The study on the interaction between squarylium cyanine dye (Sq) and porphyrin has confirmed that Sq can serve as an energy acceptor to emit red light. On basis of the principle

a red organic electroluminescent device using Sq-doped 8-hydroxyquinolium aluminum (Alq) as the emission layer (EML) has been developed. Spectroscopic beha vior on the interaction of Sqs with Alq in the solid film were investigated to help understanding the luminescence mechanism. By linking the photoluminescence spectrum and electroluminescence spectrum together

a mechanism including the energy transfer process from excited Alq to Sq was suggested. Upon application of driving voltage

TPD supports injection and transportation of holes while Alq is capable of trapping electrons. The recombination of injected eletrons and holes on the emission layer (EML) creates the excited Alq molecules. The red electroluminescence on such device is ascribed to the luminescence from the singlet excited states of Sq

which are produced by energy transfer process from the excited Alq to Sq.