Toward ultralow-bandgap liquid crystalline semiconductors: use of triply fused metalloporphyrin trimer-pentamer as extra-large π-extended mesogenic motifs.
In contrast with their dimeric homologue, triply fused zinc porphyrin trimer-pentamer, as extra-large π-extended mesogens, assemble into columnar liquid crystals (LCs) when combined with 3,4,5-tri(dodecyloxy)phenyl side groups (3 P(Zn) -5 P(Zn) , Figure 1). Their LC mesophases develop over a wide temperature range, namely, 41-280 °C (on heating) for 5 P(Zn) , and all adopt an oblique columnar geometry, typically seen in columnar LC materials involving strong mesogenic interactions. These LC materials are characterized by their wide light-absorption windows from the entire visible region up to a near infrared (NIR) region. Such ultralow-bandgap LC materials are chemically stable and serve as hole transporters, in which 5 P(Zn)  gives the largest charge carrier mobility (2.4×10(-2)  cm V(-1)  s(-1) ) among the series. Despite a big dimensional difference, they coassemble without phase separation, in which the resultant LC materials display essentially no deterioration of the intrinsic conducting properties.
Department of Chemistry and Biotechnology, School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
Seiya
S
Tanaka
Tsuneaki
T
Sakurai
Yoshihito
Y
Honsho
Akinori
A
Saeki
Shu
S
Seki
Kenichi
K
Kato
Masaki
M
Takata
Atsuhiro
A
Osuka
Takuzo
T
Aida