Stability in polysilanes for light emitting diodes

Theoretical investigations to determine the stability among different polysilanes have been attempted. Semiempirical (AM1) and ab initio calculations at Hartree Fock (HF)/3–21g* level have been performed for four polymers namely poly(di-n-butylsilane) (PDBS), poly(di-n-hexylsilane) (PDHS), poly(methylphenylsilane) (PMPS) and poly[bis(p-butylphenyl)silane] (PBPS) that have been reported as candidates for light emitting diodes. Configuration interaction (single excitation) has been carried out to predict the stability of the excited states of polysilanes. Based on the ab initio calculations, we are proposing a possibility of stabilization of PBPS and PMPS by intersystem crossing from S1 to T1 excited state, which in turn leads to higher stability of these two polymers.