A comparative study of electronic properties of disordered conjugated polymers

Abstract

The comparison of hole density of states (DOS) and hole mobilities of several organic polymer based systems was performed to gain insight into the main factors that determine the electrical properties of conjugated polymers. The DOS and the mobility of the systems under investigation were evaluated using an atomistic multiscale procedure. The results suggest that the irregularities in the shape of the polymer chains increase the diagonal disorder, while alkyl side chains act as spacers that reduce the diagonal disorder which originates from long range electrostatic interactions. Intrachain electronic coupling in relatively ordered polymers narrows the tail of the DOS, while in less ordered polymers it represents the additional component of disorder and widens the tail of the DOS. The width of the DOS tail was confirmed to be an important factor that determines the activation energy for charge carrier transport. However, it is not the only factor since the system with a smaller width of the DOS tail can have a larger activation energy due to, for example, smaller wave function overlap between transport states.