Analysis of Charge Transport in Polymer: Non-Fullerene Blend: Evidence for the Absence of Correlated Disorder

Abstract

Recently, rapid development of non-fullerene acceptors has attracted considerable attention to theirs charge transport. In this paper, charge transport and spatial correlations between the site energies in the blend of polymer PBDB-T derivative PM6 and non-fullerene acceptor Y6 are investigated. From an analysis of the temperature dependence of current density-voltage (J – V ) characteristics of hole-only and electron-only devices based on PM6:Y6 blend, it is found that consistent descriptions with equal quality are obtained using both the improved extended Gaussian disorder model (IEGDM) and the extended correlated disorder model (ECDM), within which spatial correlations between the transport site energies are absent and are included, respectively. By comparing model parameters with the typical values of organic materials, we view more realistic intersite distance obtained using the IEGDM compared to the value obtained using the ECDM as an indication that in PM6:Y6 blend correlations between the transport site energies are absent or play a minor role. Furthermore, it is found that energetic disorder is larger for hole than for electron in PM6:Y6 blend, and electron transport is intrinsically superior to hole transport.