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

The optical properties of thin films of lead phthalocyanine in both mo noclinic and triclinic forms have been studied. Optical parameters hav e been determined from both absorption and reflectivity data for wavel engths in the UV and visible regions. Monoclinic films show two absorp tion bands, identified as exciton absorption at low energy and fundame ntal absorption above 2.4 eV. A direct allowed transition at 2.42 eV w as observed. A doublet of energies in the absorption spectrum at 1.86 and 1.74 eV is in agreement with observations for other metal phthaloc yanines. 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 re sults support the view that a band model analysis of this material is valid despite the very low mobility values found for both monoclinic a nd triclinic films.