Photoluminescence properties of PVP/Tb(TTA)2(Ph3PO)2NO3 nanocomposites

Abstract

Thin films (1–10μm thickness) of nanocomposites (NCs) based on a coordinated compound (CC) Tb(TTA)2(Ph3PO)2NO3 (where TTA is thenoyltrifluoroacetonate (C8H5F3O2S), and Ph3PO is triphenylphosphine oxide) and a polymer — polyvinylpyrrolidone (PVP) ((C6H9NO)n) were obtained by chemical methods. NCs were characterized by measurements of optical transmission, and photoluminescence (PL) at different concentrations of CC in NCs. Using the optical transmission spectra, the characteristic parameters of NCs such as the threshold of absorbance versus the concentration of the CC in NCs were determined. A slight displacement of the absorption threshold to the infrared region was observed with increasing concentration of coordinated material in NCs. It was established that the excitation spectrum at which the photoluminescence (PL) in NCs takes place covers the range of wavelengths from 200 to 410nm. The PL of nanocomposites was detected as specific for internal transitions 4f→4f of the Tb3+ ion 5D4→7Fi (i=6, 5, 4 and 3) centred at 488, 543, 589 and 614nm, respectively at T=300K. The dominant PL was observed at 543nm and its half-width is less than 10nm. The intensity of the photoluminescence signal at 543nm in the case of the NC films is 2 times higher than the intensity of the PL of Tb(TTA)2(Ph3PO)2NO3 powders at equal conditions of excitation. The PL intensity of the NCs at 77K has grown more than 20 times compared with that at 300K.