AVS 45th International Symposium
    Organic Electronic Materials Topical Conference Monday Sessions
       Session OE+EM-MoM

Invited Paper OE+EM-MoM3
High Efficiency Three Color Stacked Organic Light Emitting Devices

Monday, November 2, 1998, 9:00 am, Room 327

Session: Organic Thin Film Devices I: Light Emitters
Presenter: P.E. Burrows, Princeton University
Authors: P.E. Burrows, Princeton University
G. Parthasarathy, Princeton University
G. Gu, Princeton University
S.R. Forrest, Princeton University
T. Zhou, Universal Display Corporation
Correspondent: Click to Email
Vacuum deposited organic light emitting devices (OLEDs) based on "small molecule" organic semiconductors have demonstrated adequate efficiency and lifetime for commercial monochrome flat panel display applications. For full color display applications, vertically stacked OLEDs (SOLEDs) offer increased resolution and aperture ratio over conventional, side-by-side patterned pixels. The SOLED consists of separate red, green and blue elements grown in a vertical stack by sequential vacuum deposition. The elements emit light co-axially through semi-transparent electrodes enabling any combination of three colors to be emitted from the entire area of the device. In this paper we present recent improvements in the color, efficiency and operating voltage of SOLEDs. A typical SOLED is a 13 layer device comprised of organic semiconductors, metal oxides and metal thin films. Understanding and controlling microcavity effects in the stacked device is therefore essential to generate a pixel with well separated and adequately saturated colors. We present an analytical model of weak microcavity effects in SOLEDs and apply the results to fabricate a three color pixel with minimal directionality and good color separation. We also discuss a higly transparent, metal-free cathode which defeats the microcavity effects by reducing reflections within the stack.