Tuning the extinction coefficient, refractive index, dielectric constant and optical conductivity of Gaq3 films for the application of OLED displays technology

The optoelectronic parameters of tris (8-hydroxyquinoline) gallium (Gaq3) films were tuned by means of post-deposition thermal annealing under nitrogen gas. Nanostructure evolution was seen to play a vital role in the variation of the optoelectronics parameters of these films. The results showed an increased refractive index from 1.53 to ultra-high refractive index of 5.45, along with a maximized dielectric constant of 13.92 and optical conductivity of 56.31 S/cm when the films were annealed at 235 °C. At higher annealing temperature of 255 °C, a decreased trend was noticed for the aforementioned optoelectronic parameters and the grown amorphous nanorods were completely degraded, which has led to the formation of crystalline portions. The results were interpreted in terms of molecular packing density and structural variations. The investigated Gaq3 films were seen to obey Wemple–DiDomenico single oscillator model to provide information regarding the band gap and its strength. The achieved results are greatly important for the application of OLED displays technology and their performance improvement.