Enhancement in the Photoluminescence Properties of SiO2:Ge Embedded in a Polymeric Matrix

Polymer films of styrene butadiene copolymer (SBC) mixed with SiO2:Ge powder were successfully obtained by the drop casting method. The SBC concentration (in chloroform solution) was 10%w/v and the SiO2:Ge powder was mixed (mass ratio 80:20 respectively). The thicknesses of the films obtained were 50, 100, and 200 μm. In addition, polymer films of polytetrafluoroethylene (PTFE) preparation (60% dispersion in water), were obtained mixing 2 ml of PTFE and 0.05g of SiO2:Ge powder with a mass relation of 98% polymer and 2% SiO2:Ge. The photoluminescence emission spectra (PL) of SBC doped with SiO2:Ge resulted in similar characteristics to those for SiO2:Ge powders, although their intensity shows an increase 3.5 times approximately, compared with the pure powder. On the other hand, the PTFE films with SiO2:Ge present just one peak in the PL emission at 439 nm but their intensity increases 18 times respect to the powder. The photoluminescence excitation (PLE) spectra of the SiO2:Ge powders show the characteristic peaks at 248 nm (most intense) and at 366 nm. However, when the powder is embedded either in SBC or PTFE the peak at 366 nm shows an important increase which seems to indicate an energy transfer from the polymer to the SiO2:Ge.