Electron acceptor surface states due to oxygen adsorption on metal phthalocyanine films

Abstract

The dependence of the surface photovoltage of NiPc and CuPc films on oxygen ambient has been measured, and the observed effects can be quantitatively accounted for with a theoretical model which involves the transfer of charge from the Pc ring to the adsorbed O2 and the formation of a Pcδ+–Oδ−2 species at the surface of the Pc film. Symmetry arguments based on a simple bonding model are used to explain the nature of these O2 electron acceptor surface states. Charge transfer complexes such as this are important both to the doping of these organic semiconductors, and to a fundamental understanding of the oxidations photocatalyzed by these porphyrinlike materials which are closely related to some of the processes which occur during photosynthesis.

Novel phthalocyanines with naphthalenic substituents

“…Elemental analyses correspond closely with the values calculated for (1)(2)(3)(4)(5). In compound 1, stretching vibrations of C:N (2238 cm -1 ), C=O (1753 cm -1 ), C-O-C (1191 cm -1 ) were observed at expected frequencies.…”

“…Phthalocyanine (Pc) derivatives, by virtue of their highly delocalized cyclic p-electron system, absorb strongly in the near-IR region and exhibit a number of very interesting physical effects including semiconductive [1], nonlinear optical [2], electrochromic [3], photovoltaic [4], liquid crystalline [5], and catalytic [6] properties. These properties offer a wide range application, namely, electrooptical devices [7], electronic sensors [8], optical data storage [9,10], electrochromic displays for laser address storage systems [3], and heterogeneous catalysis [11].…”

Photoemission yield spectroscopy investigations of the electronic properties of copper phtalocyanine thin films UHV annealed and exposed to oxygen

“…Because of both high temperature and high chemical stability [5], they became widely used in thin film technology for specific optoelectronic devices [6], solar cells [7], and gas sensors [8].As for the most popular copper phthalocyanine (CuPc) thin films, up to now only UPS [9 to 131, SPS [14, 151, and EELS [16] methods have been used to study their electronic properties. In the earliest UPS studies of Vilesov et al [9], reexamined by Schechtman and Spicer [lo], only the optical density of states in the upper part of the valence band up to -7 eV has been determined.…”

Influence of Oxygen Adsorption on Electronic Structure of Iron Phthalocyanine

“…Such effect was predicted for other metal substituted phthalocyanines [17]. The electronic stucture of the FeΡc-O2 complex is changed considerably in comparison with th e isolated FePc.…”

“…At that time ultraviolet photoelectron spectroscopy (UPS) spectra of some metal substituted phthalocyanines were reported [12][13][14][15]. Then surface photovoltage spectroscopy (SPS) spectra of MPcs (M = Ni, Fe, Co, Cu, Zn) were presented by Dahlberg and Musser [16,17]. They have not only investigated the electronic stucture of MPcs but also its changes under the influence of oxygen adsorption.…”