The optical absorption of thermally evaporated copper phthalocyanine (CuPc) was studied in the UV-VIS-NIR region. The absorption spectra recorded in the UV-VIS region show two well-defined absorption bands of the phthalocyanine molecules, namely, the Soret ( B ) and the Q -band . The Q -band shows its characteristic splitting (Davydov splitting) of the main absorption peak in the metal phthalocyanine correlates with the relative tendencies of the metal to out-of-plane bonding. Some of the important spectral characteristics such as the molar extinction coefficient (e molar ), the oscillator strength ( f) , the electric dipole strength ( q 2 ) and absorption half-bandwidth (Δ λ ) of the principle optical transitions were evaluated. The analysis of the spectral behavior of the absorption coefficient α in the absorption region revealed two indirect allowed transitions with corresponding energies 2.95±0.03 and 1.55±0.02 eV. The spectra of the infrared absorption allow characterization of vibration modes for the powder, as-deposited material and thin films of CuPc annealed at 423 K for two hours. Discussion of the obtained results and their comparison with the previous published data are also given.

Optical absorption studies of copper phthalocyanine thin films

This chapter focuses on the molecular electronic, molecular magnetic, and molecular iono-electronic devices to target the development of novel electro-optical information-processing systems. The significance of porphyrins can be envisaged from their involvement in most important processes of natural life. Sandwich-type, in particular, bis[(na)phthalocyaninato] metal complexes with long alkyl substituents are among the most promising species of novel liquid crystal materials. The synthesis of covalently linked aggregates of porphyrinato metal sandwiches and quinones as realized for the monomeric porphyrins that seems to be a mammoth undertaking. The synthesis of multiple-decker porphyrinato and phthalocyaninato metal complexes are expected to show more interesting electronic characteristics, and more effective π–π interactions than the corresponding coordination metallopolymers, which seems to be another approach to lead to good molecular conductors. It must be pointed out that the research to fabricate such sandwich type metal phthalocyaninato and porphyrinato complexes into molecular electronic devices still remains undeveloped at the present stage. They are sure to play an important role in developing new electronic, iono-electronic, or optical devices for information processing.

Chapter 2 – Sandwich-Type Phthalocyaninato and Porphyrinato Metal Complexes

Fourier-transform infrared and UV–vis spectroscopes of nickel phthalocyanine thin films

The optical properties of tin-phthalocyanine dichloride thin films have been studied. The films used in the characterisation studies were thermally evaporated. The spectral and optical parameters have been investigated using spectrophotometric measurements of transmittance and reflectance in the wavelength range 200–2100 nm. The absorption spectra recorded in UV–VIS region for the as-deposited and annealed samples showed two absorption bands, namely the Q- and Soret band. No remarkable effect was observed after annealing. A structure with energy separation of magnitude 0.2 eV is seen on the Q- and Soret bands. A transition involving d-electrons of the central metal atom was indicated in the high photon energy region. The dispersion curve of the refractive index showed an anomalous dispersion in the absorption region and a normal one in the transparent region. The band-model theory was applied to determine the optical parameters. The fundamental and the onset of the indirect energy gaps were determined to be 2.79 and 1.51 eV respectively.

http://www.kau.edu.sa/Files/130/Researches/23067_Optical%20properties%20of%20thermally%20evaporated%20tin-phthalocyanine%20dichloride%20thin%20films,%20SnPcCl2.pdf

J.P. Lacharme

Papers

Spectroscopic and structural studies of scandium diphthalocyanine films