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FIZIKA A 15 (2006) 3 , 147-164
 
STRUCTURAL PROPERTIES AND UV TO NIR ABSORPTION SPECTRA OF METAL-FREE
PHTHALOCYANINE (H2PC) THIN FILMS
M. M. EL-NAHASS, A. M. FARID, A. A. ATTIA and H. A. M. ALI
Department of Physics, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo, Egypt
Received 25 October 2004; Revised manuscript received 16 August 2005
Accepted 14 March 2006 Online 23 February 2007
The structural properties and absorption spectra of H2Pc thin films
have been studied. The films used in these studies were thermally evaporated on
glass/quartz substrates with thickness ranging from 60 to 460 nm. The XRD
studies of H2Pc thin films showed that the as-deposited films have
a-form with monoclinic system. The mean crystallite size (L), the dislocation
density (d) and the strain (x) were evaluated.
The molecular structure of H2Pc thin films is
confirmed by analysis of (FTIR) spectra. The surface morphology of H2Pc
thin films was examined by scanning electron microscope. The absorption spectra
of H2Pc recorded in the UV - VIS - IR region for the as-deposited and
the annealed thin films of different thickness have been analyzed. The spectra
showed two absorption bands namely the Q-band and the Soret (B)-band. The Q-band
shows its characteristic splitting (Davydove splitting) with
DQ = 0.21 eV. Values of some important optical parameters, namely optical
absorption coefficient (a¢),
molar extinction coefficient (emolar),
half-band-width (Dl),
electronic dipole strength (q2) and oscillator strength (f) were
calculated. The fundamental and the onset of the indirect energy gaps were also
determined as 2.47 and 1.4 eV, respectively.
PACS numbers: 68.55.Jk, 78.30.Jw, 78.20.Ci
UDC 538.975, 538.958
Keywords: H2Pc thin films, thermally evaporated, structural
properties, UV - VIS - IR absorption spectra, Q-band, Soret (B)-band, XRD, FTIR
spectra, SEM
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