Spatially selective flash sublimation of small organic molecules for organic light-emitting diodes and display applications

A flash-sublimation technique for the spatially selective deposition of small organic molecules is presented. Single-pulse electrically heated copper stripes (width 100 mum) serve as heating elements. The relevant time scale of our technique is on the order of milliseconds. Under high vacuum conditions, the heating elements are used to locally flash-sublimate small-molecule material from a previously coated polyimide foil onto a (ITO-)glass substrate, positioned at a vertical distance of 60 mum. The spatial resolution in our nonoptimized experiments was 250 mum. Organic light-emitting diode (OLED) devices with flash-deposited tris-(8-hydroxyquinoline)aluminum (Alq(3)) as the active material are demonstrated with satisfying electrical and optical properties. Flash sublimation of a stacked nonintermixed Alq(3) (30 nm) [2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5Hbenzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene]propane-dinitrile (DCM2) (1 nm)/Alq(3) (30 nm) layer is shown to yield a red-emitting (lambda=624 nm) DCM2-doped Alq(3) layer. Our technique presents a simple alternative to the use of shadow masks for full-color small-molecule OLED displays. (C) 2003 American Institute of Physics.