ORGANIC ELECTROLUMINESCENT DEVICES HAVING POLY(DIALKOXY-P-PHENYLENE VINYLENES) AS A LIGHT-EMITTING MATERIAL

We have successfully prepared organic electroluminescent, EL, devices having poly(2,5-dialkoxy-p-phenylene vinylene)s, RO-PPV, as light emit ting materials, ITO as a transparent electrode and Mg-Ag alloy as a ne gative electrode. Intensities of photo-, PL, and electro-luminescence for RO-PPVs depended on the chain length of alkoxy side groups. The PL intensity of the RO-PPV film increased with increasing the alkoxy cha in length, while the EL intensity of the devices using RO-PPV increase d until a decyloxy group and then decreased. The EL intensity of the d evice increased with decreasing the work function of negative electrod es. This result is in good agreement with that reported by Heeger[5]. The luminance reached about 1000cd/m2 by using both heptyloxy-PPV and Mg-Ag alloy. It is noteworthy that usage of poly(thienylene vinylene), PTV, thin film as a buffer layer between ITO and RO-PPV results in in creasing the breakdown voltage and that the luminance of the EL device reaches 1480 cd/m2.