Synthesis, photoconductivity, and photostability of soluble titaniumoxophthalocyanines and -naphthalocyanines

Abstract

Soluble titaniumoxophthalocyanines R m PcTiO with m = 4,8 and R = n-alkyl (C 3 -C 7 ), trifluoromethyl, trifluoroethoxy, and the corresponding (t-butyl) 4 -naphthalocyanine are synthesized. The compounds are characterized spectroscopically, photochemically, and photoelectrically in solution and in vapor deposited or spin cast films. The results are compared to the insoluble parent compound PcTiO. According to positions of the electronic absorption bands, the films form amorphous and several crystalline phases depending on deposition and annealing conditions. All compounds are very weak electrical conductors in the dark, but much better ones upon irradiation. Conductivity increases also extremely upon oxygen doping. This effect is kinetically investigated and assigned to light assisted formation and dissociation of stable chemical complexes between Pc and 02. Complex formation is reversible to a high degree, but also irreversibly oxidized photoproducts are formed. Photoconductivity increases as function of chemical substituents in the series alkyl ph = 10 -6 . After annealing, the yields of decomposition decrease by additional 1 -2 orders of magnitude.