Charge Carrier Doping in the Ni(dmit)2 Simple Salts by Hydrogen-Bonding Pyridinium Cations (dmit=1,3-dithiol-2thione-4,5-dithiolate)
✍ Scribed by Takeshi Hirose; Hiroyuki Imai; Toshio Naito; Tamotsu Inabe
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 417 KB
- Volume
- 168
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Three kinds of the 1:1 Ni(dmit) 2 salts with 4-(4-pyridyl)pyridinium (PP), 4-[2-(4-pyridyl)ethenyl]pyridinium (P]P), and 4-[2-(4-pyridyl)ethyl]pyridinium (P-P) cations have been prepared and structurally characterized. All of these crystals are composed of a multi-dimensional network of the Ni(dmit) 2 anions and the hydrogen-bonding one-dimensional cation chains. Compared with tight hydrogen bonds in the P]P and P-P chains, that in the PP chain is rather loose. The P]P and P-P salts show semiconducting behavior with high resistivity and large activation energy, while the PP salt shows the opposite temperature dependence with low resistivity at high temperature. The thermoelectric power indicates that the PP salt is an n-doped semiconductor. The proton defects may occur in the loosely bound PP chain which results in the carrier doping in the conduction band formed by the p-p interaction of the Ni(dmit) 2 anion radicals.