Field-effect bulk mobilities in polymer semiconductor films measured by sourcemeters

Semiconducting polymers inherently exhibit polydispersity in terms of molecular structure and microscopic morphology, which often results in a broad distribution of energy levels for localized electronic states. Therefore, the bulk charge mobility strongly depends on the free charge density. In this study, we propose a method to measure the charge-density-dependent bulk mobility of conjugated polymer films with widely spread localized states using a conventional field-effect transistor configuration. The gate-induced variation of bulk charge density typically ranges within +/- 10(18) cm(-3); however, this range depends significantly on the energetic dispersion width of localized states. The field-effect bulk mobility and field-effect mobility near the semiconductor-dielectric interface along with their dependence on charge density can be simultaneously extracted from the transistor characteristics using various gate voltage ranges.

Automated summary

Semiconducting polymers have a broad distribution of energy levels due to their polydispersity, resulting in charge density-dependent bulk mobility. This study proposes a method to measure the charge-density-dependent bulk mobility of conjugated polymer films using a field-effect transistor configuration. The gate-induced variation of bulk charge density ranges within +/- 10(18) cm(-3), depending on the energetic dispersion width of localized states. The field-effect bulk mobility and field-effect mobility near the semiconductor-dielectric interface can be simultaneously obtained from transistor characteristics using different gate voltage ranges.