Synthesis, thermal and spectroscopic characterization of Caq2 (calcium 8-hydroxyquinoline) organic phosphor.

Bluish-green photoluminescence from calcium 8-hydroxyquinolate (Caq(2)) powder, synthesized by a co-precipitation route, and a blended Caq(2):PMMA thin film is reported. The film was obtained by mixing the Caq(2) powder with PMMA (Polymethylmethacrylate) in a chloroform solution. X-ray diffraction analyses confirm the formation of the Caq(2) powder and thin film. Further structural elucidation was carried out using Fourier transform infrared spectroscopy (FTIR) in which the stretching frequencies of the Caq(2) bonds were determined. Bluish-green photoluminescence with a maximum at 480 nm was observed from the powder and the emission was red-shift by 10 nm in the case of the thin film. The UV-vis absorption bands were split and shifted due to different orientations of the Caq(2) molecules in both the powder and thin film. It was confirmed by thermogravimetric (TGA) and differential thermal analysis (DTA) that the Caq(2) powder was stable up to ≈ 380 °C. Atomic force microscopy images showed the continuous distribution of the Caq(2) atoms in the PMMA thin film. X-ray photoelectron spectroscopy data was used to estimate the binding energies of the chemical bonding in the Caq(2) powder complex. The optical properties of the Caq(2) powder and thin film were evaluated for possible applicable in organic light emitting devices.