Mechanism of electroluminescence in dye doped thiophene based conjugated polymer

The optical and electrical properties of polymer light emitting diodes base d on poly [2-(3-thienyl) ethanol butoxy carbonyl-methyl urethane] as emitti ng layer have been studied. The diode structures have been made by utilizin g indium tin oxide coated glass as an anode and aluminum as a cathode. Poly aniline and tris(8-hydroxy-quinolino) aluminum have been employed as hole a nd electron transport layers, respectively. Enhanced electroluminescence (E L) near the turn-on voltage has been observed on addition of 4-dicyanomethy lene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye. On the basis of curre nt-voltage, luminance-voltage, capacitance-voltage, and impedance measureme nts, an attempt has been made to understand the mechanism of EL emission in these polymeric light emitting diodes. (C) 2001 American Institute of Phys ics.