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Probing the Anisotropic Field‐Effect Mobility of Solution‐Deposited Dicyclohexyl‐α‐quaterthiophene Single Crystals
Author(s) -
Mannsfeld S. C. B.,
Locklin J.,
Reese C.,
E. Roberts M.,
Lovinger A. J.,
Bao Z.
Publication year - 2007
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.200600865
Subject(s) - materials science , anisotropy , single crystal , electron mobility , field effect transistor , organic semiconductor , field effect , crystal (programming language) , condensed matter physics , chemical physics , transistor , crystallography , optoelectronics , optics , voltage , chemistry , programming language , physics , quantum mechanics , computer science
Measuring the anisotropy of the field‐effect mobility provides insight into the correlation between molecular packing and charge transport in organic semiconductor materials. Single‐crystal field‐effect transistors are ideal tools to study intrinsic charge transport because of their high crystalline order and chemical purity. The anisotropy of the field effect mobility in organic single crystals has previously been studied by lamination of macroscopically large single crystals onto device substrates. Here, a technique is presented that allows probing of the mobility anisotropy even though only small crystals are available. Crystals of a soluble oligothiophene derivative are grown in bromobenzene and drop‐cast onto substrates containing arrays of bottom‐contact gold electrodes. Mobility anisotropy curves are recorded by measuring numerous single crystal transistor devices. Surprisingly, two mobility maxima occur at azimuths corresponding to both axes of the rectangular cyclohexyl‐substituted quaterthiophene (CH4T) in‐plane unit cell, in contrast to the expected tensorial behavior of the field effect mobility.