TY - JOUR
T1 - Fabrication and characterization of size-controlled CuTCNQ charge-transfer complex nanocrystals
AU - Hiraishi, Kentaro
AU - Masuhara, Akito
AU - Yokoyama, Takahiro
AU - Kasai, Hitoshi
AU - Nakanishi, Hachiro
AU - Oikawa, Hidetoshi
PY - 2009/1/15
Y1 - 2009/1/15
N2 - We report the selective fabrication of phase I CuTCNQ (TCNQ=7,7′,8,8′-tetracyanoquinodimethane) nanocrystals (NCs) in the size range from 20 nm to several μm. The NCs were fabricated by chemical reduction and/or cation exchange reprecipitation methods. Scanning electron microscopy, transmission electron microscopy and powder X-ray diffraction provide evidence that the CuTCNQ NCs have the phase I structure, with crystal growth along the [1 0 0] direction. Phase I is characterized by high electric conductivity and switching behavior. Powder X-ray diffraction patterns, Fourier transform infrared spectra and Raman spectra of the CuTCNQ NCs are the same as those of bulk crystals, regardless of NC size and fabrication method. The absorption around the near infrared region increases with increasing crystal size, due to inter-band transition. The size effect is discussed in relation to band structure (e.g., band gap and density of states) and lattice softening as a function of crystal size. This interesting phenomenon is important for novel electronic device applications.
AB - We report the selective fabrication of phase I CuTCNQ (TCNQ=7,7′,8,8′-tetracyanoquinodimethane) nanocrystals (NCs) in the size range from 20 nm to several μm. The NCs were fabricated by chemical reduction and/or cation exchange reprecipitation methods. Scanning electron microscopy, transmission electron microscopy and powder X-ray diffraction provide evidence that the CuTCNQ NCs have the phase I structure, with crystal growth along the [1 0 0] direction. Phase I is characterized by high electric conductivity and switching behavior. Powder X-ray diffraction patterns, Fourier transform infrared spectra and Raman spectra of the CuTCNQ NCs are the same as those of bulk crystals, regardless of NC size and fabrication method. The absorption around the near infrared region increases with increasing crystal size, due to inter-band transition. The size effect is discussed in relation to band structure (e.g., band gap and density of states) and lattice softening as a function of crystal size. This interesting phenomenon is important for novel electronic device applications.
KW - B1. Charge-transfer complexes
KW - B1. Nanomaterials
KW - B2. Semiconducting materials
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U2 - 10.1016/j.jcrysgro.2008.09.158
DO - 10.1016/j.jcrysgro.2008.09.158
M3 - Article
AN - SCOPUS:59749101812
VL - 311
SP - 948
EP - 952
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
IS - 3
ER -