Photoluminescence properties of porous silicon/fluorene dye composites

We report on the fabrication and the photoluminescence (PL) study of hybrid nanocomposites formed by embedding fluorene dye molecules in the vertical cylindrical nanopores of a nanoporous silicon layer. The pores had a diameter of ∼20 nm and were homogeneously filled with the fluorene molecules as evidenced by scanning electron microscopy images. Efficient PL in the blue spectral region, attributed to the fluorene dyes embedded into the pores, was obtained from the composites. The PL spectrum of the dyes in porous silicon is blue-shifted compared to their PL spectrum in solution due to the confinement and isolation of the molecules into the pores. This blue-shift was enhanced when the dyes were initially dissolved in an aromatic solvent.