Optical and Chemical Properties of Alq3:PMMA Blended Thin Films

Blended thin films of tris-(8-hydroxy-quinoline) aluminum (Alq3) and a polymer like polymethyl methacrylate (PMMA) can lead to low cost manufacturing of organic light emitting diodes (OLED), while the polymer contains the optical properties of Alq3 and the processability of the polymer is maintained. Polymethyl methacrylate (PMMA) was doped with different mol percentages of Alq3 ranging from 0.5 – 5 mol %. The photoluminescence (PL) of the films were recorded at an excitation wavelength of 355 nm. The emission was characterized by broad spectra with a maximum at ∼ 515 nm, corresponding to the well-known green emission of Alq3 in the solid state. The effects of Alq3 concentration on the PL intensity and emission wavelength were investigated.X-ray photoelectron spectroscopy studies were done on commercial PMMA powder, PMMA thin films and Alq3:PMMA thin films in order to get a better understanding of the chemical interactions between the Alq3 molecule and the PMMA.