Vacuum sublimed thin films of copper phthalocyanine were
prepared at room temperature. The optical properties of thin CuPc films
have been investigated in the spectral range 200-2100 nm. The refractive
index n as well as the absorption index k were calculated before and after
annealing. It is obvious that the refractive index showed an anomalous
dispersion in the absorption region as well as normal dispersion in the
transparent region. The analysis of the spectral behavior of the absorption
coefficient, α in the absorption region revealed direct transitions. The
analysis of α as well as the dielectric constants ε
1 and ε
2 reveals several
absorption peaks at photon energies given in the text. The fundamental and
the onset energy gaps could also be estimated as 2.74+0.02 and
1.64+0.02 eV respectively.