Color tunable organic thin film. light emitting devices based on heterostructure

Organic light emitting devices (OLEDs) have attracted great interest because of their bright future as a competitive flat-panel display technique of LCD. OLEDs based on PDDOPV [poly (2,5-bis (dodecyloxy)-phenylenevinylene)]/Alq3 (8-hydroxyquinoline aluminum) heterostructure were fabricated. The emission spectrum of the device base on heterostructure PDDOPV(70nm)/Alq3(20nm) is similar to that of single layer device of PDDOPV except the emission intensity is enhanced by several magnitude order. But the emission spectrum of the device based on heterostructure PDDOPV(70nm)/Alq3(32nm) is composed of two parts, one is originated from PDDOPV, the other is from Alq3. The emission from PDDOPV dominates at low drive voltage but the contribution from alq3 emission increases with the increase of applied voltage. Finally Alq3 emission dominates at high applied voltage.