Multiple energy transfer in porous silicon/Rh6G/RhB nanocomposite evidenced by photoluminescence and its polarization memory

Porous silicon (PSi)-laser dye composites were obtained by simply immersing PSi in ethanolic solutions of rhodamine 6G (Rh6G), rhodamine B (RhB), and RhB:Rh6G mixture. Partially oxidized PSi was also used as a host matrix. Fourier transform infrared spectroscopy suggests that the dye molecules fully penetrate into the porous matrix. Efficient photoluminescence (PL) was observed in all nanocomposites. The study of the polarization memory of PL provides a clear evidence for the presence of energy transfer from PSi to Rh6G molecules. The energy transfer was found more efficient in oxidized PSi. In RhB:Rh6G/PS composite, energy transfer from Rh6G molecules to RhB molecules was demonstrated. Rh6G molecules play the role of an intermediate radiative center in the excitation energy transfer from PSi to RhB molecules.