Phthalocyanines organic photoconductors

Titanyl phthalocyanines are used as the CGMs in commercial organic photoconductors, e.g. in the engines from Canon, Xerox, Konica and other OEMs. 

It has recently been shown that organic photoconductor-liquid crystal sandwich cells can in theory act as dynamic scattering devices 164> and the technical possibilities ought to be tested. In this context, it should be noted that dyes can be used in two-layer photocondensers (consisting e.g. of phthalocyanine and a ferroelectric ceramic), which are very sensitive to light and have a response time of lO-4 to 10-3 Sec 165). 

The semiconductor selenium is an excellent photoconductor however, its photoresponsiveness decreases sharply at wavelengths over 550 nm, which has motivated research on organic photoconductive materials.1550,1551 Many different organic compounds display photoconductive behaviour, such as phthalocyanines (596 M = metal) or squaraines (597) (Figure 6.33) today more than 90% of xerographic photoreceptors are composed of organic photoconductors. 

Ahuja, R. C. and Hauffe, K., Charge transfer across organic photoconductor/insulating liquid interface. I. Metal free phthalocyanine alkanes, Ber. Bunsen Ges. Phys. Chem., 84, 68,1980a. 

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. 

It should be pointed out that a specific modification of Ti(0)Pc 1 (R = -H) in organic polymers is the most widely used photoconductor in bilayer photoreceptor copiers and laser printers [19]. A thin film containing ethylene-bridged silicon phthalocyanine polymer dispersed in poly(vinylidene fluoride) (1 4 by weight) obtained by casting from a DMF slurry on quartz was orientated in an electrical field [20], A double-layered receptor device for measuring the... 

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