Phthalocyanines doped polymers

Recent band structure calculations have confirmed that the increase in electrical conductivity of doped polymer phthalocyanines is the result of both the existence of partially filled bands and the decrease of the M—M distance.104 They also confirm that the conduction process for the doped polymers changes from metal-centred (M = Cr, Mn, Fe and Co), to ligand and metal (M = Ni) and to ligand-centred (Cu and Zn) with increasing electronegativity of the metal atom along the first transition series. 

The majority of photovoltaic modules use silicon as the photovoltaic cell element, but other materials are, in principle, possible. The last four chapters consider the use of organic polymers (sometimes doped) as the cell element or in some related conducting property acrylonitrile, some polymeric phthalocyanines and polymers of 2-vinylnaphthalene that is doped with pyrene and 1,2,4,5-tetracyanobenzene. The study on the last group of polymers was initiated by the idea that they could be used to transfer solar energy to a reaction center and produce some type of chemical reaction. The final chapter carries this approach further in the consideration of polymeric electrodes that could be used to split water into oxygen and hydrogen. The latter could then be utilized as a source of storable, readily transportable chemical energy. 

Phthalocyanine-based polymers, such as the shish-kebab polymers (60), are also of considerable interest and significant electrical conductivities of up to ca 0.1 S/cm have been detected for chemically or electrochemically doped materials (187,188). If flexible organic substituents are present on the periphery of the phthalocyanine ring, these materials can also be soluble (at least low molecular weight fractions). 

Intensive research on the electrocatalytic properties of polymer-modified electrodes has been going on for many years Until recently, most known coatings were redox polymers. Combining redox polymers with conducting polymers should, in principle, further improve the electrocatalytic activity of such systems, as the conducting polymers are, in addition, electron carriers and reservoirs. One possibility of intercalating electroactive redox centres in the conducting polymer is to incorporate redoxactive anions — which act as dopants — into the polymer. Most research has been done on PPy, doped with inter alia Co 96) RyQ- 297) (--q. and Fe-phthalocyanines 298,299) Co-porphyrines Evidently, in these... 

The most commonly reported organic semiconductor material is phthalocyanine (Pc), although many embodiments of this material are technically classified as polymers and will not be discussed in this chapter. One sensor of this type is a p-type semiconductor sensitive to CI2 and NO2 at a 150 °C operating temperature, and has the advantage of very low sensitivity to H2, H2S, NH3, CH4, SO2, and CO [20]. Mg, Co, Ni, Cu, or Zn phthalocyanine films have also demonstrated some sensitivity to NO2 [28]. In another study, lead phthalocyanine (PbPc) was configured as an n-type semiconductor when doped with RUO2 and Pd and was shown to be sensitive to H2 and CO gases [21]. 

Poly-yne polymers composed of phthalocyanine (Pc) complexes (42) with silicon were synthesized (equation 40) by Mitulla and Hanack. The conductivities of the polymers were up to 10 S cm", and increased to 10 S cm by I2 doping. 

The cofacially stacked polymeric phthalocyanines can exhibit high electrical conductivities in either the undoped or the doped state (Table 7-1) [166,168,170]. For comparison, low molecular weight phthalocyanines MPc or naphthalocyanines MNc (M = Fe, Cu, Co, Ni, Zn) exhibit values between a = 10 and 10 S cm V For undoped polymers. Table 7-1 shows that polymerization through cyano- and tetrazine-bridging is particularly effective in increasing the conductivity. This effect can be ascribed to the existence of additional interactions (Ti-orbital interactions through the bonds) [170,194]. 

A number of other redox-dopable conducting polymer systems are also known such as those made by doping covalently-linked siloxane-phthalocyanine complexes, [Si(Pc)0]x, but the above systems and their derivatives have been the most extensively investigated,. ... 

Another interesting material consists of the doped forms of covalently linked siloxane-phtha-locyanine (Pc) complexes, [Si(Pc)0]n. In these polymers, the planar phthalocyanine units are apparently stacked face-to-face and form columns, due to the silicon-oxygen-silicon bonds. The polymers appear to be intrinsically metallic systems. The principal pathways of conductivity are perpendicular to the phthalocyanine planes. The extended n-n systems that form result from face-to-face overlaps of the phthalocyanine units. This enables the electrons or holes to travel in a perpendicular direction. 

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