Model ab initio study of charge carrier solvation and large polaron formation on conjugated carbon chains

TL;DR

This study uses ab initio methods to explore how charge carriers in conjugated carbon chains become self-localized into large polarons through solvation, revealing a distinct solvation-based trapping mechanism.

Contribution

It demonstrates, for the first time, the formation of large polarons in conjugated carbon chains driven solely by solvation effects using ab initio computations.

Findings

Polarons can form entirely due to solvation.

Atomic displacements enhance charge localization.

Both electron- and hole-polarons are demonstrated.

Abstract

Using long C_{N}H_{2} conjugated carbon chains with the polyynic structure as prototypical examples of one-dimensional (1D) semiconductors, we discuss self-localization of excess charge carriers into 1D large polarons in the presence of the interaction with a surrounding polar solvent. The solvation mechanism of self-trapping is different from the polaron formation due to coupling with bond-length modulations of the underlying atomic lattice well-known in conjugated polymers. Model ab initio computations employing the hybrid B3LYP density functional in conjunction with the polarizable continuum model are carried out demonstrating the formation of both electron- and hole-polarons. Polarons can emerge entirely due to solvation but even larger degrees of charge localization occur when accompanied by atomic displacements.