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

  • Fahmi F. Muhammad
  • Mohd Yazid YahyaEmail author
  • Fakhra Aziz
  • Mariwan A. Rasheed
  • Khaulah Sulaiman


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.



The authors would like to acknowledge Universiti Teknologi Malaysia for the financial support from Research University Grant (RUG) UTM Malaysia (Vot: Q.J130000.21A2.03E00). The financial support from University of Human Development regarding the promote of publication is also acknowledged.


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Copyright information

© Springer Science+Business Media, LLC 2017

Authors and Affiliations

  • Fahmi F. Muhammad
    • 1
    • 2
  • Mohd Yazid Yahya
    • 1
    Email author
  • Fakhra Aziz
    • 3
  • Mariwan A. Rasheed
    • 4
  • Khaulah Sulaiman
    • 5
  1. 1.Center for Composites, Institute for Vehicle Systems & Engineering, Faculty of Mechanical EngineeringUniversiti Teknologi MalaysiaJohor BahruMalaysia
  2. 2.Soft Materials & Devices Lab, Department of Physics, Faculty of Science & HealthKoya UniversityKurdistan RegionIraq
  3. 3.Department of Electronics, Faculty of Physical and Numerical SciencesUniversity of PeshawarPeshawarPakistan
  4. 4.Development Center for Research and Training (DCRT)University of Human DevelopmentSulaimani, Kurdistan Regional GovernmentIraq
  5. 5.Low Dimensional Materials Research Centre, Department of Physics, Faculty of ScienceUniversity of MalayaKuala LumpurMalaysia

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