Modeling electron mobility in organic optoelectronic materials

Subject of study. The study focuses on organic optoelectronic materials with complex molecular structures, as well as their intermolecular and interatomic interactions. Aim of study. The aim of this study was to develop models of intermolecular and interatomic interactions that could express the energy components of organic molecules and their spatial distributions in such materials. Method. The method involved determining the contributions of different fragments of the molecules constituting such organic optoelectronic materials to charge mobility using a diffusion model based on a delocalized polaron. A second method based on the interatomic potential approach was developed to determine the molecular energy and its spatial distribution. Main results. Primarily, the contributions of the structural fragments to the interactions between molecules, as well as the variations in these contributions, have been calculated. Within the operating temperature range, the static component of the standard deviation of the molecular energy in the lattice predominates, resulting in reduced charge mobility. When the distortion energy corresponding to nonlocal electron–phonon interactions changes from 5 meV to 100 meV, the mobility decreases by a factor of 17. With changes in the orientation angles between the molecules, the intermolecular interaction energy varies from 0.1 eV to 1 eV, which is consistent with the results of the charge mobility model. Practical significance. The practical significance of the study lies in the application of the developed methods in optoelectronics, including photovoltaic cells, organic light-emitting diodes, transistors, batteries, displays, and transparent electronics.