Effect of iodine incorporation on the electrical conductivity of films of nickel phthalocyanine

Abstract

Films of phthalocyanine dyes are increasingly being utilized to photosensitize a variety of optoelectronic devices. One practical limitation to further application is the insulating nature of these films. In this paper, we demonstrate how permanently conductive (2 ft-1 cm-1) films of NiPc films can be prepared by heating in an iodine ambient at temperatures ranging from 140 to 200 °C. (Pleating in iodine at lower temperatures results in NiPc films which were only transiently conductive.) These changes in conductivity are accompanied by changes in the optical absorption, morphology, and X-ray diffraction. Before treatment in iodine, the NiPc films are blue and have a sharp absorption edge at 750 nm. In contrast, the iodized NiPc films are green and have a less pronounced absorption edge at 700 nm with an additional absorption peak at 978 nm. The iodine treatment also resulted in some cracking in the NiPc film. Although the blue and green NiPc films are both tetragonal, there are pronounced shifts in the X-ray diffraction peaks, and the green films are preferentially oriented along the (200) direction.

Site-dependent charge transfer at the Pt(111)-ZnPc interface and the effect of iodine

“…Instead, we suggest that iodine is taken from the Pt surface and dissolved in the ZnPc thin film. Iodine has been used as dopant in organic films for many years [74][75][76][77][78][79][80][81][82]. Depending on the concentration the conductivity in for example PbPc was increased by as much as nine orders of magnitude [77].…”

Iodine implantation of polymeric phthalocyanines

“…The phthalocyaninatofluoroaluminium polymer (PcAlF) is such a material since it is readily sublimed and is stable in film form up to 550 "C [4]. Unfortunately, due to the polycrystalline nature of these films and the volatility of most dopants normal chemical doping techniques tend to be reversible [ 5 ] . Hence it is of interest to investigate ion implantation as a method of obtaining stable doped films with controllable doping levels.…”

“…Insignificant beam damage was detected for doses up to 6 X l O I 4 H e cm-*. Samples implanted at lOI5 cm-* and 100, 150 and 200 keV were immediately placed in the spectrometer and the iodine profiles determined (figures [3][4][5]. This reduced the time for normal anneal processes such as diffusion to occur.…”

Photoactivated Electrolysis on Nonporous Chlorogallium Phthalocyanine Thin Film Electrodes

“…Phthalocyanines have been widely used as dye sensitizers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) and are well known for their chemical and thermal stability, high molar absorptivity in the optimal region of solar irradiance, and ability to catalyze electrode reactions. While phthalocyanines exhibit rather low electrical conductivity by themselves, this conductivity can be improved by incorporating acceptor species such as Br, I, chloranil, and TCNE into the lattice (17)(18)(19)(20)(21).…”