Color-variable electroluminescence from poly(p-phenylene vinylene) derivatives
Photoluminescent and electroluminescent properties of poly(2-methoxy-5-nonyloxy-p-phenylene vinylene) (MN-PPV), one of the soluble poly(p-phenylene vinylene) (PPV) derivatives is synthesized through a dehydrochlorination reaction. The EL peak at 576nm with a low threshold voltage in the monolayer structure is independent of the bias. When the Alq3 layer is very thin (?10nm) in the bilayer structure of ITO/MN-PPV/Alq3/Al, the intrinsic emission only from MN-PPV is obtained. When the Alq3 layer gets thicker (?30nm), the intrinsic emission from Alq3 at 520nm will increase gradually with the bias, while emission from MN-PPV decreases. Based on the energy levels and field-assisted tunneling at the surface, we consider that this color-variable EL is ascribed to the redistribution of the electric field on the devices and field-assisted charge crossing through the triangular energy barrier at high biases.
color-variable electroluminescence mn-ppv bilayer devices