The effects of annealing temperature on optical properties of 2, 6-bis (3- (carbazol-9-yl) phenyl) pyridine films’

Abstract

In this research, 2, 6-bis (3- (carbazol-9-yl) phenyl) pyridine films were synthesized using spin coating to study changes in its optical properties for different annealing temperatures. The films were annealed at 30, 50, 70, 90, 110, 120, 140 and 160 ℃ degrees in the presence of nitrogen. The material studied is one of the basic materials of the organic light emitting diode and forms the light emitting layer. In the results obtained from the films, for UV ultraviolet region, the highest absorption was obtained at 50 ℃ annealing, while the lowest absorption was 160 ℃. Optical band gap energies of films range from 3.35 to 3.43 eV. Refractive index distributions depending on the annealing temperature of the films were studied in detail. The refractive indices of the films at 440 nm wavelength varied between 2.71 and 3.39 according to different annealing temperatures. It is observed that it varied between 3.06 eV and 3.19 eV. It was observed that in the visible region of the spectrum, refractive index of the films increased in a sharp linear behavior at a wavelength of 350 nm. Annealing took place in two regimes that increase and decrease the effect of the optical band gap energy of the film. It can be seen that the percentage of reflection of all films at the wavelengths after 500 nm was almost constant. It has been evaluated that the films had 70 % transmittance at 70 ℃ (up to 160 ℃) and after this point, their transmission (%) was above 70 % and films can be used in the permeability devices of this feature. As a result, the optical properties of films (bandgap energy, absorption band edge energy, refractive index, refractive (%), and transmission (%), etc.) were measured and evaluated according to the annealing temperature.