OPTICAL-PROPERTIES OF LEAD PHTHALOCYANINE (PBPC) THIN-FILMS

The optical properties of thin films of lead phthalocyanine in both monoclinic and triclinic forms have been studied. Optical parameters have been determined from both absorption and reflectivity data for wavelengths in the UV and visible regions. Monoclinic films show two absorption bands, identified as exciton absorption at low energy and fundamental absorption above 2.4 eV. A direct allowed transition at 2.42 eV was observed. A doublet of energies in the absorption spectrum at 1.86 and 1.74 eV is in agreement with observations for other metal phthalocyanines. The spectrum for triclinic material shows a strong absorption band at 1.61 eV and two shoulders at 1.72 and 1.95 eV. The present results support the view that a band model analysis of this material is valid despite the very low mobility values found for both monoclinic and triclinic films.