Inkjet-printed Ag grid combined with Ag nanowires to form a transparent hybrid electrode for organic electronics

Networks of silver nanowires (AgNW) have been shown to facilitate high transparency, high conductivity, and good mechanical stability. However, the loose characteristic and local insulation problems due to gaps between the nanowires limit their application as electrodes. This study investigates an inkjet-printed Ag grid combined with AgNW to form a transparent hybrid electrode. The printed Ag grid on AgNW film connects the gaps between the Ag nanowires to increase the overall electric conductivity. The printed Ag-grid/AgNW hybrid electrodes have low resistivity (22.5 Omega/square) while maintaining a high transmittance (87.5%). These values are similar to standard indium tin oxide (ITO) on glass which has resistivity of 20 Omega/square and transmittance of 89% at 550 nm. In addition, these hybrid electrodes are also very flexible when fabricated on a photopolymer substrate. A spin-coating process combined with a peel-off process enable the fabrication of flexible ultra-smooth Ag-grid/AgNW electrodes. We tested the transparent and flexible electrode as the anode of a flexible organic light emitting diode (F-OLED). The light emitting layer of the F-OLED is 35 nm thick tris-(8-hydroxyquinoline) aluminum doped with 0.5% 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)-benzopyropyrano(6,7-8-I, j) quinolizin-11-one. The maximum brightness and current efficiency of the F-OLED are 10000 cd/m(2) and 12 cd/A, respectively, even when bent around a radius of 2 mm. The good performance of the device with Ag-grid/AgNW hybrid electrodes show that enhanced conductive inkjet-printed Ag nanoparticles combined with Ag nanowires can produce high quality electrodes for flexible organic optoelectronic devices. (C) 2016 Elsevier B.V. All rights reserved.