Organic light emitting diodes based on dipyridamole drug

The dipyridamole drug DIP: 2,6-bis(diethanolamino)-4,8-dipiperidinopyrimido(5,4-d)pyrimidine] is widely used in treatment of coronary heart disease for its antiplatelet and vasodilating activities, and its high intensity photoluminescence (PL) has been widely reported. In this work, the fabrication and the characterization of a new OLED using the DIP molecule as an emitting layer is reported. The devices were assembled using a heterojunction between three organic molecular materials: the N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine (NPB) or the 1-(3-methylphenyl)-1,2,3,4-tetrahydroquinoline-6-carboxyaldehyde-1,1′-diphenylhydrazone (MTCD) as hole-transporting layer, the DIP layer as an emitting layer and the tris(8-hydroxyquinoline aluminum) (Alq₃) as the electron transporting layer. All the organic layers were sequentially deposited in a high vacuum by thermal evaporation onto indium tin oxide substrates and without breaking vacuum. Continuous electroluminescence emission was obtained in all configurations upon varying the applied bias voltage from 4 to 30 V, the observed wide emission band was centered at 493 nm. The luminance of the devices was about 1500 (cd)/m² with 4.5 cd/A of efficiency for the best device. The charge transport behavior in the OLED is also discussed as a function of different carrier injection levels.