Origin and Characteristics of Blue Light Emission in Solid State Cathodoluminescence of MEH-PPV

Based on our previous study Chin. Phys. Lett. 20 (2003) 1144 on the solid state cathodoluminescence from organic luminescent materials, here we study the origin and characteristics of blue light emission in solid state cathodoluminescence of Poly (2-methoxy-5-(2'-ethyl-hexyloxy)phenylene vinyene (MEH-PPV) and the dependence of each spectral peak on electric field strength. The results demonstrate that the blue spectral shift benefits from field ionization of excitons, and three regions of electric field are found, in which there are pure exciton emission, coexistence of exciton emission and radiative recombination, and pure radiative recombination.