FABRICATION OF POLYMER LIGHT-EMITTING-DIODES USING DOPED SILICON ELECTRODES

We report the fabrication of light-emitting diodes from the semiconducting conjugated polymer poly[2-methoxy,5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene], using doped silicon (both n and p type) as an electrode material. Light emission at low voltages is clearly demonstrated. The presence of a thin SiO2 layer at the silicon interface modifies the device characteristics compared to devices fabricated on indium-tin-oxide substrates. An interesting consequence of this is the ability to align the Fermi level of the silicon electrode with the lowest unoccupied molecular orbital of the polymer allowing hole injection in forward bias and electron injection in reverse bias.