17 Azulene-Based Materials for Organic Field-Effect Transistors
347
Fig. 17.5 Crystal packing structures of a DAzBT and b DAzTT. Reproduced from Ref. [24] with
permission. Copyright 2012 American Chemical Society
(DAzBT) and −5.45 eV (DAzTT) were found, and high atmospheric stabilities were
observed. Increases in the HOMO energy of azulene are suppressed by bonding at
the 2-position, which lies on the nodal plane of the HOMO of azulene.
17.3.4 OFET Properties and Thin-Film Structures of DAzBT
and DAzTT
Top-contact-type FET devices were fabricated using thin films of DAzBT and DAzTT
prepared by the vacuum-evaporation method, and their OFET characteristics were
evaluated. These devices exhibited FET properties typical of p-type semiconductors,
with carrier mobilities of 2.4 × 10
−2 cm
2 /Vs (DAzBT) and 5.0 × 10
−2 cm
2 /Vs
(DAzTT). DAzTT exhibited excellent carrier-transport behavior, and the superior
properties of DAzTT are consistent with its crystal structure. These results are
comparable to, or better than, similar end-capped compounds, such as naphthalene,
phenanthrene, and naphthothiophene derivatives.
Thin-film X-ray diffraction analysis revealed the formation of two-dimensional
conductive planes on the substrate surfaces through end-on molecular orientations
on the substrate (Fig. 17.6).
347
Fig. 17.5 Crystal packing structures of a DAzBT and b DAzTT. Reproduced from Ref. [24] with
permission. Copyright 2012 American Chemical Society
(DAzBT) and −5.45 eV (DAzTT) were found, and high atmospheric stabilities were
observed. Increases in the HOMO energy of azulene are suppressed by bonding at
the 2-position, which lies on the nodal plane of the HOMO of azulene.
17.3.4 OFET Properties and Thin-Film Structures of DAzBT
and DAzTT
Top-contact-type FET devices were fabricated using thin films of DAzBT and DAzTT
prepared by the vacuum-evaporation method, and their OFET characteristics were
evaluated. These devices exhibited FET properties typical of p-type semiconductors,
with carrier mobilities of 2.4 × 10
−2 cm
2 /Vs (DAzBT) and 5.0 × 10
−2 cm
2 /Vs
(DAzTT). DAzTT exhibited excellent carrier-transport behavior, and the superior
properties of DAzTT are consistent with its crystal structure. These results are
comparable to, or better than, similar end-capped compounds, such as naphthalene,
phenanthrene, and naphthothiophene derivatives.
Thin-film X-ray diffraction analysis revealed the formation of two-dimensional
conductive planes on the substrate surfaces through end-on molecular orientations
on the substrate (Fig. 17.6).