The energy band structures of silicon containing polymers with unsatur
ated bonds such as polysilene (PS), polysemisilene (PSS), polysilacene
(PSA) and polysemisilacene (PSSA) have been calculated on the basis o
f ab initio crystal orbital method using double-zeta basis set. All th
e silicon containing polymers are found to be less insulating than tra
ns-polyacetylene. The calculated trend in the band gap values is PSA <
PS < PSSA < PSS. Our results predict PS to be the strongest candidate
for p-doping whereas PSA is predicted to have the greatest capacity f
or n-doping.