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

Abstract

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 with ionic conductivity due to its conjugated backbone and side chains consisting of oligo(ethylene oxide). The use of this polymer in LECs leads to relatively bright light emitting devices with low response times which are obtained without blending an additional ionic conductive polymer into the film. The response times of the BTEM-LECs driven with a square wave form pulse were determined to be about 480 μs. The value for the turn-on voltage of the electroluminescence is 2 V and at 3 V a brightness of around 35 cd/m² was obtained. BTEM-PPV complexed with metal ions shows an ionochromic effect in the absorption spectrum and also in the electroluminescence spectrum due to the covalent linkage of the glymelike side chains to the PPV backbone, which represents an approach toward chemical sensors.