Synthesis and Properties of Novel Dithienothiasiline Derivatives

Dithienothiasiline (DTTS), in which two thiophene rings are linked by sulfur and silicon
atoms at the α,α‘- and β,β‘-positions of the thiophenes, respectively, was prepared. From
the results of optical and electrochemical experiments, it was found that the band gap and
HOMO energy level became larger and lower, respectively, as the bridging sulfur atom of
DTTS was oxidized step-by-step by mCPBA (m-chloroperoxybenzoic acid). DTTSs substituted
with trimethylsilyl, methylthio, and thienyl groups at α,α‘-positions and a polymer containing
DTTS and a sulfur atom as repeating components were prepared, and their electronic and
electrochemical properties were investigated. When DTTSs and poly(DTTS sulfide) were
introduced as hole-transporting materials in EL devices with the structure of ITO/DTTS or
polymer/Alq3/Mg−Ag, the maximum luminance of 4280 cd/m2 derived from an Alq3 emission
was achieved. A film of poly(DTTS sulfide) became conducting upon doping with FeCl3 with
a conductivity of 1.6 × 10-3 S/cm.