Screening semiconducting polymers to discover design principles for tuning charge carrier mobility

We employ a rapid method for computing the electronic structure and orbital localization characteristics for a sample of 36 different polymer backbone structures. This relatively large sample derived from recent literature is used to identify the features of the monomer sequence that lead to greater charge delocalization and, potentially, greater charge mobility. Two characteristics contributing in equal measure to large localization length are the reduced variation of the coupling between adjacent monomers due to conformational fluctuations and the presence of just two monomers in the structural repeating units. For such polymers a greater mismatch between the HOMO orbitals of the fragments and, surprisingly, a smaller coupling between them is shown to favour greater delocalization of the orbitals. The underlying physical reasons for such observations are discussed and explicit and constructive design rules are proposed.

Automated summary

In this study, we use a rapid method to calculate the electronic structure and orbital localization characteristics for 36 different polymer backbone structures. The results show that the reduced variation of coupling between adjacent monomers due to conformational fluctuations and the presence of just two monomers in the structural repeating units are equally important for achieving a large localization length. Surprisingly, a greater mismatch between the HOMO orbitals of fragments and a smaller coupling between them favor greater delocalization of the orbitals. The underlying physical reasons for these observations are discussed, and explicit and constructive design rules are proposed.