Amphiphilic molecular design as a rational strategy for tailoring bicontinuous electron donor and acceptor arrays: photoconductive liquid crystalline oligothiophene--C60 dyads.
For tailoring solution-processable optoelectronic thin films, a rational strategy with amphiphilic molecular design is proposed. A donor-acceptor dyad consisting of an oligothiophene and C60, when modified with a hydrophilic wedge on one side and a paraffinic wedge on the other (1Amphi), forms over a wide temperature range a photoconducting smectic A liquid crystal having bicontinuous arrays of densely packed donor and acceptor units. In contrast, when modified with only paraffinic wedges (1Lipo), the dyad forms a smectic A liquid crystalline mesophase, which however is poorly conductive. As indicated by an absorption spectral feature along with a synchrotron radiation small-angle X-ray scattering profile, 1Lipo in the lamellar structure does not adopt a uniform head/tail orientation. Such defective donor and acceptor arrays likely contain a large number of trapping sites, leading to short-lived charge carriers, as observed by a flash photolysis time-resolved microwave conductivity study.
ERATO-SORST Nanospace Project, Japan Science and Technology Agency (JST), National Museum of Emerging Science and Innovation, 2-41 Aomi, Koto-ku, Tokyo 135-0064, Japan. li@nanospace.miraikan.jst.go.jp
Wei-Shi
WS
Li
Yohei
Y
Yamamoto
Takanori
T
Fukushima
Akinori
A
Saeki
Shu
S
Seki
Seiichi
S
Tagawa
Hiroyasu
H
Masunaga
Sono
S
Sasaki
Masaki
M
Takata
Takuzo
T
Aida
D004583:Electrons; D037741:Fullerenes / Q000737:chemistry*; D008958:Models, Molecular; D010777:Photochemistry; D017062:Small-Area Analysis; D013876:Thiophenes / Q000737:chemistry*; D014961:X-Ray Diffraction
D037741:Fullerenes; D013876:Thiophenes; C069837:fullerene C60