Optical absorption in metal bisphthalocyanine sublimed films

Visible optical absorption and reflection spectra are obtained for 50 nm thick sublimed films of heavy fraction rare-earth [HF(pc) (pc*)], gadolinium [Gd(pc) (pc*)] and thulium [Tm(pc) (pc*)] bisphthalocyanine compounds when they have undergone the post-deposition treatments of voltage-cycling to blue, voltage cycling to red and annealing at 393 K for 1 h. The different post-deposition treatments produce different effects on the absorption spectra; annealing generates phase changes in the films. The changes due to the voltage cycling are believed to be a result of oxidation/reduction processes taking place in the materials. The absorption data yield information on the dispersion of refractive index and dielectric constants within the optical frequency range. The energies of transition are found to be 1.9 and 2.8 eV, respectively for Q- and Soret bands of all untreated samples. The concentration of electrons involved in resonant oscillation is estimated to be in the order of 1031 m−3 for all types of samples, both fresh and treated.