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Giant Photoconductivity in NMQ[Ni(dmit) 2 ]
Author(s) -
Naito Toshio,
Karasudani Tomoaki,
Nagayama Naoki,
Ohara Keishi,
Konishi Kensuke,
Mori Shigeki,
Takano Takahiro,
Takahashi Yukihiro,
Inabe Tamotsu,
Kinose Shota,
Nishihara Sadafumi,
Inoue Katsuya
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201402035
Subject(s) - chemistry , photoconductivity , irradiation , analytical chemistry (journal) , activation energy , nickel , spectral line , x ray photoelectron spectroscopy , diamagnetism , nuclear magnetic resonance , materials science , optoelectronics , physics , organic chemistry , chromatography , astronomy , quantum mechanics , magnetic field , nuclear physics
The simple molecular salt NMQ[Ni(dmit) 2 ] (NMQ = N ‐methylquinolinium, dmit = 1,3‐dithiol‐2‐thione‐4,5‐dithiolate) functions as a diamagnetic insulator with an activation energy E a (dark) of 0.20 eV. However, at 300 K, it exhibits ca. 40 times higher conductivity ( σ UV ) under UV irradiation [(375 ± 5) nm, 15.7 mW cm –2 ] than it does under dark conditions ( σ dark ). The ratio σ UV / σ dark rapidly increases with decreasing temperature and reaches ca. 880 at 200 K. From the temperature dependence of σ UV , the activation energy under irradiation E a (UV) is 0.12 eV. These observations cannot be explained as the result of sample heating during UV irradiation. Rather, the X‐ray photoelectron spectra of the sulfur and nickel atoms, the calculated band structure, and the UV/Vis spectra of the salt can all be explained consistently as follows: charge transfer between the Ni(dmit) 2 moieties upon exposure to 375 nm UV light induces melting of the charge‐ordered state and produces the unusually large photoconductivity of NMQ[Ni(dmit) 2 ].