Conductivity and photoconductivity of polymeric composites containing heteropolynuclear Cu(II)/Mn(II) complex in the pre
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ONIC AND OPTICAL PROPERTIES OF SEMICONDUCTORS
Conductivity and Photoconductivity of Polymeric Composites Containing Heteropolynuclear Cu(II)/Mn(II) Complex in the Presence of Ionic Polymethine Dyes N. A. Davidenkoa^, V. N. Kokozaya, A. A. Ishchenkob, A. A. Beznishchenkoa, V. G. Makhan’kovaa, N. G. Spitsynac, A. S. Lobachc, I. I. Davidenkoa, and A. N. Popenakaa aShevchenko
National University, Vladimirskaya ul. 64, Kiev, 01033 Ukraine ^e-mail: [email protected] bInstitute of Organic Chemistry, National Academy of Sciences of Ukraine, ul. Murmanskaya 5, Kiev, 02094 Ukraine cInstitute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia Submitted May 23, 2006; accepted for publication August 30, 2006
Abstract—Electrical and photoconductive properties of polymeric composites doped with heteropolynuclear Cu(II)/Mn(II) complex were studied in comparison with copper acetate and manganese oxalate. In the visible region, the internal photoelectric effect is enhanced by doping with organic polymethine dyes (capable of photogenerating the holes or electrons), as well as with donors or acceptors that provide carrier transport in a neutral polymeric binder. It was assumed that there are states for carrier recombination on the surface of heteropolynuclear complex particles. PACS numbers: 79.60.Fr, 72.40.+w, 42.70.Jk, 73.61.Ph, 78.65.Kn DOI: 10.1134/S1063782607060048
1. INTRODUCTION Photosensitive magnetic media seem promising for data recording and reproducing. Among such media are polymeric composite films with small-size particles of transition metals whose magnetic properties can be varied under exposure to light [1–11]. Light absorption in such particles should cause electrical recharging of metal ions, which results in changes in the magnetic characteristics of the medium as a whole. One indication of a change in the charge state is the appearance of the internal photoelectric effect in the photoconductive properties of polymeric composites [12, 13]. The photoconductivity can be enhanced by special additives of various types, capable of absorbing light and transferring electrons between additive and complex particles, e.g., organic dyes [14]. For example, to provide photoconductivity in the visible region of polymeric-composite films with added Fe2O3, CdS, and ZnO nanoparticles sensitive to exposure to an external magnetic field, organic compounds with intramolecular charge transfer (ICTCs) can be used [15, 16]. ICTC molecules absorb light in the visible region, are electrically neutral, contain donor and acceptor fragments in their structure, and are capable of photogenerating both holes and electrons in polymeric-composite films [14, 17, 18]. Along with ICTCs, organic dyes with more intense light absorption, but having the ionic structure of molecules, can be used [14, 19]. In the latter case, cationic organic dyes in polymeric-composite films with organic donors and acceptors provide photo-
generation of holes, while anionic dyes provide photogeneration of electro
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