ITO and graphene-covered Ag grids embedded in PET substrate by thermal roll imprinting for flexible organic solar cells

The development of a low-resistive flexible transparent conductive film (TCF) was demonstrated by showing thermal roll imprinted and an embedded Ag grid. The Ag-embedded TCF shows excellent optical and electrical properties when the secondary layer of ITO and graphene is coated onto the flexible embedded Ag grid substrate. The TCF showed an extremely high transmittance of 77.56% with ITO and 77.73% with graphene; moreover, it showed a very low sheet resistance of 4.05 Ω/□ and 14.0 Ω/□ with ITO and graphene, respectively. This high performance is achieved by thermal imprinting of channels at 15 μm wide so that the DI-based nano silver paste filled in the narrow channels using Dr. Blade's method, thus providing the embedded pattern of Ag grid in the flexible PET substrate. The succeeding TCF performance was validated by fabrication of an OSC (organic solar cell) that exhibits excellent power conversion efficiency (PCE) of 2.649% and 2.551% for the ITO-Ag grid and graphene-Ag grid, respectively. This indicates that the hybrid flexible electrode using an intaglio method can be applied to transparent conducting electrodes for highly efficient opto-electronic devices.