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| 2. |
- Matyba, Piotr, et al.
(author)
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Flexible and Metal-Free Light-Emitting Electrochemical Cells Based on Graphene and PEDOT-PSS as the Electrode Materials
- 2010
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In: ACS NANO. - Washington D.C. : American Chemical Society. - 1936-0851 .- 1936-086X. ; 5:1, s. 574-580
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Journal article (peer-reviewed)abstract
- We report flexible and metal free light-emitting electrochemical cells (LECs) using exclusively solution processed organic materials and illustrate interesting design opportunities offered by such conformable devices with transparent electrodes. Flexible LEC devices based on chemically derived graphene (COG) as the., cathode and poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate) as the anode exhibit a low turnon voltage for yellow light emission (V = 2.8 V) and a good efficiency 2.4 (4.0) cd/A at a brightness of 100 (50) cd/m(2). We also find that COG is electrochemically inert over a wide potential range (+1.2 to -2.8 V vs ferrocene/ferrocenium) and exploit this property to demonstrate planar LEC devices with COG as both the anode and the cathode.
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| 3. |
- Matyba, Piotr, 1982-, et al.
(author)
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Graphene and Mobile Ions: The Key to All-Plastic, Solution-Processed Light-Emitting Devices
- 2010
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In: ACS NANO. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 4:2, s. 637-642
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Journal article (peer-reviewed)abstract
- The emerging field of "organic" or "plastic" electronics has brought low-voltage, ultrathin, and energy-efficient lighting and displays to market as organic light-emitting diode (OLED) televisions and displays in cameras and mobile phones. Despite using carbon-based materials as the light-emitting layer, previous efficient organic electronic light-emitting devices have required at least one metal electrode. Here, we utilize chemically derived graphene for the transparent cathode in an all-plastic sandwich-structure device, similar to an OLED, called a light-emitting electrochemical cell (LEC). Using a screen-printable conducting polymer as a partially transparent anode and a micro meter-thick active layer solution-deposited from a blend of a light-emitting polymer and a polymer electrolyte, we demonstrate a light-emitting device based solely on solution-processable carbon-based materials. Our results demonstrate that low-voltage, inexpensive, and efficient light-emitting devices can be made without using metals. In other words, electronics can truly be "organic".
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| 4. |
- Robinson, Nathaniel D, et al.
(author)
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Graphene electrodes for organic metal-free light-emitting devices
- 2012
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In: Physica Scripta. - Bristol : Institute of Physics. - 0031-8949 .- 1402-4896. ; T146:014023
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Journal article (peer-reviewed)abstract
- In addition to its fascinating electrical and mechanical properties, graphene is also an electrochemically stable and transparent electrode material. We demonstrate its applicability as both anode and cathode in a light-emitting electrochemical cell (LEC), an electrochemical analogue to a polymer organic light-emitting diode. Specifically, we summarize recent progress in carbon-based metal-free light-emitting devices enabled by chemically derived graphene cathodes on quartz and plastic substrates, and explain the advantages of using LECs in manufacturing large-area devices.
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| 5. |
- Roy, Debdulal, et al.
(author)
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Does hydrogen change the fullerenelike structure in CNx thin films?
- 2009
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In: JOURNAL OF VACUUM SCIENCE and TECHNOLOGY A. - : American Vacuum Society. - 0734-2101. ; 27:5, s. 1227-1230
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Journal article (peer-reviewed)abstract
- The authors have reported the structure of the nanoclusters in carbon nitride thin films before [D. Roy , Phys. Rev. B 70, 035406 (2004)]. In this work, effects of the addition of hydrogen in the deposition gas mixture on the structures of carbon nitride thin films prepared by magnetron sputtering were investigated using Raman spectroscopy. Raman measurements showed that the structures of carbon nanoclusters remained unaffected by the addition of hydrogen in the carbon nitride films. On the other hand, the structures of amorphous thin films were affected by the addition of hydrogen in the deposition gas mixture. These are explained in terms of changes in the ratios of the D-peak to the G-peak intensities and shifts in the G-peak centers.
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| 6. |
- Tapia-Ruiz, Nuria, et al.
(author)
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2021 roadmap for sodium-ion batteries
- 2021
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In: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7655. ; 3:3
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Journal article (peer-reviewed)abstract
- Increasing concerns regarding the sustainability of lithium sources, due to their limited availability and consequent expected price increase, have raised awareness of the importance of developing alternative energy-storage candidates that can sustain the ever-growing energy demand. Furthermore, limitations on the availability of the transition metals used in the manufacturing of cathode materials, together with questionable mining practices, are driving development towards more sustainable elements. Given the uniformly high abundance and cost-effectiveness of sodium, as well as its very suitable redox potential (close to that of lithium), sodium-ion battery technology offers tremendous potential to be a counterpart to lithium-ion batteries (LIBs) in different application scenarios, such as stationary energy storage and low-cost vehicles. This potential is reflected by the major investments that are being made by industry in a wide variety of markets and in diverse material combinations. Despite the associated advantages of being a drop-in replacement for LIBs, there are remarkable differences in the physicochemical properties between sodium and lithium that give rise to different behaviours, for example, different coordination preferences in compounds, desolvation energies, or solubility of the solid-electrolyte interphase inorganic salt components. This demands a more detailed study of the underlying physical and chemical processes occurring in sodium-ion batteries and allows great scope for groundbreaking advances in the field, from lab-scale to scale-up. This roadmap provides an extensive review by experts in academia and industry of the current state of the art in 2021 and the different research directions and strategies currently underway to improve the performance of sodium-ion batteries. The aim is to provide an opinion with respect to the current challenges and opportunities, from the fundamental properties to the practical applications of this technology.
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| 7. |
- Zhu, Yiru, et al.
(author)
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Room-Temperature Photoluminescence Mediated by Sulfur Vacancies in 2D Molybdenum Disulfide
- 2023
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In: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:14, s. 13545-13553
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Journal article (peer-reviewed)abstract
- Atomic defects in monolayer transition metal dichalcogenides (TMDs) such as chalcogen vacancies significantly affect their properties. In this work, we provide a reproducible and facile strategy to rationally induce chalcogen vacancies in monolayer MoS2 by annealing at 600 °C in an argon/hydrogen (95%/5%) atmosphere. Synchrotron X-ray photoelectron spectroscopy shows that a Mo 3d5/2 core peak at 230.1 eV emerges in the annealed MoS2 associated with nonstoichiometric MoSx (0 < x < 2), and Raman spectroscopy shows an enhancement of the ∼380 cm-1 peak that is attributed to sulfur vacancies. At sulfur vacancy densities of ∼1.8 × 1014 cm-2, we observe a defect peak at ∼1.72 eV (referred to as LXD) at room temperature in the photoluminescence (PL) spectrum. The LXD peak is attributed to excitons trapped at defect-induced in-gap states and is typically observed only at low temperatures (≤77 K). Time-resolved PL measurements reveal that the lifetime of defect-mediated LXD emission is longer than that of band edge excitons, both at room and low temperatures (∼2.44 ns at 8 K). The LXD peak can be suppressed by annealing the defective MoS2 in sulfur vapor, which indicates that it is possible to passivate the vacancies. Our results provide insights into how excitonic and defect-mediated PL emissions in MoS2 are influenced by sulfur vacancies at room and low temperatures.
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