Silver nanowire (AgNW) networks have been intensively investigated in recent years. Thanks to the... more Silver nanowire (AgNW) networks have been intensively investigated in recent years. Thanks to their attractive physical properties in terms of optical transparency and electrical conductivity, as well as their mechanical performance, AgNW networks are promising transparent electrodes (TE) for several devices, such as solar cells, transparent heaters, touch screens or light-emitting devices. However, morphological instabilities, low adhesion to the substrate, surface roughness and ageing issues may limit their broader use and need to be tackled for a successful performance and long working lifetime. The aim of the present work is to highlight efficient strategies to optimize the physical properties of AgNW networks. In order to situate our work in relation to existing literature, we briefly reported recent studies which investigated physical properties of AgNW networks. First, we investigated the optimization of optical transparency and electrical conductivity by comparing two types ...
ABSTRACT The sintering of both a powder with a wide particle size distribution (0-63 mum) and of ... more ABSTRACT The sintering of both a powder with a wide particle size distribution (0-63 mum) and of a powder with artificially created pores is investigated by coupling in situ X-ray microtomography observations with Discrete Element simulations. The micro structure evolution of the copper particles is observed by microtomography all along a typical sintering cycle at 1050° C at the European Synchrotron Research Facilities (ESRF, Grenoble, France). A quantitative analysis of the 3D images provides original data on interparticle indentation, coordination and particle displacements throughout sintering. In parallel, the sintering of similar powder systems has been simulated with a discrete element code which incorporates appropriate sintering contact laws from the literature. The initial numerical packing is generated directly from the 3D microtomography images or alternatively from a random set of particles with the same size distribution. The comparison between the information drawn from the simulations and the one obtained by tomography leads to the conclusion that the first method is not satisfactory because real particles are not perfectly spherical as the numerical ones. On the opposite the packings built with the second method show sintering behaviors close to the behaviors of real materials, although particle rearrangement is underestimated by DEM simulations.
Ultra-long silver nanowires are rapidly synthesized at low temperatures by using 1,2-propanediol ... more Ultra-long silver nanowires are rapidly synthesized at low temperatures by using 1,2-propanediol as the reaction solvent and lead to transparent electrodes with excellent optoelectronic properties.
Silver nanowire (AgNW) networks have been lately much investigated thanks to their physical prope... more Silver nanowire (AgNW) networks have been lately much investigated thanks to their physical properties and are therefore foreseen to play a key role in many industrial devices as transparent electrodes, but their stability can be an issue.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
This work directly compares the percolation threshold of silver nanowire networks to predictions ... more This work directly compares the percolation threshold of silver nanowire networks to predictions from Monte Carlo simulations, focusing particularly on incorporating the impact of real world imperfections. This SEM image of silver nanowire networks compared to MATLAB simulation based on the physical characteristics of the sample.
A new model is presented to describe charge scattering at grain boundaries in degenerately doped ... more A new model is presented to describe charge scattering at grain boundaries in degenerately doped polycrystalline semiconductors such as transparent conductive oxides.
In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin ox... more In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin oxide (F:SnO₂, aka FTO) thin films to form hazy Al₂O₃-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites integrating ZnO and sulfur doped TiO₂ (S:TiO₂) nanoparticles (i.e., ZnO-FTO and S:TiO₂-FTO nanocomposites), the newly developed Al₂O₃-FTO nanocomposites show medium haze factor H of about 30%, while they exhibit the least loss in total transmittance T In addition, Al₂O₃-FTO nanocomposites present a low fraction of large-sized nanoparticle agglomerates with equivalent radius r > 1 μm; effectively 90% of the nanoparticle agglomerates show r < 750 nm. The smaller feature size in Al₂O₃-FTO nanocomposites, as compared to ZnO-FTO and S:TiO₂-FTO nanocomposites, makes them more suitable for applications that are sensitive to roughness and large-sized features. With the help of a simple optical model developed in this work, we have simulated the optical sc...
Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerge... more Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerged as one of the most attractive alternatives to transparent conductive oxides to be used in flexible optoelectronic applications. However, AgNW networks still suffer from chemical, thermal and electrical instabilities which in some cases can hinder their efficient integration as transparent electrodes in devices such as solar cells, transparent heaters, touch screens or organic light emitting diodes (OLEDs). We have used atmospheric pressure spatial atomic layer deposition (AP-SALD) to fabricate hybrid transparent electrode materials in which the AgNW network is protected by a conformal thin zinc oxide layer. The choice of AP-SALD allows to maintain the low-cost and scalable processing of AgNW based transparent electrodes. The effects of the ZnO coating thickness on the physical properties of AgNW networks are presented. The composite electrodes show a drastic enhancement of both thermal...
Electrical stability and homogeneity of silver nanowire (AgNW) networks are critical assets for i... more Electrical stability and homogeneity of silver nanowire (AgNW) networks are critical assets for increasing their robustness and reliability when integrated as transparent electrodes in devices. Our ability to distinguish defects, inhomogeneities, or inactive areas at the scale of the entire network is therefore a critical issue. We propose one-probe electrical mapping (1P-mapping) as a specific simple tool to study the electrical distribution in these discrete structures. 1P-mapping has allowed to show that the tortuosity of the voltage equipotential lines of AgNW networks under bias decreases with increasing network density, leading to a better electrical homogeneity. The impact of the network fabrication technique on the electrical homogeneity of the resulting electrode has also been investigated. Then, by combining 1P-mapping with electrical resistance measurements and IR thermography, we propose a comprehensive analysis of the evolution of the electrical distribution in AgNW net...
Whereas the integration of silver nanowires in functional devices has reached a fair level of mat... more Whereas the integration of silver nanowires in functional devices has reached a fair level of maturity, the integration of copper nanowires still remains difficult, mainly due to the intrinsic instability of copper nanowires in ambient conditions. In this paper, copper nanowire based transparent electrodes with good performances (33 Ω sq-1 associated with 88% transparency) were obtained, and their degradation in different conditions was monitored, in particular by electrical measurements, transmission electron microscopy, x-ray photoelectron spectrometry and Auger electron spectroscopy. Several routes to stabilize the random networks of copper nanowires were evaluated. Encapsulation through laminated barrier film with optical clear adhesive and atmospheric pressure spatial atomic layer deposition were found to be efficient and were used for the fabrication of transparent film heaters.
ABSTRACT Thermal annealing is shown to be a successful approach to reduce the electrical resistan... more ABSTRACT Thermal annealing is shown to be a successful approach to reduce the electrical resistance of transparent electrodes made of randomly oriented silver nanowires (AgNWs). A decrease in the electrical resistance by several orders of magnitude, whilst maintaining optical transmission (above 85%), is demonstrated. Several mechanisms involved in the electrical behaviour induced by thermal treatment both in air and under vacuum are identified using a combination of ramped, stepped and isothermal annealing. Some mechanisms lead to the reduction of the electrical resistance such as local sintering, while others, such as spheroidisation, induce irreversible damage to the network. It is also shown that the polymer used in the synthesis of Ag nanowires plays a crucial role as a thermal stabiliser under vacuum conditions. Finally, optimised samples exhibit an optical transmittance of 83% (without substrate contribution removal) and a sheet resistance of 9.5 Ω/sq.
The morphology of gamma&amp;amp;#x27; precipitates of AM1 single crystal superalloys has been... more The morphology of gamma&amp;amp;#x27; precipitates of AM1 single crystal superalloys has been studied by small neutron scattering (SANS), and electron microscopy. Due to the single crystal nature of the samples, the SANS patterns are anisotropic and exhibit a fourfold symmetry corresponding both to the shape and to the spatial arrangement of the precipitates in a (001) plane. Measurements for other
The past few years have seen a considerable amount of research devoted to nanostructured transpar... more The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells, flexible light-emitting devices, touch screens, electromagnetic devices, and flexible transparent thin film heaters. Currently, the most commonly used TCM for such applications (ITO: Indium Tin oxide) suffers from two major drawbacks: brittleness and indium scarcity. Among emerging transparent electrodes, silver nanowire (AgNW) networks appear to be a promising substitute to ITO since such electrically percolating networks exhibit excellent properties with sheet resistance lower than 10 Ω/sq and optical transparency of 90%, fulfilling the requirements of most applications. In addition, AgNW networks also exhibit very good mechanical flexibility. The fabrication of these electrodes involves low-temperature processing steps and scalable methods, thus making them appropriate for future use ...
Advancement in the science and technology of random metallic nanowire (MNW) networks is crucial f... more Advancement in the science and technology of random metallic nanowire (MNW) networks is crucial for their appropriate integration in many applications, including transparent electrodes for optoelectronics and transparent film heaters. We have recently highlighted the discontinuous activation of efficient percolating pathways (EPPs) for networks having densities slightly above the percolation threshold. Such networks exhibit abrupt drops of electrical resistance when thermal or electrical annealing is performed, giving rise to a "geometrically quantized percolation". In this letter, Lock-in Thermography (LiT) is used to provide visual evidence of geometrical quantized percolation: when low voltage is applied to the network, individual "illuminated…
Silver nanowire (AgNW) networks have been intensively investigated in recent years. Thanks to the... more Silver nanowire (AgNW) networks have been intensively investigated in recent years. Thanks to their attractive physical properties in terms of optical transparency and electrical conductivity, as well as their mechanical performance, AgNW networks are promising transparent electrodes (TE) for several devices, such as solar cells, transparent heaters, touch screens or light-emitting devices. However, morphological instabilities, low adhesion to the substrate, surface roughness and ageing issues may limit their broader use and need to be tackled for a successful performance and long working lifetime. The aim of the present work is to highlight efficient strategies to optimize the physical properties of AgNW networks. In order to situate our work in relation to existing literature, we briefly reported recent studies which investigated physical properties of AgNW networks. First, we investigated the optimization of optical transparency and electrical conductivity by comparing two types ...
ABSTRACT The sintering of both a powder with a wide particle size distribution (0-63 mum) and of ... more ABSTRACT The sintering of both a powder with a wide particle size distribution (0-63 mum) and of a powder with artificially created pores is investigated by coupling in situ X-ray microtomography observations with Discrete Element simulations. The micro structure evolution of the copper particles is observed by microtomography all along a typical sintering cycle at 1050° C at the European Synchrotron Research Facilities (ESRF, Grenoble, France). A quantitative analysis of the 3D images provides original data on interparticle indentation, coordination and particle displacements throughout sintering. In parallel, the sintering of similar powder systems has been simulated with a discrete element code which incorporates appropriate sintering contact laws from the literature. The initial numerical packing is generated directly from the 3D microtomography images or alternatively from a random set of particles with the same size distribution. The comparison between the information drawn from the simulations and the one obtained by tomography leads to the conclusion that the first method is not satisfactory because real particles are not perfectly spherical as the numerical ones. On the opposite the packings built with the second method show sintering behaviors close to the behaviors of real materials, although particle rearrangement is underestimated by DEM simulations.
Ultra-long silver nanowires are rapidly synthesized at low temperatures by using 1,2-propanediol ... more Ultra-long silver nanowires are rapidly synthesized at low temperatures by using 1,2-propanediol as the reaction solvent and lead to transparent electrodes with excellent optoelectronic properties.
Silver nanowire (AgNW) networks have been lately much investigated thanks to their physical prope... more Silver nanowire (AgNW) networks have been lately much investigated thanks to their physical properties and are therefore foreseen to play a key role in many industrial devices as transparent electrodes, but their stability can be an issue.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
This work directly compares the percolation threshold of silver nanowire networks to predictions ... more This work directly compares the percolation threshold of silver nanowire networks to predictions from Monte Carlo simulations, focusing particularly on incorporating the impact of real world imperfections. This SEM image of silver nanowire networks compared to MATLAB simulation based on the physical characteristics of the sample.
A new model is presented to describe charge scattering at grain boundaries in degenerately doped ... more A new model is presented to describe charge scattering at grain boundaries in degenerately doped polycrystalline semiconductors such as transparent conductive oxides.
In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin ox... more In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin oxide (F:SnO₂, aka FTO) thin films to form hazy Al₂O₃-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites integrating ZnO and sulfur doped TiO₂ (S:TiO₂) nanoparticles (i.e., ZnO-FTO and S:TiO₂-FTO nanocomposites), the newly developed Al₂O₃-FTO nanocomposites show medium haze factor H of about 30%, while they exhibit the least loss in total transmittance T In addition, Al₂O₃-FTO nanocomposites present a low fraction of large-sized nanoparticle agglomerates with equivalent radius r > 1 μm; effectively 90% of the nanoparticle agglomerates show r < 750 nm. The smaller feature size in Al₂O₃-FTO nanocomposites, as compared to ZnO-FTO and S:TiO₂-FTO nanocomposites, makes them more suitable for applications that are sensitive to roughness and large-sized features. With the help of a simple optical model developed in this work, we have simulated the optical sc...
Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerge... more Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerged as one of the most attractive alternatives to transparent conductive oxides to be used in flexible optoelectronic applications. However, AgNW networks still suffer from chemical, thermal and electrical instabilities which in some cases can hinder their efficient integration as transparent electrodes in devices such as solar cells, transparent heaters, touch screens or organic light emitting diodes (OLEDs). We have used atmospheric pressure spatial atomic layer deposition (AP-SALD) to fabricate hybrid transparent electrode materials in which the AgNW network is protected by a conformal thin zinc oxide layer. The choice of AP-SALD allows to maintain the low-cost and scalable processing of AgNW based transparent electrodes. The effects of the ZnO coating thickness on the physical properties of AgNW networks are presented. The composite electrodes show a drastic enhancement of both thermal...
Electrical stability and homogeneity of silver nanowire (AgNW) networks are critical assets for i... more Electrical stability and homogeneity of silver nanowire (AgNW) networks are critical assets for increasing their robustness and reliability when integrated as transparent electrodes in devices. Our ability to distinguish defects, inhomogeneities, or inactive areas at the scale of the entire network is therefore a critical issue. We propose one-probe electrical mapping (1P-mapping) as a specific simple tool to study the electrical distribution in these discrete structures. 1P-mapping has allowed to show that the tortuosity of the voltage equipotential lines of AgNW networks under bias decreases with increasing network density, leading to a better electrical homogeneity. The impact of the network fabrication technique on the electrical homogeneity of the resulting electrode has also been investigated. Then, by combining 1P-mapping with electrical resistance measurements and IR thermography, we propose a comprehensive analysis of the evolution of the electrical distribution in AgNW net...
Whereas the integration of silver nanowires in functional devices has reached a fair level of mat... more Whereas the integration of silver nanowires in functional devices has reached a fair level of maturity, the integration of copper nanowires still remains difficult, mainly due to the intrinsic instability of copper nanowires in ambient conditions. In this paper, copper nanowire based transparent electrodes with good performances (33 Ω sq-1 associated with 88% transparency) were obtained, and their degradation in different conditions was monitored, in particular by electrical measurements, transmission electron microscopy, x-ray photoelectron spectrometry and Auger electron spectroscopy. Several routes to stabilize the random networks of copper nanowires were evaluated. Encapsulation through laminated barrier film with optical clear adhesive and atmospheric pressure spatial atomic layer deposition were found to be efficient and were used for the fabrication of transparent film heaters.
ABSTRACT Thermal annealing is shown to be a successful approach to reduce the electrical resistan... more ABSTRACT Thermal annealing is shown to be a successful approach to reduce the electrical resistance of transparent electrodes made of randomly oriented silver nanowires (AgNWs). A decrease in the electrical resistance by several orders of magnitude, whilst maintaining optical transmission (above 85%), is demonstrated. Several mechanisms involved in the electrical behaviour induced by thermal treatment both in air and under vacuum are identified using a combination of ramped, stepped and isothermal annealing. Some mechanisms lead to the reduction of the electrical resistance such as local sintering, while others, such as spheroidisation, induce irreversible damage to the network. It is also shown that the polymer used in the synthesis of Ag nanowires plays a crucial role as a thermal stabiliser under vacuum conditions. Finally, optimised samples exhibit an optical transmittance of 83% (without substrate contribution removal) and a sheet resistance of 9.5 Ω/sq.
The morphology of gamma&amp;amp;#x27; precipitates of AM1 single crystal superalloys has been... more The morphology of gamma&amp;amp;#x27; precipitates of AM1 single crystal superalloys has been studied by small neutron scattering (SANS), and electron microscopy. Due to the single crystal nature of the samples, the SANS patterns are anisotropic and exhibit a fourfold symmetry corresponding both to the shape and to the spatial arrangement of the precipitates in a (001) plane. Measurements for other
The past few years have seen a considerable amount of research devoted to nanostructured transpar... more The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells, flexible light-emitting devices, touch screens, electromagnetic devices, and flexible transparent thin film heaters. Currently, the most commonly used TCM for such applications (ITO: Indium Tin oxide) suffers from two major drawbacks: brittleness and indium scarcity. Among emerging transparent electrodes, silver nanowire (AgNW) networks appear to be a promising substitute to ITO since such electrically percolating networks exhibit excellent properties with sheet resistance lower than 10 Ω/sq and optical transparency of 90%, fulfilling the requirements of most applications. In addition, AgNW networks also exhibit very good mechanical flexibility. The fabrication of these electrodes involves low-temperature processing steps and scalable methods, thus making them appropriate for future use ...
Advancement in the science and technology of random metallic nanowire (MNW) networks is crucial f... more Advancement in the science and technology of random metallic nanowire (MNW) networks is crucial for their appropriate integration in many applications, including transparent electrodes for optoelectronics and transparent film heaters. We have recently highlighted the discontinuous activation of efficient percolating pathways (EPPs) for networks having densities slightly above the percolation threshold. Such networks exhibit abrupt drops of electrical resistance when thermal or electrical annealing is performed, giving rise to a "geometrically quantized percolation". In this letter, Lock-in Thermography (LiT) is used to provide visual evidence of geometrical quantized percolation: when low voltage is applied to the network, individual "illuminated…
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