| 1. |
- Gao, Lingfeng, et al.
(författare)
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A Facile Approach for Elemental-Doped Carbon Quantum Dots and Their Application for Efficient Photodetectors
- 2021
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Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 17:52
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Tidskriftsartikel (refereegranskat)abstract
- The present work demonstrates a facile hydrothermal approach to synthesize lanthanide-doped carbon quantum dots (CQDs) with europium and/or gadolinium elements. Taking the advantage of broadband adsorption in the ultraviolet-visible region, the doped QDs are directly used as building blocks for photo-electrochemical (PEC)-type photodetectors (PDs) and their performance is systematically investigated under various conditions. The europium (Eu) and gadolinium (Gd) co-doped (C:EuGd) QDs exhibit better photo-response than the single-elemental doped ones and also show outstanding long-term stability. According to the apparent response to light from 350 to 400 nm, the C:EuGd QDs are demonstrated to hold great potential for narrow-band PDs. This work highlights the practical applications of lanthanide-doped CQDs for PDs, and the results are beneficial for the development of elemental-doped CQDs in general.
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| 2. |
- Chen, Hualong, et al.
(författare)
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Direct Observation of Photon Induced Giant Band Renormalization in 2D PdSe2 Dichalcogenide by Transient Absorption Spectroscopy
- 2023
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Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 19:46
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Tidskriftsartikel (refereegranskat)abstract
- Insight into fundamental light-matter interaction as well as underlying photo-physical processes is crucial for the development of novel optoelectronic devices. Palladium diselenide (PdSe2), an important representative of emerging 2D noble metal dichalcogenides, has gain considerable attention owing to its unique optical, physical, and chemical properties. In this study, 2D PdSe2 nanosheets (NSs) are prepared using the liquid-phase exfoliation method. A broadband carrier relaxation dynamics from visible to near-infrared bands are revealed using a time-resolved transient absorption spectrometer, giving results that indicate band filling and bandgap renormalization (BGR) effects in the 2D PdSe2 NSs. The observed blue-shift of the transient absorption spectra at the primary stage and the subsequent red-shift can be ascribed to this BGR effect. These findings reveal the many-body character of the 2D TMDs material and may hold keys for applications in the field of optoelectronics and ultrafast photonics.
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| 3. |
- Gao, Lingfeng, et al.
(författare)
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Applications of Few-Layer Nb2C MXene : Narrow-Band Photodetectors and Femtosecond Mode-Locked Fiber Lasers
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:1, s. 954-965
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Tidskriftsartikel (refereegranskat)abstract
- Although the physicochemical properties of niobium carbide (Nb2C) have been widely investigated, their exploration in the field of photoelectronics is still at the infancy stage with many potential applications that remain to be exploited. Hence, it is demonstrated here that few-layer Nb2C MXene can serve as an excellent building block for both photoelectrochemical-type photodetectors (PDs) and mode-lockers. We show that the photoresponse performance can be readily adjusted by external conditions and that Nb2C NSs exhibit a great potential for narrow-band PDs. The demonstrated mechanism was further confirmed by work functions predicted by density functional theory calculations. In addition, as an optical switch for passively mode-locked fiber lasers, ultrastable pulses can be demonstrated in the telecommunication and mid-infrared regions for Nb2C MXene, and as high as the 69th harmonic order with 411 MHz at the center wavelength of 1882 nm can be achieved. These intriguing results indicate that few-layer Nb2C nanosheets can be used as building blocks for various photoelectronic devices, further broadening the application prospects of two-dimensional MXenes.
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| 4. |
- Gao, Lingfeng, et al.
(författare)
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Emerging applications of MXenes for photodetection : Recent advances and future challenges
- 2022
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Ingår i: Materials Today. - : Elsevier. - 1369-7021 .- 1873-4103. ; 61, s. 169-190
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Tidskriftsartikel (refereegranskat)abstract
- The development and applications of transition metal carbides, nitrides and carbonitrides, commonly denoted as MXenes, have during the last few years rapidly expanded in various technological fields owing to their unique and controllable properties. These materials exhibit competing performance comparing with traditional materials and have created numerous opportunities for technology markets. Taking the advantage of excellent optoelectronic features, MXenes have been utilized for the construction of photodetectors with various structures and unique functionalities. While the appli-cation of MXenes in this area can be traced back to 2016, we have during the recent three years witnessed a dramatic development of MXene-based photodetectors, calling for a timely review to guideline their future direction. In this work, synthetic strategies of pristine MXenes are briefly introduced and their properties are discussed focusing on the optoelectronic aspects that are fundamental for the photoelectric conversion. Recent advances of MXene-based photodetectors are comprehensively summarized based on different types of MXenes and innovative designs of device construction. Finally, we provide perspectives for future challenges and opportunities of MXene-based photodetectors, which may enlighten their further development.
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| 5. |
- Gao, Lingfeng, et al.
(författare)
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Hetero-MXenes : Theory, Synthesis, and Emerging Applications
- 2021
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Ingår i: Advanced Materials. - : John Wiley & Sons. - 0935-9648 .- 1521-4095. ; 33:10
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Forskningsöversikt (refereegranskat)abstract
- Since their discovery in 2011, MXenes (abbreviation for transition metal carbides, nitrides, and carbonitrides) have emerged as a rising star in the family of 2D materials owing to their unique properties. Although the primary research interest is still focused on pristine MXenes and their composites, much attention has in recent years been paid also to MXenes with diverse compositions. To this end, this work offers a comprehensive overview of the progress on compositional engineering of MXenes in terms of doping and substituting from theoretical predictions to experimental investigations. Synthesis and properties are briefly introduced for pristine MXenes and then reviewed for hetero-MXenes. Theoretical calculations regarding the doping/substituting at M, X, and T sites in MXenes and the role of vacancies are summarized. After discussing the synthesis of hetero-MXenes with metal/nonmetal (N, S, P) elements by in situ and ex situ strategies, the focus turns to their emerging applications in various fields such as energy storage, electrocatalysts, and sensors. Finally, challenges and prospects of hetero-MXenes are addressed. It is anticipated that this review will be beneficial to bridge the gap between predictions and experiments as well as to guide the future design of hetero-MXenes with high performance.
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| 6. |
- Gao, Lingfeng, et al.
(författare)
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Optical Properties of Few-Layer Ti3CN MXene : From Experimental Observations to Theoretical Calculations
- 2022
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:2, s. 3059-3069
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Tidskriftsartikel (refereegranskat)abstract
- Despite the emerging interest in research and development of Ti3CN MXene nanosheet (NS)-based optoelectronic devices, there is still a lack of in-depth studies of the underlying photophysical processes, like carrier relaxation dynamics and nonlinear photon absorption, operating in such devices, hindering their further and precise design. In this paper, we attempt to remedy the situation by fabricating few-layer Ti3CN NSs via combining selective etching and molecular intercalation and by investigating the carrier relaxation possesses and broadband nonlinear optical responses via transient absorption and Z-scan techniques. These results are complemented by first-principle theoretical analyses of the optical properties. Both saturable absorption and reverse saturable absorption phenomena are observed due to multiphoton absorption effects. The analysis of these results adds to the understanding of the basic photophysical processes, which is anticipated to be beneficial for the further design of MXene-based devices.
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| 7. |
- Gao, Lingfeng, et al.
(författare)
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PbSe Nanocrystals Produced by Facile Liquid Phase Exfoliation for Efficient UV-Vis Photodetectors
- 2021
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 31:17
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Tidskriftsartikel (refereegranskat)abstract
- Lead selenide (PbSe)-based nanomaterials have been extensively investigated as building blocks for next-generation optoelectronic devices owing to their unique properties. In this work, PbSe nanocrystals (NCs) have been successfully fabricated by a facile liquid phase exfoliation approach and directly applied as active materials for photo-electrochemical (PEC)-type photodetectors (PDs). Taking advantage of broadband absorption and fast carrier dynamics, the PbSe NCs-based PDs exhibit excellent photo-current density (11.88 μA cm−2), photo-responsivity (12.37 mA W−1), response/recovery time (0.12/0.13 s), and long-term cycling stability. The working mechanism of PbSe NCs-based PDs is explored by density functional theory calculations based on their structural and electronic properties under various conditions. It is anticipated that this contribution paves the way to readily fabricate low-dimensional PbSe NCs and extend their practical applications in PEC-type PDs.
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| 8. |
- Gao, Lingfeng, et al.
(författare)
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Ultra-Small 2D PbS Nanoplatelets : Liquid-Phase Exfoliation and Emerging Applications for Photo-Electrochemical Photodetectors
- 2021
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Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 17:5
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Tidskriftsartikel (refereegranskat)abstract
- 2D PbS nanoplatelets (NPLs) form an emerging class of photoactive materials and have been proposed as robust materials for high-performance optoelectronic devices. However, the main drawback of PbS NPLs is the large lateral size, which inhibits their further investigations and practical applications. In this work, ultra-small 2D PbS NPLs with uniform lateral size (11.2 +/- 1.7 nm) and thickness (3.7 +/- 0.9 nm, approximate to 6 layers) have been successfully fabricated by a facile liquid-phase exfoliation approach. Their transient optical response and photo-response behavior are evaluated by femtosecond-resolved transient absorption and photo-electrochemical (PEC) measurements. It is shown that the NPLs-based photodetectors (PDs) exhibit excellent photo-response performance from UV to the visible range, showing extremely high photo-responsivity (27.81 mA W-1) and remarkable detectivity (3.96 x 10(10) Jones), which are figures of merit outperforming currently reported PEC-type PDs. The outstanding properties are further analyzed based on the results of first-principle calculations, including electronic band structure and free energies for the oxygen evolution reaction process. This work highlights promising applications of ultra-small 2D PbS NPLs with the potential for breakthrough developments also in other fields of optoelectronic devices.
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| 9. |
- Kuklin, Artem V., et al.
(författare)
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Point and complex defects in monolayer PdSe2 : Evolution of electronic structure and emergence of magnetism
- 2021
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 104:13
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Tidskriftsartikel (refereegranskat)abstract
- Layered transition-metal dichalcogenides (TMDs) constitute an emerging class of materials that provide researchers a platform to realize fundamental studies and to design promising optoelectronic devices. While defects are an almost unavoidable part of TMDs, they bring additional interesting properties absent in defect-free layers. Moreover, the controlled introduction of defects in TMDs makes it possible to tailor the electromagnetic properties of the materials. Here we report defect-induced properties of single-layer PdSe2 and demonstrate the emergence of magnetism at the nanoscale. Our first-principle calculations indicate that Se vacancies create in-gap defect states, which can be responsible for trapping of carriers. The complex square V-Pd(+)4Se vacancy induces spin-polarized states with a total local magnetic moment of 2 mu B per defect, making it possible to introduce magnetization into PdSe2 and therefore expand the family of two-dimensional (2D) magnets. The defect formation energies are much lower compared to many other TMD materials that can explain the presence of a large number of Se defects after mechanical exfoliation of PdSe2 layers, while the central location of the Pd atoms preserves them from exfoliation-induced defect formation. The negatively charged vacancies are prone to form and in many cases demonstrate spin-polarized states. The small diffusion barrier of V-Se in 2D PdSe2 leads to an easy room-temperature migration, while V-pd demonstrates a high diffusion barrier preventing its spontaneous migration. As a guide for experimentalists, we simulate and characterize scanning tunneling microscope images in valence and conduction states and estimate the electron-beam energy for a controllable production of various defect patterns. These intriguing findings make PdSe2 an ideal platform to study defect-induced phenomena.
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| 10. |
- Kuklin, Artem V., et al.
(författare)
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Two-Dimensional Gold Halides : Novel Semiconductors with Giant Spin-Orbit Splitting and Tunable Optoelectronic Properties
- 2020
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Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 11:22, s. 9759-9765
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a new family of 2D materials with unique structure and optoelectronic properties, namely, single-layer gold(I) halides (AuHals). We propose their stability as well as structural, electronic, and optical properties using first-principles calculations. The cleavage energy is found to be similar to that of graphene from graphite, indicating the possibility for mechanical exfoliation. We show that AuHals are stable and have tunable direct (AuBr) and indirect (AuI) band gaps depending on the number of layers. We discuss the possible origin of the giant spin-orbit coupling (SOC) induced conduction band splitting in terms of orbital-decomposed band structure to guide future investigations on the design of materials with highly effective SOC. Exceptionally high excitonic binding energy, high hole mobility, and tunable band gaps indicate that AuHals are promising candidates for optoelectronic devices with excellent performance.
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| 11. |
- Li, Tianzhong, et al.
(författare)
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Material-based engineering of bacteria for cancer diagnosis and therapy
- 2021
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Ingår i: Applied Materials Today. - : Elsevier. - 2352-9407. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- Various categories of biomaterials have been utilized for drug delivery, genetic modification, photodynamic and photothermal therapies due to their distinct physicochemical properties, including photothermal convertibility, stimuli-responsiveness, and inherent capability to generate photodynamical radicals. However, successful treatments of cancer are largely hindered by the limited accessibility of nanomaterials into hypoxic or metastatic tumor tissues. Among the various tumor-targeting strategies, bacterial fabrication exhibits particular advantages such as specific hypoxia tropism, high motility, and rapid self replication. Biomineralization, i.e. bacterial modification, involves the fabrication of bacteria by nanomaterials for precise cancer imaging as well as targeted drug delivery, overcoming the physiological barriers and improving the therapeutic efficiency. Fabrication of bacteria strains can be conducted by various methods, including direct adsorption, electrostatic interaction, covalent ligation, and surface precipitation. In this review, a brief introduction to commonly-utilized biomaterials and bacteria species is provided. A systemic overview of recent advances of bacteria fabrication strategies and techniques are then discussed, followed by future prospective of bacteria-facilitated cancer therapy and diagnostics.
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| 12. |
- Zhao, Yiming, et al.
(författare)
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Fabrication of lead telluride quantum dots and their application in photoelectrochemical-type photodetectors
- 2023
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Ingår i: Nano Today. - : ELSEVIER SCI LTD. - 1748-0132 .- 1878-044X. ; 52
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Tidskriftsartikel (refereegranskat)abstract
- IV-VI semiconductors have been extensively applied in photo-electrochemical (PEC)-type photodetectors. However, electrolytes with relatively high concentrations have been addressed which could induce electro-chemical reactions during the measurement and result in a performance decrement. In this work, lead telluride quantum dots (PbTe QDs) with uniform size distribution are fabricated for PEC-type photodetectors and their performance is systematically investigated in electrolytes with concentrations as low as 10-4 mol/L. As revealed, the PbTe QD-based photodetectors show apparent photo-response with excellent stability in 1000 cycles (decrement of 0.018 % per cycle). In addition, the as-fabricated photodetectors show a broadband response to light in a region of 350-700 nm. These results are well supported by density functional theory calculations based on structural features and electronic and optical properties. Hence, we envisage that this work paves the way to fabricate high-performance photodetectors in relatively low-concentration electrolytes, which also can extend their applications to other optoelectronic devices.
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