Hole Transport Property of α-phenyl-4'-(diphenylamino)stilbene Single Crystal Prepared Based on Solubility and Supersolubility Curves

Mitsuhiko KATAGIRI  Shofu MATSUDA  Norio NAGAYAMA  Minoru UMEDA  

IEICE TRANSACTIONS on Electronics   Vol.E102-C   No.2   pp.132-137
Publication Date: 2019/02/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.2018OMP0006
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Organic Molecular Electronics and Biotechnology)
triphenylamine derivative,  single crystal,  anisotropic conductivity,  activation energy,  

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We describe the preparation of an α-phenyl-4'-(diphenylamino)stilbene (TPA) single crystal and the evaluation of its hole transport property. Based on the characterization using optical microscopy, polarizing microscopy, and X-ray diffraction, a large-scale TPA single crystal of dimensions 7.0×0.9×0.8mm is successfully synthesized using a solution method based on the solubility and supersolubility curves of the TPA. Notably, the current in the long-axis direction is larger than those in the short-axis and thickness directions (i(long) > i(short) > i(thickness)), which reveals the anisotropic charge transfer of the TPA single crystal. The observed anisotropic conductivity is well explained by the orientation of the triphenylamine unit in the TPA single crystal. Furthermore, the activation energy of the long-axis direction in the TPA single crystal is lower than that of the short-axis in TPA and all the axes in the α-phenyl-4'-[bis(4-methylphenyl)amino]stilbene single crystal reported in our previous study.