Optical properties of titanium dioxide nanoparticles/3-(2-benzothiazolyl)-7-N,N-diethylaminocoumarin/polymethyl methacrylate composite films

Abstract 3-(2-benzothiazolyl)-7-N,N-diethylaminocoumarin organic laser dye-polymethyl methacrylate (PMMA) composite films doped with inorganic titanium dioxide (TiO2) particles are fabricated by spin-coating technique. TiO2 nanoparticles exhibit a strong influence on optical properties of the organic laser dye/PMMA composite films. The refractive index and absorbance (absorption intensity) of organic laser dye/PMMA composite film with micro- and nanoparticles of TiO2 are reduced, compared to those without TiO2 particles. The organic laser dye/PMMA composite film with TiO2 nanoparticles has the lowest refractive index and absorbance values. Photoluminescence intensities of all systems exhibit a maximum peak around the excitation wavelength, close to that of the organic laser dye, at 450 nm and the minimum around the excitation wavelength of 350 nm. Photoluminescence intensity of the organic laser dye/PMMA composite film with TiO2 microparticles is always the lowest at all excitation wavelengths. However, the photoluminescence intensity of the organic laser dye/PMMA composite film with TiO2 nanoparticles has the highest value at excitation wavelengths of 330 and 380 nm, while the photoluminescence intensity of composite film without TiO2 particles is more than that with nanoparticles at other excitation wavelengths.