Method for fast estimation of lattice distortion energy in organic semiconductors

The efficient operation of organic electronic devices requires a high mobility of charge carriers in their active layers. According to modern concepts, the charge mobility in the best organic semiconductors is limited by dynamic disorder, i.e., fluctuations of intermolecular charge transfer integrals caused by the nonlocal electron-phonon coupling and thermal motion of molecules. However, the estimate of nonlocal electron-phonon coupling currently requires time- and resource-consuming methods, which complicates the search for high-mobility organic semiconductors among numerous candidates. In this work, a method has been proposed to rapidly estimate the lattice distortion energy, which is the main characteristic of the nonlocal electron-phonon coupling, by comparing the reorganization energies of molecules and molecular dimers. The determined lattice distortion energies are in good agreement with the values previously obtained by other methods. Furthermore, the proposed method has allowed addressing the effect of intermolecular delocalization on the nonlocal electron-phonon coupling. The results obtained indicate that the proposed approach is promising for the efficient search for organic semiconductors with a weak nonlocal electron-phonon coupling and a high charge mobility.