Transparent stacked organic light emitting devices. I. Design principles and transparent compound electrodes

Vertical stacking of organic light emitting devices (OLEDs) that emit the t hree primary colors is a means for achieving full-color flat panel displays . The physics, performance, and applications of stacked OLEDs (SOLEDs) are discussed in this and the following paper (Papers I and II, respectively). In Paper I, we analyze optical microcavity effects that can distort the emi ssion colors of SOLEDs if not properly controlled, and describe design prin ciples to minimize these parasitic effects. We also describe the fabricatio n and operating characteristics of transparent contacts that are an integra l part of SOLEDs. We demonstrate that both metal-containing and metal-free transparent electrodes can serve as efficient electron and hole injectors i nto the stacked organic semiconductor layers. Two different transparent SOL ED structures (metal-containing and metal-free) that exhibit sufficient per formance for many full-color display applications will be discussed in Pape r II. (C) 1999 American Institute of Physics. [S0021-8979(99)03120-5].