<title>Novel characteristics of electroluminescent diodes utilizing poly(3-alkylthiophene)s and organic molecules</title>

Abstract

Novel characteristics of visible electroluminescent (EL) diodes utilizing poly(3- alkylthiophene)s and organic molecules with superlattice structure have been presented. The diodes with poly(3-alkylthiophene)s emit red-orange light with a broad band emission of 640 nm. The EL diode has unique characteristics in temperature dependence of emission intensity. Superlattice (SL) structure which consists of thin films of organic i-hydroxyquinoline aluminum (Alq₃) and aromatic diamine (TPD) has been grown by organic molecular beam deposition. The SL structure was determined by X-ray diffraction, optical absorption and photoluminescence. Photoluminescence peak of Alq₃ shifts to higher energy with decreasing layer thickness, suggesting a quantum size effect. The EL diodes with SL structure emit green light at around 520 nm. Quantum size effect in the organic SL structure has been discussed.