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1 March 1991 Modified chloroaluminium phthalocyanine: an organic semiconductor with high photoactivity
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Proceedings Volume 1436, Photochemistry and Photoelectrochemistry of Organic and Inorganic Molecular Thin Films; (1991)
Event: Optics, Electro-Optics, and Laser Applications in Science and Engineering, 1991, Los Angeles, CA, United States
The crystalline structure of chloroaluminum phthalocyanine (ClAlPc) is modified upon contact with an acidic solution (pH equals 3) containing 0.1 M of salts like KCl, KBr, KClO3, KBrO3 or NaHSO3. This modification is labelled 'H type' on the basis of the film Q band shape. Even though the absorbances in the Q band region are the same for all the salts used in this work, the photoactivity of the transformed films varies greatly from one salt to another. Indeed, under 35 mW cm-2 white light illumination, short circuit photocurrents range from 0.25 mA cm-2 (NaHSO3) to 1.0 mA cm-2 (KCl) depending upon the salt used during the modification of ClAlPc. It is shown by electron diffraction, that transformations of the H type induce the same changes for all salts in the interplanar distances of the ClAlPc crystallites. It is probably the result of anion penetration into the film to compensate for the protonation of the macrocycles. This anion uptake in the ClAlPc structure is demonstrated by X-ray absorption in the case of KBr for which Br...C distances of 2.6 angstrom and Br...N distances of 4.2 angstrom are measured. The most photoactive H type transformations of ClAlPc are obtained in the presence of KCl, KBr and KClO3. They have a common point: a similar film morphology. For these salts, the long axis of the crystallites lies along a direction parallel to the substrate surface while it was perpendicular before the transformation. After the H-type modification with NaHSO3, the film morphology is similar to the one of the as-sublimed ClAlPc. NaHSO3 transformed films display the lowest photoactivity even if the crystallinity of those films is comparable, if not better, than the crystallinity of ClAlPc transformed with KCl.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jean-Pol Dodelet, Louis Gastonguay, George Veilleux, Robert G. Saint-Jacques, Roland Cote, Daniel Guay, and Gerard Tourillon "Modified chloroaluminium phthalocyanine: an organic semiconductor with high photoactivity", Proc. SPIE 1436, Photochemistry and Photoelectrochemistry of Organic and Inorganic Molecular Thin Films, (1 March 1991);


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