Highly conductive silver nanowire networks by organic matrix assisted low-temperature fusing

In silver nanowire (AgNW) percolation network electrodes, the junction resistance at the wire-to-wire contact is crucial for the electrode performance. We introduce an organic sublayer between the substrate and the AgNW electrode to improve the sheet resistance and avoid the frequently applied high-temperature post-annealing process. Upon introduction of such a sublayer, a strong reduction of the sheet resistance (R-S) in the same order as it would be expected from a post-annealing process (e.g. 90 min@210 degrees C) is observed. This effect is investigated in-depth by using different sublayer material classes such as polyelectrolytes, tensides or differently charged polymers. Independent of charge and material class, especially those materials with hydrophobic and hydrophilic parts, dramatically reduce the sheet resistance. Consequently, hydrophobic interaction between substrate and nanowires and capillary forces during drying can be attributed as driving force. Using polyvinylpyrrolidone (PVP), also used as stabilizer for the AgNWs, leads to the largest reduction in sheet resistance of the investigated materials resulting in AgNW electrodes exhibiting R-S = 10.8 Omega/square h at 80.4% transparency (including substrate) without additional post-annealing at high temperatures. Finally, we demonstrate the application of the novel NW electrode to organic n-i-p type solar cells resulting in devices with higher power conversion efficiencies than reference AgNW electrodes without sublayer. (C) 2014 Elsevier B.V. All rights reserved.