Flexible powder electroluminescent device on transparent electrode of printed invisible silver-grid laminated with conductive polymer

Abstract

Invisible Ag-grid transparent electrodes at a line width of the Ag-grid of 5 μm, spacing between the grid lines of 150 μm and a line thickness of 0.6 μm have been prepared on a 50 μm thick flexible polyethylene naphthalate (PEN) film substrate by a conventional gravure offset printing using our newly developed Ag nanoparticle ink. Furthermore, the Ag-grid electrode was laminated with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer. The Ag-grid laminated with PEDOT:PSS (Ag-grid/PEDOT) transparent electrode was applied to a commercial alternating-current powder electroluminescent device (ACPELD) as an ITO replacement. The as-prepared Ag-grid/PEDOT-based ACPELD shows uniform luminescence with a luminance of 292 cd m−2 at 150 V0-p and 2 kHz. Repeated bending durability of the fabricated ACPELD was evaluated by a cyclic bending test at a bending radius of 1.5 mm up to 20 000 bending cycles. Luminance of the Ag-grid/PEDOT-based ACPELD is stable throughout the bending cycles compared to that of an ITO-based ACPELD. Luminance of the 20 000 cycle-bended Ag-grid/PEDOT-based ACPELD maintains 97% of that of the as-prepared. These results demonstrate that the Ag-grid/PEDOT on PEN-based ACPELDs develop stable luminance characteristics throughout the bending cycles.