Reduction of Concentration Quenching in a Nondoped DCM Organic Light-Emitting Diode

We obtain a nondoped red organic light-emitting diode (OLED) structure ITO/pc-PPV (~30 nm)/DCM (~30 nm) /BCP (~30 nm)/Mg:Ag, where DCM refers to 4-(dicyanomethylene)-2-methyl-6-[(4-dimethylaninostyryl)-4-H-pyran]. The OLED shows pure and stable red luminescence depending on the driving voltages. The maximum luminance is 330 Cd/m2 and the turn-on voltage is as low as ~2 V. The reason why the concentration quenching of DCM could be reduced in this structure is investigated. In the preparation process, both the hole-transporting layer and the emitter layer are formed by the spin-coated method. It is believed that this method can lead to a new way to avoid the concentration quenching of red-emitting materials.