Copper phthalocyanine photoconductivity

Photoelectrochemical behavior of metal phthalocyanine solid films (p-type photoconductors) have been studied at both metal (93,94,95,96) and semiconductor (97,98) electrodes. Copper phthalocyanine vacuum-deposited on a Sn02 OTE (97) displayed photocurrents with signs depending on the thickness of film as well as the electrode potential. Besides anodic photocurrents due to normal dye sensitization phenomenon on an n-type semiconductor, enhanced cathodic photocurrents were observed with thicker films due to a bulk effect (p-type photoconductivity) of the dye layer. Meier et al. (9j>) studied the cathodic photocurrent behavior of various metal phthalocyanines on platinum electrodes where the dye layer acted as a typical p-type organic semiconductor. 

Law (1993) has reviewed the widespread polymorphism in phthalocyanines and its relationship to their photoconductivity and use in xerographic applications. These are best demonstrated by the prototypical copper phthalocyanine CuPc (6-XIX, M = Cu), whose structural chemistry is discussed in detail in Section 8.3.3.1. The polarized absorption spectra of five forms are given in Fig. 6.9. One outstanding feature of these spectra is the rather intense red shifted band at 770 nm in the 5 and modifications compared to the solution absorption at 678nm (Law 1993). This... 

Yagishita, T., Ikegami, K., Narusawa, T. and Okuyama, H. (1984). Photoconduction of copper phthalocyanine-binder photoconductor sensitized with poly-A-vinylcarbazole. IEEE Trans. Ind. Appl, IA-20, 1642-6. [207]... 

The phthalocyanines are still of some interest, and Ayers has interpreted the photoelectrochemistry of copper phthalocyanine in terms of the band-model for semiconductors. Menzel et alf have studied the photoconductivity and electrical field-induced fluorescence quenching in metal-free phthalocyanine films. Doping of the film increases charge-carrier photogeneration, and it seems likely that the mechanism is extrinsic, involving field-assisted exciplex dissociation. These are complicated materials, which are difficult to purify, and the mechanisms of carrier generation in polycrystalline and amorphous films are still obscure. The porphyrins and monolayer assemblies of chlorophyll on SnOj electrodes 2 72,273 ijggjj studied. 

Photoconductivity in copper phthalocyanine (III) now has been observed to occur with near-infrared light. Weak absorption of light in the near infrared by copper phthalocyanine has previously been observed. Although the ratio of extinction coefficients for visible and infrared light is 100 1, the ratio of the photoresponse peak heights (Fig. 7) is 3 1. This suggests that the... 

Copper phthalocyanine (CuPc) thin films deposited at room temperature (30°C) on quartz and post-annealed gold-coated quartz substrates were examined using FESEM [4]. Such structures can be used for the development of photoconductive or catalytic devices. FESEM images showed daisely packed nanoparticles and nanoflower-like structures on the annealed gold-coated quartz substrates. The further characterization by fiactal dimension of the assanbly of nanostructures in the films, estimated from FESEM images, agreed with optical measurranents and indicated significant effect and potential control of the electronic and optical propalies of these films. 

Recently, the preparation of monolayer and polylayer LBFs from a carbazole containing copolyimide and copper phthalocyanine has been reported. The stacked molecular organization of the layers and small intermolecular distances in these LBFs ensure the high mobility of the charge and impart the good photoconducting properties. ... 

Photoconductivity has also been detected in polymers prepared by glow-discharge polymerization of tetramethylsilane, tetramethyltin and tetramethylgermanium [85], polymers of copper phthalocyanine [86] and rhodium(i) aryldiisocyanide polymers [87]. 

Mo, X. Chen, H.-Z. Wang, Y. Shi, M.-M. Wang, M. Fabrication and photoconductivity study of copper phthalocyanine/perylene composite with bulk heterojunctions obtained by solution blending. J. Phys. Chem. B 2005, 109, 7659-7663... 

One restriction however has to be made octacyanosubstituted phthalocyanines most probably always contain a certain amount of sheet polymerized material, which might contribute to the observed photoconductivity [199b]. Tetracyano-phthalocyaninatometal complexes are unable to form sheet polymers and are therefore presently under investigation [203]. The central metal atom also influences the photoconductivities whereby generally larger G and values were observed for the copper compounds. 

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