Study on luminescence characterization of physical vapor deposition-modified bis (8-hydroxyquinoline) copper

Abstract

Bis (8-hydroxyquinoline) copper (CuQ₂) is an important organometallic complex based on a central metal cation coordinated to quinolate ligands. However, CuQ₂ exhibits limitations such as low fluorescence intensity, short fluorescence lifetime, and low efficiency of visible light absorption. In this study, density functional theory (DFT) calculations were performed to investigate the frontier molecular orbitals of CuQ₂, revealing its potential for excellent luminescence properties. Subsequently, CuQ₂ was synthesized using physical vapor deposition (PVD), yielding micron-sized CuQ₂ particles. CuQ₂ micron particles were characterized using scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), ultraviolet visible spectroscopy (UV–Vis), photoluminescence and fluorescence lifetime. The results demonstrate that the deposition temperature significantly influences the morphology, thermal stability and fluorescence properties of CuQ₂. At a deposition temperature of 200 °C, the CuQ₂-C sample forms spherical micron particles with uniform morphology, enhanced thermal stability, optimal visible light absorption efficiency, and highest fluorescence intensity. The CuQ₂-C sample exhibits a maximum emission wavelength of 660 nm, a maximum excitation wavelength of 333 nm, and a fluorescence lifetime of 10.646 μs.

Graphical abstract