Investigation of optical properties of annealed aluminum phthalocyanine derivatives thin films

• Thin films of chloroaluminium phthalocyanine (AlPcCl) and bidentate amines were deposited.
• Studies of the optical properties have been done using films deposited and films annealed.
• The fundamental energy gaps associated with the films were determined.

Semiconducting molecular materials based on aluminum phthalocyanine chloride (AlPcCl) and bidentate amines have been successfully used to prepare thin films by using a thermal evaporation technique. The morphology of the deposited films was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Studies of the optical properties were carried out on films deposited onto quartz and (1 0 0) monocrystalline silicon wafers and films annealed after deposition. The absorption spectra recorded in the UV–vis region for the as-deposited and annealed samples showed two absorption bands, namely the Q- and B-bands. In addition, an energy doublet in the absorption spectra of the monoclinic form at 1.81 and 1.99 eV was observed. A band-model theory was employed in order to determine the optical parameters. The fundamental energy gap (direct transitions) was determined to be within the 2.47–2.59 and 2.24–2.44 eV ranges, respectively, for the as-deposited and annealed thin films.

Plot of (αhν)2 vs. photon energy hν of (a) compound 1 and (b) compound 2 thin filmsFigure optionsDownload as PowerPoint slide