Publication de Mélanie Lagrange 2017

Le papier "Understanding the mechanisms leading to failure in metallic nanowire-based transparent heaters, and solution for stability enhancement" a été publié dans Nanotechnology
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"Silver nanowire (AgNW) networks are emerging as one of the most promising alternatives to indium tin oxide (ITO) for transparent electrodes in flexible electronic  devices. They can be used in a variety of optoelectronic applications such as solar cells, touch panels and organic light-emitting diodes. Recently they have also proven to be  very efficient when used as transparent heaters (THs). In addition to the study of  AgNW networks acting as THs in regular use, i.e. at low voltage and moderate  temperature, their stability and physical behavior at higher voltages and for longer  durations should be studied in view of their integration into real devices. The properties  of AgNW networks deposited by spray coating on glass or flexible transparent  substrates are thoroughly studied via in situ measurements. The AgNW networks'  behavior at different voltages for different durations and under different atmospheric  conditions, both in air and under vacuum, has been examined. At low voltage, a  reversible electrical response is observed while irreversibility and even failure are  observed at higher voltages. In order to gain a deeper insight into the behavior of  AgNW networks used as THs, simple but realistic physical models are proposed and  are found to be in fair agreement with the experimental data. Finally, as the stability of  AgNW networks is a key issue, we demonstrate that coating AgNW networks with a  very thin layer of TiO2 using atomic layer deposition (ALD) improves the material's  resistance against electrical and thermal instabilities without altering optical  transmittance. We show that the critical annealing temperature associated to network  breakdown increases from 270 °C for the as-deposited AgNW networks to 420 °C for  AgNW networks coated with TiO2. Similarly, the electrical failure which occurs at 7 V  for the as-deposited networks increases to 13 V for TiO2-coated networks. TiO2 is also  proved to stabilize AgNW networks during long duration operation and at high voltage. Temperature higher than 235 °C was achieved at 7 V without failure."