Ionochromism in a light-emitting electrochemical cell with low response time based on an ionic conductive poly-phenylene vinylene

Characterizations of red-orange light-emitting electrochemical cells (LECs) based on poly[1,4-(2,5-bis(1,4,7,10-tetraoxaundecyl))phenylene vinylene], (BTEM-PPV), are presented, BTEM-PPV combines good electronic conductivity w ith ionic conductivity due to its conjugated backbone and side chains consi sting of oligo(ethylene oxide). The use of this polymer in LECs leads to re latively bright light emitting devices with low response times which are ob tained without blending an additional ionic conductive polymer into the fil m. The response times of the BTEM-LECs driven with a square wave form pulse were determined to be about 480 mu s. The value for the turn-on voltage of the electroluminescence is 2 V and at 3 V a brightness of around 35 cd/m(2 ) was obtained. BTEM-PPV complexed with metal ions shows an ionochromic eff ect in the absorption spectrum and also in the electroluminescence spectrum due to the covalent linkage of the glymelike side chains to the PPV backbo ne, which represents an approach toward chemical sensors. (C) 1999 American Institute of Physics. [S0003-6951(99)04740-3].