Plastic Substrates Make Flexible Displays

With organic light-emitting diode technology, not only are displays crisp, but their useful life could reach tens of thousands of hours. One drawback is that most are built on glass substrates, limiting their flexibility. Plastic substrates seem like an obvious solution, but moisture permeates them more easily and shortens display lifetime. Now researchers at Universal Display Corp. in Ewing, N.J., and Pacific Northwest National Laboratory in Richland, Wash., report fabrication of long-lifetime organic LED displays using an organic-inorganic-multilayered barrier coating on 175-µm-thick, heat-stabilized polyethylene terephthalate. As described in the Oct. 14 issue of Applied Physics Letters, the devices' water vapor permeation through the plastic substrate is estimated at 2 x 10^-6 g/m²/day, and their lifetime was measured at 3800 hours with initial luminance of 425 cd/m².