Theoretical study of polaron binding energy in conformationally disrupted oligosilanes

Abstract

Density functional theory was used for a quantum chemical study of oligo[methyl(phenyl)silylene] structures containing a conformational defect: a kink in the silicon backbone. Oligomers were studied in the neutral state as well as in the form of positive (P(+)) and negative (P(-)) polaron quasiparticles. Computations performed using the B3LYP model and the 6-31G(d) basis set revealed that the charge distribution is not influenced by the presence of the kink, but the positive charge on the Si backbone differs slightly in P(+) and P(-) quasiparticles. On the other hand, the spin density is significantly shifted away from the chain part that contains the kink, and this effect is more intense in P(-) polarons. Changes in electron density are also evident from the frontier molecular orbital distribution. The deformation energy (which is associated with the relaxation of polarons) decreases with the number of atoms in the oligomer backbone in P(+) but shows the opposite behavior for P(-) quasiparticles.

Effect of backbone conformation and its defects on electronic properties and assessment of the stabilizing role of π–π interactions in aryl substituted polysilylenes studied by DFT on deca[methyl(phenyl)silylene]s

“…Another cause that is responsible for a rearrangement of the oligosilylene molecule can be identified as a charge carrier in its vicinity. From this reason, we have also investigated polaron quasiparticles of OMPSi n with the introduced kink [ 21 ]. In that research, a significant change has emerged in a dependence of the spin density on the conformation of a backbone and its shift to more regular part of a Si–Si chain, i.e.…”