Electroluminescence of organic light emitting diodes with a thick hole transport layer composed of a triphenylamine based polymer doped with an antimonium compoundThe optical and electrical properties of polymer light emitting diodes based on poly ͓2-͑3-thienyl͒ ethanol butoxy carbonyl-methyl urethane͔ as emitting layer have been studied. The diode structures have been made by utilizing indium tin oxide coated glass as an anode and aluminum as a cathode. Polyaniline and tris͑8-hydroxy-quinolino͒ aluminum have been employed as hole and electron transport layers, respectively. Enhanced electroluminescence ͑EL͒ near the turn-on voltage has been observed on addition of 4-dicyanomethylene-2-methyl-6-͑p-dimethylaminostyryl͒-4H-pyran dye.On the basis of current-voltage, luminance-voltage, capacitance-voltage, and impedance measurements, an attempt has been made to understand the mechanism of EL emission in these polymeric light emitting diodes.