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 of AgNWs with different morphologies, including PVP layer and AgNW dimensions. In addition, their response to thermal treatment was deeply investigated. Then, zinc oxide (ZnO) and tin oxide (SnO2) protective films deposited by Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD) were compared for one type of AgNW. We clearly demonstrated that coating AgNW networks with these thin oxide layers is an efficient approach to enhance the morphological stability of AgNWs when subjected to thermal stress. Finally, we discussed the main future challenges linked with AgNW networks optimization processes.

Furthermore lithography and patterning are often performed in cleanrooms, thus adding to the cost of the final devices. In this context, there have been much progress in bringing the resolution of inkjet printing down to the micrometer level. [6] And other new bottom-up strategies are being developed, for example based on microfluidics and interfacial convective assembly. [7,8] Another new approach to so-called area-selective deposition (ASD) has been developed in the last years in the field of atomic layer deposition (ALD). [3,9] In ALD, solid-gas, surface-limited, selfterminating reactions take place. [10-12] This results in very compact and continuous thin films with a sub-nanometer thickness control and unique conformality, key assets for engineering the interfaces and surfaces of different functional materials and devices. [13-16] Given the surface-limited nature of ALD, several strategies can be implemented to control the reactivity of ALD precursors toward different surfaces to generate selectivity and result in ASD. These involve the use of a substrate with different materials (growth inhibition or delay taking place in one of them) or the use of self-assembled monolayers to block the growth in certain parts of the surface, as recently reviewed by Mackus et al. [17] While these approaches are very appealing and have proven to be efficient, there is still the need to have a surface with different materials, and in most cases a prepatterning step is necessary. Also, some of the ASD approaches require intermediate etching steps. [18] Finally, these approaches suffer from the inherent low deposition rate of ALD and the use of expensive vacuum equipment. In the last years, spatial ALD (SALD) has established itself as a high-throughput, low-cost alternative to conventional ALD. SALD is based on the spatial separation of precursors, as opposed to the sequential (temporal) separation in ALD. [19,20] Thus, precursors are continuously injected in different locations, which are spatially separated by an inert gas region. As the sample is exposed to the different regions, the standard ALD cycle is reproduced. Because no purge steps are needed, SALD can be up to two orders of magnitude faster than ALD. [21,22] In addition, SALD can be performed at atmospheric pressure (AP-SALD), thus resulting more convenient for scalingup than vacuum-based ALD. [23-25] But because SALD is based on the same surface-limited, self-terminating chemistry than Spatial atomic layer deposition (SALD) is a recent approach 100 times faster than conventional atomic layer deposition (ALD), even at atmospheric pressure. Previous works exploited these assets focussing on high-rate, large-area deposition for scaling-up into mass production. Conversely, this work shows that SALD indeed represents an ideal platform for area-selective deposition of functional materials by proper design and miniaturization of close-proximity SALD heads. In particular, the potential offered by 3D printing is used to fabricate low-cost customized close-proximity heads, w...