The polymer light-emitting electrochemical cell (LEC) provides a novel approach for light emission from the conjugated luminescent polymers. However

a phase separation occurs intrinsically in the electroluminescent (EL) device due to the addition of polymer electrolyte. To reduce or eliminate the phase separation

a novel block copolymer was presented as the luminescent polymer for the fabrication of the LEC in this work. The block copolymer is composed of the rigid segments

1

5-di(3

5-dimethoxystyrylene)naphthalene (DMSN) and the flexible segments

tri(ethylene oxide) (TEO). Optical and electrochemical properties of DMSN-TEO were studied firstly by the absorption

photoluminescence spectra and cyclic voltammetry measurements

and the data show that this copolymer is a typical p-type material with a blue emission in solution. The polymer LEC was fabricated successfully by sandwiching a blend film composed of DMSN-TEO

PEO and lithium triflate between an ITO and an Al electrode

and characterized by current-voltage-luminance characteristics

d.c. response and a.c. impedance measurements. Efficient blue-green light emission of the LEC was demonstrated with an onset voltage at 25V and the maximum EL efficiency of ～42cd/A at 28V. The response time of the LEC is less than 5s. All the results suggest that an improved morphology of the blend film is achieved in the LEC due to the presence of TEO segments in the copolymer. The a.c. impedance data indicate the electrochemical doping mechanism of the LEC.