrinsic activity and the exposure of more density of the interfacial active sites. The heterointerface is one of the most attractive ways that plays a key role in electrochemical water oxidation. Herein, atomically cluster-based heterointerface catalysts with strong metal support interaction (SMSI) between WMn2O4 and TiO2 are designed. In this case, the WMn2O4 nanoflakes are uniformly decorated by TiO2 particles to create electronic effect on WMn2O4 nanoflakes as confirmed by X-ray absorption near edge fine structure. As a result, the engineered heterointerface requires an OER onset overpotential as low as 200 mV versus reversible hydrogen electrode, which is stable for up to 30 h of test. The outstanding performance and long-term durability are due to SMSI, the exposure of interfacial active sites, and accelerated reaction kinetics. To confirm the synergistic interaction between WMn2O4 and TiO2, and the modification of the electronic structure, high-resolution transmission electron microscopy (HR-TEM), X-ray photoemission spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) are used.
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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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