Search

International audience; Transparent electrodes (TE) are essential components in a huge variety of emerging applicationssuch as photovoltaic, lighting, sensing and heating devices.[1,2] Indium tin oxide (ITO) has been themost efficient and widely used TE but suffers from serious limitations related to fabrication cost,brittleness and indium scarcity.[3] Among emerging transparent conductive materials (TCMs), metallicnanowire (MNW) networks, and especially silver nanowire (AgNW) networks, appear to be one of themost promising alternatives to ITO, since: i/ they exhibit excellent optical and electrical properties, ii/they are very flexible, and iii/ they can be fabricated by low-cost, solution-based techniques suitablefor large scale, industrial production.[4] Despite the advantages mentioned above, to build a robust andmature technology, there are still challenges to be tackled. Stability is a crucial issue that can beattributed to several degradation mechanisms involving electrical, thermal and mechanical aspects,ageing and chemical degradation.[5] Our present study focuses on the fundamental understanding ofthe physical phenomena that take place at different scales, from the whole network (macroscale) tothe nanowire-to-nanowire junctions (nanoscale). Combining both experimental and modellingapproaches, one of the main goals aims to understand the origin of failure in AgNW networks duringelectrical stress. In situ measurements of the electrical resistance with a parallel recording of thespatial surface temperature by IR imaging have yielded useful information about the failure dynamicsof AgNW networks.[6] The simulation of the electrical distribution and power-induced heating offer adeeper understanding of the underlying physics and can be used to predict the networks electrical andheating performances.[7] Moreover, we observe the drastic enhancement of the electrical and thermalstability when we encapsulate the AgNWs networks with protective oxides such as ZnO, Al: ZnO(AZO) and Al2O3, using the Spatial Atomic Layer Deposition (SALD). This emerging open air, low-costand scalable approach enables the deposition of ultrathin, high conformal and transparent oxidecoatings at low temperatures.[8–10] Such work represents both fundamental and applicative aspects.For the latter, one aims to integrate AgNW based TE for instance in solar cells, transparent heaters,low-emissivity coating and energy harvesting devices.

International audience; Nowadays, conductive and transparent materials are limited. The main material is In-dium Tin Oxide (ITO). Despites their excellent property in terms of transparency and con-ductivity, ITO is brittle and not easily processable to produce patterns for radio-frequencies applications for example. To answer this problematic, we propose in this study a new solution with an ink, formulated with nanocellulose and a conductive material, for screen-printing application. The oxidized cellulose nanofibrils used have multiple roles: i) as a transparent matrix with adapted rheological properties, ii) as an adhesion link between the substrate and the silver nanowire iii) as a dispersing agent to favor the nanostructured network of the conductive material. The hybrid system has been characterized by AFM, SEM-FEG, rheometer and the final antenna by anechoic chamber. The ink developed present new results with a high conductivity (Rs70% @550nm) by keeping adapted rheology properties (G’ and G”). These results allow printing of conductive and transparent pattern usefull for various applications.

International audience; Cet article propose d'étudier l'influence des différentes géométries de maillage constituant une antenne dipôle à 2.45 GHz sur leur gain. Les dipôles sont produits par impression sérigraphie [1] sur un substrat polymère transparent de type Poly Ethylène Téréphtalate (PET). Les résultats de simulation sont en accord avec ceux de mesure. Les gains mesurés sont plus faibles que ceux simulés. Ces écarts s'expliquent par la tolérance de fabrication.

International audience

International audience