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Synthesis and Transistor Properties of Asymmetric Oligothiophenes: Relationship between Molecular Structure and Device Performance
Author(s) -
An Tae Kyu,
Jang Sang Hun,
Kim SeulOng,
Jang Jaeyoung,
Hwang Jihun,
Cha Hyojung,
Noh Young Ri,
Yoon Soon Byung,
Yoon Yong Jin,
Kim Lae Ho,
Chung Dae Sung,
Kwon SoonKi,
Kim YunHi,
Lee SangGyeong,
Park Chan Eon
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201302588
Subject(s) - terthiophene , alkyl , oligomer , thiophene , materials science , suzuki reaction , transistor , crystallography , absorption (acoustics) , solubility , chemistry , polymer chemistry , organic chemistry , aryl , quantum mechanics , voltage , composite material , physics
A series of three thiophene–naphthalene‐based asymmetric oligomers—5‐decyl‐2,2′:5′,2′′:5′′,2′′′‐quaterthiophene (DtT), 5‐decyl‐5′′‐(naphthalen‐2‐yl)‐2,2′:5′,2′′‐terthiophene (D3TN), and 5‐(4‐decylphenyl)‐5′‐(naphthalen‐2‐yl)‐2,2′‐bithiophene (DP2TN)—was synthesized by Suzuki cross‐coupling reactions. The long alkyl side chains improved both the solubility of the oligomers in solvents and their tendency to self‐assemble. UV/Vis absorption measurements suggested that DtT, D3TN, and DP2TN form H‐type aggregates with a face‐to‐face packing structure. In addition, the three oligomers were found to adopt vertically aligned crystalline structures in films deposited on substrates, as revealed by grazing‐incidence wide‐angle X‐ray scattering. These oligomers were used as the active layers of p‐type organic field‐effect transistors, and the resulting devices showed field‐effect mobilities of 3.3×10 −3 cm 2 V −1 s −1 for DtT, 1.6×10 −2 cm 2 V −1 s −1 for D3TN, and 3.7×10 −2 cm 2 V −1 s −1 for DP2TN. The differences in transistor performances were attributed to the degree of π overlap and the morphological differences determined by the molecular structures.