Photouminescence and optical properties of PVP/Tb(TTA)2(Ph3PO)2NO3nanocomposites

Abstract

Thin films (1-10 μm thickness) of nanocomposites (NCs) based on coordinated compounds (CC) Tb(TTA) 2 (Ph 3 PO) 2 NO 3 (where TTA is thenoyltrifluoroacetonate (C 8 H 5 F 3 O 2 S), Ph 3 PO - triphenylphosphine oxide) and polymer – polyvinylpyrrolidone (PVP) ((C 6 H 9 NO)n)) were obtained by chemical methods. NCs were characterized by measurements of optical transmission (T(λ)), and photoluminescence (PL) at different concentrations of CC in NCs. Using the optical transmission spectra, the characteristic parameters of NCs such as threshold of absorbance and the position of the absorption edge versus the concentration of the CC in NCs, etc., were determined. A slight displacement of absorption threshold to infrared region was observed with increasing of concentration of coordinated material in NCs. It was established that the excitation spectrum at which the photoluminescence (PL) in NCs take place covers the range of wavelengths from 200 to 410 nm. The PL of nanocomposites was detected as specific for internal transitions 4f → 4f of the Tb 3 + ion 5 D 4 →7Fi (i = 6, 5, 4 and 3) centered at 488, 543, 589 and 614 nm, respectively at T=300 K. The dominant PL was observed at 543 nm and its halfwidth is less than 10 nm. The intensity of photoluminescence signal at 543 nm in the case of NCs films is 2 times higher than the intensity of PL of Tb (TTA) 2 (Ph 3 PO) 2 NO 3 powders at equal conditions of excitation. PL intensity of the NCs to 77 K is growing more than 20 times compared with that at 300 K.