High hole mobility in the molecularly ordered oligosilanes

A single-dispersed oligosilane with a mesophase (smectic B) was utilized fo r fabricating molecularly ordered films. Their carrier transport properties were examined by the time-of-flight (TOF) transient photocurrent technique . In polycrystalline films of permethyldecasilane, molecular orientation al most parallel to bias electric field and a multi-layered structure were fou nd, possessing large domain size (>20 mu mm). This unique molecular order r esulted in non-dispersive TOF photocurrent with a clear plateau, whose hole mobility exceeded 1 x 10(-3) cm(2)/V s at 293 K, 1 x 10(5) V/cm. The high carrier mobility with small distribution can be ascribed to their well-orde red hopping sites. The unprecedented structure together with possible contr ol of hopping sites makes oligosilanes a new class of hole transport materi als. (C) 2001 Published by Elsevier Science B.V.