Avilés, Spain
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Jose Andres L.,Energy Area | Fe Menendez M.,Energy Area | Gomez D.,Energy Area | Luisa Martinez A.,Energy Area | And 4 more authors.
Nanotechnology | Year: 2015

Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed. © 2015 IOP Publishing Ltd.


Alvarez-Martos I.,University of Oviedo | Fernandez-Gavela A.,University of Oviedo | Rodriguez-Garcia J.,University of Oviedo | Campos-Alfaraz N.,Energy Area | And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2014

Carbon nanotubes (CNTs) have been widely used in many fields of chemical analysis to achieve more sensitive detection systems. In this work, we performed fundamental studies on grown or bottom-up fabricated MWCNTs (both non-oriented and oriented configurations), showing how variables like orientation, density, underlayer deposition, or synthesis time strongly determine their behavior (physical, electrochemical and analytical) as transducers. The electrochemical performance of these surfaces was demonstrated by cyclic voltammetry and chronoamperometry of dopamine (DA) solutions in 0.1 M H2SO 4. The carbon nanotubes surfaces pre-treated with 1 M HNO3 lead to increased signals, sensitivity and enhanced limits of detection (LOD). The grown working electrodes (WE) were reproducible and stable over the time. The peak variations gave RSD values of 8%, 4% and 3% for high-density spaghetti-like and ITO or Al underlayered forest-like MWCNTs grown for 30 min, respectively. This study highlighted the importance of controlling the synthesis variables to achieve better analytical parameters. © 2013 Elsevier B.V.


Campos N.,Energy Area | Gomez D.,Energy Area
2014 IEEE 9th Nanotechnology Materials and Devices Conference, NMDC 2014 | Year: 2014

The possibility of using graphene as a key element to develop low-cost terahertz sources has been considered on the basis of theoretical predictions showing non-linear effects leading to frequency multiplication phenomenon. For the integration of graphene in real devices of such kind, special attention must be paid to the processes of synthesis and transfer to suitable substrates, focusing on the needed properties of the final samples. In this work, all the steps followed towards the preparation of the optimal samples of graphene on polyimide substrates are described in detail with particular emphasis on the electrical properties required for the final application. © 2014 IEEE.


Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 m, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS=20.2 /sq), whilst maintaining high optical film transparency (T=94.7%), driving to the highest reported figure-of-merit (FoM=338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed.

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