C. Daniel Frisbie Group
Chemical Engineering & Materials Science
University of Minnesota - Twin Cities 		Films & Interfaces,
Molecular Crystals,
Molecular Electronics,
Organic Semiconductors,
Scanning Probe Microscopy

Seongho_Choi Seongho Choi
Korea University - Seoul; 1999
B.S. Chemistry
 Korea University - Seoul; 2001
M.S. Organic Chemistry
 Email: choix128@umn.edu

Study of the Electrical Transport in Conjugated Oligoimine Wires up to 5 nm in Length

Electrical transport issues in molecular wires are of great interest for their intrinsic importance to potential single-molecule electronic, thin-film electronic, and optoelectronics applications. In particular, length dependence studies in molecular wire systems provide guidelines to interpret the transport mechanism. Recently, theoretical investigations have shown that the non-resonant tunneling mechanism eventually turns to hopping at a critical molecular length. Thus, my research will be focused on four conjugated oligoimine wires up to 5 nm in length in order to verify the theoretical predictions. In addition, I will examine electrical transport in the hopping regime in order to strengthen the fundamental background of charge transport in organic films. The proposed wires will be synthesized via the step-wise growth approach. Wires composed of as many as 7 layers can be grown after benzenedicarboxaldehyde or phenylenediamine is added alternatively on the four different accomplished self-assembled monolayers (SAMs). SAMs will be built by the adsorption of 4-Aminothiophenol (ATP), (4-Amino)phenylmethanethiol (APmT), 4-Mercaptobenzaldehyde (MBA), and 4-Mercaptomethylbenzaldehyde (MmBA) on flat gold.

This research will be achieved by measuring I-V characteristics with conducting probe - atomic force microscopy (CP-AFM). Monolayers will be characterized by attenuated total internal reflection (ATR) FTIR, ellipsometry, and X-ray photoelectron spectroscopy (XPS). Electronic states in the films will be defined by UV photoelectron spectroscopy (UPS).

Publication/Patent List

“Electrical Resistance of Long Conjugated Molecular Wires.” Choi, Seong Ho; Kim, BongSoo; Frisbie, C. Daniel Science 2008, 320, 1482-1486.

“Synthesis and Luminescence Properties of Four-armed Conjugated Structures Containing 1,3,4-Oxadiazole Moieties.” Cha, Soon Wook; Choi, Seong Ho; Kim, Kyungkon; Jin, Jung-Il. J. Mat. Chem. 2003, 13, 1900-1904.

“Photoluminescence and Electroluminescence Properties of Poly(9-vinylcarbazole) Doped with Anthracene Derivatives Containing Bis(ethynylphenyloxadiazole) or Bis(vinylphenyloxadiazole) Substituents.” Nam, Nguyen Phuong Hoai; Cha, Soon Wook; Kim, BongSoo; Choi, Seong Ho; Choi, Don Soo; Jin, Jung-Il. Synthetic Met. 2002, 130, 271-277.

“Hyperbranched Thermotropic Liquid Crystalline Polyesters Composed of Aromatic Ester Type Mesogens and Polymethylene Spacers.” Choi, Seong Ho; Lee, Nam-Heui; Cha, Soon Wook; Jin, Jung-Il. Macromolecules 2001, 34, 2138-2147.

“Manufacturing Method of a Stamping Foil.” Choi, Seong Ho; Yoon, Kyung Keun; Park, Jong Min; Park, Ho Jin. International Patent No. WO 2004/033201 A1. Rights owned by KOLON Industries INC., April 22, 2004.

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