High-efficiency stacked white organic light-emitting diodes

Abstract

We report efficient tandem white organic light-emitting diodes (WOLEDs) by using bathocuproine:Cs2CO3∕MoO3 as an effective interconnecting layer. We utilized two primary colors of sky blue and orange fluorescent emitters to obtain efficient white electroluminescence. Although single WOLEDs using two adjacent emitting layers showed a maximum current efficiency of 7.96cd∕A with Commission Internationale d’Eclairage (CIE) coordinates of (0.28, 0.34), the tandem WOLED device made by stacking two single color OLEDs in series demonstrated doubled maximum current efficiency of 17.14cd∕A with CIE coordinates of (0.28, 0.41). The stacking of different single color OLEDs in series instead of double stacking of WOLEDs can be useful to achieve highly efficient WOLEDs because it can reduce the number of layers of the devices.

Shaping White Light Through Electroluminescent Fully Organic Coupled Microcavities

“…OS2 is fi lled with a standard organic material which should have a high energy gap to avoid the absorption of light. Compared to tandem technology, [ 13 ] in which both the stacked cells are active, the presented structure is based on a single active cell (OS1) and a passive one (OS2). Because of this intrinsic confi guration the applied voltage is not increased as in the tandem structures and, therefore, an improvement of current effi ciency will result in an improvement of power effi ciency as well.…”

White organic light-emitting diodes with an ultra-thin premixed emitting layer

“…Although the basic principle to obtain white light is always to mix either two or three emitters with complementary colors [6][7][8], three different global approaches can be used to achieve this goal, each with its advantages and drawbacks [2]: the lumiphores can be blended in a single layer [9][10][11], separated in different layers in the same OLED [12,13], or contained in several formally independent devices each of which emits light of a different color [14], the latter being however excessively complex and costly compared to the two other approaches. For those first two categories, however, several technical issues have to be addressed.…”

Organic Light-Emitting Diodes (OLEDs) and Optically-Detected Magnetic Resonance (ODMR) studies on organic materials

“…However, this comes at the cost of an increased operating voltage. But in any case, the power efficiency of such a device can be higher than for a conventional device [59][60].…”