Two-dimensional electronic and charge-transport properties of a monolayer organic crystal: Impacts of the collinear transfer-integral correlations

Electronic transfer integrals between the frontier orbitals of adjacent molecules represent the most important parameter governing charge transport in organic crystals. Different transfer integrals may be significantly modulated by the same modes of molecular vibrations as a result of nonlocal electron-phonon couplings, leading to spatial correlations between the transfer integrals. Here, by employing a multiscale modeling approach, we investigate theoretically the impacts of transfer-integral correlations (TICs) on the two-dimensional electronic and charge-transport properties of a monolayer pentacene crystal. In particular, we focus on the collinear TICs that are present between molecular pairs along the same direction of molecular packings in the crystal. We reveal that the interplay of the collinear TICs along different directions leads to diverse landscapes of nonlocal electron-phonon couplings in reciprocal space, of which the impacts explicitly manifest themselves in the band structures at finite temperatures. We also evaluate the anisotropic hole mobility of the pentacene monolayer and demonstrate that the consequence of the collinear TICs can be reflected in the behaviors of the temperature-dependent band-like mobility observed in experiment. These findings provide an insight into how nonlocal electron-phonon couplings operate through TICs to impact the electronic and electrical properties of organic crystals in two dimension.