Synthesis of π-Conjugated Oligomers Containing Dithienosilole Units

π-Conjugated oligomers having a dithienosilole unit(s) in the backbone were prepared, and their optical
properties were examined. Their UV−vis absorption spectra and the emission spectra display maxima at
395−498 nm and at 498−576 nm, respectively, which are at longer wavelength than the oligomers that
do not contain silole units with the same π-conjugated chain length. This clearly demonstrates the influence
of silole segments in enhancing the conjugation in the oligomer backbone. The crystal structure of a
bi(dithienosilole) derivative was determined by X-ray crystallographic analysis, showing high coplanarity
of the two dithienosilole rings. One of the present dithienosilole-containing oligomers was found to be
FET active in its vapor-deposited film as well as spin-coated film with a hole mobility of μ = 2.6 ×
10-5 cm2/V s and μ = 1.2 × 10-7 cm2/V s, respectively.