Optical Spectroscopy and XRD Study of Molecular Orientation, Polymorphism, and Phase Transitions in Fluorinated Vanadyl Phthalocyanine Thin Films

Abstract

The molecular arrangement and phase transitions in the vanadyl hexadecafluorophthalocyanine (VOPcF 16 ) thin films grown by physical vapor deposition have been studied using in situ X-ray diffraction, atomic force microscopy, and optical spectroscopy techniques (UV, IR, and Raman). The complete transition from the low-temperature linear cofacial structure to the slipped dimeric one occurs in the temperature range 160−220 °C. This conversion was found to be irreversible upon cooling the VOPcF 16 film back to 20 °C. The structural transformation leads to decrease of the in-plane conductivity of the film by 2 orders of magnitude. According to the polarized Raman spectroscopy measurements, the mean tilt angles between the VOPcF 16 species and the substrate surface were 59 ± 5°and 30 ± 5°in the as-deposited and annealed films, respectively. For the sake of comparison, the structure of the thin films of vanadyl phthalocyanine (VOPc) was also studied. The mean tilt angle between the VOPc species and the substrate surface was found to be 77 ± 5°, in good agreement with existing experimental data (∼70°). All intense bands in the experimental IR and Raman spectra of VOPcF 16 and VOPc were assigned using DFT calculations (B3LYP) and the 15 N isotopic shifts in the vibrational spectra of VOPc.

Molecular organization in the thin films of gallium(III) phthalocyanine chloride and its μ-(oxo)dimer: Optical spectroscopy and XPS study

“…Among the huge variety of experimental techniques, vibrational spectroscopies (IR and especially Raman) have been shown to be very useful for studies of the surface structure and properties of thin films [10,25,26]. Note, however, that the vibrational spectroscopy methods (in our case, polarized Raman spectroscopy) can give insight into the structure of thin films only provided the detailed assignment of the vibrational spectra of the deposited species is available.…”

“…A facile way for such dimerization is thermal annealing of the thin films in the presence of atmospheric moisture. Apart from chemical transformations, annealing might also lead to polymorphic phase transitions in the films [10]. The crystal structure and the structural organization of the thin film, in turn, can influence the properties of a material [10].…”

“…Apart from chemical transformations, annealing might also lead to polymorphic phase transitions in the films [10]. The crystal structure and the structural organization of the thin film, in turn, can influence the properties of a material [10]. Therefore, the molecular arrangement and morphology of the film play a crucial role in particular device applications.…”

Thin Films of Unsubstituted and Fluorinated Palladium Phthalocyanines: Structure and Sensor Response toward Ammonia and Hydrogen

“…This makes fluorine substituted phthalocyanines possessing more sensitivity to the reducing gases like NH 3 and H 2 as compared to unsubstituted analogues [13,14,17]. Although the structural features and sensor response of 3 some fluorosubstituted M(II)Pc (e.g., CuPc, ZnPc, CoPc) were studied in details [14,[18][19][20][21], much less seems to be known about fluorosubstituted palladium phthalocyanines.…”

Fabrication and characterization of inverted organic solar cells using shuttle cock-type metal phthalocyanine and PCBM:P3HT

“…Shuttle cock-type phthalocyanines are groups of semi-conductive materials with Q-band absorption in red to near-infrared wavelength. Non planar phthalocyanine such as titanyl phthalocyanine (TiOPc), lead phthalocyanine (PbPc), and vanadyl phthalocyanine (VOPc) have a variety of crystal structure at phase transition between H-aggregation (phase I) and J-aggregation (phase II) that absorbs at longer wavelength [1][2][3]. They are applied for electronic and optical devices, chemical pigments and photovoltaic application as used for donor materials in organic solar cells [4][5][6][7].…”