Sulforhodamine B intercalated layered double hydroxide thin film with polarized photoluminescence

Sulforhodamine B (SRB) and dodecylbenzenesulfonate (DBS) with different molar ratios cointercalated into the interlayer region of Mg-Al-layered double hydroxide (SRB-DBS/LDH) were prepared. The structure and chemical composition of the composites were characterized by X-ray diffraction, elemental analysis, thermogravimetry, and differential thermal analysis (TG-DTA). Fluorescence spectra demonstrate that the sample with 4.76% SRB molar percentage, with respect to the total organic material, exhibits the optimal luminous intensity. The fluorescence lifetime of SRB in SRB-DBS/LDH is enhanced significantly compared with that of pristine SRB in solution (4.14 vs 2.05 ns). SRB-DBS/LDH thin films on the quartz substrates were constructed by the solvent evaporation method. Steady-state polarization photoemission spectra show that the luminescence anisotropy of SRB-DBS/LDH thin films (r=0.10) was enhanced remarkably compared with that of a powder sample (r=0+/-0.01) at ambient temperature, whereas the anisotropy of both film and powder samples was largely improved at low temperature (77 K). Furthermore, the SRB-DBS/LDH thin films exhibit a luminescence anisotropy decay effect in the range of their fluorescence lifetime. These results demonstrate that the SRB-DBS/LDH thin films could be used as a good candidate for the immobilization of laser dyes and polarized luminescence materials.