Enhanced electroluminescence using polystyrene as a matrix

Poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) blends with polystyrene (PS) were used as emitting layers in polymer light-emitting diodes. Studies of photoluminescence and electroluminescence (EL) of the blends indicate that interchain interactions were tremendously suppressed due to the dilution effect. The device of MEH-PPV/PS (50/50) shows much higher EL efficiency compared to pure MEH-PPV devices. Since there is neither energy transfer nor charge transfer involved in MEH-PPV/PS blends, the observed efficiency enhancement is mainly attributed to the suppressed interchain species, which are responsible for the low photoluminescence yields. In addition, the addition of PS into MEH-PPV improves the thermal stability of polymer thin films and reduces the sensitivity of device performance to processing conditions. (C) 2002 American Institute of Physics.