Abstract
Vacuum sublimed thin films of gallium phthalocyanine chloride, tin phthalocyanine oxide and aluminum phthalocyanine
hydroxide are prepared at room temperature. Optical absorption spectra of films of different thicknesses are taken over a
wavelength range of 300 to 900 nm and the optical energy band gap Eg and the onset energy gaps are calculated. The
absorption spectra consist of two well defined absorption bands of the phthalocyanine molecules, namely, the Soret (B) and
the Q- bands at about 300-400 and 600-800 nm respectively, showing an enhanced broad optical window with lower linear
absorption at about 500 nm. Tin phthalocyanine oxide has very different absorption spectra. The characteristic Davydov
splitting of the Q-band in tin phthalocyanine oxide correlates with the relative tendencies of the metal to out-of-plane
bonding. It is observed that the band gap decreases with the increase of film thickness.
Keywords
Phthalocyanine, Thin film, Optical band gap.
Citation
SUSAN MATHEW, C. S. MENON, C. SUDARSANAKUMAR, Effect of thickness on the absorption spectra of GaPcCl, SnPcO and AlPcOH thin films, Optoelectronics and Advanced Materials - Rapid Communications, 2, 6, June 2008, pp.349-352 (2008).
Submitted at: Jan. 31, 2008
Accepted at: June 5, 2008