Optoelectric Characteristics of Porous Silicon Using a Conducting Polymer

The simple porous silicon-based devices producing stable electroluminescence (EL) by the deposition of a poly-4-dicyanomethylene-4H-cyclopenta dithiophene monolayer (PCDM) into the nanostructure is reported. The structure of these devices is Au/PCDM/porous silicon/Si/Al. The EL emission is bright, visible by the naked eye under normal daylight and broad in wavelength covering the whole visible range with a peak at 620 nm. The emission area of the devices is 1 cm
²
. The EL starting voltage is in the range of 14-30 V and the current is around 300 mA. The time stability is good for all the devices tested. After exposure to the air for more than three months, the devices show nearly the same emission intensity without increase of external power supplied. The I-V curves are fitted to a Schottky barrier model with a barrier height of 0.8 eV. The orange photoluminescence band from the porous silicon is due to recombination in the silicon quantum structures both before and after coating with PCDM