Effect of Si-skeleton dimensionality on optical and electrical properties of poly(methylpenylsilylene) and poly(phenylsilyne)

A comparative study of the optical and electrical properties of poly(methylphenylsilylene) and poly(phenylsilyne) was carried out. Poly(phenylsilyne), which has a Si-network structure, showed a broad absorption band extending to 420 nm, while poly(methylphenylsilylene) with a linear Si skeleton showed a sharp σ-σ∗ absorption band at 334 nm. The broad emission spectrum and the low fluorescence quantum yield of poly(phenylsilyne) suggest a distribution of trapping sites in the Si skeleton. The network poly(phenylsilyne) did not show an improvement in electric conductivity because of the carrier trapping at the sites. Molecular weight measurements on poly(methylphenylsilylene) after iodine doping showed that cleavage of SiSi bonds occurs with extensive doping.