The doping effects on optical and electrical properties of polysilanes have been investigated by in-situ Measurement. An optical absorption associated with σ–σ* transition was observed near 330 nm for polymethylphenylsilane. By iodine doping, a new absorption was observed at the longer wavelength around 420 nm, which should originate from the charge transfer between dopant and Σ-conjugated system. Similar spectral changes have also been observed for most of investigated linear polysilanes.
Furthermore, we have found drastic spectral change upon iodine doping into polysilane with p-N,N-dimethyIaminophenyI substituent. It has very strong absorption up to 700 nm. It Might originate from a strong interaction between the substituent and iodine. At the same time, Σ-conjugation Might also play a significant role on doping into this system.