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Thiophene–Benzothiadiazole Co‐Oligomers: Synthesis, Optoelectronic Properties, Electrical Characterization, and Thin‐Film Patterning
Author(s) -
Melucci Manuela,
Favaretto Laura,
Zanelli Alberto,
Cavallini Massimiliano,
Bongini Alessandro,
Maccagnani Piera,
Ostoja Paolo,
Derue Gwennaelle,
Lazzaroni Roberto,
Barbarella Giovanna
Publication year - 2010
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200901424
Subject(s) - materials science , thiophene , alkyl , amorphous solid , thin film , electrochemistry , characterization (materials science) , homo/lumo , crystallography , optoelectronics , nanotechnology , molecule , electrode , organic chemistry , chemistry
Newly synthesized thiophene (T) and benzothiadiazole (B) co‐oligomers of different size, alternation motifs, and alkyl substitution types are reported. Combined spectroscopic data, electrochemical analysis, and theoretical calculations show that the insertion of a single electron‐deficient B unit into the aromatic backbone strongly affects the LUMO energy level. The insertion of additional B units has only a minor effect on the electronic properties. Cast films of oligomers with two alternated B rings (B–T–B inner core) display crystalline order. Bottom‐contact FETs based on films cast on bare SiO 2 show hole‐charge mobilities of 1 × 10 −3 –5 × 10 −3 cm 2 V −1 s −1 and I on /I off ratios of 10 5 –10 6 . Solution‐cast films of cyclohexyl‐substituted compounds are amorphous and do not show FET behavior. However, the lack of order observed in these films can be overcome by nanorubbing and unconventional wet lithography, which allow for fine control of structural order in thin deposits.