Charge-transfer materials

Solid State Properties. Perhaps as a result of the limited intermolecular interactions of these complexes in the solid state, they exhibit few solid-state properties of interest. The dianionic 7a did successfully produce a charge transfer material by mixing it with a solution of the tetrathiafulvalene-based salt (TTF)3(BF4)2. Elemental analysis of the resulting black product gave the formula (TTF)4[7a]3 and the material exhibited a conductivity of 9 x 10 S... 

M. R. Bryce and M. C. Petty, Electrically conductive Langmuir-Blodgett films of charge-transfer materials, Nature 374,771-776 (1995). 

Since the end of the seventies, interest in cyclotriveratrylene has moved towards the use of its cone shaped structure for applications in various fields, including investigations of the electronic transitions of the benzene chromophore via UV and CD spectroscopy, studies in the area of host-guest chemistry, synthesis of new types of liquid crystals, and searches for new three-dimensional organic charge-transfer materials. These works have been made possible because efficient synthetic... 

As mentioned at the beginning of Section III, the conducting properties of organic charge-transfer materials are critically dependent on (1) their stoichiometry (i.e., the number of donor to acceptor molecules), and (2) the degree of charge transfer p per acceptor molecule. In particular, as a result of inherently strong Coulomb repulsions, all 1 1 TCNQ salts with complete ionization, or p = 1, are insulators [45]. 

Although fatty acids and their salts are the classical materials for LB him formation, much activity has focused on the incorporation of electroactive groups into such long-chain compounds. Some examples are depicted in Figure 4. Charge-transfer materials, such as the Af-octadecylpyridinium-Ni(dmit)2 complex, are important organic conductors. These are formed from a variety of molecules, primarily aromatics that can behave as electron donors (D) and electron acceptors (A) [8]. Complete transfer of an electron from a donor to an acceptor molecule results in a system that is electrically insulating (e.g., the transfer of a valence electron in a Cl atom to a Na atom to form the compound NaCl). However, if the ratio of the number of donor molecules to the number of acceptor molecules differs from 1 1 (e.g., the stoichiometry is 1 2 or... 

Bryce. M.R. Tetrathiafulvalenes as n-electron donors for intramolecular charge-transfer materials. Adv. Mater. 1999, 11 (1), 11-23. 

The application of organic CTMs in photovoltaic devices is a new research field, which still is in its infancy. Figure 2 overviews the organic charge transfer materials that were scrutinized with regard to their application in solid-state dye-sensitized solar cells. A much wider range of materials is mentioned in the patent literature [13-15]. 

An advancement in efficiency of polymeric solar cells, from 3 to 5%, came in 2009 when it was observed that promising efficient charge transfer materials can be prepared from combinations of poly (alkyl-thiophenes) donors with l-(3-methoxycarbonyl)propyl-lphenyl-[6,6]-methanofullere acceptors [265]. Mild heating disperses the acceptor molecules among the donor molecules ... 

Ulman, A. "Formation and Structure of Self-Assembled Monolayers." Cbcni. Rea, 96,1533 (1996). Bryce, M. R., and Petty, M. C. "Electrically Conductive Langmuir-Blodgett Films of Charge-Transfer Materials." Nature, 374,771(1995). 

Mori, Y, Okamoto, M., Wada, X, and Sasabe, H., A new intramolecular charge transfer material for nonlinear optics piperonal derivatives, in Nonlinear Optical Properties of Polymers (MRS Symp. Proc., 109), Heeger, A. J., Orenstein, J., and Ulrich, D. R., Eds., MRS, Pittsburgh, 1988, 345. 

Charge-transfer materials based on metal-ligand charge transfer and in which metals play an important part in conductivity, such as metallo-phthalocyanines (e.g. copper or cobalt phthalocyanines) ... 

Charge-transfer materials based on donor-acceptor complexes, such as tetrathiafulvalene/tetracyanoquinodimethanide (TTF/TCNQ), once the subject of intense study as the future organic conductors, much before CPs came on the scene ... 

---