In pursuit of further enhancement in luminance and efficiency of organic light-emitting devices (OLEDs), it is worth exploring what benefits could be obtained by combining two luminance-enhancement techniques, i.e., microcavity and tandem OLEDs. In this letter, we have investigated theoretically and experimentally the characteristics of noncavity and microcavity tandem OLEDs. Results show that with well designed microcavity and device structures (i.e., consistent with resonant and antinode conditions), a fivefold enhancement in luminance can be achieved with cavity tandem devices having only two emitting units. A very high efficiency of 200cd∕A has been demonstrated with a phosphorescent cavity two-unit device.

Exploiting the reactivity of the P-atom of phosphole-based oligomers, we have achieved access to the first organophosphorus-containing organic light-emitting diode (OLED) materials. The versatility of these P-materials is demonstrated with the synthesis of a corresponding gold complex that has also been used as an OLED material. Optimization of the OLED devices by doping the phosphole layer with a red fluorescent dye is described.