Photoluminescence in the blue spectral region from fluorene molecules embedded in porous anodic alumina thin films on silicon

The photoluminescence (PL) in the blue spectral region from fluorene molecules embedded in the pores of anodic alumina thin films on silicon was investigated in detail. It was found that the PL was strongly dependent on the diameter and depth of the pores, as well as on the solvent used to dissolve the fluorene molecules. A photoluminescence blue shift with a maximum value of 30 nm was observed when the fluorenes were embedded into 40 nm pores of the alumina film compared to the corresponding spectrum in solution. The results have shown that the penetration of the molecules into the pores, as well as the formation of nanosize aggregates are favored when the molecules are dissolved in an aromatic solvent.