Increase in quantum efficiency and stability of multilayered polymer light-emitting diode with lonomer

Sodium sulfonated polystyrene ionomer is used as an electron injecting and hole blocking layer on the poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] layer and polyaniline as a hole injection electrode. Heterostructured light-emitting devices show the reduction of threshold voltage by60 % down to 2.5 V and the several hundreds-fold enhancement in the quantum efficiency compared with the corresponding single-layer device, and the mechanical stability. Formation of the junction helping the electron injection at the interface between the ionomer and the cathode is expected.